VolvoPenta 3.0 Thermostat Removal?

[TFastle]

I want to replace the thermostat on my FourWinns Volvo Penta 3.0 (2000 model). I have the thermostat housing pulled off but it's not clear how the thermostat is removed. It looks like you basically pull straight back and out the large hole with a pair of pliers and maybe push the new one in? If so, it is not clear to me what holds it in place. Or, is there some sort of keeper that is holding it in. Any help would be appreciated and, I am sure, save me a lot of time. Thanks. Also, below is a description of the overheating problem I am having. If anyone cares to read it and give me their thoughts, that would be appreciated too!

My FourWinns with a 3.0 Volvo Penta was heating and cooling in a very odd manner yesterday at the lake. It usually runs about 150 degrees give or take. I noticed it was running a bit higher than that while pulling skiers and would edge up to 180 and stay fairly consistent. Then, when pulling one skier out the temperature shot up and I stopped the engine and let it cool down to 170. Then when I took off it cooled down to 145 (all of the sudden, as if the thermostat just opened) and then back to 160 and stayed for a while and then started shooting up again so I again stopped and paddled it in. I assumed I had lost a blade off the water pump and pulled it apart only to find it in fine condition. I suspected debris in the lines, maybe from a prior water pump failer so I pulled the lines and blew them all out and found no debris. I put it back together and it ran fine at first, about 150 or so for 10 minutes and then started edging up to 180 and stabilized there for a bit and then shot up again. I stopped for a minute, started it at an Idle and it again cooled down suddenly, as if the thermostat opened. It did this a number of times so I have decided it's a faulty thermostat. Does this thinking sense or am I missing something?

Thanks again!

 

[Don S]

Re: VolvoPenta 3.0 Thermostat Removal?

I noticed it was running a bit higher than that while pulling skiers and would edge up to 180 and stay fairly consistent.

That sounds more like a raw water pump impeller problem than a thermostat problem.
When was the last time the impeller was replaced? Should be an every other year maintenance item.
There are links to the OEM service manuals up in the adults only sticky. But you will need a full model number as Volvo doesn't go by year, plus, the year of your boat may not be the year of your engine.

 

[TFastle]

Re: VolvoPenta 3.0 Thermostat Removal?

Thanks for the reply, the impeller was replaced last year and I pulled it out yesterday and it was in good condition. I also cleaned and blew out all of the hoses and lines and found no obstruction but still had somewhat erratic heat issues. I did have an impeller a few years ago lose some blades but was pretty careful about finding them all (actually accounted for them by piecing back together the impeller) and have had no issues since. I guess my thinking is two fold. One, since the impeller seems fine and no obstructions I suspect that is working fine. Two, since it will get very hot and then quite suddenly start cooling to a normal operating zone it strikes me as a sticky or improperly operating thermostat although not the most common presentation.

I do have the thermostat out now and will replace. I am curious what holds it in? It looked like there was a cork or some sort of sealant that I scraped out and then it just pulled out. Does something come with the thermostat that pushes in behind it or what holds it in? My plan now is to replace and see if it fixes my problem (only $18). If not, back to the drawing board.

Thanks for your time.

 

[Don S]

Re: VolvoPenta 3.0 Thermostat Removal?

There is probably an oring in a groove holding the thermostat in the housing.

Do you boat in salt water?

 

[CayugaCobalt]

Re: VolvoPenta 3.0 Thermostat Removal?

Thermostat should be held in by black rubber O-ring which you can pick out using a special pick (like a dentist pick). I bought one at the hardware store for 99cents

 

[TFastle]

Re: VolvoPenta 3.0 Thermostat Removal?

I now see how it works with regard to the o-ring. Thanks. I have had the boat for 6 years and never had it in salt water. The prior owner told me he had had it in salt water once but I am fairly sure it was much more than that. It was very clean when I bought it and about 4 years old but I do have some mild corrosion issues that would only come from some salt water exposure. I do think he always rinsed it fairly well but that salt water is hard on boats. I have ordered the thermostat, oring and gasket and they should be here on Friday. I will install and again flush all hoses that I can get to and hope for the best.

Thanks for the responses!

Tim