odd 4age oil pressure issues. up and down in pressure.

[wiso]

***Solution found. See my post on page 2***


hi guys i have a really weird oil pressure issue on a rebuilt 4age bigport to stock specs.

the history on first start i ran the engine the took it around the block before i noticed the oil guage showed nothing. this was my stupidity. the cheap gasket kit had no flow hole in the gasket so it all forced back through the relief valve.

so on went the original bigport pump (differant one to the issue above) and new gasket. the pump was working fine on the motor before rebuild. started it again this time had good oil pressure. although i got a metal screech for a short time on start up but it faded quickly. i had checked the bearings after the initial issue they looked ok.

so ran the car for 150km everything was going great. then went on a 400km drive and in the last 50km only the oil pressure started to show lower on the stock guage then it had for the previos 500km.

so pull the sump check all bearings the conrods look bad so i bought new ones. test drove again. first 10-15km oil pressure was great. then started to dip again. then went back to normal. then dipped so on an so on.

put another pump i had on also from old running engine. same thing. great at first then starts to dip. then normal etc.

so i got a mecanical oil pressure guage and fitted it up today. drove it. yes at first at 3000rpm the oil pressure was steady at 50psi. at idle it was steady at 20psi. then after the 10-15km and warmed up at 3000rpm it had droped the 45psi. then abit further on it had dropped to 35psi. and idle at first had droped to 7psi. but when i got home and put her back in the garage it dipped to under 5psi.


so the question is anyone know what what the go is here. is it very likely to be pump or something else could be at play. i find it odd that 2 pumps act the same way.

i have 3 car regos due this month and 3 insurance next month so money is very tight for a new oil pump atm. so i don't want to buy one if i don't need to.


thanks

[wiso]

i forgot to mention i have pulled the gears and relief valve from both pumps and both are withing the manuals spec using a feeler guage.

[allencr]

Very unlikely to be the pump or even a sticky relief valve.
Bad assembly or journal damage from that first dry try. Smegma, dirt in galleys, parts mismatch - rod & main caps.
Also, can you estimate how much torque it took to to spin it. before & after the pistons?
Sorry. Good luck.

[wiso]

on original build, it was tight to spin by hand, used original toyota bearings and matched the block marks with the crank marks to get the tgp bearing marks.

I am positive everything was align correctly when assembling. but even still after the first low oil pressure happened I replaced all the conrod and main bearings. popped the conrods off the crank and replaced them and span in new main bearings. so ahould have changed the assembly if it was done incorrectly. No caps were mismatched. I scratch the side of them before disassembly and put them straight back together.

I am worried about oil journal damage or blockages.

[oldcorollas]

what oil are you using?

[wiso]

woolies home brand 20w-50. since still bedding engine i need stuff as mineral as possible with no additives. shitbox oil basically.

[oldcorollas]

it may not quite be 20w-50 then

what rpm does the pressure rail out at, when cold and warm?

has oil been changed yet? does the oil smell like fuel?
if it'S rich, and fuel is getting past the rings, the oil could be quite a bit thinner than out of the bottle per'aps?

is the oil pressure gauge location affected by bypass? ie filter bypass? (i dunno where it is on 4A).

[allencr]

Is the dipstick level 1-4cm over what you put in it?
Cut the filter open to see what's been trapped. Anything there is from pump damage, new bearing damage or what you left in the engine that did it to the pump.
It's gotten bearing damage with good & more then adequate oil pressure, so it's shit after the filter or bad assembly clearances.

[wiso]

it may not quite be 20w-50 then

what rpm does the pressure rail out at, when cold and warm?

has oil been changed yet? does the oil smell like fuel?
if it'S rich, and fuel is getting past the rings, the oil could be quite a bit thinner than out of the bottle per'aps?

is the oil pressure gauge location affected by bypass? ie filter bypass? (i dunno where it is on 4A).

no the oil does not smell like fuel, its reasonably clean.
The oil pressure really wigs out mostly at idle. but its lower constantly through the whole rev range once it has gotten low at idle. if it never gets low at idle it is better.

Pressure guage is in the stock location, on the block directly after the pump feeds into the block.

Is the dipstick level 1-4cm over what you put in it?
Cut the filter open to see what's been trapped. Anything there is from pump damage, new bearing damage or what you left in the engine that did it to the pump.
It's gotten bearing damage with good & more then adequate oil pressure, so it's shit after the filter or bad assembly clearances.

