[newmexicosaint]

Ok, guys..

I just dropped a 598 c.i. ford stroker in my mustang and I am facing an unusual oil pressure issue. The engine holds 45lbs pressure cold and 15lbs pressure hot. The pressure does not increase with RPMs more than 1-2lbs.
We have changed oil pump, gauge, and checked oil galley plugs. we have also pulled the pan and primed the engine to see if we had a cam bearing washed out. I am at a loss and could use your insight and theories. Thanks folks.

[Gokussj5okazu]

That's not extremely unusual if you think about it. It holds good pressure when it's cold because the oil is thick, but thins out alot when it gets hot. Sounds like you just need to run a thicker oil. What weight are you using?

[67 Deuce 4 Me]

Only gaining 1 or 2 psi when revved is not normal. Taking into consideration what you have already checked. I would have to think there is excessive clearance between your crank and bearings allowing pressure to bypass just my .02. Did you search old threads for similar problems?

[curtis73]

Possibly a bypass valve stuck open?

[KULTULZ]

Originally Posted by curtis73

Possibly a bypass valve stuck open?

Did you use a HV pump (MELLINGS hopefully) and did it come with two springs? You might want try the higher pressure relief spring and see what happens. Did you take a mechanical oil pressure reading at both the front and rear galleys?

[newmexicosaint]

Per Jon Kaase racing engines I used a melling hv pump and valvoline racing oil 20-50. This is a new pump replacing a new pump. I dread checking the rod and main bearing clearances but I am about out of options (man, this sux). You guys have all been great for responding. Let me know if you come up with anything else. I'll keep you posted.

I did not change the spring in the pump but achieved higher pressure with the replacement. I also have not checked pressure at the oil galleys-I have only checked at the back of the block. This is the ford racing A-460 block and I am new to the ford thing. (been a chevy guy all my life, I just have a mustang fetish, he he)

[xntrik]

Originally Posted by KULTULZ

Did you use a HV pump (MELLINGS hopefully) and did it come with two springs? You might want try the higher pressure relief spring and see what happens. Did you take a mechanical oil pressure reading at both the front and rear galleys?

Spring limits the maximum pressure, not the minimum.
If it did 45 cold then the spring will allow at least 45 hot === if there is any pressure available through the bearings.

[KULTULZ]

Earlier Tech Post- Not FORD Specific

Originally Posted by Gene Neal 10-26-2003

Well, I would start with a manual gauge. Look along the side of the engine block and you well find a plug that goes in to the oil passage (make sure it is the oil and not the water passage) If you can't find one remove the oil sender unite and screw a flex line into it and attach a pressure gage (0 to 60 lbs.) to the other end. start the engine and check the oil pressure in this manner. You know at idle and then reve it up to say 1500 rpm. and so on. If the oil pressure is more to the liking or it has a big deference, then may be the sending unit is bad. Also it could have a small chip from the overhaul in it. And that would make for a faulty reading.

Here are a few other thing that I seen happen: New Short block and OLD oil pan. When the old engine let go it knocked the baffle plat lose in the oil pan. So they welded it back in place before they reinstalled it. After reinstalling the engine it would have oil pressure at idle and then when you revved it up and held it there for a very short time the oil pressure would full to almost 0! After about third. R/R of the oil pan they discovered that the baffle would hold the floating oil sump up when installed, just at the top of the oil level. At idle it would get enough oil to show pressure on the gauge, But at high RPM's. it couldn't keep up and showed a very low to 0 oil pressure.

This one was almost the same thing but it had a fixed oil sump pipe and screen. They somehow had bent the oil sump pipe up just enough that it would not pick up the oil and so it had 0 oil pressure. Someone said DID YOU PUT ENOUGH OIL in it? The answer ----Y! but then he put two more quarts of oil in the crank case, and it had real good pressure.

Any way just thought I would shear them with you. Check it out never know what will work! -------------------Gene Neal

-MELLING TECH TIPS-

You need to take a oil pressure reading at the filter boss (QUALITY MECHANICAL GAUGE) as this will read the actual oil pump output. The boss at the rear of the block is after the oil has gone through all the passages/bearings/lifter bores.

Have you contacted FORD RACING TECH?

[RCCR]

Did all the same things, even pulled bearings. after about the third time pulling the pan rechecking everything again. I decided to replace the brand new oil filter I had just replaced and my pressure came back to normal! Yes I had bought a filter that went bad after about 3days of driving. Cheap to try and easy to overlook. Good luck.

[newmexicosaint]

I will check at the filter, change the filter, and check at the side of the block and check oil pressure there as well. Gosh I hope that the issue is simple

[67 Deuce 4 Me]

Originally Posted by RCCR

Did all the same things, even pulled bearings. after about the third time pulling the pan rechecking everything again. I decided to replace the brand new oil filter I had just replaced and my pressure came back to normal! Yes I had bought a filter that went bad after about 3days of driving. Cheap to try and easy to overlook. Good luck.

Thats a great point! I had a buddy in school years ago that had a built 302.It developed oil pressure problems. The filter had came apart inside. Filter fixed the problem!