Banjo

Are you replacing an existing alternator for one with a larger output capacity ? Does the existing alternator have an external, or internal regulator ? If external, is it a switching relay type or a solid state one ? Is there any external wiring already present ? This is a fairly easy modification, which requires just a few mods for charge warning light on the dash. Sorry about all the questions, but need to know, to give you the right answer. A few pics of the existing setup, would assist. Have you got a new or alternate alternator there ready to go in ? If so, take a couple of pics of it, especially the rear connection face. Cheers Banjo

Hi Hayden, Squirt some WD40 into the ignition barrel. They are a bugga to change, although it can be done. There are two conical bolts underneath, that break off when they were originally fitted, so you have to grind or cut a slot in in the "cones", so you can remove with a large screwdriver. Lets know how you go with the black wire on the +ve terminal of the ignition coil. Good luck ! P.S. Just off interest, can you list the wire colours of the five (5) wires on the back end of the ignition switch itself. I want to know if Toyota kept the same colours, in every model. Cheers Banjo.

Hi Hayden, Have you got the engine cranking over, now that you've shorted out the wires that originally went to the "Neutral" interlock switch, when the Rolla had an auto gearbox in it ? Here is the very basic setup for the starter motor. Yours and most other cars from this era were wired up like this. The only difference with your wiring, is that the auto neutral interlock switch, is depicted on the other side of the relay coil, in circuit above. I'm assuming your ignition barrel / switch is OK. I've yet to find a car manual wiring diagram, that can depict the ignition switch adequately, which indicates how it works. Lots of guys & gals get frustrated when trying to work it out. Frankly, the wiring diagrams in the back of most auto manuals are pathetic, & very hard to follow. The little black dots in the table above, indicate which outputs are connected, when the switch is in each of its four (4) positions. In the "Lock" or OFF position, there are no connections at all through the ignition switch. There is one supply wire to the ignition switch in our Rollas, which comes directly from the battery, via the "fusible link", which is usually very close to the battery itself. In my Rolla this wire is a black wire with a red stripe Black/Red. There are four (4) output wires. In the Accessory position, the Blue/Red wire is powered. This wire usually goes off to the fuse block to power accessories like radios etc. In some models, it also powers the cigarette lighter. In the Ignition position, the Black/Yellow wire is powered, as well as the Accessory wire above. The Black/Yellow wire is connected to the end of the ballast resistor, not connected to the +ve terminal of the coil. It also goes across to the other side of the engine bay to power the fuel solenoid, built into some Aisin carbies. In the Start position, all sorts of things happen. The accessories are turned off, so there are no additional loads on the battery, so all its available power can be provided to starting the engine. The Back/White wire provides power to the starter relay, which in turn provides power to the starter motor solenoid. The Black wire provides battery voltage directly to the +ve terminal of the ignition coil, effectively short circuiting the ballast resistor. This assists in starting the car, when battery volts are low, during starting on a cold morning. Despite what the guy told you, it appears from the symptoms that your car is not wired up correctly. Assuming the ignition coil that is fitted, has the correct "primary resistance" (about 3 ohms), so it can be used without a ballast resistor, you need to find the Black/Yellow wire that was originally connected to the "ballast" resistor, & then connect it to the +ve terminal of the coil. If the harness is unmolested, it should be close to the existing coil, if it is in the standard location. If you can't find it, & the carby has a fuel solenoid on it, with an electrical wire running to the carby, you could run a wire from the carby temporarily,, to the +ve terminal of the coil, & see if that solves your issue. Good luck, & let us know how you go. Cheers Banjo

Hi Hayden, I went & checked this morning, to make sure I'm not advising you some untruths. I still had my olde auto shifter in the garage, complete with the lead & plug. I buzzed out the connections & confirmed the following. Assuming Toyota kept the same wiring colour codes in your particular model Rolla, the white socket is a 4 way. 1. There are two wires that are red. One is red with a white stripe, & the other a red wire with a blue stripe. These two wires close a switch, when the auto changer is placed in "Reverse". These two corresponding wires in your loom under the dash, just to the RHS of the console, should be connected to the reversing switch in the manual gearbox. 2. There are two wires that are black. One is black with a white stripe, & the other is just fully black. These two wires close a switch, when the auto changer is in "Neutral", which allows the car to be started. These two corresponding wires in your loom under the dash, should be shorted together. This should solve your problems. Let us know how you go. There are two other "single" wires coming out from the auto changer in these pics above. One is red with a black stripe, & the other a white with a black stripe. Theses are purely for powering the light behind the auto changer, when driving at night. The corresponding ones under the dash, are basically the same circuit as your dash lights. You will not need to use these. I know they are "sockets", under the dash, but just tape them up, so they don't short against chassis anywhere. Cheers Banjo

