overheating

[bobkat]

help! i am a novice. i have recently bought a 1984 oday 28. it has a universal m12 diesel engine. last summer i experince overheating. this spring i have done the following: flushed cooling system, replaced internal and external impellers, v belt, sea water pump, fresh water pump, coolant cap, thermostate, hoses and clamps, oil filter. seawater is pumping outexhaust great, no white smoke. any suggestions

 

[PJ]

overheating too

Overheating has been my problem as well. I have a 37 Oday with a 32HP Universal(Kubota). After doing all of the obvious, I finally checked the head and there were some small cracks. Four pins have been put in by a machinist but the engine is still not 100%. Now the engine gets me away from the dock...runs for 2 hours and the temp slowly climbs. After 2 hrs the rate of climb increases substantially so it has restricted my range.

 

[Jim Hague]

Actual or Indicated Overheating?

How do you know that your engines are overheating?

 

[Ken Sturgill]

Replace sending unit

You might try to replace you sending unit, also install a real gauge. Other idea is to intall a T with a valve thread for a hose. Use a 6 gal. bucket with a hose fitting on it, use a short garden hose and set the bucket so gravity will do the work. You can buy a product called Salt-X, warm up your motor then run the Salt-x through, you'll need to dilute the Salt-X and you might shut down and let it sit for awhile. The Salt-x will clean the deposits off. I've also heard that you can get similar results from vinegar and vinegar costs less.Give that a try, and let us know how things go.

 

[Don]

Heat exchanger

That is the only thing you didn't mention. If you sail in salt water, the salt will crystalize and block the passages. Also, PO could have let the raw water impeller go until a tab broke off and is now lodged in the heat exchanger. Pull it off and take it to a radiator shop and have it rotted out. If that doesn't help, then I would look for a restriction in the engine exhaust, such as a blocked mixing elbow. Good luck.

 

[larry w.]

overheated

Bobkat; Jim may have something there. Leave the heat exchanger cap off, run the engine under load at the dock to warm it up. DON'T BOIL IT! Put a meat thermometer or candy thermometer into the expansion tank and compare the readings to your guage. The guage, the sending unit, or the wiring may be faulty.