Banjo

In my research on things coolant, in K series engines, I've always presumed all K series engines had coolant bypass circuits, from the base of the thermostat housing to the 16mm spout on the inlet of the water pump. The Toyota Yellow Bible depicts it that way. All the 3K & 4K after market, replacement water pumps on the net, are depicted with a 16mm spout off the water pump inlet, to connect a bypass coolant circuit to. However, around my garage, are a few old genuine Toyota K series water pumps, that have no 16mm spout off the water pump inlet, so I can only presume that maybe some early 3K engines in KE10 & KE15 models, didn't have a coolant bypass circuit. Has anyone got an original Rolla, without a bypass circuit ? I even have a new aftermarket K series water pump, that has the 16mm spout on the water pump inlet, but is blanked off inside. Presumably, this is so it can be used in either application. If you need it for a bypass application, you just drill out the blank aluminium casting. Cheers Banjo

Well, sometimes you can be lucky ! I picked up an Echo radiator & fan complete, this afternoon, here in Brisbane, which I found on Gumtree. The older retired mechanic, had had it in his garage wrapped up for 10 years. Came off an Echo, written off, which he bought for other bits, he needed to repair another Echo. The Echo it came off, had 18K+ klms on it. It's like new. Bargain $ 35.00 ! As you can see, there is not much between them, size wise. The Echo one looks a bit bigger, but some of that illusion, is a piece of plastic on the RHS (looking from the front) that can be cut off. Inlets are on the same side at the top, but outlets on opposite sides, at the bottom. Outlets & are a fraction smaller in dia. (28mm vs 30mm) I'll see how easy it is to attach the fan assembly to the KE radiator, but really, it might be just as easy, to swap the whole radiator & fan complete. What do you think. Probably easier to make a decision, once I remove the KE radiator out, & see how it all fits. Cheers Banjo

Here is the thermostat housing I had all the time, that is perfect for this experiment. That hole there is blanked off, & unused. It is quite large, & it should be easy to drill & file out the back of the hole & break into the thermostat area. there is plenty of "meat" around the hole, to thread it to any size hose fitting I choose. Alternatively, if I want to, or need to run the coolant return line on the opposite side of the engine, then there is a large spout already to be used, but this is designed for the radiator bypass, so I'll probably retain that function. There are two (2) temp sensor points on the thermostat housing, & if I use a cover spout with the threaded hole in the top, I get another measuring point, effectively at the top of the radiator. Happy days ! Cheers Banjo

Hi Bill, Managed to get hold of this elusive pulley late yesterday, but it was too dark to take some pics last night, when I got home. Here are a few shots of the pulley, some along side the standard, & most common conical one, here in Australia. Picture no: 4 clearly shows they are both have the same O.D. Picture no: 3 shows how this pulley is "shallower" than the standard conical one, by about 8mm. The remaining pics show that the centre mounting/alignment hole is much bigger, than our standard 16mm one, but at 32mm, is greater than the 24mm on the mounting boss you have there on your 4K engine. The four (4) off 6mm bolt holes, are spaced 40mm apart, unlike the conical one, where they are only 31mm apart. The pressed on mounting boss on your water pump, is different, in that it has a shoulder on it, to centre the pulley, where the standard conical one, just uses the 16mm dia. water pump shaft. The boss is just pressed on, so I guess it wouldn't be too hard to align the centre of the belt groove, with the crankshaft & alternator pulleys, if needed, by repositioning it, as your shaft appears to have plenty of length. So I'm not sure whether you can use either of the pulleys I have here. Maybe, you can just buy another new aftermarket 4K water pump, on line, as they don't seem to be too expensive, & see what size mounting boss it comes with. Let me know, if I can assist any further. Cheers Banjo

Hi Jeremy, The top piece with the hose outlet spout is the thermostat cover to me. The thermostat sits entirely down inside the lower section, so that to me, that is the thermostat housing, because it houses the thermostat. The first picture is not back to front. It's a guy here in Australia, with a 4K in a KE25, who fitted a Nissan SR20 aluminium radiator, which has it's inlet & outlet spouts reversed to the standard 4K radiator arrangement, so required the top spout to be reversed. You can look at his build here, on Performance Forums. http://www.performanceforums.com/forums/showthread.php?67299806-KE25-corolla-without-powers Cheers Banjo

And to think this thread started out about "Oil Pump Failures". Here are a couple of close up pics I found on the net. There are quite a few different arrangements of the thermostat housing on K series engines fitted to various Corollas, Starlets, Hi Ace Vans etc. However, I think I have found a perfect one, right under my nose, fitted to a 5K engine I have on a test bed, out in the yard. I'll take some pics, (when it stops raining) and post here, & see what you think. P.S. I like that 3rd pic one, with the two large access points on the RHS of the housing. Anyone got one of those ? Cheers Banjo

