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Oil Pressure Problems


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Hi Guys & Gals,

Been out of the loop for a while as my bastard boss sent me overseas (H.K.) for a spell. But that's another story, and I'll just say I'm going to take him to Oxley's Hotel on Coro Drive for Christmas; get him drunk, tell him what I think of him; then throw him overboard ! I hope he doesn't read this forum ! He drives a Saab !

Not that I've got anything against Saabs. But you get the picture.


Anyway, I'm back and have a problem I hope your collective minds can assist with.

Heaven's Nicks been at work hasn't he. There's a thing down the bottom of this page called "Guided Mode Off"

(are they fitting auto pilot to old Corollas now ? And another called "Check Post Length" A new reader could think we're in to building fences. Anyway, I digress.


I'll be brief.


KE55 with 5K now onboard has been singing along for several months like a bird, according to my better half. When I got in it after an absence, It was just great.


Anyway, one afternoon while driving normally, there was a great mechanical crunch in the engine, a big sudder & then off she went again OK. This happen another two times before I got it back home. It sounded horrible, even terminal. After that there was a mechanical ticking noise. My first guess was the timing chain, so off it came. It looked all right, until I washed all the sprockets. The single chain had been riding up on the sprocket indicating the sprocket was bent. The sprocket was not bent. The last person to assemble the engine (not me) had left a little bit of swaft between the back of the camshaft sprocket & the end of the camshaft. The camshaft sprocket was running slightly out. As the chain was a bit stretched, and the tensioner was close to the end of it's takeup, the chain rode up, which had resulted in the crunch & probably stretched the chain even more. I didn't notice whether the chain had jumped a sprocket, cause I didn't take notice when removing same.


Anyway, on with a double row chain and sprockets, (thank you Rob !) and we are back to normal; well almost. There is a slight ticking noise every now and then.


I drive it for a week, and except for the slight ticking noise occasionally, it runs like a new one.


Then, it does a horrible thing. The oil light comes on, and I rapidly pull to the side of the road. Visual inspection shows nothing, and I restart the engine, and it provides oil pressure & drives like a good one. Back in the garage, take the distributor out & check oil pump dog slot or anything that could cause sudden loss of oil pressure.


Nothing obvious. As all I have on the dash is the oil pressure idiot light, I connect up an electric oil pressure guage so I can observe oil pressure whilst driving. It runs pefectly for a week, with driving oil pressure between 60 -70 PSI, and idle around 20 PSI.


The all of a sudden the oil pressure starts fluctuating whilst driving, and drops quite low sometimes, but the engine stays as quiet as if it has full oil pressure. I even suspect the guage now, but after taking it out & putting it on another motoor, it proves to be working perfectly.


So I've got a problem. I've never had an oil pump fault before in any car. After pulling another 4K oil pump I have to pieces, I can't see anything that could fail that would create a fault which results in pump working perfectly at some times, & low pressure at others.


The only part of the oil pump that I could see being a problem is the relief valve & maybe it's associated spring.


But then it occurred to me that the oil pump might be alright, but there is somewhere in the lubrication systems where something that is partially broken is dumping oil back to the sump & lowering the pressure.


Tomorrow, the pump is coming out, and hopefully the problem will be clear to see. However, if the pump shows no problems, what else could it be.


I have a few other 3K & 4K oil pumps here, so I was just going to change the whole pump out, and see whether it has an effect or not.


Does anyone know if 3k, 4K, & 5K oil pumps are all the same & interchangeable ?


Has anyone ever had a oil problem with any similar symptoms to those I describe.


Whatever has happened to the pump, or something else mechanical. appears to clearly have happened when the chain jumped the sprocket.


I'm here scratching my head, so any thoughts or suggestions your collective heads can offer will be gratefully accepted.



:( :) :)

Edited by Banjo
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you got me scratching my head too.


i'll have a look tomorrow at the oilpumps i have. i have a 5k one and a couple of 4k ones in the shed. i'll compare them and let you know.


some oil filter bases also have an oil pressure relief in them.


what sort of oil filter is it (brand/size)?


is the 5k still using hydraulic lifters?


guess you won't know until you pull the sump, but is there any crap blocking the pickup?


if i think of anything else i'll ask later.

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Is it a capillary guage, or an electric one? If it's electric, I'd change senders.....


*edit* Having re-read that, I'm not sure thats the problem, as you seem to have gone from what was there, to a guage....

Edited by Redwarf
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i'd be checking the drive on the bottom of the dizy to make sure it's not worn, sloppy or the pins about to break.

the next thing would be the pressure relief valve on the pump to make sure thats not sticking, while you've got the sump off check ALL the bearings just to be safe.


i'd be interested to see what the problem is???

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Thanks for those suggestions fellas !


Before the 5K went it, I had the head done up, and I pulled the sump off & cleaned the oil pickup, so I know that is perfectly clean.


