Volvo engine question, re: thermostat

[Keith Fawcett]

A friend asked me to post this question. He has replaced the thermostat on this VOLVO engine in his CD 28. He replaced it because the water temperature would fluctuate from normal to hot, almost to the redline. Well after the new thermostat was installed all was good. Then the water temperature began to act up again the same thing. Several years ago he had the heat exchanger cleaned and replaced.

Here is the question...do you need a thermostat in southern climates where you do not experience a freezing problem? Can you just yank it out and button the housing up with some gasket tex type stuff. Appreciate the information and the help.

Keith Fawcett



georgesail@aol.com

[mike]

Keith,

I wouldn't remove the thermostat, it moderates the engine temperature to keep in in the prime temperature range for optimum performance.

Perhaps he should check his impeller and see if any vanes are missing, they can sometimes clog a region of the cooling system, next i would check the intake screens and hoses. they could be fouled with marine growth.

hope this helps.

mike
LaVida
cd33

A friend asked me to post this question. He has replaced the thermostat on this VOLVO engine in his CD 28. He replaced it because the water temperature would fluctuate from normal to hot, almost to the redline. Well after the new thermostat was installed all was good. Then the water temperature began to act up again the same thing. Several years ago he had the heat exchanger cleaned and replaced.

Here is the question...do you need a thermostat in southern climates where you do not experience a freezing problem? Can you just yank it out and button the housing up with some gasket tex type stuff. Appreciate the information and the help.

Keith Fawcett

lavida@seascan.com

[Ken Cave]

There are thermostats, and there are Volvo thermostats. Be sure that the thermostat installed is capable of handling salt water, exhaust build up, and is the right temp.

You can run your engine without one, but it won't be efficient, and will eventually cause other problems. like carbon buildup, etc.

Also, you really need to change your thermostat on a regular basis, like once a year when you service your impeller just to be on the safe side.

Waiting for it to heat up is a no-no, especially when you are cruising and out in "nowhere" land.

Ken Cave
CD28 #227
Anacortes, WA



bcave@whidbey.net

[Larry DeMers]

Ken,

Once a year? I don't think that is really needed, and frankly doubt anyone does that on a regular basis. The thermostats cost around $60 (or more) each, so this is not a $12 impellor we are talking about. There is nothing in the Volvo thermostat that would go bad on a regular basis either. Lastly, there is no mention of this practice in the manual, so I would have to believe that yearly replacement is a bit excessive.

I would think that a spare thermostat on board would be a darn good investment though, as would a yearly inspection and perhaps a test of the existing one. Then if there was a problem developing, the thermostat could be exchanged as needed.

Otherwise, I agree with your post about the need for a thermostat to insure efficiency.

Larry DeMers
s/v DeLaMer
Cape Dory 30

There are thermostats, and there are Volvo thermostats. Be sure that the thermostat installed is capable of handling salt water, exhaust build up, and is the right temp.

You can run your engine without one, but it won't be efficient, and will eventually cause other problems. like carbon buildup, etc.

Also, you really need to change your thermostat on a regular basis, like once a year when you service your impeller just to be on the safe side.

Waiting for it to heat up is a no-no, especially when you are cruising and out in "nowhere" land.

Ken Cave
CD28 #227
Anacortes, WA

demers@sgi.com

[Ben Thomas]

A friend asked me to post this question. He has replaced the thermostat on this VOLVO engine in his CD 28. He replaced it because the water temperature would fluctuate from normal to hot, almost to the redline. Well after the new thermostat was installed all was good. Then the water temperature began to act up again the same thing. Several years ago he had the heat exchanger cleaned and replaced.

Here is the question...do you need a thermostat in southern climates where you do not experience a freezing problem? Can you just yank it out and button the housing up with some gasket tex type stuff. Appreciate the information and the help.

Keith Fawcett

Keith, When I had my volvo md7a the temp gauge was very irregular I replaced the Temp. sending unit Volvo part # VOL840074-9 and all settled down. Earlier I replaced the thermostat which didn't change the gauge reading.

Be careful as their are two different sending units one will work the other doesn't. the number I gave you worked on my volvo.
Good luck, Ben



bt@benthomaslandscapers.com

[Boyd]

Ken...

I agree the thermostat in a fresh water system should last a long time. I suggest checking the heat exchanger for lost impeller blades. Usually you can remove the end caps. Sometimes parts of the heat exchanger zinc come loose and clog the passages. Wouldnt hurt to acid dip the heat exchanger also.

Boyd
s/v Tern
CD30 MkII
Fort Lauderdale, Fla

Ken,

Once a year? I don't think that is really needed, and frankly doubt anyone does that on a regular basis. The thermostats cost around $60 (or more) each, so this is not a $12 impellor we are talking about. There is nothing in the Volvo thermostat that would go bad on a regular basis either. Lastly, there is no mention of this practice in the manual, so I would have to believe that yearly replacement is a bit excessive.

I would think that a spare thermostat on board would be a darn good investment though, as would a yearly inspection and perhaps a test of the existing one. Then if there was a problem developing, the thermostat could be exchanged as needed.

Otherwise, I agree with your post about the need for a thermostat to insure efficiency.

Larry DeMers
s/v DeLaMer
Cape Dory 30

There are thermostats, and there are Volvo thermostats. Be sure that the thermostat installed is capable of handling salt water, exhaust build up, and is the right temp.

You can run your engine without one, but it won't be efficient, and will eventually cause other problems. like carbon buildup, etc.

Also, you really need to change your thermostat on a regular basis, like once a year when you service your impeller just to be on the safe side.

Waiting for it to heat up is a no-no, especially when you are cruising and out in "nowhere" land.

Ken Cave
CD28 #227
Anacortes, WA

boyd@wbta.cc

[Ken Cave]

The last time I replaced a thermostat I purchased one for $17.00 at a local auto dealer-and was the same unit that Volvo sells for $60.00!!

Also, as I have mentioned in other messages, DB Marine in Great Britain is also a great place for engine parts-and they ship within a weeks time!

When I blew my engine, I was approximately 30 miles from the nearest port that I could get it replaced (or repaired) Cost for towing was a mere $800.00 Now, think of how many thermostats you can purchase to cover a towing charge when your engine overheats!!

Nuff said

Ken Cave
In port and at home



bcave@whidbey.net

[brian]

save $7oo dollars and join Boat US or Seatow

Nuff said.

[Leo MacDonald CD33]

Hi Keith,

Never had an overheat problem on ‘Heather Ann’ (CD30K with Volvo MD7A raw water cooled). But, I also would not remove the thermostat. The engine is designed to run at the temperature the thermostat provides and the thermostat is designed to last a while. If offshore a spare might be a good idea.

More for ‘preventive maintenance’ than anything else, I checked mine by removing it from the engine and heating it slowly on the stove with a meat thermometer. I have forgotten the exact numbers, but it seems like it ‘should start to open’ at 165 Deg.F and be ‘filly open’ at 170 Deg.F. Mine was right on, so reinstalled that and busied myself with something else.

If you have a FW/SW Heat Exchanger check for lost impeller blades / fouling in the HX – common problem. Remove the end caps and use wire/pipe cleaners and a thick twine. Can be surprising the amount of crap you get out.

Fair Winds,
Leo
'Evening Light' CD33 #38
Formally of 'Heather Ann' CD30K #57
Port; Groton, CT



macdoreNOSPAM@aol.com

[Ken Cave]

Boat US paid the bulk of it-but it still was a pain!!

Ken Cave



bcave@whidbey.net