use of JB WELD on my exhaust manifold

mhawk4

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Apr 21, 2011
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Long time reader with no posts and new to boating, so please do not hit me to hard

I have a 1989 bayliner Capri with an OMC cobra 5.0. i have been working on it since we got it 4 month ago; the boat is running good so far, already did some interior work and general maintenance on the engine and hull.
right now i am debating on buying a new exhaust manifold (port side) or patch the hair line crack with JB weld, the engine is running at a good temp, Steady 175 on the gauge, so i do not think the crack is affecting cooling operation, just dumping some water into the bilge.
Like i said before the boat is running great, and the fam love it - just need to make sure it will last.

one more question, do you guys know which is the the factory spec on propeller for this engine? right now i am running a 14P23 at WOT i barely hit 4000rpm at 43+/-mpg. my WOT rpm should be between 4000-4400.
should i go 14p21 or 14p19

your advice is greatly appreciated.

Luis
 

RogersJetboat454

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Jul 9, 2010
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Re: use of JB WELD on my exhaust manifold

right now i am debating on buying a new exhaust manifold (port side) or patch the hair line crack with JB weld, the engine is running at a good temp, Steady 175 on the gauge, so i do not think the crack is affecting cooling operation, just dumping some water into the bilge.


Are you willing to bet your great running engine on a JB weld repair? It's not about the cracks you can see, but the cracks you can't. A crack on the inside can allow water into the combustion chambers and you would be looking at a hydro-lock situation at that point. What you do is your business, but if it were me, I would be looking at a PAIR of manifolds and risers, especially if the old ones are originals. If the old ones are originals and have been in salt, it's a miracle they have lasted this long.

one more question, do you guys know which is the the factory spec on propeller for this engine? right now i am running a 14P23 at WOT i barely hit 4000rpm at 43+/-mpg. my WOT rpm should be between 4000-4400.
should i go 14p21 or 14p19

This would probably best answered by the prop guys, but what you could do is find a place that will lend you a 21P and a 19P prop to try before you buy.
 

bruceb58

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Mar 5, 2006
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30,454
Re: use of JB WELD on my exhaust manifold

Replace the manifolds and risers. Like the previous poster said, if you are lucky the manifolds are only cracked on the outside. If you aren't, you may be buying a new engine.
 

firehog6305

Petty Officer 1st Class
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Jun 30, 2007
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283
Re: use of JB WELD on my exhaust manifold

I would listen to the master chief, I used jb weld on a cracked engine block once, it works for a while, but when it did let loose more damage was done to the motor. JB weld is a quick fix, and you dont want problems on the water, its a good way to ruin a family outting real fast
 

mhawk4

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Re: use of JB WELD on my exhaust manifold

thanks for the help, looks like is time to get serious with my homework. i got some info about a conversion kit, this manifolds are hard to find. thanks again
 

bruceb58

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30,454
Re: use of JB WELD on my exhaust manifold

Is this a ford or chevy 5.0?

if Chevy, you should have no problem finding manifolds for this.
 

mhawk4

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Re: use of JB WELD on my exhaust manifold

it is a ford, kind of tough to find the part
 

mcleaves

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Sep 15, 2003
Messages
521
Re: use of JB WELD on my exhaust manifold

ebasicpower.com carries the Ford's. Got a set for my EFI 5.0 last season. I also found them several other places, but ebasic is the cheapest. Finding them isn't the problem. It's the cost!!
 

mhawk4

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Re: use of JB WELD on my exhaust manifold

Yes sir COST is the word. question, those the manifolds from basic power have an inlet for the hose coming from water pump. the original part i am using now has a water hose going to cool the exhaust.
thanks for the help.
 

mcleaves

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Sep 15, 2003
Messages
521
Re: use of JB WELD on my exhaust manifold

Can you point me to the ones you think won't work? I am not understanding what your setup is. water to the manifold typically comes from the thermostat housing, not the water pump.
 

mhawk4

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Re: use of JB WELD on my exhaust manifold

Sorry, i need to give better explanations. yes you are right the water to the manifolds comes from the hoses connected to the thermostat assembly.
i did called basic power, the only answer i got is what you see is what you get; when i ask if those manifold have water inlets, nipples or barbs so i can connect the water hoses the CS guy told me those manifolds get the water from some other place:confused:. gave me the impression the guy did not understand me or just plain does not know. (maybe he had a problem with my accent, sometimes SPLANGLISH is hard to understand:rolleyes::D)
i am looking at item -part # BPIMANOMCFRDLOG - Manifold Kits - OMC - OMC Ford Small Block V8 5.0/5.8L - Log Style to Center Riser Repalcement - this the same item you pointed out earlier?

luis
 

mcleaves

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Re: use of JB WELD on my exhaust manifold

Oops.. didn't read your full post...... Still looking.
 

mcleaves

Chief Petty Officer
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Messages
521
Re: use of JB WELD on my exhaust manifold

Are you sure this is not your setup? The nipples are on the bottom of the manifold. This is how mine is, it's a 95 (probably a mfgr year '94)

Look up BPIFSBOMCCARB

Also take a look here under the Volvo OMC section:

http://www.oscomotors.com/catalog/download.asp

EDIT: I suggest this is your setup becasue the one you point out is for OLDER style 5.0's. 1989 is near the end of the life of that engine (around 1995)
 

mhawk4

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Apr 21, 2011
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Re: use of JB WELD on my exhaust manifold

i have a ford engine and it is an 89 model with log style manifolds; looks like i will need the replacement kit - finding an use one in good shape and at a good price is going to be difficult
 
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