Diesel engine runs hot

[Gary Meadows]

I would like to ask for some advise and help. I have a 84 Catalina 30 with a diesel engine...the M25... Just bought it about a month ago and have finally got it to start and run. It was in a slip and not cared for. Had not been running for over a year. When I start it now, after about 30-45 minutes, the temp gauge willgo up to a tad over 200 degrees before I cut the engine off. I have read the operating range is 175-190 degrees. I have checked the thru hull and am getting water there. I have changed the water filters. I havent looked personally, but the previous owner told me that there is no thermostat. Any suggestions as to what is causing this and how can I correct it? The only thing I can think of left to do is check the screen over the thru hull under the boat. Maybe it is just restricting the amount of water. If that is the case, how can I correct that this time of year? The water is too cold for me to get in...Any suggestions would be appreciated..ThanksGary

 

[Stu Jackson]

M25 Overheating Answers

GaryTry the link below and use the search engines in both the main website and the message board section.Best info on M25 engines available.Also try the C30 website.Ther are suggested links to Universal and Westerbeke in here also.The most apparent thing to check is the heat exchanger.

 

[Randy]

M25 overheating

Be sure to check the raw water impeller--it may be cracked, dried out (hard) or missing, and not pumping water. Check the flow of cooling water coming out through your transom. It should be a significant amount of water.  If the impeller's ok but the water flow is low, your heat exchanger or mixing elbow may be clogged. They will need to be disassembled for inspection, and cleaned.Randy

 

[Ed]

Air pocket in the engine block

I recently changed the coolant in the engine. After making the change, I started the engine and let it heat up, but the temperature kept going past 160 degrees.Since everything else had been OK, I assumed I had an air lock in the engine block. I tried letting the engine cool down for an hour, and then re-starting, but that didn't help.What finally solved my problem, was I loosened the hose clamp on the underside of the water pump at the front of the engine. This is the bent hose that travels down the port side of the engine to the heat exchanger. I slipped the edge of the hose of the water pump, and since the engine was still hot, she burped like a baby after feeding (I'm a new father).I tightened the hose clamp, started the engine, and presto!, everything worked great.Maybe this will help.Ed

 

[D.St.Denis]

M25 Overheating Answers

Heat exchanger change to larger one this is common trouble.Raw water pump inspect forleaks in system and the impeller change ifold and crack the amount coming out of your transom should pin point trouble.Also if youengaged the gear you could have something wraparound the wheel this seems to be over lookeda lot.

 

[Tim Dranttel]

Same problems

Had the same problem with my 86 30' TR w/M25.I replaced all the hoses, the radiator cap, the thermostat, the raw water pump.The only thing that worked was replacing the heat exchanger with the one specified for the M25XP. It was much larger than the one original to the motor. Works great now even with the hot water heater engaged! Ordered it through Defender.If all else fails...go bigger!Tim

 

[Eric Ludin]

check the heat exchanger

I have the same engine. I use the smaller heat exchange unit and found the boat ran nice and cool (160) when the unit was taken out, boiled at a radiator shop, and reinstalled. This should be done every couple years or so. IT makes a huge difference.But, first make sure your're getting water out the transom. If not, you have other issues.

 

[Gary Meadows]

I want to thank everyone that responded to my post concerning my overheating problem. I think I have enough info to hopefully solve my problem.Again, thanks everyone for the help. Maybe I can return the favor one day...