Hi Hayden, Have a look at this link. It's all been done before/ https://www.rollaclub.com/board/topic/72760-ke55-auto-to-manual-conversion-wiring/?tab=comments#comment-704960 Trust that assists. Cheers Banjo

Will answer you tomorrow morning. Definitely the auto interlock has to be shorted before you can start it. I've got a KE30 that was an auto when I got it. I fitted a 5 speed manual gearbox, and went through the same issue. Cheers Banjo

Thank you LittleRedSpirit & Altezzaclub, for your advice on this one. Like you said, it wasn't so hard after all. The reluctor type sensors used to sense the heads of the bolts holding the disc onto the hub, produce a sort of sinewave output, where the frequency is proportional to the speed or rotation of the wheel. To get a good output from these sensors, requires a fairly small gap between sensor & bolt head in the order of 2-4 mm. The output, (amplitude of the waveform), also drops off at low frequencies. As I only want this sensor for detecting fairly low frequencies, that represent road speeds of 0 - 10klm/hr, I decided in the end to use a Hall Effect device. These are powered, & require a 3 wire connection, but their output amplitude is unaffected by frequency completely. ie: The output amplitude is maximum, whether the speed is 1 Hz or 10 kHz. The one I used was an OH090U, which looks like a small transistor. I made up a sensor, very similar in construction to the Terra Trip unit, using a bit off 10mm dia. threaded tube, I had lying around, from an old desk lamp, or the like. I then drilled a 10 mm hole through the backing plate & strut flange to mount the sensor. Simply then a matter of mounting the sensor & positioning it with the nuts, so that the gap between bolt head & sensor is adequate. Here is the sensor mounted. This is what it looks like from the rear. Just like a bought one ! To get the gap right, requires the hub & disc being removed & refitted a couple of times, until you get it right. I was able to look inside, down the gap between rear of the disc & the backing plate, with a small torch from the end where the caliper is normally fitted. A Hall Effect sensor can be configured to sense a ferrous protrusion, like the bolt heads, but it requires a small magnet fitted at the rear of the sensor, which has its field concentrated when the bolt head is close on the front side of the sensor. I didn't want to go down that path, so simply fitted a small rare earth magnet to one of the disc to hub bolts, as seen in the following pics. There was no need to attach a magnet to each of the four bolt heads, as in my application, to start the thermo-fan once the car slows right down, is very non critical, & the Deluxe Frequency Switch can switch right down to 1 Hz. The rare earth magnet I used was 20mm lg x 4mm dia. I covered it with some adhesive heatshrink, & trimmed it off flush at both ends. I then drill a 5mm hole in the centre of the bolt. I was a bit lazy, as I hadn't figured how hardened these bolts are in this application. I wore out 2-3 drills, & gave up in the end when the hole was about 14mm deep. I then filled the hole in the bolt up with good old Araldite & slid the magnet in. That is why it is sitting 5-6 mm proud of the head of the bolt. The great thing about using a Hall Effect sensor & strong magnet is that the gap between magnet "south pole" & Hall Effect sensor is not critical at all. The Hall Effect sensor switches when the magnet gets to within 13mm from the sensor, & doesn't switch off until the magnet is 20mm away from the sensor. (built-in hysteresis) All that was left to do was test it with a 12Vdc power supply & an L.E.D. Worked perfectly ! For reliability, I used some Teflon coated 3 wire & shield cable I had floating around, & strapped it to the strut & up through the inner guard, through a rubber grommet. Do this with the wheel full hanging, so the cable is not compromised, as it will be moving up & down with the suspension. Well, that's it. Couple of hours work, & a good result. PCB for the Silicon Chip Deluxe Frequency Switch should arrive on Monday, & then I can see if starting the thermo-fan, in stop start traffic, rather than waiting until the 95 deg C thermo-switch closes, will get rid of some of those wild swings in coolant temperature. Cheers Banjo

