'88 mercruiser 454 oil pressure

[Duwat]

my engine runs about 40 psi when cold but after its warmed up pressure drops to about 10. if i go to idle sometimes it drops to 0 but if i bump the throttle up a hair it pops up to about 5. changed transmitter and had mechanical gage check. my son knows small block chevys but not big blocks. he thinks that the oil pump pickup tube may have broken off but doesn't know if big blocks have them. my mechanic is trying to sell me a new engine.

 

[Haut Medoc]

Re: '88 mercruiser 454 oil pressure

At 5# P.S.I. I would be alarmed.Welcome to iboats If you don't hear any noise you will soon.....You need to verify the gauge first, but is this a new occurance or has it been around for awhile? New? be WORRIED Old ...well Chevys are weird that way....0 # can't be good though....It's easy from the armchair Q.B. seat to say it but....Pull the engine and seei f the tube is leaky or the pickup screen is gunked....If you haven't heard any noise you can still save it.....JK

 

[imported_scott_m]

Re: '88 mercruiser 454 oil pressure

Ideally, you want 10PSI per thousand, or 1PSI per hundred, so if your idling at 700-800 RPMs and seeing 0, you have a problem. Any idea how many hours are on the motor? Could simply be a matter of worn bearings. If you're at 10 at idle and the drop to 0 is just a gague thing...well, then you're fine, the motor is just getting tired.<br /><br />FYI, I have a pair of 88 454's in my boat - about 920 hours on them and I still see 60-70PSI at startup (cold), and 30-40 PSI at idle. After a hard run they might drop back to 20PSI for a while till things cool down a bit.

 

[Duwat]

Re: '88 mercruiser 454 oil pressure

Thanks guys. The problem began to drop slowly about 20 hrs. ago. The engine has about 1200 hrs. on it. The other engine pressure runs steady at 60 psi. Unfortunatly, the boat is a sedan and it's going to be expensive to pull the engine. Oh well, at least it survived 3 hurricans.<br /><br />Edit: When I bring up to about 2000rpm the pressure will return to 40. I have heard no valve train noise. This is not a guage problem becuase the mechanic put a mechanical guage on the block and it shows the same thing. And the seperate low pressure warning alarm has gone off, shutting down my fuel pump, which I had to bypass to get back from the open sea.