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Oil pressure problem with 2.0

12K views 13 replies 5 participants last post by  CPOdaddyduke 
#1 ·
Hi folks,

I bought a 2001 NB that had overheated. I pulled the engine and rebuilt it. The crank was within spec as were the rods. I had to install new pistons and all new bearings. The head was rebuilt. I also installed a new oil pump and pickup tube.

It started right up, which was great! However, I put an oil pressure guage on it to ensure pressure was good. But its not. I have 10w30 Castrol oil in it. At cold startup, it has about 50 PSI at idle and accelerating will raise the pressure to 60 PSI. As it warms up, the pressure drops to 20 pounds at idle.

I used plastigauge on the camshaft to ensure there is no excessive clearance there. I did not do this on the crank. At this point I think I have to pull it out and apart to try to find the problem.

Anyone have any ideas of something else to check before I do this? I tried two pressure gauges on the engine - same result. Also two oil filters - no change.

Thanx in advance!

Z
 
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#5 ·
Just pulled everything oil related off, checked, reinstalled, and added a second pressure gauge. Now I have one gauge going into the filter and one coming out. They both read about the same - still about 50 PSI at cold startup. Didn't let it warm up, but am assuming that it will drop again.

I checked the oil galleys and they are unobstructed. Checked everything on the oil filter flange and it is working well. At this point, if I only have 50 PSI coming from the pump, I can't expect more. So I believe this pump to be defective. I will order a replacement on Monday and see what happens then.

I will keep everyone posted.

Z
 
#6 ·
Quick update. I thought more about it and thought it practically impossible for a mechanical oil pump to go bad. I also deduced - after talking to others - that a weakness in the system after the filter would cause the pressure at the filter to drop.

Based on this, I pulled the engine and took it apart again. No apparant issues to be seen. Used plastigauge on all main bearings and they are all at about 0.00175". The big end of the rods were checked by a machine shop, so I assume they should be fine.

Now I am wondering if there isn't a crack in the case? I will sleep on it and tackle it again in the morning...

Z
 
#10 ·
GTRAFF said:
You have probably already checked this, but just in case - the oil pump has a pressure relief valve set at 175 psi. If it is defective you might not get the correct pressure.
That certainly is a possibility. I loked at it and it seems ok. I ran the pump by hand in a bucket of oil with a drill and it seems to be pumping plenty of oil. If I can't find any other issues anywhere, I will try another oil pump. Probably should have done that first, but it just seems like a very remote possibility.

Thanx!
 
#14 ·
Is this thread still being looked at? I am having similar issues (oil pressure a little lower than spec at idle when warm).

Thinking about trying a heavier weight oil (like 10W40 vs 5W30) to see what happens.

My engine has 175,000 miles (AZG 2.0L, 2001 NB) engine replacement or rebuild is not an option. Should I just replace oil pump?

Where is the relief valve and how do you get to it?
 
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