Hi Hayden, How you going ? Getting to that time of the year when it starts to get chilly where you are. By "starter motor wire" are you referring to the big thick cable, between battery & starter motor, or the wiring to operate the starter motor solenoid ? By "reds", I'm assuming you are referring to the oil & charge lights on the dash panel, which illuminate, as soon as you turn the ignition on. Look for power on the fuse panel near the drivers RHS knee, under the dash. Check all fuses. There is a fuse called engine or ignition. Use a multimeter of a simple 12V test ligh, with one end connected to the chassis. I would suggest that your KE55 is wired up for a a ballast resistor before the ignition coil. It could be missing or open circuit. That would explain why you get power in the start position, but not in the "run" position of the ignition key. If you haven't got a Rolla manual with a wiring diagram at the back, then there are wiring diagrams here on the Rollaclub website. They look complicated, but the best way is just to sketch the area of the electrical system out, then work through it from battery to "device". Don't forget the earths to chassis & back to the -ve terminal of the battery. Cheers Banjo

Hi Keith, Had a real good look at this possibility yesterday afternoon. My setup on my KE30 2 door front suspension, is not standard, with RA65 Celica struts & Cresida large thick rotors & giant calipers (compared to the original Rolla ones). Removed the caliper & disc., & located the four (4) head bolts on the back of the hub, securing the disc. itself. I removed one bolt completely, then refitted the disc, rotating it slowly with a very thick round pencil through the hole, from the outside, where the bolt had been. This marked an arc on the backing plate; then I removed the disc again. The radius from the centre line of the axle was smaller than expected, & it was nearly in line with the four bolts holding the backing plate onto the strut flange. There was only one spot where I could mount the sensor to detect the four (4) head bolts. Top & bottom where shielded at the back by the strut itself, & the forward side, had the caliper in the way. I marked a spot, on the rear end, between the backing plate bolts, which had the strut flange behind it. I drilled a pilot hole through the backing plate & flange, then refitted the disc. Pushing a piece of coat hanger wire through the hole , from the rear, I could measure the distance between the back of the backing plate & the head of the bolts. It was 35mm. The area of the bolt heads to be picked up by the sensor is 12mm in dia. When I open the pilot hole out, & I wouldn't want to go much more than 14mm, as I will taking metal out of the strut flange. I've not been able to find on the net the dimensions of the Terra Trip T005, you suggested. Just looking at the pictures, it appears to not be long enough, & maybe a bit too big in diameter. You don't happen to know what it's length & dia. were ? I might have to make up my own sensor with a Hall Effect device, and a piece of threaded tube. Is the wiring to your T005 a 2 or 3 wire connection ? Hall Effect devices usually require 3 wires, but some of the pictures on the net, seemed to indicate the T005 had only 2 wires. Strangely, while Googling Terra Trip products, I came across a T007, which is a natty little device, that interfaces between the gearbox & speedo cable itself. It is apparently made for Japanese cars, which would make for a very easy conversion. Unscrew speedo cable, insert T007, screw speedo cable into the rear end of the sensor. Have you come across this device before ? Cheers Banjo

How long ago did you purchase it off ebay, & how long has it been in service in your Rolla ? Open it up, & all will be revealed. Cheers Banjo

