Logo
FULL SITE MENU

Merc 57 high oil pressure

W

wellcraftnova230

Contributing Member
"Hello,
I have a 1989 Chev

"Hello,
I have a 1989 Chevy 350 H.O. marine block and my oil pressure guage reads 75 psi at idle as well as at higher speeds. The guage goes up to 80 psi. Could it be a bad sender or guage, or could the engine have that much oil pressure even at idle. I checked the oil and it was over filled a little so I took a half quart out and it did not make a difference. Thanks Jon"
 
Sounds a little high. think I&

Sounds a little high. think I'd buy a cheap manual gauge and install kit and hook it up as a test tool to see if factory gauge or sender show different. Can even hook them both up to a tee to compare .

Bob
 
"I would bet on a bad (hig

"I would bet on a bad (high resistance) electrical connection somwhere in the circuit, expecially since you do see some deflection on the gage."
 
"There is a pressure relief sp

"There is a pressure relief spring that is in the cast aluminum piece that bolts to the block and holds your oil filter in. It is possible also that that spring has jammed. It is easy to take out and check... just take out your filter and there us two bolts holding it in. Use a 7/16 socket and just take it out and look at the spring. If it is broke, you can get the part from any auto junk yard for cheap... Otherwise clean and replace.... its an easy if it is the problem....."
 
"The oil pressure would read l

"The oil pressure would read low if the circuit had high resistance. remove the wire from the sender and see if the gauge goes to zero. If it does, check the resistance of the sender with the key off, on and running. If you go to a parts store, they'll probably let you test the resistance of a new one to compare. I would bet that your sender is bad.

If the motor overheated badly, there's a chance that the wire from the oil pressure sender was laying on the motor and is now causing an erroneous reading. If this is the case, cut out the bad section of wire, solder a new piece in and use heat shrink tubing to seal it."
 
Don't chance anything with

Don't chance anything with that electical gage. Install a analog physical pressure gage into the 1/8 NPT that the sender uses and check it. If it truly maintains that pressure at idle you may have to get into the oil pump and change the pressure relief spring. Some shops shim them or install a different rate spring. What oil are you running? Keep the 50 wt stuff out of there. It should like straight 30.
 
"My engines (Chrysler 360s

"My engines (Chrysler 360s) run 40 psi at hot idle, 60 at 2,500, and 80 at cold start up (on 10W30 oil). Your pressure is too high, but not for the reasons stated. The gears that run the oil pump and distributor will wear out at such high loads--I've seen it done.

Buy a manual gage and see whats really happening. If the pressure is okay on it, then you'll need to change the sender unit or gage head. If it's still too high, though, you'll need to find out why.

Jeff"
 
Back
Top