Question on Cooling...

[GEM555]

We have an '84 Catalina in Freeport Maine with a A4 that overheats and a boatyard that is telling us that the engine is not worth spending $$ on. They have an A4 guy there (70 years old) who says it's "shot" and he won't touch it further.

Which leaves us in a bit of a pickle. Replacing that engine is gonna cost most of 7K for a rebuilt unit + installation. Not in the cards.

But I'm not sure what to do next. Like to find a usable used engine but they are getting pretty rare apparently.

At the suggestion of Mr. Moyer, I am putting this out to the community to see if anyone has any thoughts or suggestions. Or any source for another engine!

Thanks!!!

[Peter]

Welcome Gem,

Some more info would be useful.

1) is it fresh or raw water cooled?
2) are you running a thermostat?
3) does your engine have the bypass valve installed and if so, does adjusting the valve make any difference to the overheating situation?
4) have you flushed the block recently (or at all)?
5) does it overheat slowly under load or rapidly after you start it?
6) are you getting good water flow out of the exhaust?

A copy of the Moyer Marine Manual (available from our hosts http://www.moyermarine.com/cgi-bin/s...rebuilder.html ) is a remarkably useful resource.

If the engine runs well, it should be possible and worthwhile to solve the overheating issue.

peter

[GEM555]

Thanks for the response.

This has been a fresh water run engine for it's whole (known) life.

It's "fresh" water cooled with Ocean water at this point.

I assume I am running a thermostat, but don't have a replacement gasket so I can remove it and check operation.

I don't know about the Bypass valve

Never flushed the block and would not know how. The mechanic on site did not want to do that when suggested ("waste of money, son. I've worked on a lot of these and I'm telling you it's shot").

It goes to steam fairly quickly under load. You still get water out of the exhaust and the steam does not seem to have any oil in it.

[ndutton]

If your engine is running well but overheating, I think the mechanic is full of shi-shi. The very worst case is a modest tear down (water jacket side plate and head removal) to physically muck out the coolant passages, removal of the thermostat and addition of a bypass valve. It's possible the heat exchanger needs cleaning out too but these are all very manageable at modest expense.

As a first step I'd remove the thermostat and add the bypass valve (the valve is necessary when the stat is removed) and give it a try. If that solves the issue I'd give it an acid flush.

Can you post some pictures of the engine so we have a good idea of how it's plumbed?

[Peter]

Gem,

It sounds like your engine is raw water cooled.

A fresh water cooled engine runs antifreeze in the block and has a heat exchanger that the sea water (fresh or salt, the sea water is the raw water) is pumped through.

A raw water cooled engine pumps the sea water directly through the engine to cool it.

With a raw water cooled engine, rust builds up in the cooling jackets. As well, a charming black sludge from organic matter forms in there. All of which is detrimental to cooling.

The block has two water jacket drains on the starter-alternator side of the engine. I had an engine which was missing a drain plug and it was so sludged up that it did not leak!

The Moyer manual has an excellent description of the flushing procedure. You get a bunch of fittings that allow you to connect a garden hose to the block drains and you run water - with pressure from the water mains - into the block. You disconnect the cooling system at various points (my manual is on my boat and my memory is not 100% accurate on this procedure) and let the water flow. It is amazing how much KRUD comes out. It took me a couple of on-off cycles with the water pressure just to get it to start flowing. My recollection is that the thermostat needs to be removed and a bypass-valve needs to installed to force the water through the block. You carry out a similar procedure with the manifold.

It might be wise to follow this up with an acid flush (again described in the manual) to get rid of some of the bigger bits that cannot be flushed out.

Cost - maybe $100 (including the manual) if you assemble the flushing gear yourself, and a day of effort.

Or, our hosts will sell you a flushing kit (http://www.moyermarine.com/cgi-bin/s...rebuilder.html ) and the bypass valve kit, along with the manual and the thermostat gasket.

The flushing equipment will be something you will use on a long term basis, so if you revive the engine, a good investment.

However, it would be interesting to know if the cooling issue is the only issue that leads the mechanic to declare the engine "shot".

Does the engine run well otherwise?