Sounds great guys ! Was thinking it was going to be quite difficult. Will let you know how I fare. Well, I took the KE30 for a run today to town, after I reinstated the radiator bypass hose over the weekend. Over the weekend, I also fitted a proper temperature guage, so I could see more closely and accurately, in real-time, what was happening. I mounted it on top of the steering shaft cowling, so I didn't have to move my eyes too much whilst driving. The guage was surprisingly accurate, considering it originated from China, delivered, complete with mounting surround, & sensor for less than $ 10.00. Well, after I got home, & downloaded the data, you could knock me over with a feather. The simple action of reinstating the bypass, made the whole coolant temperature variations, change dramatically, for the better. It's like there has to be a constant flow, whether the thermostat is opened or closed, to stop the sudden changes than occur, when the thermostat closes, & the flow stops altogether. Ever since I ran a return line from the back of the head, the rear head temperature has lowered considerably, but Keith & I were very puzzled as to why the rear head temperature, at times, was actually less than the lower radiator hose coolant temperature. From the graph above you can see that that has changed completely. Where we had a rear head coolant temperature about 10 deg C above the front of head temperature, now it actually less than; by 6-7 deg C. Now the whole system is stable, I might put a clamp on the rear of head return line hose, & restrict it little by little, to see if I can't get the front & rear head temperature even closer together. On the right of the graph, you can see a "circled" area of the graph, where for 15 mins, I had a good long straight run, without any stops at all, all at about 80kph. Here is that section, of graph, which is very telling. Notice the top & rear head coolant temperatures, mimic each other perfectly, about 6-7 deg C apart. Gone are the ups & downs, of the coolant temperature, directly under the thermostat. The rear head return coolant is now returned to a point directly under the thermostat, which is why these two temperatures look so much alike in shape. The lower graph line is the lower radiator hose coolant temperature. The zig zag nature of this graph is very easy to explain. The outside ambient air temperature was fairly mild today, at an average of 25.5 deg C, as shown on the stats at the bottom of the graph. This resulted in the radiator hardly being needed at all. You will notice the top hose (black trace) is averaging at 82.4 deg C. The thermostat does not crack open until 82 deg, & is fully open by the time the coolant reaches 87 deg C. So what was happening was the thermostat would just crack open, & flow would commence through the radiator. The coolant temperature reduced very quickly, once the radiator was in circuit, & the thermostat instantly closed up again, stopping flow through the radiator altogether. i could actually see this happening on the temperature guage I fitted behind the steering wheel. The meter is damped, but, I could see it rising and falling about 2-3 deg C. continuously, at the rate shown in the graph. I was actual watching the thermostat crack open & close continuously. On a hotter day, this will not happen, as the operating temperature will be nearer the mid point of the thermostats range of 82 - 87 deg C. So riddle just about solved. Just need to install this speed switch, so that in traffic, when you stop, the fan comes on automatically, to pre-empt, & flatten out all those sudden rises. In the first graph, you will notice the electric fan only came on three times. The first time was for 48 sec. Second time for 24 sec, & last time 48 secs. That's a total fan operation of 2 minutes, in about 90 mins driving. Keith's original statement is very true, that the fan is rarely needed. Cheers Banjo

Hi Keith, I would certainly like to fit the sensor to a front wheel, rather than the diff input flange, as I indicated. If only to keep the wiring short. How difficult was it to fit to the front lower strut ? What car did you do it on? I presume it was a gear tooth hall effect sensor that you used, if you were just detecting a bolt head? Didn't involve any external magnets? Can you remember what particular sensor you used? Was it off a later model Toyota? I will pull a front wheel off this afternoon, & have a look, how much room there is behind the disc. I've ordered the Silicon Chip PCB & programmed micro processor, for the Deluxe Frequency Switch, so that should be here in the next couple of days. I did a run this morning, so am about to download the data logger, & see what effect the raditor bypass addition, had on the rear of head coolant temperature, if any. Cheers Banjo

The vacuum actuator/bellows on these old distributors are known to have failed in the past. I came across one recently. The quick check is to remove the distributor cap & rotor, so you can view the mechanism easily. Remove the rubber hose from the carburetor base, or the inlet manifold in your case. Put it in between your closed lips, & suck in. You should be able to see the plate moving counter clockwise in the dizzy. If it doesn't move at all, then problem is in the dizzy. It could be the vacuum bellows itself, or maybe the mechanism of the stationary & moving plates are all "jammed" up. Time to dissemble the dizzy & clean & oil it thoroughly. Once you have the bellows assembly out, you can test it by sucking, as it now doesn't have anything attached. Let us know how you go. Cheers Banjo

Hi Guys & Gals, Well my Silicon Chip May 2018 magazine arrived in the mail today, & there inside is a project for a "Deluxe Frequency Switch", on page 36. It allows you to feed a stream of pulses from any sensor, into the unit, & it will trip a relay, with hysteresis, when the rate of pulses goes above or below, limits which you set. It has a timer builtin as well. There are many applications this switch could be used, and the article lists a number of them, to get the readers mind working. The very second suggestion advanced says . . . "Switching a fan on at low vehicle speeds, to provide improved cooling". Just what we have been discussing, in this thread. Looks like just what the doctor ordered Keith ! Cheers Banjo P.S. Just waiting for this rain to stop, to get out there & complete this radiator bypass addition. Hopefully, some sun tomorrow. Well, it is Qld. Beautiful one day, & perfect the next.

