3 blown exhaust gaskets

swampy2646

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Sep 19, 2009
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I have a 2010 350 mag. mpi, repowered last year and have blown 3 exhaust manifold gaskets (both sides) in the last two seasons. Any mercruiser professionals come across this problem??? I've been boating for 40 years and only changed gaskets when i replaced manifolds every 7-10 years!
 

1977 SILVERLINE

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Re: 3 blown exhaust gaskets

Run a straight edge across the manifilds and check if they are warped or twisted. You can probably get away with .oo5" but any more than that you will need to get the manifolds re-surfaced at a machine shop
 

Volphin

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Re: 3 blown exhaust gaskets

Are the manifolds new with the engine? Are they iron or aluminum?

V
 

Volphin

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Re: 3 blown exhaust gaskets

I have always retightened the exhaust manifold bolts after the first few hours of operation on new engines. If that's not it, perhaps the bolts are loosening up over time? Some red locktight might help if that is the case.

Another thing to consider is maybe cheapo gaskets are at work here. See if there are some nice thick ones available.

V
 

John_S

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Re: 3 blown exhaust gaskets

New engine and new manifolds does not mean there are "good". The fact remains, you blew 3 gaskets, so something is wrong. What type of exhaust are you running and what exhaust gasket are you using?
 

Volphin

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Re: 3 blown exhaust gaskets

New engine and new manifolds does not mean there are "good". The fact remains, you blew 3 gaskets, so something is wrong. What type of exhaust are you running and what exhaust gasket are you using?

VERY true.

V
 

Bondo

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Re: 3 blown exhaust gaskets

New engine and new manifolds does not mean there are "good". The fact remains, you blew 3 gaskets, so something is wrong. What type of exhaust are you running and what exhaust gasket are you using?

Ayuh,.... Amen to that bro,...
And I'll add, Have the gasket mating surfaces been Cleaned to shiney metal each time the gaskets are changed,..??
 

1977 SILVERLINE

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Re: 3 blown exhaust gaskets

swampy2646 it sounds like you already know what your problem is so why are you asking us for help?
 

EddiePetty

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Re: 3 blown exhaust gaskets

Correct me if I am in error but I can think of only five things that would cause repeated exhaust gasket failures:

Excessive heat (lack of cooling water)
Excessive back pressure (exhaust restriction i.e. flappers)
Incorrect gasket and/or material
impropper fasteners/torque
non-parallel mating surfaces
 

svxtech

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Re: 3 blown exhaust gaskets

Why did you do a repower. what were the running symptoms/failure of the previous engine... as volphin said are they new manifolds with the eng, or did you reuse on the long block? not enough information
 

bruceb58

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Re: 3 blown exhaust gaskets

Mercruiser manifolds or aftermarket Chinese ones?

Can you tell I like using OEM manifolds?
 

swampy2646

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Re: 3 blown exhaust gaskets

this is a brand new complete engine out of a mercruiser box! no aftermarket nothing! after the 1st replacement of each gasket i did a re-torque after 20 hrs. i wasn't looking for answers, i was wondering if this was like a re- call issue or a factory problem that you mechanics were aware of.
 

bruceb58

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Re: 3 blown exhaust gaskets

this is a brand new complete engine out of a mercruiser box! no aftermarket nothing! after the 1st replacement of each gasket i did a re-torque after 20 hrs. i wasn't looking for answers, i was wondering if this was like a re- call issue or a factory problem that you mechanics were aware of.
You have contacted Mercruiser right?
 

Bondo

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Re: 3 blown exhaust gaskets

Why did you do a repower. what were the running symptoms/failure of the previous engine...

Ayuh,... Great question,...

It could very well be relevant...

i was wondering if this was like a re- call issue or a factory problem that you mechanics were aware of.
No, nothin' I've seen, or heard about...
 

swampy2646

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Re: 3 blown exhaust gaskets

thank you bondo,any other feedback would be appreceited. I purchased boat with a bent push rod, probally hydro locked due to a bad manifold, but i did a complete package, from a alpha to bravo drive, including a raw water strainer. why would previous failure be revelant?
 

Volphin

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Re: 3 blown exhaust gaskets

Do the gaskets always "blow" in the same place? If so, where? If not, where have they happened? How did they "blow" exactly? Were you leaking water or exhaust gasses?

V
 

Don S

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Re: 3 blown exhaust gaskets

this is a brand new complete engine out of a mercruiser box! no aftermarket nothing! after the 1st replacement of each gasket i did a re-torque after 20 hrs. i wasn't looking for answers,

After 3 times, maybe you should be looking for some answers. The first time should have been a warranty item, was Merc contacted then with the problem?


i was wondering if this was like a re- call issue or a factory problem that you mechanics were aware of.

No recall or service bulletin on it, but Mercruiser may have run into this before, and may know what the problem is and will fix it, even if out of warranty now, but if they haven't been contacted, they sure won't help. As Bruce asked before, have you contacted Merc?
 

swampy2646

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Sep 19, 2009
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Re: 3 blown exhaust gaskets

Thanks Don, I will contact Mercruiser. Volphin, I'm not sure where the gaskets failed. This happend 4 mos. apart and on two different sides, it was an exhaust leak only, they were both under warranty, This time i saw the gasket, it wasn't "blown" but there was some carbon or burn marks on one of the port holes. My dealer "did the right thing" by me. but he could not give me an answer as to why this happend again. He thought maybe it wasn' seated squarely.
 

svxtech

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Re: 3 blown exhaust gaskets

It could be relevant if you had an over heat/ignition/human error symptom to warp the manifolds. did you install them yourself? your next post said it was a complete replacement, prior to that more info was needed... also i talked to some folks from other marinas, and they have experienced this problem (myself a few) but untill this post never looked into it any further. no confirmed reason why tho, sorry.
 
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