1997 mercruiser 4.3l oil pressure

[Jamesukbayliner]

Hi my 1997 mercruiser 4.3l appeared to lose oil pressure and sounded alarm. Was cruising at about 3800rpm no problem at all. As soon as I backed of the throttle the alarm sounded and appeared to lose oil pressure (gauge dropped to zero). I shut down engine and looked for obvious problems. Tried re starting and was like I had a flat battery. Limped home on the aux engine took about 20mins. Once moored up I tried re starting and it started like nothing had happened. I'm noticing the voltage meter is fluctuating abit now and appears not to be charging correctly at times. Not sure if it could be connected to the original problem. Any ideas. Iv serviced the engine now and since been back out and no further probs other then the voltage not always being up.

 

[Scott Danforth]

welcome aboard.

check your oil level. get a mechanical gauge and check oil pressure

you had two separate systems telling you that you had zero oil pressure (gauge and alarm). pretty good chance you had zero oil pressure.

what was your engine temp?

 

[achris]

I have seen a wiring harness porblem on those engine that allows the harness to rub on the enigne block behind the distributor. It can wear down the wires and short them to ground. that could account for the continued voltage fluctuations... That's an easy and no-cost check... I'd look at that. It's a long shot, but as I said, I have seen it happen.

Chris.........

 

[Jamesukbayliner]

I'm not 100% sure but I think the temp was ok and just the oil had dropped.

As said b4 it all happened as I let the throttle go. Was running fine till that point. It was still running fine as I shut it down.

What's chances of losing oil pressure then getting it back tho. Am I correct in thinking it's a mechanical pump ran on the dist shaft

 

[Jamesukbayliner]

Spoke to a mechanic and he said it's rare to have intermittent oil pressure and said Mabey a blocked oil filter ???

 

[achris]

There's a bypass valve that opens and allows unfiltered oil through if the filter blocks up.

 

[Scott Danforth]

severe overheat, lack of oil, plugged oil pump pickup, spun bearing and failed oil filter are the most likely culprits of true low oil pressure

 

[Jamesukbayliner]

Well Iv changed oil and filter just gota take it out for a good run and hope for best I guess.

Glad I brought a brand New 6hp yam aux now.

Oil pressure all seems ok now 40psi ticking over and up to 60psi wot. Guna give it some wot and back to idle to try re create the fault. Fingers crossed it was a blocked filter but who knows. Thanks for help