Hi Graeme, The easiest check on this fault is to cut it in half, when it happens next time. To me the half way point is the starter motor relay, which I think in your girl's KE55, is down behind the driver's kick panel. If you remove the kick panel, you can locate it by sound or feel, as it a bigger than normal 12 volt relay, so has a good "clunk". If you turn the key to the start position, & the relay does (audibly or "feel wise") not operate, then the problem will be the relay itself, the ignition barrel, or an intermittent 12V supply to ignition, or the wiring between ignition barrel & starter relay. If the relay does operate, then it is more than likely that the fault lies beyond the relay, in wiring to the Starter motor solenoid, or possibly in the starter relay contacts themselves. If however, you can hear the starter solenoid come in, but no starter rotation, then the issue will be either in the heavy duty cabling or connections between battery & starter, or the brushes in the starter itself. A quick check you can do, is on a cold start, measure the 12 volts at the starter motor itself, to the engine or starter motor frame. Couple of long leads with a couple of little alligator clips will do. This may show up any potential issue with the battery to starter motor cabling or terminals, if the reading is very low. P.S. Prevention is always better than cure, on a cold winters might on a back road in Buccan ! Cheers Banjo

Hi Graeme, Intermittent electrical problems are always the worst ones to uncover. Open circuits, or short circuits are easy. I agree with what Jeremy has said about battery terminals, as starting the car from a cold start, is the highest load you can ever put on the battery & associated wiring. Unfortunately, it will happen again, as it unfortunately is not a "one off event". I would be inspecting all the heavy duty terminals between battery post & the starter motor. Don't discount the starter motor itself, either. The brushes on them do wear, & they can get to the point where they just make contact, with little pressure on the armature. There are two other items, that could cause the problem in a 40 year old KE55. The starter relay, which is hidden down behind the drivers kick panel, off memory. Not unheard of, for them to fail. usually contacts, because they handle a fair current to drive the starter motor solenoid. Never forget the ignition barrel switch. They do get tied after many years, & I have seen a couple in my time, where they worked sometimes, & not others, just as you describe. Probably a couple of hours work there, but you will solve the riddle eventually, which may be better than the fury of a teenage daughter, as I have one just like yours. Cheers Banjo

Hi Graeme, Yeh, hope it is something simple, & not the Accuspark unit. Was there a ballast resistor on the coil before you added the Accuspark ? If not, what was the primary impedance of the ignition coil you have fitted, as Accuspark unit can only handle coils with primary resistance of 3.0 ohms, without ballast resistor. If a ballast resistor is used, the total series resistance of coil & ballast should be no more than about 3.0 ohms. Low resistance primary coils, should not be less than 1.5 ohms. Cheers Banjo .

Hi Graeme, Good to hear you got it all up & going OK. Initially, you probably won't see any more improvement, than if you had just replaced a new set of points. However, unlike points, which start deteriorating from the moment they are fitted, the Accuspark unit, will not experience any drop off in performance, over time, EVER. However, the major way of improving the ignition performance of your girl's KE55, is with the advance curve. The Accuspark unit does not affect that. It is simply an electronic points replacement/substitue. Advance is still provided by the springs & bob weights below the dizzy mounting plate. These should always be kept clean & oiled lightly. I've been running my Accuspark for a couple of years now, without issues at all. I have seen a great improvement in performance, but I locked the dizzy advance mechanism up, & provided a far more aggressive advance curve, with a Jaycar programmable ignition controller. The Accuspark unit is purely used as a trigger for the Jaycar unit. If you ever want to go down that path, give me a yell, & I'll come across to Buccan, & show you what is involved. Cheers Banjo

