Catalina 30 Overheating

[perlasowner]

Hello,

I am new to boating. I recently bought a Catalina 30 sailboat. Here is the problem:

When starting the engine at the marina, the engine seems to run ok, after about 10 minutes the water temperature needle starts to go up and it does not stop climbing up to 200 degrees and going beyond. I usually stop the engine at this point. The running temperature usually is about 160 degrees and before when I took the boat out it always ran at around 160 degrees.

Am I doing something wrong by running the engine while tied at the marina? I do give it a bit of power in order to make sure that water is running through the cooling system and water comes out of the exhaust.

Could it be that debris went up the raw water intake and it is blocking the system. How common is this?

I have been reluctant to take the boat out since I noticed this. Thanks for any help

The engine is a universal m320b. Water does come out of the exhaust. I do check the coolant and it appears to be normal. The prior owner had the impeller replaced, but I do not know when this was done.

[sailingdog]

Does water come out of the exhaust when you start the engine?? If not, you have a problem. If the water is sporadic or very low flow...

When was the last time you checked the raw water strainer for the heat exchanger? When was the last time you replaced the impeller for the raw water pump? When was the last time you cleaned out the HX. If you don't have good answers to these questions, I would expect that all are well overdue.

[Faster]

Assuming it's Fresh Water cooled? If so your coolant reservoir could be low, causing the engine to overheat despite adequate raw water flow.

Alternately check the thermostat - might be stuck - you could remove it to see if the engine runs cool without it. - but check your reservoir levels first if FWC.

Finally is the water at the exhaust 'normal' in volume? When was the last time the raw water pump was looked at? You could have some issues with the impeller too.

[k1vsk]

What engine is it?

Some raw water cooled engines only spit water so indication of water flow is misleading.

[bebevett]

if thermostat, they make a fail-safe one, any auto parts store carrys them. around $10. other wise it could be a leak in the head casket.

[Claudia1002]

It'd help to know what engine.
Check the normal maintenance things first (thermostats, fluid levels, leaks etc). If those check out, then move to diagnosing cracked blocks and such.

FWIW, it's better to let the engine get to it's operating temp than to start it, run it, and stop it before it warms up.

[PalmettoSailor]

That engine has both a raw water circuit and a fresh water circuit. As others pointed out check the stainer, impleller and pump on the raw water side.

On the fresh water side, check:
1. adequate coolant.
2. that the coolant is good (should be replaced every couple of years)
3. Thermostat is opening
4. Heat Exchanger is not blocked (Check the zinc while you're at it)
5. Air lock (often you'll find an air bubble trapped in the circuit for the engine water heater after a boat has been winterized) to address this remove both hoses going to the water heater from the theromstat and add fresh coolant through a funnel into one of the hoses until coolant is running out the other hose then reattach them.
6. Check the fresh water coolant pump.

HTH, good luck

[swadiver]

Perlas,

I had a similar problem with the Universal X25 in my 86 Catalina 30 just after I bought her 3 years ago. Water raw water flow looked good but after 5 minutes of normal operation the temp would be climbing over 200 degrees. After checking the impeller and the raw water flow going into the heat exchanger which was good, I checked the flow coming out of the heat exchanger. It was much less. Took the heat exchanger in to a radiator shop to have it boiled out but it was toast. Installed a new exchanger and have had no problems since. Although, I take the exchanger apart every year to make sure there are no zinc bits laying around that could cause problems. I also use a pellet gun cleaning kit to clean the exchanger tubes to make sure they are clear. When you take the end caps off you need to replace the gaskets, you can get these at any marine engine supply store. Also, do not forget about the Heat Exchanger zinc as they do not last long.

Good luck.

[CalebD]

This from the OP: The engine is a universal m320b.
I'll go with the HX clogged crowd. Check the pictures of a HX rebuild to see how it can get fouled: Westerbeke / Universal Marine Heat Exchanger Photo Gallery by Compass Marine at pbase.com
As I understand it diesel engines don't really like to run at idle for extended periods, at the dock or anywhere else. They prefer to be run under load (fwd, reverse) and will run best and cleanest when the engine is fully warmed up.
It is also possible that you may have a restriction in your engine exhaust system but I would look at the HX first.