Been thinking about this overnight, & have another thought. The heater coolant return line, is connected to the input side of the water pump, which is feeding "cooled" coolant from the radiator. It struck me then, that the heater return coolant, never passes through the radiator. It bypasses it completely, except for when it gets mixed inside the engine. This makes perfect sense, when you think about it. Remember the heater coolant, only flows when you have the heater on. You only have the heater on, because it is cold inside & outside the vehicle. If it is cold outside, then this is not a situation, where your coolant will ever get excessively hot. The cabin air passing through the heater box coil, is also extracting heat from the engine coolant. Certainly this is not a time you would want, or need, to cool the coolant any more, by passing the heater return coolant, through the radiator, & cooling it even more. In cold weather, the issue is to keep the engine coolant temperature up to the idea engine operating temperature. That's why trucks put covers over their radiators, in deep winter regions. So, when the heater is "Off", & we take hot coolant out of the back of the head, we certainly do not want to return it to the water pump inlet, & bypass the radiator altogether. So basically, I would leave the heater coolant circuit completely alone. At the point where the coolant comes out of the back of the head, I would put a "T" joint, before the heater coolant tap, & feed this coolant through another tap, and then return the coolant to a point directly under the thermostat, so that this returned water, would always pass through the radiator. The two water valves on the back of the head, would never be opened together. When one is "A" is open, "B" is closed. When "B" is open, "A" is closed. This would hopefully, achieve the result we want, without too much complication. Maybe the mechanical valves could be "tethered"" together, so they worked in tandem, but opposed. Alternatively, an electric valve/s, but they are expensive. Have a think through this logic, & see if you can find any holes in it. Like a said, the proof is in the pudding. So I need to find a thermostat housing, which has a spare space, or hole where we can attach the return coolant hose-line from the back of the head. There are a number of different thermostat housings on K series motors. I know I've got a few in the shed, & I'll try & round them up tonight. If anyone could post some pics of any thermostat housings you have, that would be great, & we'll find one that suits this purpose best. Cheers Banjo

Hi Bill, On another thread here, I've been looking at the various water pumps, with their different inlet & outlet configurations; to find one suitable for a mod, I want to carry out for the return coolant circuit, from the back of the head. In that research, I came across several different K series pumps; & surprise, surprise, some of them had a different water pump pulley, with different (bigger) centre hole diameter, & a different spacing for the four attachment bolts. The pictures appear to indicate, that the pulley, is a lot flatter, than the standard "conical" one. Overall, the O.D. appears to be very similar. This lines up with your description, as my standard pump has a 16mm centre hole, whereas, yours is 24mm. Apparently, these were fitted primarily, to K engines that had the larger plastic fans, with a clutch in them. These apparently, were fitted, in the main, to 5K engines here in Australia, which Toyota used in commercial vehicles, like vans, & forklifts etc. I have managed to find one here in Brisbane, & I'm going to catch up with this guy this afternoon, so may soon have one in my hand, that I can photograph for you, & measure up accurately, to see if it suits your 4K application. Stay tuned ! Cheers Banjo

Hi Jeremy, Just remember, we are not just cooling the head. The coolant also flows around all four (4) cylinder walls, inside the block. Cylinder no: 4 walls, also are the hottest in the engine. There are many on this forum, like myself, that will atest, that if you are going to do a ring or rings in, 9 times out of 10, it will be no: 4 piston. You'll never get perfectly even temperatures across the coolant system, because at the intake point at the front of the block, the coolant will be at it's lowest temperature. When it exits the engine through the front of the head into the thermostat housing, the temperature of the coolant will be at it's maximum. What we presently have, (and I will prove with real readings), is that the water at the back of the head can be 10 + deg C higher than the water entering the thermostat. Introducing cooled coolant directly into the head, may sound good, but I think it would result in serious issues. All cooled coolant should enter the engine through the block. What I'm looking for is a simple solution, that anyone can do to their K Series engine, without great cost, or need for machining or fabrication. A two (2) way water tap/valve seems like a simple "doable" idea. It might not be perfect, but I'm confident, it will result in a much better coolant temperature differential across the whole engine/block. As I said earlier. We could theorise all day, but experimenting & measuring the results, is the only way to get to a reasonable compromise, without "re-engineering". P.S. I'm just about to hop on the net, and source a suitable mechanical water tap/valve. If any one has a suggestion, of an existing product, or one from another auto, please post your suggestion here, & have your say. Cheers Banjo

