Oil Pressure issues... stumped

[91SHOInterceptor]

Ok. Ive read through various threads but havent found exactly what I needed for my specific problem. I think its either a bad oil pump or rod bearings.

Problem: Oil light flickers after the car has been running for about 15 minutes at idle only.

Scenario: I recently changed the bearings and the old ones didnt have much wear at all. I have found no metal in the oil pan at all. The oil pump is the original one and has about 150K miles on it. I was using 5W30 but then switched to 10W40 recently. I also recently installed an Autometer oil pressure and water temperature guage to help find the problem.

When I first turn the car on oil psi is about 50 at idle. The car warms up and temp guage reads in between 180 and 215. The oil slowly falls at idle to almost 0 over 15 minutes. Eventually the stock oil pressure light flickers and stays on constantly (at idle). The oil psi goes up to about 15 to 20 psi when I am actually driving and the oil pressure light goes away. I have not had any overheating or oil leak issues at all. I can smell oil alittle at times but have not found anything on the heads, cam seals, block, starter, or oil pan.

There is no knocking and the car performs great. The only noise I can hear is from the clutch when the car is not in gear.

I did buy a used oil pump off ebay with a new gasket but I have no way to test if it is a good one. Is there a way to test it before installing it?

Any ideas of what could be causing this? too lean of a mixture? rod bearings? bad oil cooler? bad oil pump?

Any additional info would be appreciated. Thanks in advance.

 

[twr]

Question, was the oil pressure this low before the bearing replacement?? If not it is possible the crank was reground at one time. If you installed factory sized bearings, this would result in low oil pressure.

Other thing that comes to mind is that whatever you are using as a tee to get pressure to the idiot light and Autometer gauge is restrictive and the sending units aren't getting full pressure.

I haven't heard of to many SHO oil pumps going out like that.

 

[SHOZ123]

Did you change the main bearings too when you did the rod bearing swap?

 

[Slo-Sho]

91SHOInterceptor:

The oil psi goes up to about 15 to 20 psi when I am actually driving and the oil pressure light goes away.

How many psi do you get at 3k hot? Did you use an (oil pump-to-p/u tube) gasket or RTV?

 

[91SHOInterceptor]

I dont know if the oil psi for this engine was low or not. Everything was replaced when the 3.2L swap was done. I bought the engine from a guy who restores Mustangs. His wife had a 94 ATX SHO and was rear-ended which totaled the car. He said the engine was running great and only had about 84K miles on it. Everything was replaced as far as main bearings, rod bearings, piston rings, etc. I used the oil pump from my engine since it was working fine before. I couldnt tell if the crank was ever regrounded before I got the engine.

The SIL (Stock idiot light) was flicking before I installed the T connection for the stock oil sensor and the autometer sensor. I used a brass 1/4" T connector to connect both sensors. Its the same size as the threading for the stock oil sensor.

I found a gasket for the oil pick up tube right before they were discontinued several years ago. I started collecting parts a couple of years before I actually did the swap last year(too expensive to buy them all at once). Plus I had help to do the swap.

I get about 20 psi at 3K rpm.

I guess what confuses me is that the problem is not constant. Everything is fine when first start the car. No lights... pressure is good at idle... its just after the engine warms up and sits at idle. shrug Any other thoughts? Can any blockage of coolant be a problem? The entire water manifold, water pump, radiator, and heat core were all replaced during the swap as well. Everything was taken apart, cleaned, and put back together.

 

[NotSoSlowSHO]

Your oil pressures are WAY low. 20 pSI @ 3k?
Hot, 3k should give you about 50 PSI.

Did you check the oil pump for wear prior to installing? Was it to spec?

 

[pjtoledo]

Did you put the 3.0 oil pump in your 3.2? They are supposedly different, but I don't know how. You did a complete rebuild? Lots of possibilities for problems.


Perry

<small>[ March 24, 2004, 09:08 PM: Message edited by: pjtoledo ]</small>

 

[Electricat]

pjtoledo:
Did you put the 3.0 oil pump in your 3.2? They are supposedly different, but I don't know how. You did a complete rebuild? Lots of possibilities for problems.


Perry

The 3.0 pump has an "arm" of the casting that extends up the block from the right hand side of it. This area is occupied by the timing belt tensioner on the 3.2. AFAIK, they are otherwise identical.

 

[91SHOInterceptor]

While running the engine "hot". The psi is about 12.5 at 3K, 20 at 4K, 25 at 5K. Thats about it. I am looking for some options to figure out what it can be. I dont want to start ripping things apart before I have an idea. I would like to try and see if it is the bearings or oil pump or something someone hasnt considered yet. Any tests that anyone can suggestion to narrow done the possiblities?

 

[Electricat]

Until recently, I was having oil pressure problems also, not quite as bad as yours, but close. I replaced the rod bearings, which showed normal wear for my 114k miles, and I also did a front 60k while I was at it. The actual cause of the pressure issues turned out to be a clogged pickup. All the crud and burned oil had plugged the entire bottom of it, so it was only taking in oil around the edges! My pressure is still a bit on the low side, but MUCH improved (hot @ idle 10psi, hot @ 3k 36psi). Since your engine has recently been torn down, this is probably not the issue, but it is a possibility that I thought I should mention.

BTW, if you are still driving that car, PARK IT! You are risking accelerated wear, and possibly catastrophic engine failure.

 

[RAYJAY]

Your oil pressures are WAY low. 20 pSI @ 3k?
Hot, 3k should give you about 50 PSI.

Did you check the oil pump for wear prior to installing? Was it to spec?

what is the spec on the 3.2 oil pumps and how do you check them

jeff