What is the cause of my over heating???

[POPPA-T]

I have a 1982 40 foot Albin Trawler. Powered by a single Volvo TAMD40A. Engine starts and runs great from idle to 2700 rpm, temp is 180. At 2800 rpm temp goes to 185 anything above 2800 rpm temp keeps rising. I have let it get as hot as 195 before slowing to 2600 rpm. Engine doesn't make black smoke at any speed. I have taken apart and cleaned heat exchanger, changed impeller, I have cleaned the fresh water side of the cooling system by running an approved cleaner through the engine for a hour. Can anyone tell me if I might be missing to do something??? Prop size is a 24X18 three blade.

[Tree]

I can't quite remember if this engine has an aftercooler fitted? If so, have you checked to make sure the matrix is intact?

[TomA]

Was the heat exchanger boiled out by a professional mechanic. I.E removed from the boat a boiled out in an offsite boiler? Simply cleaning on the boat while installed probably did not get the heat X clean. TomA

[catalina_mike]

Possible thru hull issue or strainer. Check the raw water pickup for blockage or restriction.

[Mark Deeser]

Bottom and prop clean, nothing wound around prop shaft? Here in Fla. On the St. John river the water is getting pretty warm. Thanks, Mark.

[catalina_mike]

Up inside... Coat hanger through the slots in the pickup. Your bottom can be beautiful and you won't see the growth up inside the scoop.

[Russell]

Yes, I have cleaned out oysters and a live crab that must have gone in the pickup slots when it was much smaller. In southern waters the sea life takes over in a short time.

[POPPA-T]

For anyone wondering what happened. I found the rubber cap on the end of the heat exchanger had gotten soft and flexed out of place, this allowed water to bypass the heat exchanger to some extent. Replaced with a new one and problem solved.

[rnummi]

I've got the same issue. Lehman 4D61. Runs like a champ up to 2500 starts getting warm at 2800. China Syndrome beyond that. New raw water pump, impeller, newly boiled heat exchanger. What am I missing?

[mike66]

The fresh water side should be up to snuf as well, meaning coolant, hoses, water pump and belts, thermostat, pressure cap. Hoses delaminate on the inside, so keep that in mind for the raw water side too. I had one that I chased for weeks on my generator. Lesson learned, new hoses all around every five years. Overkill maybe, but two happy diesels since.
Raw water side, besides hoses, where else does the water go? Heat exchanger, oil cooler, exhaust riser/mixer?

[rnummi]

Thanks! I'll chase down this gremlin yet. Better question, What's the temp supposed to be on a 4D61 at wide open throttle? For that matter what's the RPM at WOT?

[mike66]

Documents section of the forum has an owner's manual for your engine.

[Jhill]

I lived with 2 TAMD 40B's in a 37 palm beach model. I spent two years chasing an over heating issue. I must have removed the heat exchanger a dozen times. A very helpful Volvo man on boat diesel .com gave me the answer.
The heat exchangers have 2 chambers upper & lower which work in 2 stages. The rubber boat located at the end of the HE fits in a baffle plate welded inside. That baffle plate will break loose and allow the water flow to get messed up and then you over heat. I removed the HE had the plate welded and no more over heating. I could run 3400 all day if I wanted. Remember the 37 was a Raymond hunt copy, But it only lasted one year before the HE corroded out so bad I had to buy a new one. That lasted one year before the Rubber boot started to budge out again. I stuck a dam hockey puck behind it and problem solved. Those engines are the worst engineered hunks of metal ever built. I hope you are not hooked to MS3C transmissions cause they are another man made disaster.