The plate on the back of the head was always going to play a crucial function, in correcting this design issue, of higher temperatures at the rear of the K Series engines. Industry's approach was to block the coolant transfer holes between block & head water jackets, in the front of the head gasket. This had the desired effect of forcing the water to flow to the back of the block and then up into the head, then back forward to the thermostat housing, at the front of the engine. This does improve the temperature differential from the front to back of the head, but not totally. However, it also reduces the flow rate of coolant in the system, by effectively throttling it, midstream, which is undesirable. The real problem is that the water pump forces "cooled" coolant into the front of the block, & the hot water exits the head, at the front of the head. The water will always take the path of least resistance, so flow to the back of the block & head is reduced considerably. There are lots of radical things we could do, like mounting an external water pump, that fed water into the centre, or rear of the block via a Welsh plug point, but initially, I have a few ideas I want to try. Many KE series Rolla's take hot water from the back of the head, for the cabin heater, which does improve flow, through the rear of the head. The return of the hot water heater coil, is usually through a pipe or hose, to a point on the water pump, as this water doesn't need to be cooled, as it has given it heat off in the cabin. If the ON/Off tap on the coolant line at the firewall, was replaced with 2 way water valve, then coolant would flow out the back of the head, even when the heater was off, (which is most of the time). My plan is to try this out with multiple temp readings taken before & after the mod, to see how well it works. It must improve it, as currently, there is no flow out of the back of the head, unless the heater is engaged. If there is still a differential, I believe we can equalise it, by restricting flow slightly out of the front of the head to the underside of the thermostat, which should result in increased flow to the rear. I would also reinstate a head gasket, without any blocked transfer coolant holes. The proof is always in the "eating of the pudding', so I'll see what eventuates. Changing the flow between head & thermostat housing at the front of the engine, is easily accomplished with a restrictor plate between the two. Cheers Banjo

Hi Dave, Not into Ardinuo as yet. Love my PICAXEs. Hardware is so simple, & chips are so cheap, & the code only takes a few minutes to put together, for simple applications like a thermofan with multiple sensors, & run on timer etc. I'll give you a look, once I get to that stage. Stage 1, is grab this fan next week, & get it fitted to a KE radiator, then the fun begins. Cheers Banjo

Hi Dave, I'm aware you can get two (2) switches in one housing, but they are pre-set fixed switching temperature points, & I want to be able to adjust these switching points slightly, so I can achieve an ideal solution, once I've logged it all, at multiple points in the coolant sysytem, over different driving scenarios, & see how it all pans out. Thanks ! Cheers Banjo

That's exactly what I plan on doing. Instead of using commercial sensor/s with the switch built in, where the switching temperature is fixed, I was thinking of a single sensor only, (no switch), fed to a PICAXE programable uP, so that I can assign any control regime or system I wish, with adjustable temp switching points. The PICAXE output, would, just switch an auto relay, to turn the fan on & off. Could be fun, & allow ability to experiment, & get a result as good as possible. Cheers Banjo

Hi Jeremy, It was in a post called A Bit of Lateral Thinking. https://www.rollaclub.com/board/topic/73209-a-bit-of-lateral-thinking/?tab=comments#comment-708383 Unfortunately, there aren't any points on the block that you could easily fit engine mounts to to make an East/West engine, fit a RWD Rolla. Mating a RWD gearbox, would also require a purpose made adaptor plate. Cheers Banjo

Great Viterbo ! I'm pretty sure I've got one in my shed somewhere, but I couldn't find it a couple of weeks ago. If I can't find it, I'll grab one off ebay, or see if I can find a Starlet at a wreckers here in Brissy. Is that on your engine. If so, what thermo-fan did you use ? Cheers Banjo

Thanks Mate ! That solves that riddle. Might get one, as I bought a Echo radiator & fan assembly on Gumtree yesterday, here in Brisbane, & will pick up this coming week, & fit to the KE30, so that it has a thermofan, doing away with the plastic noisy water pump fan. All the existing "spare" temperature pick up points on the thermostat housing, are physically, behind the thermostat, so the point on the top of the thermostat outlet spout, is basically the temperature at the top of the radiator. Cheers Banjo

Hi Pete, I liked the bug eye Sprite, as when you remove the whole front grill/guards/bonnet piece, you have easy access to the engine bay. Cheers Banjo

Hi Bill, Have compared the pics of your water pump & mounting boss, with my posted ones, & they appear to be different. The water pump shaft on our water pump is 16mm in dia., as is the centre hole of the pulley. The four (4) mounting holes for the pulley are each 31mm apart. C/P to C/P. The distance between the front face of the mounting boss & the centre line of the fan belt is 36.5mm. The pulley, weighs 500g, so packed would be about 1kg. If it it is suitable, let me know, give me your full name & address details, & I will post it over. Cheers Banjo

