How Bad is a Cracked Exhaust Manifold?

[stb100]

Would be very grateful for insight/experience with the following -- Found about a 2" crack in port-side exhaust manifold on '84 Wellcraft (200 elite 260HP merc.) Runs horizontal, cente, sort of low. Little bit of rust, water seepage. Evidently been there awhile

Few questions from stupid ?? dept.:

-- Worst case scenario?? How urgent is need to fix?
-- How big of a repair job is it? Time/effort/cost... (Other stuff that'll need fixed due to this)
-- Any recommendations on DIY vs shop


THANKS in advance

STB

 

[tommays]

Re: How Bad is a Cracked Exhaust Manifold?

Outside leaks are BAD but the problem is its hard to see the INSIDE leaks which are really BAD


Tommays

 

[stb100]

Re: How Bad is a Cracked Exhaust Manifold?

Thanks. BAD (outside) would become clear to me exactly how...? Something quick and catastrophic or something a little less dramatic... ; )

BAD (inside) means water and oil together, no?, which you're right is, uh, very BAD.

 

[milkyway]

Re: How Bad is a Cracked Exhaust Manifold?

Exhaust manifold is the exit passage of carbon monoxide and if there's a crack, it will spill into your engine compartment. How bad is that?

 

[tommays]

Re: How Bad is a Cracked Exhaust Manifold?

Outside leaks from cracks point to freeze dammage

which makes the inside a time bomb and the dripping water tends to cause a LOT of rust dammage to the sheetmetal parts and electric parts

Tommays

 

[milkyway]

Re: How Bad is a Cracked Exhaust Manifold?

And even worse if you have unburned fuel coming out of your exhaust and it's coming out of the crack.

 

[bruceb58]

Re: How Bad is a Cracked Exhaust Manifold?

You aren't going to be getting exhaust out that crack because that is the water passge.

However, like a previous poster said, an outside crack means it could be likely that the inside passage could be cracked which is worse since you could damge your engine with water ingestion.

When you change your manifolds, you should change your risers. The dificulty of this job depends mainly on how easily accessible the manifolds are and the amount of corrosion on the manifold bolts. Mine come off easy because there is so much room. On a previous boat it was more difficult because the manifold was on studs and the manifols couldn't clear the studs before the boat got in the way...PITA!!

 

[bjcsc]

Re: How Bad is a Cracked Exhaust Manifold?

BAD (inside) means water and oil together, no?, which you're right is, uh, very BAD.

Actually it doesn't mean water in your oil. It means water can get to your exhaust valves, which then means either the valves temper and break (BAD) or the corresponding cylinders fill up with water, which does not compress. (VERY BAD, esp. if it occurs while running hard)


As said, if the manifolds and risers are easy to get to, they're pretty straightforward to replace. The bolts and holes should be cleaned with a die and tap before installing the new parts in order to get accurate torque readings.

 

[milkyway]

Re: How Bad is a Cracked Exhaust Manifold?

I suppose you still don't own the boat. You have not stated that you have actually seen anything coming out of the cracked manifold.

 

[AlanR]

Re: How Bad is a Cracked Exhaust Manifold?

if its outside it will leak into ur motor compartment. Mine leaks really bad and i just run the bilage pump every 2 hours and shes fine.

 

[bruceb58]

Re: How Bad is a Cracked Exhaust Manifold?

I hope he is kidding!

if its outside it will leak into ur motor compartment. Mine leaks really bad and i just run the bilage pump every 2 hours and shes fine.

 

[cobra 3.0]

Re: How Bad is a Cracked Exhaust Manifold?

By the description of where it is, it's just a little water coming through on the belly of the manifold. ..probably from not draining the manifolds and freezing occuring.

I seriously doubt any of the gloom and doom based on the location of the crack. If you don't run in salt, take it off, grind out the crack, and JB Weld it...or get it welded.

You will certainly want to inspect all the passages on the engine and manifold when it's off. It should be quite evident if it's something more serious.

If you run in salt water or the boat had at one point, get new manifold(s). The're probably shot from corrosion anyway. Again, this will be evident once it's off.

 

[stb100]

Re: How Bad is a Cracked Exhaust Manifold?

THANKS for all the input and clarification.
The more I know, the more I know I oughta know.

Crack is low, not under, but near bottom of vert surface of manifold...don't know but could be due to freeze... : ( There is a very small amt of water seepage coming out w/ engine off. Haven't had chance to look w/ engine on. (for the record I own the beast, mw...Or it owns me)

STB

 

[Haut Medoc]

Re: How Bad is a Cracked Exhaust Manifold?

Pull it off & look for rust on the exhaust valves.....
If they are clean, replace the manifold & riser & go boating.......
Assuming that this is a raw water cooled system, you should replace the other side at this time as well .......JK
Oh, & make sure you learn the proper way to winterize/drain your system.....

 

[MelLandry]

Re: How Bad is a Cracked Exhaust Manifold?

If you're worried about this while you're running, are you really going to enjoy yourself on the boat? I got my whole set for my new engine (manifolds, risers, gaskets) for $400. If you're enjoying yourself, you'll burn more gas than that in a season, and it'll all be worth it. These are expendable parts that are intended to be replaced every-so-often.

 

[stb100]

Re: How Bad is a Cracked Exhaust Manifold?

Excellent point, Mel. ...someone wiser than me put it, 'enjoy yourself,
it's later than you think.'

Looking em up online this aft. Where'd you get your set? Curious about best online parts sources...

THANKS -- stb

 

[MelLandry]

Re: How Bad is a Cracked Exhaust Manifold?

I got mine from aftermarket marine.

www.amarket.com

It's not the most attactive website... but it works. Give them a call, tell them what you have, and they'll tell you what you need and how much.

I like them because they're local (one city over). Someone else may have a better source.