Volvo Chronic Overheating

[Aimee Lynn]

I have a Grady White 25 Ft. Sailfish 254 with Volvo Penta KAD42A deisel (fresh water cooled) with duo prop outdrive.<br />Engine overheats at 3600 rpm (max rpm is 3900). Overheats at lower RPM in strong headwind or rough sea. Temp. goes up to 205 and remaing there. If I reduce RPM temp goes back to normal 185-190.<br />Before I purchased it a through hull raw water intake was added.<br />The Grady dealer has tested thermostat, heat exchanger, aftercooler, heat sensors, guage etc. no improvement.<br />I took it to Volvo Deisel authorized dealer. After 10 days and $2500. still overheats.<br />We have spent 2 seasons trying to diagnose and repair with no results.<br />Any one dealt with this engine?<br />thanks,<br />Alex

 

[akriverrat]

Re: Volvo Chronic Overheating

did you tell the people that worked on it about the overheating at lower rpm going into head wind/rough seas? with your description my first thought is location of water pickup causing pump to suck air at certain boat attitudes.

 

[Aimee Lynn]

Re: Volvo Chronic Overheating

Yes! Water inlet is at stern. Doubtful there is an intake problem. Last summer we pulled boat and inspected inlet valve and it checked ok. I think that any extra resistance (wind, weight, sea)cause temp to spike. I believe engine runs normally too close to high limit.<br />Thanks! Any other thoughts?<br />Alex

 

[yoced]

Re: Volvo Chronic Overheating

How well does it start?<br /><br />I ask because a diesel with a bad fuel pump (not dead, just out of spec) will run hot due to a lean condition.<br /><br />Just a shot in the dark, but it would take the cause out of the cooling system.

 

[Aimee Lynn]

Re: Volvo Chronic Overheating

Thanks! It starts and runs great. I love the engine except for the high temp. it runs at. <br />Alex

 

[Peter J Fraser]

Re: Volvo Chronic Overheating

A diesel never has a lean burn condition that causes overheating. The power output of the engine is controlled by the amount of fuel delivery not by the air fuel ratio as per a gasoline engine. <br />As you reduce the fuel qty the engine simply slows down until it gets too slow to keep running and just stops.<br />Nearly all diesels do not have a manifold butterfly valve to control the airflow into the engine.<br />If the pump timing is retarded you will get a late burn into the manifold. This may put more heat into the water jacket. The side effect from this is that the engine will start easily with a retarded injection but would be less than happy running under load at higher speed.<br />It would be advisable to have the pump timing checked to confirm it is on spec but it would appear the your problems are in the cooling system.<br />BTW, I have 35 years working with heavy duty diesels.<br /><br />Good luck, <br /><br />Peter

 

[yoced]

Re: Volvo Chronic Overheating

Man I love the 'more experience' thing around here. That makes much more sense with what I've seen than what my diesel mechanic was trying to say. Thanks for the schooling, Peter.