[evilgidget]

Can it be done with the engine still in the car?

I've got an issue with oil pressure dropping too low as the engine warms up. It was checked with a mechanical gauge and unfortunately it's not the sender...
Pressure slowly drops down to about 1 bar at highway speeds, with a corresponding increase in top-end noise. This may last for 5 minutes or so & then spike back up to 3-4 bar, then drop slowly again...
The engine temps also climb 10-15 degrees according to the dash while the pressure is low, so I imagine it's not ALL in my imagination

This is obviously concerning to me, so I want to get it sorted out soon.
Any other suggestions first?
Oil is semi synth, but it's what i've always used with no issues prior, and it's reasonably fresh still.

 

[Alfisto Steve]

I doubt you can get pump out of engine with front cover on engine even with pan off because one of the mounting bolts is hidden behind front cover so that means timing belt and front pulley has to come off first. It is real hard to get to that third bolt with front cover on engine.

But if problem is with pressure relief valve spring or popppet located on bottom of pump once you get pan off you can get to cotter key and relief valve threaded cup that sets spring tension.

Have you tried changing oil filter first just to be sure valve in filter element is not your problem?

Hope these pictures help:

 

[Alfisto Steve]

164 12v engine front cover and oil pan

Front cover, oil pan and pick up tube:

 

[Alfar7]

Probably not oil pump

With your discription of problems, I would not head for the oil pomp,
Th #1 source of low oil pressure is the clearance between the cams & cam caps (bearings) The aluminum caps take all the load from the cams/springs. As they wear the clearance under the cam becomes excessive and since the oiling is from the bottom it has a straight shot out from under the cam due to the excessive clearance.
The clearance tolerance is from .0008 to .002 (thou/inch). Max should be about .0015. Proceedure for modifying the bases of the caps is simple & I have covered in earlier post on BB.

 

[gt601]

I replaced mine with the engine in the car. Took around 3 hours.

Paul

 

[ChazzyD]

Do you guys cut down an allen wrench to get to that third bolt? Seems the only way to get it out.
Charles

 

[evilgidget]

Th #1 source of low oil pressure is the clearance between the cams & cam caps (bearings) The aluminum caps take all the load from the cams/springs. As they wear the clearance under the cam becomes excessive and since the oiling is from the bottom it has a straight shot out from under the cam due to the excessive clearance.

Given the mileage on my motor, initially I thought big end bearings & clearances, but surely if that was the case, I would expect the oil pressure to drop & stay low? Mine comes back up after a short while.

If the pump checks out i'll look into cam clearances anyway - If I can find the post

The main reason I wanted to pull the pump is to check it's clearances - I take it once I have the sump off (like in Steve's pics - Thankyou again ) that I should just be able to remove the 3 bolts holding the relief valve/cover & I should be able to go at it. Correct?

 

[gt601]

I used a long 3/8" allen ball socket from Snap on or Matco. Forgot where I bought the set. It was not a walk in the park but it can be done. If I knew that it was going to take me that long on top of replacing the heads I would have pulled the motor. I lowered the subframe and jacked the engine up enough to remove the pan and then the pump came out. I found a used one on ebay but now that I look back and as well as the car runs with the new cams I probably should have bit the bullet and got a new one.

Paul

 

[Alfisto Steve]

Given the mileage on my motor, initially I thought big end bearings & clearances, but surely if that was the case, I would expect the oil pressure to drop & stay low? Mine comes back up after a short while.

If the pump checks out i'll look into cam clearances anyway - If I can find the post

The main reason I wanted to pull the pump is to check it's clearances - I take it once I have the sump off (like in Steve's pics - Thankyou again ) that I should just be able to remove the 3 bolts holding the relief valve/cover & I should be able to go at it. Correct?

Those bolts hold pump cover on. I believe if you pull them pump driven rotor gear will fall out. Drive gear is attached to shaft with nut on end.

If you want to check relief valve spring and poppet you have to pull cotter key and screw out adjustment cap but count turns until cap is flush with end of pump housing so you can reset it correctly. You will probably need to test spring height and tension at a certain compression measurement which is in shop manual.

Spring free length is 49.29 mm (1.941") and loaded test length 31.90 mm (1.256") at 170-176N (38.2 to 39.6 lbs) of force on spring test dynamometer.

See pages 01-79/80 for measuring gears and testing spring in shop manual.

If relief valve poppet sticking you may have to pull bottom of pump off but there maybe a gasket that maybe damaged pulling cover so be careful but you can then be sure poppet bore not scored and rotoru gear not worn.

 

[elite38868]

Do you guys cut down an allen wrench to get to that third bolt? Seems the only way to get it out.
Charles

That's what I did! I would not recommend doing this job with the engine in the car...

 

[evilgidget]

*Minor update*

Just to confirm that it WASN'T the oil/filter, I put a new filter on & some nice clean Edge oil (Syntec, but renamed for Australian market...). I now get 6 bar while the engine is warming up, but after the engine hits 80*C, it starts to slowly drop again. Not as low as before, but still quite low. Now i'm not suspecting the oil pump...

Alfar7 - can you point me in the direcion of the cam thread you referred to? I can't find it.

Actually, can this be a sign of something wierd like, say my water pump not working, lowering coolant flow & having the engine technically overheating without me knowing it? I have noticed the car wants to be at 90*c a lot lately (although it's hotter than Hades here just at the moment)
Wife also reported that mother-in-law saw car 'smoking in some way' the other day (not surprising given the mileage on it).

Should I be considering a full tear-down & rebuild? (no, as i'll be murdered for spending that much money on it )

 

[ChazzyD]

For about a month before my engine spun number 5 conrod bearing and a crank bearing, I was experiencing the oil light flickering on toward the end of my daily commute of ~45 min in length (and just after interstate stop and go traffic). So sounds like a similiar issue you are having. I wish now I had parked the thing before I tore it up so bad as it would have been an easier rebuild project than it is now. I did find a replacement engine though and the car is back on the road with a younger engine so all is well, but I feel a little guilty for running the other so far into the ground. Sounds like yours may be headed in the same direction, sorry to say.
Charles

 

[evilgidget]

So it spun due to being overly worn?

Always a possibility in a high mileage engine I guess, although my oil pressure isn't getting bad enough to flick the low pressure light on (yet).

 

[Alfisto Steve]

Worn engine bearings

So it spun due to being overly worn?

Always a possibility in a high mileage engine I guess, although my oil pressure isn't getting bad enough to flick the low pressure light on (yet).

My son's Green ebay special that had 12 bent valves (now repaired) also has oil pressure problem when warmed up and oil light does come on. It has rattling bearing noises so we know lower end living on borrowed time. It runs good and drives good but we put it away for safe keeping until a day when we can either part out or replace engine.

Not sure it is worth the effort but we hate to thrash out a good running 164 no matter how low the market prices go.

Guess that is what a Rescue Society is all about.

As for checking bearings for wear you pretty much need to pull pan which is a
Royal PITA with engine in the car and valve covers and apply air pressure to oil system to see which main , rod or cam bearing cap shows the most leakage and then pop that cap and inspect.

 

[ChazzyD]

Weeeeeeell... I wasn't driving it gingerly to say the least, when I heard the evil noises begin to develop. So, low oil pressure mixed with high stress and out of spec clearances was the final nail, you get the picture. Drive it nice.
Charles