Diagnose my motor problem. (please)

[IDWITHELD]

Motor is Chev 350.
12 hours on motor. 8 months old. Bought new (less than 1 hour on motor).

Running at 3800rpm today and engine suddenly slowed down. Kind of like when you suck in a plastic bag and the pump cavitates. Lots of vibration. I naturally thought the intake grate was blocked. Beached the boat, jumped in and cleaned the intake. Nothin was on the grate.

Started motor back up and noticed oil pressure was at 10psi at idle (aprox 2200 rpm). It is normally 40psi, hot at idle. I also noticed the temp was at 200 (normally 150). Oil pressure increased with throttle to about 20psi, but not the 40 as I would expect. Noticed on the starbord exhaust was "steammy". Not smokey (no oil smell or blue smoke), but white steam. Port was totally normal (not visible). Shut off motor. Immediatly checked oil stick. Full (as it was on my pre-inspection before leaving home).

Pulled plugs on the steamy bank. All identical, normal with minor oil on thread casing. Electrode in perfect condition, not steam cleaned like I expected to find.

What do you think happened?

[GSD]

From your description: engine overheating, steam coming from
the exhaust etc. , I would say there is a possible restriction in the fresh water cooling intake system. If your engine has the rubber flex-hose exhaust, with little or no water flow through them, they will be toast quickly.
:twocents: but could be wrong :passout:

William

[IDWITHELD]

GSD, thanks for the response. Me thinks you are right on. :cheers:

And thanks to Garth over at Beaverton Marine. Garth got me back on the water in the same day!

Well, it seems there was no problem found. I took the boat out for a test drive. I did 10 miles (most at WOT). Motor ran like a champ, purred like a kitten. No oil pressure or temp issues.

Makes me think I had something on the intake that fell away later....boy do I feel like a dunce. :redface:

Thanks Garth, my salmon weekend is saved!

[Green Machine]

The over-heating issue makes sense, but not the drop in oil pressure. Keep a close eye on her. With a new motor, sometimes you get a bad oil pump from the factory. I would think you'd be covered under warranty if it is.

Good Luck,
Green Machine

[IDWITHELD]

Thanks Green Machine.

Tight lines.

[Tilla]

Wouldn't high temps lower the oil viscosity (thin) lowering the resistance and thus lower the oil pressure?

[IDWITHELD]

yes.