2.9L high oil pressure

[koldcustoms]

I bought an '87 XLT 4x4 5spd last September knowing the truck had a few issues. First; the rocker covers were leaking. I soon found out that this was a common problem with the 2.9L. When I pulled the covers off to replace the gaskets, the sludge build-up was an inch thick (no exaggeration). The covers were like jello molds! I was surprised that anything was able to move under there. I scooped out as much as I could before re-installing the covers with new gaskets.

The factory oil pressure gauge read right on the mark between normal and high at this point. The previous owner was running 10W-40 oil and with my discovery under the rocker covers, I figured there's an oil passage blocked somewhere, causing the high oil pressure indication.

I had a litre of ATF lying around my shop and decided to use it to flush the oiling system. After 10 minutes of warm up, oil pressure fell to the mid point of the 'Norm' band. I then preformed an oil/filter change using 10W-30 and a bottle of Rislone. After restarting the motor, the oil pressure immediately rose again to the high mark.

Since then, I've preformed 4 oil changes using a commercial grade oil system flushing chemical before each change. I now run 5W-30 and Rislone in the truck, and still have high pressure. I'm beginning to suspect an indication problem. Any thought on this?

Can somebody give me the procedure to run an oil pressure check to verify this? Where do I connect the gauge/ what fittings do I need? The manual I have will not help me here.

There is one other problem, but I'll save it for a new thread.

Thanks

 

[MAKG]

Unscrew your oil pressure sender from the block, and replace it with an aftermarket mechanical gauge. Warm up the engine and run it to 2000 RPM. Measure pressure. Spec is 40-60 PSI.

I strongly suspect a bad sender, though it's possible the pressure relief valve is sticking (or is plugged with sludge!). That's BAD; it can make the oil filter explode at high RPM, with catastrophic results.

Man, I'd be pissed with that much sludge. It seems someone doesn't believe in oil changes....

 

[koldcustoms]

Yes. The previous owner admitted to neglecting the maintenance on this truck. In the 4 years he owned it, he never preformed a tune up. Again, more surprises for me to discover.

There were severe vacuum leaks in the PCV system, among other places. Who knows how long it had been like this before I received it. Gasoline fumes + never changing the oil = sludge, and lots of it in my case.

I'll check the sender and the pressure relief as you say. I'm going to guess that they are located on the passenger side of the block near the oil filter. Is this correct?

 

[MAKG]

I believe the pressure relief valve is built into the oil pump on this model, so it's hard to check out physically. Maybe someone else will have a better idea.

However, you can check it out with your pressure gauge. Oil pressure should be proportional to RPM to a point. That point is the pressure relief valve. If it keeps going (say, above 100 PSI), assume it's gone.

Replacing the oil pump requires pulling the engine. But then, you can scrape the few inches of sludge out of the oil pan that way....

BTW, when you changed the oil, how much did you put back in before it was full? Should be pretty close to 5 qts. That might give you a clue how much sludge is in the oil pan.

On a 2.9L, the pressure gauge sender is underneath the power steering pump.

 

[ronclark]

Replacing the oil pump requires pulling the engine. But then, you can scrape the few inches of sludge out of the oil pan that way....

I have replaced the oil pump without pulling the engine, you will need to unbolt the motor mounts and lift it up abit. but it was not to bad. took me about about a hour

 

[koldcustoms]

5 quarts was overkill the first couple of times I changed the oil/filter. I preformed the last change 3 days ago; a 4.4 quart jug of oil and a bottle of Rislone filled the pan to the overservice mark on the dipsick before the engine was ran. The old filters weigh a ton once they're removed! So my engine flushing regiment is working, from what I can tell.

There is a slight improvement in engine performance this go around. However, my indication remains the same. I'll get around to checking the pressure this weekend.

 

[UnderMedikated]

High oil pressure even possible in a 2.9?

Can you even get high oil pressure from a 2.9 V?

 

[holyford86]

i had one that ran about 55-60 psi @2,000 and about 45@idle warm

 

[UnderMedikated]

Why do you need to pull the engine to change the oil pump. That is plain retarded?

 

[holyford86]

well, its kind of hard to pull the oil pan off because there is a nice big crossmember in the way