Oil on intake hard start up and low oil pressure

[sebas54]

Hi, I have a 1988 4,3l gm v6 I/o. After running the boat for a couple of minutes I will see a little bit of oil pooling up on the intake manifold. It's never much , about a tablespoon or two. This only happens in certain spots. Where does this come from?

Also after not starting the boat after a day or two it wont start up right away. It takes about 4 or 5 tries. why?? When it does start the rpms are low at around 5000-6000rpm.

Also when running the boat for the first couple of minutes the oil pressure is perfect but after a about 15-20 minutes the oil pressure will only go to 20-35psi at wot. Why?

Please help. thanks

 

[JustJason]

Re: Oil on intake hard start up and low oil pressure

I bet your overfilled.....

Put the boat in the water and check the level again (cold)

 

[bomar76]

Re: Oil on intake hard start up and low oil pressure

1. There are no oil passages in the intake manifold, so it's leaking from below somehow....a wild guess is it's actually dripping out of the crankcase vent hoses that should be on your flame arrester.

2. Carbed engines are much different to start than injected engines, it takes some throttle work to set the choke. You need to learn how to do that. Also, you may have fuel leaking from carb after shutdown.

3. 5,000-6,000 RPMS??? And you say that's LOW rpms? Either you have a prop that has like a 11" pitch or your tach is in need of attention. If you are truly turning beyond 6K your other troubles will soon be over.

4. The oil pressure varies 'cause it's warming up. Maybe gas in the oil (see laeking carb above), oil that hasn't been changed in years, using low viscousity oil in summer, or, more likely, bearings are wearing and you are loosing pressure through increased clearances.

 

[Fishermark]

Re: Oil on intake hard start up and low oil pressure

I would suspect the oil is coming from your intake manifold bolts. They need a sealer on the threads or the oil will wick up from inside the engine.

On the issue of hard to start after sitting a few days - you don't mention what kind of carb you have, but it sounds like it is leaking out from the fuel bowl. I know Quadrajets were/are notorious for that.

On the oil pressure... I would certainly agree with captjason that you need to check your oil level. It is also possible that after warming up, the oil viscosity is thining out. Just guessing on that.

 

[cutlas]

Re: Oil on intake hard start up and low oil pressure

if your intake bolts have loosened up and are leaking there is a good chance oil could be sucked into the intake ports wich would cause a hard start as it will get on the plugs....

 

[Coors]

Re: Oil on intake hard start up and low oil pressure

Are the rocker cover gaskets leaking?

 

[sebas54]

Re: Oil on intake hard start up and low oil pressure

Hi, thanks for all the info.

The rpms at idle are at 500 - 600(only when i fisrt start it up), sorry I added an extra zero by mistake.

THe rocker covers are good with new gaskets.

So should I buy new bolts and seal them. What type of sealer do I need lock tight?

 

[JustJason]

Re: Oil on intake hard start up and low oil pressure

perfect seal will work fine... did you check your level?

 

[wca_tim]

Re: Oil on intake hard start up and low oil pressure

Are crankcase vents attached to your flame arrestor? could be that engine is just tired... blow-by pushes oil in pcv tubing out drips on intake either from connections or out of flame arrestor...

Oil pressure typically drops once oil is hot because it thins out... from as low as yours is it sounds like your bearings are about shot...

what are you running for oil??? if it's (way) too thin...

I might try running thicker oil and see if it helps on all fronts...

and if you're oil is getting thinned out by a gas leak in carb, etc... find the problem and fix it before its too late...

oil pressure that low at wot is waaay too low!

Hard starting... does it smoke then when it starts? or just take a while to get fuel?

 

[JustJason]

Re: Oil on intake hard start up and low oil pressure

oil pressure gets low if its overfilled too....