I totally agree with Big G. Take out all four spark plugs & compare colour, and you will probably find one is very clean & white. That will confirm, its time for the head to come off. Cheers Banjo

OK, the gearbox measurement mentioned above is 55cm or 21.5 inches. the water pump snout looks pretty much the same. Here are a few pics. The measurement of the gearbox, mentioned above, on our 4 speed is 55cm, or 21.5 inches approx. Cheers Banjo

Hi Bill, Thanks for the pics. Gives us a clear idea. The letter after the 4K, never appears in the engine S/N on the block. It is usually on a sticker attached to the side of the rocker cover, just above no: 4 spark plug. From your pics, looks like that sticker has long since gone. I don't know if it is an optical illusion, but it appears that the point the gear stick comes out of the gearbox rear extension, is much further back than normal, for a 4 speed. Have you worked out where it will "appear" on the Healey's floor tunnel ? What is the measurement between the centre point of the gear stick pivot ball, to the front edge of the bell housing mating point to the block ? I'll go & measure a 4 speed box I've got on the garage floor, & post it here. Our 5 speed gearboxes, had the gear stick further back. The water pump pulley I have will fit your pump OK. I'll go & take a pic, & post here with hole dimensions. Can't imagine they would be different in the USA, but you never know. Cheers Banjo .

Hi Bill, Welcome aboard ! Do you have the plastic fan blades already ? Can you post a pic of this "water pump with the wider snout" , so we are not crossing paths here. Plenty of pulleys here, but would hate to send you one & then find it doesn't suit. Do you know what type of 4K engine you have. I'm presuming that it is a 4K-C, where C stands for "California". Lots of 4K-Cs here in Australia, as we adopted the same emissions regulations at the time. Is the transplant very complicated ? Have you got some pics of the 4K sitting in the engine bay ? What gearbox, have you got behind it ? I Googled it, but couldn't find anyone previously on the net that had done a 4K swap. Found someone who did a Toyota 20R motor swap, so I presume if it fits, then the 4K would also. http://autoweek.com/article/car-life/toyota-engined-austin-healey-sprite-will-haunt-me-forever Cheers Banjo

Hi Keith, Did a bit of research, on suitable fan sizes that would suit the standard KE radiator, but the answer was right under my nose. I bought my daughter a 2004 Echo last year, & I went out and measured it's radiator & fan up this morning, & it is almost perfect. It's outside frame couling/shroud, is within a cm of the KE radiator core dimensions, in both directions. If anyone has utilised an Echo fan on a KE sucessfully, please give me a yell. I will get hold of one, & adapt it, using a spare radiator I have in the shed, then pop it in one weekend. On paper, it should be an easy & clean swap. I'll post a pic on here, when it is done, after which I'll do some temperature data logging exercises, with multiple temp points, to see exactly how well it performs. Cheers Banjo

Strangely enough, when I was digging around in all my bits & pieces the other day, looking for the box of old thermostats, I came across an old 3K thermostat cover/spout/outlet thingy, that actually had a hole right in the top of the housing. It was OEM, as the hole had a land around it, not just previously drilled out & threaded, by some enterprising individual. Just went out, & looked for it in the shed, so I could take a pic of it, but it is almost 40 deg C, so retreated to my office. Looked up the net & low & behold, someone in Thailand, is selling aftermarket ones. https://www.ebay.com/itm/THERMOSTAT-HOUSING-FOR-3K-ENGINE-TOYOTA-COROLLA-KE20-KE25-KE26-KE30-KE36-KE38/152473006588?hash=item23801971fc:g:cmoAAOSwax5YyQiY&vxp=mtr Have no idea what was fitted into this hole originally. Probable a temp sensor of some kind. There you are Jeremy. Get one, & fit a little tap or cock to it, & you've got a coolant bleeder, & you won't have to remove & reinstall the thermostat cover ever again. Cheers Banjo

Hi Jeremy, There should not be a necessity to do this, if everything is OK. Imagine if the Toyota manual used that instruction, you describe. It would indicate a design fault. Based on the picture of your head that you posted, & what the quality of your local water did, in terms of corrosion, I have a gut feeling, that there is something very wrong inside the coolant system of your engine. You are correct, that the water pump is needed to produce flow in a closed circular coolant system. Based on your statements, my first suspect would be the water pump itself. Have you had it off lately, & had a look inside. I wouldn't be surprised if the vanes on the impellor are all corroded away, & doing little more than cavitating the water in the local area. As you presently have the head off, I'd be removing some whelsh plugs on the block & having a look inside. You might be shocked. With the head off, it would also be a good idea to remove the plate on the very back of the head, which gives access to the head's water jacket. Again, you might be shocked. Cheers Banjo