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Discussion Starter · #1 ·
I'm wondering why my oil pressure goes really low on iddle. Is it because the pump's gears gaps are getting too big. What causes it to fluctuate like that? Is the only way to fix it is to change the pump? Could I put thicker oil to fix it? :confused: nic
 

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i'm keen to get some answers about that too! I also have an 86 and my oil pressure is very low (practically non-existant) when idling. my truck runs fine though, I get good mileage, but my pressure is way down. I had my timing chain replaced about 9 months ago and the fellow that did it said my oil pump was fine! so who knows??

nicolas_bc said:
I'm wondering why my oil pressure goes really low on iddle. Is it because the pump's gears gaps are getting too big. What causes it to fluctuate like that? Is the only way to fix it is to change the pump? Could I put thicker oil to fix it? :confused: nic
:canadian :beer :canadian
 

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Discussion Starter · #3 ·
I just did my timing chain 2 weeks ago and I checked my oil pump at that time. Sure looks good but the gaps were getting a little over. My truck is running very good too. I can't stop looking at the pressure gauge. I didn't actually checked the pressure to see if it was fine. Maybe it's the gauge itself. Did you check your pressure?
 

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If memory serves me correctly , @ idle the oil pump pressure is is 8-10 lbs .

A cause for lack of pressure usually overlooked is the timing cover , where the pump bolts to .
if it is grooved , it will cause a lower oil pressure .
 

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Discussion Starter · #5 ·
why would the cover size get any bigger though? The gears are not touching the cover. It could be a reason. I don't know. WWWWWWWHHHHHHHHHYYYYYYY:soso
 

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the back side of the oil pump , the part that doesnt come off when you remove it .... is the timing cover , and yes the gears do touch it ....If it is grooved , it can create lack of pressure .

I'm not saying this is the problem , it is quite normal for the guage to right down . 8-10lbs .....check it out .
 

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my book says 4.3psi minimun at idle and 36-71psi at 3000rpm.
your pressure drops simply cause the pump isnt turning as fast.
 

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that sounds good, takes a bit of a load off. too bad there's no #'s on the gauge, I haven't manually checked my pressure either, but the needle runs just below about half way when driving. again though, truck runs really well. oh well guess I just half to sit back and wonder.... but

:beer is good!!
 

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mine was really low, got a new guage still low. took the pan off and found the thrust bearings burt out, engine shop told me yotas have a problem with the thrust bearings cause of the low pressure and pushing the clutch in at idle(lo oil pressure)
 

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I was going to ask the same question. I'm new to this list and I just bought a Black 85 Toyota ext-cab 4x4 SR-5 for $2900!!! The box is rough but the rest is pretty much mint. Anyways it has low oil pressure too so these replies make me feel a little better.:D
 

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One cheap trick is to replace the oil pump relief valve spring. I replaced mine and my oil pressure increased noticeably. Going by the gauge of course. Like $5 at Toyota.
 

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Discussion Starter · #13 ·
Thanks for the tip. Why does the pressure goes up though when you change the pressure valve spring?
 

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I guess the springs get weak, and the valve opens too easily. This results in a lower operating oil pressure at lower rpms.
Sound right?
 

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Discussion Starter · #15 ·
Is your oil pressure still going up and down now that you've changed your spring?
 

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Oh ya, it still rises and falls with engine rpm, but the needle remains quite a bit higher at idle. Of course, if your pump is overly worn, it may not do the trick. But hey, worked for mine, and I've got 312,000km on it. I changed the spring when I did my timing chain.
 

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Discussion Starter · #17 ·
well it sounds good. I'll change it since it's pretty cheap anyway and easy to do. My oil pressure is not that bad so it might bring it up pretty good. thanks for your reply.
 

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read your wanted add
 

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I've always felt that before you tear into an engine you should put a good mechanical shop gauge on the motor, and take cold and hot pressure readings.
From what I've seen, factory gauges, even toyota are notoriously inaccurate.
Put a shop gauge on and see what it says, and don't be alarmed by a motor with 200 000km's that has 4psi at idle, watch what the hot readings are at higher rpm.
8 psi at 2500 is something to worry about, but then again I've seen some motors rattle on with hardly any oil pressure for years, go figure.
 
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