Oil pressure... falling off

02-03-2007, 08:19 PM
Just wanted a discussion on my worries. .

Just got my park at the right temp with a new thermostat. But now that it heats up right the oil pressure seems to fall off when its hot and idling. It comes up fine when I pull away from a stop but stopped, hot and idling it falls almost to the red zone..

What me worry?

02-03-2007, 08:54 PM
My oil pressure has ALWAYS shown low pressure on the gage. I've checked off 1 and 2...just some ideas
1)Oil level
2)Oil sending unit
3)Oil pick up tube/ screen
4)Oil pump

02-04-2007, 03:31 PM
Mine is fine till it idles when hot then dropps way down.


I did replace my sendor to get it to work.

03-01-2007, 11:32 AM
this used to happen to me, i think its because the tolerances in the cam shaft bearings get wider over time due to wear and tear and the pressure drops. Put some slick50 in your next oil change and it helps "perma lube" the camshaft and keep it pressurized.

mine used to go all the way to red zone and red light come on when i idled at stop sign or light. this fixed it for me, keeps above 30psi now. but 3800 should run fine at 20psi even

03-01-2007, 12:59 PM
Mine is fine till it idles when hot then dropps way down.


I did replace my sendor to get it to work.

What is it reading hot at idle?

03-01-2007, 03:41 PM
When the indicated temp is 180 and idling it falls off to, I guess, about 20 but not quite to the red.

Since the post I found the wife took it to get oil change while I was away.. She had 10W30.. I usually put 10W40..


03-01-2007, 06:19 PM
Several years ago, my Ultra (150K) would idle @ 35-40 psig with 10W-30 Mobile-I, when it was at operating temp. I put a new crank kit (crank, rod & main bearings) in about 1 years ago, (for a different reason) and the pressure is now is @ 55 idle RPM and @ 1500 RPM, the pressure is 65-70 with the same weight oil. I did replace the sending unit last spring due to pressure fluctuations and now the pressure remains steady, so I have to assume it is close to being correct. It does not take much additional clearance on the rod & main bearings to loose oil pressure. The cam bearings last much longer, due to the fact that the cam only rotates at the the speed, (RPM) of the crank and it has much less load force applied.

If you don't use sythenitics, it might be a good idea to use the "High Mileage" oil, that has a higher viscosity at operating temperature.:iceslolan

BTW, if you use the right oil to begin with, you do not need a bunch of additives to increase the viscosity.:shakehead

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