Please help with oil pressure problem

I just picked up a deuce that seems to run ok but I am concerned about the oil pressure. It is a 1968 with a Hercules with turbo. I put on a manual gauge & it reads 50 psi at idle cold, then drops to 10 hot at idle. At 1200 rpm it goes to 25 hot. it shows 24k on odometer & low hours. The engine is quiet when running the first fifteen minutes then it seems to have deep knocks after it warms up. Could it be an oil pump, relief valve or simple as wrong oil? Any suggestions would be greatly appreciated. I have been a mechanic all of my adult life & I never seen anything quite like this. Usually when an engine is wore out, it is sludged & noisy both hot & cold. This one looks extremely clean on inside as far as I can see. Thanks for your help in advance

It is supposed to have 15W40 in it. What is in yours?

-Chuck

I am not sure what was put in it. It is clear & seems thin even when cold. The 15w40 oil we use at work has a yellow tint (Exxon/Mobile).

I change oil, hopefully tomorrow. I will have to find some filters first.

Remember, these have electric gauges. There are two different senders and gauges. 60 and 120 PSI. If they are intermixed either way, the gauge will be all over the place. Before you go pullin' your hair...or what you have left of it...out, VERIFY the pressure. Use a known good gauge or better yet, a digital MM with a pressure transducer. IIRC, when I checked mine it was 70 cold idle, 30 to 40 hot idle and around 55 hot, going down the road. The dash gauge reads about 10 PSI low on mine.

Check out OD iron. He has the filters with the correct gaskets. Read the TM for the oil change.

MIne has a 60 psi gauge and reads 30 cold 25 hot at idle 650 rpm and 30 hot at 1000 rpm, I've been wanting to check it with a manual gauge just to see if its right but I haven't had time.

Cougarman did say it had a mechanical gauge.
But I suppose the mechanical gauge could be bad.

Why not just install a mechanical gauge in the dash? They're cheap. I had to run my truck at 1000rpm to see any oil pressure. Installed jatonkas(john tennis) spin on filters and have never worried about oil pressure since. some complane about the price but its one of the best mods to make on these trucks!

What is the oil pressure supposed to be in theses engines anyhow? And what is the base idle setting supposed to be at?

cbvet said:

Cougarman did say it had a mechanical gauge.
But I suppose the mechanical gauge could be bad.

Click to expand...

Why yes he did! Didn't see that There is a regulator on the turbo side of the block. It could be stuck or full of muck. I tried searching. No luck. PM Cranetruck. He has a good set o f pics of it and how to disassemble it.

Are you "growing" engine oil? Had the same prob. Diesel thinning the motor oil.