Re: freeze cracked exhaust manifolds

I agree, you don't want to spend a lot :-) It's difficult to pressure
test a boat cooling system. You need to disconnect and block the lines
to the exhaust in order to pressure test the block. There is no good
way to pressure test the cooling side of most exhaust systems as they
basically dump the water into the exhaust stream at some point.
Usually you have to remove the part, block off something with a plate
and then pressure test it.

I'd run it around and then check the oil for signs of water. Most
freeze problems result in water getting into the oil. Also you can
remove the plugs and crank it to see if it has water in the cylinders.
That's a bit more catch as catch can so to speak. If the exhaust valve
is closed it may keep the water out even though there is a leak in the
manifold. Let it sit for a little while to give the water a chance to
leak down.

You have an old engine and that may be your savior as the old blocks
were frequently thicker castings. Newer engine castings are often
thinner to reduce weight for fuel savings. Epoxy the external leaks
and then see what happens. Do you boat close to shore or on a lake?
That is to say is an engine failure a safety problem or just
embarassing?

Next time hang a trouble light with a 150 watt bulb in it in the engine
compartment when the temp is expected to fall.


GSS wrote:
Well, I failed to winterize at all...just got busy while it was getting
cold...I'm in Austin and we had one cold snap of about 24 degrees...I
really didn't think it would be a problem. I guess where do I go from
here? Is there a way to pressure test the block to make sure it
doesn't have a a crack? As one respondent noted, the engine is over 25
years old, and I don't want to waste anytime on the manifolds if the
block is cracked too.


James wrote:
For what it's worth if you use epoxy you don't have to take them off.

"JohnH" <jherring1@xxxxxxxxx> wrote in message
news:n943f21fvlrf1koe3m4k5quk92gve6hl13@xxxxxxxxxx
On Sun, 27 Aug 2006 12:00:22 GMT, "James" <james@xxxxxxxxxx> wrote:

I have not heard of anyone brazing them. There is some success with
epoxy.
It will eventually crack off but them you just do it again.

"GSS" <gssmith1986@xxxxxxxxx> wrote in message
news:1156626717.132533.17610@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I finally pulled my boat out of storage (way late for the summer, I
know), and discovered that I had two freeze plugs pushed out of the
block and my 1 year old exhaust manifolds had tight freeze cracks at
the back of the log. This is on a Mercruiser with a Ford 302. I
pounded the freeze plugs back into the block, and started the engine
which ran fine, but the exhaust manifolds are leaking water into the
bilge through through the cracks-not much, just steady drip. Can these
cracks be brazed shut? They are Barr Marine Cast Iron Manifolds.
Don't know if there are any cracks on the exhaust side of the manifold,
but I'll figure that out when I take them off...I know Cast Iron is
highly durable in compression and terrible in tension...the exterior
cracks are certainly tension induced from the ice expansion, so I'm
hoping the exhaust side didn't suffer any damage because it would have
been in compression.

Please respond to the group.



If I were going to take the trouble to take the damn things off, I'd put
new ones back on.
--
******************************************
***** Hope your day is great! *****
******************************************

John

.

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