Hi Keith, Well my 16 x 1.5M hose adaptor arrived today, so I can now install a radiator bypass hose, & see what effect that has on the various logged temperatures in the coolant system. I like your idea of using an ABS sensor to provide a signal that the car has stopped. It is not a very important sensor, for our application; unlike the real ABS application, where you need a toothed wheel, so you can measure rate of change of speed, as well as actual speed. I've been thinking about how I could mount a sensor, without too many issues. ABS sensors are pretty cheap on ebay. It's probably a bit difficult to modify a front KE hub, & fit a sensor. I was thinking of maybe attaching the sensor to the diff housing, and have the sensor measure the tail-shaft to diff flange going round. Probably no need to fit a toothed wheel. Maybe just sense the heads of the four (4) flange bolts whirring around, with a Hall Effect Magnetic sensor. After all, it's just a Go/No Go condition we are looking for. However, we could actually bring on the thermofan, above stopped, if you are crawling along in traffic, on a hot day, by switching the fan on when the speed is between 0 - 5 kph. Actually, whilst writing this I just remembered I've got a little "potted" reed relay, that is used for sensing a tiny magnet clipped to the spoke of a bicycle for driving the bike speed module. Could hook that up, real easy me thinks. So when the ignition is on, and there are no pulses, that would indicate the engine is running, but the car is stopped, & the thermofan could be switched on. You don't want the fan coming on, whilst you are doing a cold start first thing in the morning, so could add another condition, that the temperature has to be above some reasonably high limit. That would limit the fan to automatically come on, only when it is really needed. Lots of possiblities there. I'll let you know how I go. Cheers Banjo

Hi Jasper, It could well be ignition or carburation, but it is a bit hard without hearing the motor under load. 1. Does the flat spot feel like it is load related ?. If so, it could be running on 3 cylinders, or a spark plug or lead breaking down under load. 2. Does this shudder feel like the ignition cutting out altogether, intermittently ? 3. If it is fuel related, it will feel more like a "starving" condition, without jerkiness (dying sound). Have a look at the engine HV electics in the complete dark,, & look for any break down around or inside the leads. Have a good look for leaks in the inlet manifold, where it may be leaking more air in. Cheers Banjo

Hi Keith, I can assure you the rear head & lower radiator temp sensors are hooked up to the correct data logging inputs. It is however, a bit difficult to get your head around the rear of the head being cooler than the coolant at the bottom of the radiator. If it stayed that way, then there would certainly be something wrong. However, it doesn't, as & there are long periods, where the rear of the head coolant temperature is greater than coolant exiting the bottom of the radiator. This changeover, only occurs when the car stops, & the air is no longer passing through the radiator, & the top radiator hose coolant temperature is not yet high enough, to switch the thermofan on. You can clearly see this in graphs a few posts back on this page 10. The problem is, that as soon as the car stops, the coolant at the bottom of the radiator rises in temperature very, very quickly. The rear of the head has to play catchup. This sort of things always occurs in "systems" that have "transport" lags. First I am going to see what difference the radiator bypass creates. You will notice, that this occurrence, only happens in stop start traffic, but not on a long straight runs. I was thinking, I could flatten the response right out, by fitting a N.O. relay contact across the thermoswitch, with the relay automatically coming on, whilst ever the ignition was on, (engine running), & the car was stopped. That would result in air passing through the radiator at all times, and should reduce, & hopefully almost illiminate the sudden rises in lower radiator coolant temperature. I can test this out, without fitting the relay, as I have this switch on the dash, that can bring the fan on, irrespective of the conditions. I'll log a run in traffic, but every time I pull up, I'll switch the fan on. Likewise as soon as I move off again, I'll turn the fan off. The resulting graph, should clearly show the difference in coolant system performance. All fun, but learning lots at the same time. Cheers Banjo

Hi Keith, Although initially it sounds strange, that top & bottom of the radiator could be at the same temperature. When you think about what is happening, it is not so strange at all. Here is a graph of that small period of the previous graph. The Rolla had only been stopped at the Dentist for about 30 minutes, after the trip there, so the coolant was still at an elevated temperature above ambient, at around 48 deg C, when the car is started. The fan is not running at all, but the water pump is. However, by the time the temperature reaches say 87 deg C, the thermostat is fully open, & as water pump is running, so coolant flow through the radiator is constant, & therefore top & bottom radiator coolant temps are at the same temperature. However, as soon as the temperature of coolant at the thermostat area reaches 92+ deg C, the electric thermofan switch automatically kicks in. The radiator then does it's thing, & the bottom hose temp instantly drops rapidly. That cooled water then feeds through the engine block/head, and within 30 secs. the top hose temp starts to drop off also, to then be controlled by the thermostat, & held at between 80 & 90 deg C. All good, as should be. Note the fan ran for only 40 seconds, before it dropped the top hose temp; to the point where the fan was not required any longer. Your earlier point about the fan hardly ever required, is proving very, very true. What a waste of power driving that old plastic fan all the time. Ideally, every component in the system should be matched in terms of performance. However, in this case in mild ambient conditions, the aluminium radiator appears to be more efficient than needed at that time, & therefore the system cycles a bit, at around 4-5 minutes as you describe. As the ambient temperature rises, to say a very hot 40 deg day, I would expect the 4-5 minute cycling to decrease, & the top hose temperature to be fairly flat. The only way to prevent this "cycling", would be to fit thermostatically controlled louvers in front of the radiator, as are common in big trucks, to control the amount of air through the radiator; or fit an electric water pump, as are common in some racing cars, so they can control engine temperature to a very tight controlled point. It will be interesting to see what reinstating the radiator bypass hose does in terms of control, & "the cycling" you have identified. Just waiting on a 16 x 1.5M barbed 14mm hose adaptor to arrive, so I can reinstate the bypass function. Actually, I have an old TPS sitting around here. It wouldn't be too hard to hook it up & log how hard I push the accelerator pedal. P.S. As the bypass hose is very close to the point where I am measuring the "top hose" temperature, (under the thermostat), I thought I might move the measurement point to the bypass hose, which would allow it to react quicker, like the rear head sensor, which has a hose each side of it. Cheers Banjo