No in the time I have driven it nothing has been added or taken from the oil, the level is constant where I fill it to. and the engine is not blowing any smoke.

I did 1 lot of running in oil for the first 500km, a bit more than I usually like, normally I don't like to change more than 250km. then changed to this and did another 400km thus far. I am thinking about putting a oil flush through and changing it now as I usually do 250km then 1000km oil changes on a new engine.

I have not cut the filter open but when I drained the oil and took the sump off on the first change I had some metal flakes rather than shavings in the bottom, but I have pulled all bearing and cams and can't see where that damage may have come from so it could be pump, I am going to open the pump back up today to look see.

---------------------------------


The plot thickens alittle. On sunday I put a 3rd pump on the engine just to try it. this time a smallport pump. It ran Sunday very nicely, it ran Monday VERY nicely. But today, oil pressure has dropped again.

On sunday and monday it ran consistent 50psi @ 3000rpm once warm and idled @ consistant 15psi.

Today @ 3000rpm its got 35psi, and @ idle is 5psi.

What the hell. New pumps seem to run fine for a few days them revert.


So how do I tell if there is journal damage? when I pulled the bearings off all the edges of the oil journals on the crank look clean, no burring or damage to the edge and plenty of oil drained from the holes in the crank when I span it around.

[knightrous]

According to the 1989 AW11 BGB (page 333), 4.3psi or higher at idle is fine for oil pressure and at 3000rpm anything between 36psi and 71psi is within spec.

[wiso]

indeed it says that. but this is how it started last time, was higher giving good readings, then dropped to about 5-6psi, then made a nice drop well below 5psi.

I just can't fathom as to why its fine for a few days then just suddenly starts dropping. it can't be normal.

[wiso]

found another bloke who's had the exact same issue, unfortunately he never posted up if he found a cause of the issue.


4age low oil pressure [Archive] - Hachiroku.net | Forums

[Harreh]

Redacted..

[oldcorollas]

pressure drops cos either
a) oil viscosity is decreasing. it decreases with temp, and should start out reasonably similar when cold. hot viscosity depends how hot it is getting
c) oil leaking out from somewhere or more being consumed (as in bearing consumption)..

assuming a) is ok, and you are not overheating oil when it does funny things...

could be some clearance opening up when engine is warm and letting more oil out through gaps? or stuff getting caught in the relief valve and preventing it from sealing shut (so it reduces pressure everywhere)...
umm.. seal between pump and block, or between pump and pickup? either leaking oil or picking up air?

not sure about galleries to head tho...


oh.... are you 100% sure you have not left a rag or anything in the engine?
I left a tissue/bit of paper towel in a sump once... would run ok fo ra while, then suck the paper onto the pickup, and oil pressure would drop.. stop engine, oil presure back again.. run along for a while, then oil pressure drops again.....

if you can't find anything else.. drop sump and see if you left something in there
you might be covering X% of the pickup

[wiso]

I have had the sump off 5 times in the last 2 weeks, there is definitely nothing in there.

a) I am not sure about, don't have an oil temp guage. Today I am using an oil flush to see if it clears up any galleries and then I will change to a differant oil, maybe GTX3 or something decent mineral based. as the engine has 1000km on it now.

could be some clearance opening up when engine is warm and letting more oil out through gaps? or stuff getting caught in the relief valve and preventing it from sealing shut (so it reduces pressure everywhere)...
umm.. seal between pump and block, or between pump and pickup? either leaking oil or picking up air?

not sure about galleries to head tho...

This is about all I have to go on, but would this act like it is? I mean pressure being perfectly fine for a few days and about 150km then going low. Why would the bearing clearances open up more after a few days? when the bearings haven't changed

the second pump was changed in when the bearings were replaced and it was fine for a couple of days then the oil pressure dropped, then a new pump was changed in it was fine for a couple of days then the oil pressure dropped. Does this sound like bearing clearances to you? I would have thought if it was bearing clearance I would have thought it to get low pressure once the engine heats up on the first day, not wait for a few days.



the first pump that had the oil pressure drop maybe I can understand a little of what happened, opened it up yesterday, got a large gouge around the pump gears in the aluminium housing that wasn't there when i first opened it before I ran it.