Overheated universal m25

[86Cat30]

Hi all,
Made a huge mistake (maybe a very costly one) and opened the wrong through hull to cool the engine, leading to it overheating after like 45 min of use. Im hoping i can save the engine and am looking into the smaller cheaper fixes first. I was planning to replace the thermostat and impeller but also just noticed that the oil has leaked out of it. Im guessing ill have to replace all the gaskets and seals on the engine as theyve probably melted away. Not sure where to start and wondering if people think this is a lost cause.

its a Universal m25 engine in an 86 catalina 30 by the way.

 

[jssailem]

Not necessarily. Keep thinking good thoughts.

It is not good that the engine overheated. What you need to do is to assess what has happened. If this is in your DIY skills, start by examining the engine top to bottom. Make a note of everything you see. Are there burnt hoses, wires, heat-discolored metal, or warped metal? Change the engine oil. What do you see in the oil? Change the coolant. What do you see, smell? Examine the water pumps. Are there coolant stains by the weep holes? This would be a sign of a failed pump seal.

It is a tedious process, but one you can do if your disiplined. Once you have fully assessed the condition, then, having replaced the raw water pump impeller and confirmed that your heat exchanger is not plugged, with fresh oil & coolant in the engine, see if it will turn over (open the raw water thru-hull).

If you feel overwhelmed, consult with an engine mechanic. There is bound to be a skilled diesel mechanic in Port Angeles who can help you. You are not the first boat owner to overheat an engine. Most of us try to stop the engine when the temp horn starts blaring.

This experience will likely add "CHECK FOR WATER OUT OF THE EXHAUST WHEN THE ENGINE STARTS!" to your engine start procedure checklist.

 

[Stu Jackson]

and impeller but also just noticed that the oil has leaked out of it

Not clear what it means. If it's the raw water pump, then here's the fix.

Oberdorfer Pump Rebuild 101 - http://c34.org/bbs/index.php/topic,6766.0.html

John is right, take it step by step. Our C34 website has a ton of M325 info:
Engines 101 - The BIGGEST & BEST collection of M25 Series Universal Engine Information on the Internet, plus some M35, too This includes a link to the Critical Upgrades topic which has more engine information please read it too.
Diesel Engine - c34.org

 

[Ralph Johnstone]

leading to it overheating after like 45 min of use.

What indicates it had overheated ........... the engine siezed, burning smell, high temp alarm ? What RPM when you shut it down ?

i can save the engine and am looking into the smaller cheaper fixes first.

Im guessing ill have to replace all the gaskets and seals on the engine as theyve probably melted away.

Settle down. Settle down. Now is NOT the time to panic and start replacing every bloody thing on the engine without knowing if it's failed or not. Go through it step by step and determine what has failed (leaks? doesn't work anymore? melted?) and then replace.

One thing to do (because it costs nothing) is change the oil and see if anything looks unusual ........ milky? Water on the bottom after a few days?

As you may have heard, these little diesels are almost indestructable (unless you forget the cooling water) but it wouldn't surprise me if this is another trial which this engine has survived.

As far as avoiding this little mishap again, try one of these. With some of the crews I have on my boat, we couldn't go a mile without it:

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[kappykaplan]

This experience will likely add "CHECK FOR WATER OUT OF THE EXHAUST WHEN THE ENGINE STARTS!" to your engine start procedure checklist.