Volvo Penta 2007 5.0 GL-H overheating

[JW lax]

I have a 2007 Volvo Penta 5.0 GL-H. I inspected the impeller and it is fine. With my boat out of the water on the trailer, I hooked my garden hose (completely opened) to the fresh water flush and turned on the engine. After about 5-10 minutes of revving the engine between 2000-4500 rpm the engine temperature rises above 200 F. I notice the temperature gauge will move, slightly, when the temperature goes above 160 F (thermostat appears to be working). I turned the engine off when it went above 200 F. I suspect I should not have been running the engine above idle. It seems higher idle speeds will cause the impeller to draw more water, which my garden hose can not provide, so it will start to draw from the outdrive intake, sucking air into the impeller housing and eventually the engine. After waiting for the engine to cool down I turned it on again, this time only at idle speed ~1000 rpm but the temperature still rises above 180F. If I open the lower engine block drain plugs the temperature goes down to 100 F, but if I close them the temperature will rise above 180 F. I suspect there is a blockage preventing the exhaust water from discharging out the risers.

Also, does anyone know if the hoses going to the exhaust manifolds are controlled by the thermostat? It appears it only works for the hose going to the engine block.

 

[Don S]

Re: Volvo Penta 2007 5.0 GL-H overheating

Do you have good flow of water from the thermostat housing TO the exhaust manifolds? If you do, perhaps the risers themselves are plugged up. Do you boat in fresh water or salt water?
Have you done anything to the thermostat? There is a bypass hole in the thermostat housing to allow water to the manifolds with the thermostat is closed, but, if it gets clogged up, the engine usually runs cold because the pump pressure opens the thermostat. It may even be a stuck thermostat.

 

[JW lax]

Re: Volvo Penta 2007 5.0 GL-H overheating

I'm not familiar with the minimum pressure requirements from the thermostat housing to the exhaust manifolds. It appears to me when the lower drain plugs are open there is a steady stream of water flowing out of them when the engine is at idle.

I boat only in fresh water. I recently purchased the boat (70 hours on engine), though I suspect the previous owner was somewhat derelict in caring for it. I did not touch the thermostat yet. I'm thinking I may have damaged the impeller when I was running it at high idle while my garden hose was attached to the fresh water flush. I think readers need to understand not to go above idle when only using the fresh water flush, otherwise you risk damaging the impeller, as a result of sucking up air through the outdrive.

Thanks for the help Don!

 

[Gcl14]

Re: Volvo Penta 2007 5.0 GL-H overheating

I bought a used Hurricane GS232 w/ 5.0 GL last summer and it had a brand new reman Engine that was just installled. I icruised around adhering to the break in procedure as recommended. We'll the first time that I opened her up for a little while and had a nice cruise I pulled over and asked the wife "what u think about the boat?" And before she could answer the alarm went off.... It was getting hot. After checking everything I could think of I yanked the big hose off that runs from the rawwater pump to the Tstat housing. We'll the end of the hose just before the Tstat housing was slam full of the shredded up impeller from the previous owner. I assumed that when the long block was installed they left the pump, hose, Tstat housing all hooked together, installed a new impeller and let her rip. So it's possible that ur previous owner had an impeller go to pieces and obstructing your hose like mine. I was amazed that mine didn't get hot before it did cause I had run it a good bit just not very hard due to it being new. I even found some more impeller trash when I winterized last fall.