OK, so went to the Dentist & back, & recorded the trip at 1 second intervals. Here is the complete trip. This following graph is the trip home. The differential between the front & rear of the head is still around 9 deg C. However, despite that, the thermostat is working perfectly, maintaining the coolant temperature between 80 & 90 deg C. The graph below shows that clearly, and the thermofan kicking in, whenever the car physically stops, & the temperature shoots up over 90 deg C. Next step will be to reinstate the radiator 15mm bypass hose, & see what transpires, after a run with that. P.S. Still can't believe the lower radiator hose temperature drops so quickly to around 50 deg C, after stopping the car. Cheers Banjo

Hi Scott, The fuel guage not working makes sense, & is what you would expect with a polarity reversal. The DC supply feed to the fuel guage & temperature guage is usually a regulated voltage of around 7 - 10Vdc, depending on the model. These regulators in the Starlet, are most probably solid state, & it has been made U/S from the reversal. My guess is the ECU / ECM is U/S also. Off memory, the Starlet EFI only uses just a single injector. You could take the injector out, & take it to a injector cleaning service, which should have the equipment to test whether it is working. Cheers Banjo

Hi Keith, Good morning ! One thing I have not fitted on my coolant system, during these tests, is the thermostat bypass hose. My theory has always been, that here in the northern half of Australia, where it rarely gets cold, that the bypass hose wouldn't do anything much that was useful. To me, the bypass flow, would only lengthen the period of initial engine coolant warm up, which you want to be as quick as possible. Currently, without a bypass, my graphs indicate that period is about 8-12 minutes, from a cold start. Once the thermostat cracks open, the bypass hose function is basically redundant, to my mind. However, in reading up on it overnight, there appears to be several reasons for it's inclusion. One is to stop steam pockets forming in the head, during the warm up period, and the other is to prevent the water pump impellor from cavitating, which could happen during warmup, whilst the thermostat is completely closed. So this morning I thought I might remove the "block off caps" I currently have on there, and insert a piece of hose. It was then that I realised I have a mismatch between lower thermostat house bypass outlet point, & water pump bypass inlet point. I have a lower thermostat housing with a bypass 8mm outlet & a water pump with bypass 15mm inlet, on the LHS of the engine. It appears that somewhere during the K series development, Toyota in their wisdom changed the size of the heater bypass hose from 8mm to 15mm ID. I noticed there were a couple of pics in a thread you contributed to back in early 2015. This one clearly depicts the 8mm bypass hose on the LHS of the water pump, viewed from the front of the engine. However, on later K series engines, the bypass was increased to 15mm ID hose, & fitted to the RHS of the water pump, as depicted in this pic. I have the option of fitting either size to my existing setup, but I am wondering what was the reason Toyota increased the bypass hose size, & what existing issue with the small bypass hose size prompted this. My guess is that, the smaller 8mm hose just simply blocked up, as I have witnessed over the years, but I was wondering whether it was to increase flow, & why. Can you throw any light on this, from your experience ? I'm just a bit concerned, that if I fit the 15mm bypass hose, whilst running the high flow thermostat, the thermostatic control, might not be as good. I suppose, the proof will be in the eating. P.S. Going for a run shortly for about an hours trip, with the data logger set at 1 second logging rate, & see how that looks. Cheers Banjo