How Bad is a Cracked Exhaust Manifold?
 

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, center, 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

How Bad is a Cracked Exhaust Manifold?
 

Sort of depends on the overall condition. If the manifold is generally
in poor shape and there is the possibility that water may also be
leaking into the exhaust area you could have big problems. Water
leaking back into the exhaust and possibly into the cylinder can cause
major motor damage.

If you are certain it is only leaking outside you can try epoxy to see
if you can seal it. Most people find epoxy works for a while and then
fails due to expansion/contraction. But some of them are ok with
applying new epoxy once in a while :-)

Replacing the manifold is not really a very hard job. It is heavy.
Soak it down by occasionally applying wd40 or penetrating oil of your
preference for a while before attempting to take it apart. The worst
case scenario while removing is breaking off bolts in the engine block.

Steve wrote:
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, center, 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

How Bad is a Cracked Exhaust Manifold?
 

THANKS
Overall condition is...pretty old -- 22 yrs. A little rust at gasket w/
exhaust elbows. Both sides. Definite rust on inside @ water pump and
thermostat housing. Runs smooth tho and sounds OK

So far, oil still looks good but don't know if that's something that
could just go all of a sudden...How am I certain of outside-only leak
and whether or not leaking back into the exhaust and possibly into the
cylinder ?

STB

How Bad is a Cracked Exhaust Manifold?
 

That's really old for an exhaust manifold. Imho I'd replace all of it, both
sides. If I was forced to make a call I'd look at the crack to see if it
was possibly created by water freezing and bulged it out. That would be
preferable to the alternative that it just wore through.

Here's the deal with water in the exhaust. If it leaks back into the
exhaust yopu won't notice it until you go to start the egngine and it is
hydrolocked. That's water in the cylinder. Now you can be a little unlucky
with a hydrolocked engine and you can be a lot unlucky. A little unlucky is
the engine just won't crank. You take out the plugs and get the water out
and it fires up.

A lot unlucky is the water leaks in on a cylinder that just finished the
compression stroke, you crank and couple other cylinders light up right away
cause maybethe engine is still warm. Next your cylinder with water starts
it's commpression stroke being pushed by a several other cylinders just
having fired off. Now water doesn't compress so that piston attempts to
stop the engine cold. Now sometimes it succeeds. Other times you get half
a rod sticking out the side of your engine.

"Steve" wrote in message
oups.com...
THANKS
Overall condition is...pretty old -- 22 yrs. A little rust at gasket w/
exhaust elbows. Both sides. Definite rust on inside @ water pump and
thermostat housing. Runs smooth tho and sounds OK

So far, oil still looks good but don't know if that's something that
could just go all of a sudden...How am I certain of outside-only leak
and whether or not leaking back into the exhaust and possibly into the
cylinder ?

STB

How Bad is a Cracked Exhaust Manifold?
 

"Steve" wrote in message

Overall condition is...pretty old -- 22 yrs. A little rust at gasket w/
exhaust elbows. Both sides. Definite rust on inside @ water pump and
thermostat housing. Runs smooth tho and sounds OK

A 22 year old exhaust manifold is generally a catastrophe waiting to happen.
The timing and severity of the catastrophe are strictly a matter of luck.


So far, oil still looks good but don't know if that's something that
could just go all of a sudden...

Yup, it could. And there are usually no advance symptoms. You check one
day, and you've got syrupy coffee instead of oil.

How Bad is a Cracked Exhaust Manifold?
 

THANKS for all the input and clarification. The more I know, the more I
guess I oughta know. Not real thrilled by the sound of "hydrolocked".
Easy to guess which project just cut to the front of the line...

STB