Univ M-25xp running a little hot (diesel)

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chelsabella

chelsabella

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Jun 2, 2004
64
Catalina 30 Ruskin/Tampa Bay
Recently had to replace the circulating water pump. Prior to this the Univ M25XP always ran about 160 degrees, since thyen it appears to be running a bit warmer in the 180-190 degree range when at full throttle. Any ideas. I have bleed the system a couple of times and plan on trying that again. If at full throttle for a while and she warms if i back down the temp also goes back to the 160 degree range Looking for some suggestions Ron Chels-A-Bella 3532
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
23,343
Catalina 34 224 Maple Bay, BC, Canada
More M25 Diagnostics

1. Check your heat exchanger 2. Check your thermostat 3. Assure that the fresh water side is clear - it may have to be "burped" although if you've been running the engine for awhile and it didn't overheat, that shouldn't be an issue. Burping is done by simply opening the valve on the top of the thermostat and letting any air escape. Assuming you have a hot water heater on board, in lieu of opening the valve, take one of the hoses to the heater off the thermostat and fill it with distilled water or antifreeze to assure air is out of that loop. 4. Check the faceplate on the pump. Please advise what kind of pump, Sherwood or Oberdorfer. The Oberdorfer is easier to service and check. Make sure any new gaskets you put in are in the proper position and set right. May have to get new gaskets. Bleeding the system has to do with diesel fuel, which has nothing whatsoever to do with overheating, unless you're talking about #3 above.
 
N

Nice N Easy

Gasket

I am not familiar with that engine, but lots of them use the same water pump for many applications. the only difference between several engines being the gasket, which can be different. Different holes open or covered up. Such as a thermostat bleed or bypass hole. Since it started when you changed the pump, has to be something to do with the change.
 
Maine Sail

Maine Sail

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Feb 6, 1998
11,759
Canadian Sailcraft 36T Casco Bay, ME
It sounds like..

It sounds to me like you may have one of the older M-25's with the smaller diameter heat exchanger. Almost all of the M-25's with the small diameter heat exchanger would heat up if run at full throttle although full throttle should only be used for brief periods of time anyway. I believe they went to the bigger diameter exchanger on the M-25 XP-B series. The new style heat exchanger will fit but you'll need the brackets and the exchanger. Here's a photo of my old gold colored M-25 with the updated & larger diameter blue XP-B heat exchanger. If it's not over heating at cruise then there's no rush but I'd upgrade it if it's the series with the small diameter exchanger.. M-25 Upgraded Heat Exchanger http://www.pbase.com/mainecruising/image/83280520
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
23,343
Catalina 34 224 Maple Bay, BC, Canada
It is my understanding that the M25XP

was the next generation of the venerable M25 engine - a little bit more bore & stroke and a 3 inch HX. The M25s had the old 2 inch HXs. He stated he has an M25XP. Either way, removing, cleaning and checking not only the tubes but the inlet and outlet ports, is a good first step.
 
Richard19068

Richard19068

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Jun 11, 2004
1,918
Oday 31 Redondo Beach
maybe not too hot

according to the attached, the operating temp is 165 to 195 so 180 to 190 wouldn't seem to be a problem would it? 160 might even be too cool.
 
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