SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: SomeThingWilder on May 27, 2017, 12:50:23 PM

Title: oil on spark plugs
Post by: SomeThingWilder on May 27, 2017, 12:50:23 PM
replacing plugs on my buddy's boat 2 of the plugs had a good amount of oil on them. is this pretty common or is he looking at something worse. also does he need the vacumm hose from the valve cover to carb or can he eliminate them and put breathers on?

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Title: Re: oil on spark plugs
Post by: GT Jets on May 27, 2017, 04:28:56 PM
Just my opinion, but depending on which plugs, could be valve stem seals, intake gasket leak or cracked manifold, location of pcv, even rings.

Time for a leak down test to verify no major issues.

GT

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Title: Re: oil on spark plugs
Post by: SomeThingWilder on May 27, 2017, 10:12:26 PM
cylinder 2 and 5 . time for leak down. lots of oil around hoses from value covers to carb

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Title: Re: oil on spark plugs
Post by: WhyNot76 on May 29, 2017, 12:27:22 AM
Just my opinion, but depending on which plugs, could be valve stem seals, intake gasket leak or cracked manifold, location of pcv, even rings.

Time for a leak down test to verify no major issues.

GT

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Not to thread jack but out of curiosity (since I run a pcv) Mine seems to work great but what are the do's and dont's as far location? I have mine in the right side valve cover to the rear of my intake.


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Title: Re: oil on spark plugs
Post by: GT Jets on May 29, 2017, 09:54:20 AM
Not to thread jack but out of curiosity (since I run a pcv) Mine seems to work great but what are the do's and dont's as far location? I have mine in the right side valve cover to the rear of my intake.


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Think about it.

If you're venting from the rear of the cover, the bow rises under acceleration, it could pick up raw oil if the bow stays high long enough and the vacuum levels are low enough to pull the oil like a straw.

It's rare, but does happen. Oil does not compress.

A PCV can work as long as the engine is pretty tight and the carburetor is not oversize. With a proper sized carburetor (which is technically oversize) will run the manifold vacuum at near zero inches, the PCV does nothing at that point. Dual carburetors this is even worse.

I would put the vents at the front. PCV on one side and an open breather on the other side. I like the MOPAR style with a hose connection and route it to the flame arrestor/scoop.

GT


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Title: Re: oil on spark plugs
Post by: Rivernut on May 29, 2017, 02:42:07 PM
On a clockwise engine pcv valve goes on the right because oil is slung up on the left side by the crank.  Breather in the back left for cross flow.  This one has an improvised "puke can" detour on the PCV hose.  It is a Craftsman water trap for an air compressor.
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi887.photobucket.com%2Falbums%2Fac77%2FRivernut_photos%2FMobile%2520Uploads%2F5FC0CE4B-DEB4-4FB5-A46A-6DEF25940D99.jpg&hash=8db89534c544b99e7bc783b3024cb04d39127a82) (http://s887.photobucket.com/user/Rivernut_photos/media/Mobile%20Uploads/5FC0CE4B-DEB4-4FB5-A46A-6DEF25940D99.jpg.html)
Title: Re: oil on spark plugs
Post by: GT Jets on May 29, 2017, 03:11:25 PM
On a clockwise engine pcv valve goes on the right because oil is slung up on the left side by the crank.  Breather in the back left for cross flow.  This one has an improvised "puke can" detour on the PCV hose.  It is a Craftsman water trap for an air compressor.
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fi887.photobucket.com%2Falbums%2Fac77%2FRivernut_photos%2FMobile%2520Uploads%2F5FC0CE4B-DEB4-4FB5-A46A-6DEF25940D99.jpg&hash=8db89534c544b99e7bc783b3024cb04d39127a82) (http://s887.photobucket.com/user/Rivernut_photos/media/Mobile%20Uploads/5FC0CE4B-DEB4-4FB5-A46A-6DEF25940D99.jpg.html)
If the oil sling makes it all the way up to the valve cover, you have much much bigger problems.

JMHO

GT

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Title: Re: oil on spark plugs
Post by: 76Challenger on May 29, 2017, 03:59:28 PM
Here is how my original stock Harman Marine is set up. I assume it's correct since this is the way it came new lol.


1977 Challenger

Title: Re: oil on spark plugs
Post by: 69kona on May 29, 2017, 05:01:18 PM
If the oil sling makes it all the way up to the valve cover, you have much much bigger problems.

JMHO

GT

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Right


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Title: Re: oil on spark plugs
Post by: Rivernut on May 29, 2017, 06:02:58 PM
It probably doesn't make much of a difference, but windage occurs with cranks.  I'm sure that a windage tray and good valve cover baffles helps control oil atomization much more than which hole gets which.  It doesn't cost anything to put the PCV on the other (right) side where there is less oil getting the crap beat out of it, unless it is interfering with the throttle linkage.  There are lots of little seemingly insignificant engine performance tricks that when taken collectively add up to a win.
Title: Re: oil on spark plugs
Post by: GT Jets on May 29, 2017, 09:01:57 PM
Well, if you want to adjust for windage, even though it won't effect anything, it wouldn't be I the right, but the left. And normal rotation is counter clockwise., not clockwise.

But anyway, forward on the engine, not rearward.

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Title: Re: oil on spark plugs
Post by: mash on it on May 29, 2017, 10:03:25 PM
Well, if you want to adjust for windage, even though it won't effect anything, it wouldn't be I the right, but the left. And normal rotation is counter clockwise., not clockwise.

But anyway, forward on the engine, not rearward.

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Glenn,

This is absolutely wrong.

Looking at the balancer, the engine goes CLOCKWISE.

Dan'l
Title: Re: oil on spark plugs
Post by: GT Jets on May 30, 2017, 12:43:34 AM
Glenn,

This is absolutely wrong.

Looking at the balancer, the engine goes CLOCKWISE.

Dan'l
The flywheel cares not which way a balancer rotates............

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Title: Re: oil on spark plugs
Post by: mash on it on May 30, 2017, 06:53:49 AM
The flywheel cares not which way a balancer rotates............

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How many flywheels do you see, VS. balancers, while the engine is running?

Oh, and the front of the flywheel goes clockwise.


Well, if you want to adjust for windage, even though it won't effect anything, it wouldn't be I the right, but the left. And normal rotation is counter clockwise., not clockwise.

But anyway, forward on the engine, not rearward.

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My right or your right? Stage right? Right field?

Your right.

Always.

Dan'l
Title: Re: oil on spark plugs
Post by: GT Jets on May 31, 2017, 10:47:24 PM
How many flywheels do you see, VS. balancers, while the engine is running?

Oh, and the front of the flywheel goes clockwise.


My right or your right? Stage right? Right field?

Your right.

Always.

Dan'l
All I'm saying is a "CW engine" by definition is counter rotating. You say "right side" looking at the engine from the rear, the rotation should be done the same way.

No reason to get hostile. Just facts.

GT

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