Oil Leaking in the intake Manifold

barko

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Aug 1, 2012
Messages
25
Hello,
I have an engine mercruiser 470 I noticed that I'm getting oil in my bielge.
When I traced it, I found out that it's coming from the intake manifold.
My question is: "Is there something serious going on in my engine and that I will be alarm?"
The engine is running smooth and not overheating.

Thanks in advance.
 

Don S

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62,321
Re: Oil Leaking in the intake Manifold

Well, since there is no oil in the intake, yeah it might be a problem. Are you sure you don't have a valve cover gasket leaking and running down past the intake? Or maybe the side covers leaking?
 

Bt Doctur

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Aug 29, 2004
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19,350
Re: Oil Leaking in the intake Manifold

Don, the 4 bbl manifold has provisions for the oil cooler. page 7A-6 of the manual
May be the hose connection or the " O" ring for the plate on the underside of the manifold.
470oilcooler.jpg
 

Don S

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Re: Oil Leaking in the intake Manifold

Don, the 4 bbl manifold has provisions for the oil cooler. page 7A-6 of the manual
May be the hose connection or the " O" ring for the plate on the underside of the manifold.

470's, don't have 4bbl carbs or oil coolers. The newer models under different models, might have an oil cooler there, but not a 470. And he has a 1977 470
 

barko

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Re: Oil Leaking in the intake Manifold

Thank you for the Reply!
Maybe the side cover, I'll check this cover.
By the way I attached a picture of my engine so you know my the type.
IMG_0861.jpg
 

Don S

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Re: Oil Leaking in the intake Manifold

The serial number is what's needed, not just a picture. They all look very close to what you have there.
 

barko

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Re: Oil Leaking in the intake Manifold

Hello, sorry it's been a while and boating season is now around the corner. I attached the serial number of the engine I hope you can still read this.
I will try to check the side cover this week and see if this cause the issue. Figers cross.
Thank you.photo.JPG
 

Don S

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Re: Oil Leaking in the intake Manifold

You are in the serial number range of the 76 to 79 engines.
No oil coolers in the intake, and no oil going to it.

I would be looking at other things causing the leak, like the side cover, fuel pump, or even the oil filter.
 

barko

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Joined
Aug 1, 2012
Messages
25
Re: Oil Leaking in the intake Manifold

Thanks Don!
One more question, is there a gasket on this side cover?
I research and found the picture of this cover so I know what I'm refering to and I'm sure this the side cover that I'm seeing from my engine.
Just want to know if there's a gasket if I remove mine from the engine so I can order the gasket that I need.
cover1.JPGcover2.JPG
 

Robert D

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Feb 21, 2009
Messages
338
Re: Oil Leaking in the intake Manifold

If it's the side cover leaking, you might want to look as to the cause. (High crankcase pressure) Might want to do a compression check, make sure your crankcase vent isn't plugged and such. If your losing compression past worn rings, it'll build excess crankcase pressure and you'll start to get leaks. If that's the case, you might be able to buy some more time and use out it by installing a regular vacuum PCV system, rather than just a standard ventilated one that goes up to the top of your carb. If the compression tests out okay, and your pcv hose isn't plugged, probably just an old dried up gasket that's number came up!
 
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