Peter

[thatch]

Gem, Is your Catalina a 27 or a 30. I ask this because working on an engine in a 30 is far easier than a 27. Once you have removed the galley in a 30, the engine is basically sitting in your "living room". Since your engine is running, the process of removing and cleaning the factory plumbing fittings along with doing an acid bath should provide enough water flow. A4's actually require very little water flow for adequate cooling. I would start by removing the thermostat (if equipped) and also by removing and checking for clear fittings and passages in the manifold. On my previous boat, a Cat 27, I enlarged the access panel in the starboard quarter-birth for better access. My current boat is a Cat 30 which is a "piece-O-cake" to do engine work on.
Tom

[GEM555]

Hi All:

The boat is a 30 so yes, the engine is (blessedly) accessible. Take out the kitchen return and it's even better.

The engine water jacket panel is non-removable - it's bolts are rusted/welded and some sort of glue like substance was used just to bond it to the block to stop it from leaking (but it still does, a bit).

I'll go up and get some shots of the whole thing to post.

The flushing kit/manual sounds like a good possibility, but even before that, I think I might start by pulling a few hoses and check to see if the pump is even working correctly in the first place.

What does "run well" mean (or sound like)?

[ndutton]

By well running I meant easy to start, smooth idle, good power. As for removing the side plate, depending on where this leads it may be necessary but if so it sounds worse than it is. We can talk you through it when the time comes.

[JOHN COOKSON]

Thanks for the response.
This has been a fresh water run engine for it's whole (known) life.
It's "fresh" water cooled with Ocean water at this point.
It goes to steam fairly quickly under load. You still get water out of the exhaust and the steam does not seem to have any oil in it.

This is good information.
If the engine overheats almost instantly there is no cooling water going through the engine. The most likely cause of this is a thermostat stuck in the closed position or not enough water being pumped through the engine. What does the water flow out the back of the boat look like?
If the engine takes a while to over heat there's not enough cooling water going through the engine. The most likely cause is a blockage somewhere or inadequate water pump output. There are easy ways to figure this out.
BTW: When the engine is cooled with the water the boat is in we consider it to be raw water cooled. (RWC) When an engine is cooled with antifreeze we consider it to be fresh water cooled. (FWC) The heat is removed from the antifreeze in a heat exchanger. I don't know why antifreeze is considered "fresh water".

TRUE GRIT

[mary]

I'm somewhat a newbie with this engine, but I'd also check that there's nothing obstructing the seawater from coming in the through-hull from the outside, check the raw water pump for leakage and/or impeller damage (if a piece of the impeller is missing, it could be lodged somewhere restricting flow).
If you're careful, you can probably remove and replace the thermostat housing without damaging anything. The studs that hold the housing on also go to the head, so make sure to torque them down to spec to avoid leaks (ask me how I know :-) ).

[GEM555]

Ok, so I'm RAW water cooled (NOT "fresh"). Thanks for the correction.

That being said, the boat floated in fresh water up until a month ago - now in the Ocean.

Clearly, my next step is an on site inspection to figure out for myself what the actual situation is. Last time I ran the engine, it sounded OK, but overheated. Plus I can get some visual for people to see. Onwards!

[Administrator]

I'm somewhat a newbie with this engine, but I'd also check that there's nothing obstructing the seawater from coming in the through-hull from the outside, check the raw water pump for leakage and/or impeller damage (if a piece of the impeller is missing, it could be lodged somewhere restricting flow).
If you're careful, you can probably remove and replace the thermostat housing without damaging anything. The studs that hold the housing on also go to the head, so make sure to torque them down to spec to avoid leaks (ask me how I know :-) ).

I personally experienced a problem years ago where the yard guys painted the strainer shut with bottom paint. The boat had to be pulled.

Bill

[ndutton]

I personally experienced a problem years ago where the yard guys painted the strainer shut with bottom paint. The boat had to be pulled.

JOSO, there shouldn't be an external strainer in the first place and this is only one reason why.

[ILikeRust]

Did the guy give you any more details as to why he opined that the engine was "shot"? Other than "oh, that engine's shot"?

[goodoldboat]

ran fine for 1 hour

Boat when was launched today engine ran fine for 1 hour then over heated
had great water flow during the 1 hour

water temp ran at 140 or so , then dropped to 100 ..
engine slowed and eventual stopped .


had to be towed in .. where do I start in the process .


PS this was was my maiden on a new boat