When the problem first appeared, it had a Ryco oil filter on it. Only a week ago I gave it an oil change & fitted a new Japanese Osaka oil filter, and the problem is the same, so I'm pretty sure it is not related to the oil filter.


The distributor is a 5K electronic one, which I had rebushed professionally, before the 5K was fired up. It had a new pin fitted at the time, where the gear at the bottom of the shaft is attached to the shaft. The distributor is in excellent nick.


I've measured all the lengths of distributor shaft and distance to oil pump locator, with distributor removed to make sure that the dog at the bottom of the dizzy shaft locates OK in the slot at the top of the oil pump shaft. The dog goes into the slot 5mm by my measurements, and that correlates with the pressure marks on the dog at the bottom of the dizzy shaft.


The 5K still has the hydraulic lifters, and it is the ticking noise that has me baffled. I'd be glad if it was the pressure relief valve, playing up, but the ticking noise is not related to that. The tick seems to be at camshaft speed.


I'll let you know what I find tomorrow, but would love to hear from you Doug as to whether there are any differences in the 4K & 5K oil pumps.





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i don't have any suggestions beyond what the others said, but i do have a little favour to ask if possible. when you have the pump off next, would you be able to get a photo of the pump outlet where it bolts to the block? i can't put my hands on a spare pump, i don't think i have one that's not in an engine. no big deal if not, cheers :(

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there is a difference in some oil pumps between a 5k and 4k, the oil pump body is 3mm larger.

saying that i think it's the early 4k which had the small body, there's also a bolt on oil pick up type you can get, these were in some vans but i have seen one on a 3k before.

not real common but they are out there.

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I had a similar problem with the erratic oil pressure reading on my speco electric oil pressure sensor gauge. At 5000RPM the gauge got really erratic and even dropped to 0 PSI at times. However, when the car was on a Dyno with a workshop oil pressure gauge (i guess its mechanical), the oil pressure was a constant 70PSI under acceleration. I have never had the stock oil pressure light come on though.


Might be worth checking that there is no rubbish in either of the sensors, if you havent done so already.


My 5K also has an intermittant ticking noise (like a lifter). I too am running Hydraulic lifters, but have never considered it to be a severe mechanical noise. But annoys me regardless, considering its only 1400kms old.

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Jamie, here is a picture of the 5K oil pump, depicting the outlet at the top of the pump shaft.


If you want my old discarded 5K pump for measuements or something, yell out, and I will post it down to you.







Edited by Banjo
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Well made some progess today, and found the problem, I hope !


Not wanting to pull the engine out again, I took the easy way out, by dropping the front cross member & getting full access to the sump.


post-270-1130586909_thumb.jpg post-270-1130586936_thumb.jpg post-270-1130587023_thumb.jpg


post-270-1130587057_thumb.jpg post-270-1130587120_thumb.jpg post-270-1130587914_thumb.jpg


I had the sump off & oil pump in hand in just on an hour.


The sight of the oil pump pickup screen, with small black fragments hanging all over it, gave me the horrors.


Close examination showed they were not metal fragments, but bits of very hard rubber.


When the timing chain had jumped on the sprocket, it bit badly into the tensioner rubber, & chewed it up like a chainsaw.




The sump had lots of bits in the bottom.


I carefully disassembled the oil pump & found the smallest fragments of a black substance, on the end of the pressure relief valve. The valve is a square cut device & is not self cleaning. I have seen tappered ones in other makes of cars that are to some extent self cleaning.


I sorted through my 3K & 4K oils pumps & found a 3k one in remarkable condition. My yellow K series Toyota engine manual, which covers 2K to 5KC engines does not define any differences in specifications for any of the K series oil pumps.


post-270-1130586778_thumb.jpg post-270-1130586841_thumb.jpg


There are a couple of different configurations, including a picture of the one with a bolt on pickup that Tony referred to, earlier in this thread. (good book says bolt on pickup was fitted to KM20 series)


I got out the vernier & steel ruler and measured everything I could & they all seem to be exactly the same.


There seems to have been two main types, the ASCO & AISIN types.


Anyway, I cleaned the sump, the 3K pump, checked all big ends & mains for damage, & replaced oil filter again.


Just awaiting a new sump gasket which I didn't have, and I'll fire it back up on Monday, and hopefully confirm the problem was as described above.


Thanks for the help guys !





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that is excellent, thanks so much for the pics ;)


i've dropped the crossmember instead of taking the engine out before, i ended up wishing i'd just taken the motor out. don't forget to book a wheel alignent, you'll have slightly changed the geometry of the front end, tho perhaps not enough to matter?


i've never seen a single row timing chain before. at first glance i was like "[email protected]$k it's only half there!!!" lol


top effort with all photos and finding your problem, that's what it's all about :jamie:

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