2007 Volvo Penta 3.0 135 Temp Problems

[AugustChapman]

The first day back in the water my engine blew the rubber cap next to the thermostat housing. We replaced the cap and later that day the primary cooling hose split.

We removed thermostat, which was clearly blown, replaced and got back on the water.

The next day we blew the cap again. It was replaced, and I checked temps on engine with an infrared thermometer after operating to help determine if there was a blockage in the manifold or the riser.

Operating temp was registering a solid 180 on the guage and 180 at the thermostat housing. The front of the manifold cover was averaging 186, the stern 180. Riser temp 120.

Today manifold temp is averaging 190 to 200 but when I checked the temp of the oil filter it was registering at 250 degrees. Nothing else on the engine appears that hot.

Initially I thought I might have scaling or buildup in the manifold or riser, now I'm not sure where the problem lies.

No overheating alarm is going off so far.

All input appreciated.

 

[lashke]

Re: 2007 Volvo Penta 3.0 135 Temp Problems

What do you mean by "blown" thermostat? The thermostat has a spring on it that compresses when heated and opens it to let water flow. I've never heard the term blown used in describing a thermostat. Also, are you sure it was not in backwards? The spring end should be facing the large hose that is taken off to get to it. Is there any other work you've done recently before putting it in the water. How about the raw water impeller? Have you checked / changed it lately?

 

[AugustChapman]

Re: 2007 Volvo Penta 3.0 135 Temp Problems

What do you mean by "blown" thermostat? The thermostat has a spring on it that compresses when heated and opens it to let water flow. I've never heard the term blown used in describing a thermostat. Also, are you sure it was not in backwards? The spring end should be facing the large hose that is taken off to get to it. Is there any other work you've done recently before putting it in the water. How about the raw water impeller? Have you checked / changed it lately?

Thanks for the reply.

The small metal cap that hold the spring in place had rusted through and the spring was totally extended ( what I called blown ). Both the old one and the replacement are defiintely facing the facing the right direction.

The raw water impeller was replaced just before it was put in the water.

No other work was done other than winterizing then summerizing ( including the impeller replacement ) before putting it in the lake.

 

[lashke]

Re: 2007 Volvo Penta 3.0 135 Temp Problems

I know what you mean now. The same thing happened on my thermostat, except only one side of the cap was corroded and broken. I am having similar issues with the exception of hoses blowing out. My boat has never run hot before and I had changed my impeller this spring as preventative maintenance and found that one of the rubber splines had a small piece missing that I never could find. I took the boat out and had no problems but then I got concerned about that missing piece. So, I then opened up the thermostat housing to see if I could find the piece in there and that was when I found the thermostat broken. I took the boat out again with it like that with no problems and ordered a new stat. I then put the new stat in and now my boat runs about 20 degrees hotter. (180-185) No alarms, just runs hotter. Maybe this is where my boat normally runs at with a good stat in it. I tested it and it opens around 165-170 deg. I bought the boat used so I don't know the temp. from when it was new. I've had mixed advise about whether that is too hot or not. I'm planning to try to see if that piece of missing impeller is maybe lodged somewhere and causing a blockage. When you changed your impeller where there missing pieces that you did not find? Could be the culprit...

 

[lashke]

Re: 2007 Volvo Penta 3.0 135 Temp Problems

What was the temp your boat ran at new?

 

[AugustChapman]

Re: 2007 Volvo Penta 3.0 135 Temp Problems

When you changed your impeller where there missing pieces that you did not find? Could be the culprit...

Yes, there were several bits missing from the old impeller that I was unable to find.

When I replaced the thermostat, I completely removed the thermostat housing. I didn't find any bits lodged near the opening to the manifold.

When I was reading up on the thermostat, I was under the impression it was supposed to open at 160. This one definitely seems to open about 20 degrees hotter. I can see the temp guage hit about 185 then it suddenly drops back to 180, which seems to indicate the thermostat opening.

On a tubing run, I checked the top of the manifold with an infrared thermometer and it was reading 200 degrees even though the temp guage still read 180. Every other check it reads between 180 and 185, matching the temperature gauage.

I also wondered whether the new impeller was just providing more pressure and if the hose and rubber cap that blew were just weak with age and not able to stand up to full pressure anymore.

So far no more problems, hoping if there were bits of the impeller they cleared the manifold and riser, but plan on having everything checked out at the end of the season when it's out of the water and the boat dealer can hopefully test water flow.

 

[AugustChapman]

Re: 2007 Volvo Penta 3.0 135 Temp Problems

What was the temp your boat ran at new?

i don't know, I bought it used, with one season in the water. I never noticing any issue with the temp, so I never really paid much attention to it.