Low Oil Pressure

[martinimit]

I've been reading up on the problem and here's my situation:

I just had to replace the oil pump. While my mechanic was in there, he suggested replacing all that needed replacing. O rings, etc. $1400.00
A week later the Stop Car, No oil pressure light comes on.
Take it back to the mechanic, he doesn't know

Oil pressure light come on when the car is hot and idling or I let off the gas. It runs fine with nothing out of the ordinary EXCEPT, sometimes it does stall when starting.

Is there no way that the oil pump has anything to do with it? The mechanic is telling me it's a separate issue.

Thanks,

jv

2001 XC70
185,000 miles and counting - I hope

[dhayner]

Start out with why you replaced the oil pump.

[Astro14]

If you've replaced the pump and O-rings for low pressure and you still have low pressure, then the pump and O-rings were not needed.

You need to have a serious conversation with your mechanic, because that $1400 did not fix your problem. The pump is no longer a possibility, but the problem remains.

The light coming on when hot and idling leads me to believe that the light is working correctly, if you had low oil pressure, that would be when it is the lowest. Low pressure with a good pump and good o-rings is caused by either oil that's too thin, or excessive bearing clearance. So, back to the mechanic...and yes, they are absolutely related...your oil pump may have been fine in the first place...

What did your mechanic say when you "had to replace the oil pump"? What was his diagnosis then? When he had the pan off, how sludged up was the engine? Did he replace and/or clean the pick-up? In a heavily sludged up engine, there are many possible issues.

As a stop-gap (and for curiosity) you cold try replacing your oil with something a bit heavier, try a 5W40 like the Shell Rotella T6 (inexpensive at Wal-mart, synthetic, runs a bit heavier in grade than many other -40s) and see if that will get the light to stay off when hot and idling...frankly, in this engine, given your miles, and given the problems that you are having, I would run the Rotella T6 5W40 anyway - it will help clean up (slowly) the sludge that I suspect is present.

[hoonk]

Does the warning ever come on at times other than at idle? If so, low oil pressure in these engines can be caused by a clogged oil pickup tube - clogged from "sludge" that forms due to lack of oil changes or maybe poor quality oil. Remove the pan, replace the tube with the new design, clean all the passageways and the remaining sludge from the oil pan and reinstall making sure the orings sealing the pan to the lower block stay in place during that process. Normally takes a few hours in time, with most spent cleaning the oil pan. A word of caution - if the oil pickup tube is clogged there's a good chance the oil feed tube to the turbo is partially clogged also - most of the time we find a low oil pressure condition AFTER replacing the bad turbo and clogged oil feed tube. (Car arrives smoking badly out the tailpipe)

Occasionally I will find just a problem with the orings, possibly from a previous repair. Many times my shop has had to do the job twice because an oring was dislodged when the pan was reinstalled.

The other possibility is the clearances are too large in the rod and main bearings, cam bearings - you would have more serious problems if that were the case.

"had to replace the oil pump" - it's possible but I've never seen it, Sorry for your wasted dollars.

[martinimit]

Hello all, thanks for the replies and my apologizes for the delay in getting back.

It started with a crack oil filter. Oil all over the ground and had the car towed to my mechanic. We've been taking our car to him for years and have no reason to doubt his work, except he's been ill over the last few months with a friggin' brain disease. I'm not trying to throw him under the bus, just letting you know all the facts.

Upon replacing the cracked oil filter, he said the oil pump needed to be replaced. We went for it and it's been downhill since.

Since I posted this originally, I have discovered that it is, in fact, happening when the engine gets hotter. And only when the car is idling in traffic or at a stop.

Today I'm am having the oil replaced with the heavier grade as recommended by Astro14.

Thanks again!

[dhayner]

My guess is going to be worn bearings, causing excessive clearance and low oil pressure.

[martinimit]

Thanks dhayner, and that might be part of it also.

Went to a place called Mr. Oil (decent yelp reviews), had the oil changed as suggested by Astro14. The person working on the car thought it was sludge in the tubes as Hoonk had stated. The inside of the oil filter housing had quite a bit of sludge at the bottom of the cap. Upon inspection of the oil filter which is only 1 month old, it was jammed with sludge. He said to bring it back in a month and replace the oil filter.

After driving it for the last few days I have seen a slight improvement - I think. When cold the car runs fine, now when it gets to the "hot" temperature, the "low oil pressure" isn't coming on as quick. Meaning it takes 10 minutes instead of 1 minute.