Diesel motor overheating

[wonko]

I have a Volvo TAMD41A (six cylinder diesel with turbo) that the temperature slowly rises when it is running between 2500 and 3200 RPM's. It has a closed cooling system, the impeller has been changed and it spits out water pretty good. I'm not all that familiar with diesels or the way the water routes through the turbo system. Anybody have a quick list of things to check as to why a diesel may be running hot?<br /><br />I know there are a lot of outboard questions on this board and a lot of good answers, just thought I would try my luck with this one.

 

[dick]

Re: Diesel motor overheating

How hot is hot? In the water or out?We'll start there.

 

[captsara]

Re: Diesel motor overheating

I'll play, for what's it worth, my 2cents worth.<br />Running between 2500 and 3200 RPM's is a big spread. If 3200 is balls to the wall, I'd cruise at 2900, tops.<br />Things to check.<br />Raw water-cooling.<br />Intake, starting under the boat if possible. Check for plastic bags or other obstructions. You should be able to feel cold water at your raw water intake, check out your sea strainer, and make sure water is moving. (Don’t mess with the fittings unless your sure there's a problem) look at your raw water intake valve. Chances are it didn't suddenly close, but make sure it's all the way open. It will probably be a gate or ball valve. If it's all rusted and nasty, it's time for dry-dock. I believe the raw water is cooling your exhaust. I would recommend a running engine check. Look for exhaust leaks around the exhaust manifold. Carbon deposits and hot air coming from your manifold and gasket bolt up. Put your hand on the face of your raw water pump, where the impeller plate is, and make sure it's cool. Make sure your exhaust risers aren't glowing red or melting. Then on to the fresh water heat exchange. Check the fluid, pop the petcock at the bottom and make sure its not sledge. Tighten hose clamps, again, watch it run, look for problems, belt driven pumps. If your fresh water was leaking, you would have to adding fluids. Feel for bad hoses. Check the oil lines to your turbo, I believe they are fairly high pressure and make a mess when they fail. If your turbo is going (from my limited experience) you'll hear it screaming and when it goes it will poor black smoke. Sounds fun, good luck.

 

[VANGELIS]

Re: Diesel motor overheating

another writer pointed out many things to be checked .<br /><br />check one more .<br /><br />if engine has been smoking more lately , <br />although I do not know how many hours the injectors have , I would point out that hot fresh water can be the result of bad combustion .<br /><br />bad combustion can be caused by poor injection (injectors may require overhaul, the fuel high pressure pump checking and correct timing) or bad diesel quality which is rather seldom.<br /><br />best regards

 

[Ross J]

Re: Diesel motor overheating

This may sound a bit daft but check out the air intake. Check if there is sufficient air available in the engine room. If there is insufficient air getting into the engine room then dark smoke and temperture rises are to be expected. <br />Ross

 

[DJ]

Re: Diesel motor overheating

Maui Girl pretty much said it all. Use her list. Do you have an exhaust temp. pyrometer in your guage set? If so, has this temp. also climbed? Exhaust temp. much over 900 degrees far. indicates overfueling and/or overboost.

 

[G DANE]

Re: Diesel motor overheating

Wonko - Maui girl gave you almost every point. Check everything and be sure you are cooling.<br /><br />However i have one advise based on a problem i had with my volvo 135 HP gasoline.<br /><br />Mesure the temperature another way !! I had the same problem once. When i ran it for some time the temparature slowly raised. After engine shut down or iddle, temparature fell to normal, but raised again faster when speeding again.<br /><br />I checked every valve- flushed tubes and cylinderhead, removed frost plugs and cleaned internal distributor tube changed thermostat. Untill i one day when temperature raised, reached red field opened engine room and felt on cylinderhead - i could hold my hand on it.<br /><br />I got to an electrician, who mesured the alternators charging voltage, it had raised to 14.4 volts. As the sender to the temperatur gauge is a termo resistance, i just got hotter and hotter readings when batteri was fully charged after some times high speed run.<br /><br />Check if this is your problem, i got a voltage regulator placed across instruments and viola everything was normal.<br /><br />But first, be sure you are not running hot -or you can destroy your engine.