2007 Volvo Penta GL-P SX-A drive overheat

[borz170]

I think I have a blockage inside my cooling system, resulting from running in low mucky water at low tide. The boat will overheat after warming up to operating temperature, even at 3200 RPM's. Thermostat is out of boat and impeller is good. Thermostat is out b/c I haven't put in the new one yet.
If I disconnect the 1" hose that comes from the thermostat housing and goes into the manifold, then put a water hose in the hose to flush the manifold, It will not flow very fast at all. In fact, it acts like there is a large blockage. If I open up the manifold drain, water will flow faster and easier. A little dirt did come out of manifold. I was able to put a water hose in the main exhaust pipe below the risor (barely), and found that it is not obstructed there. I believe my obstruction is between the rubber connector from the risor to the pipe, and the manifold. I plan on taking the risor off of the manifold to check her out. This way I will be able to make sure the exhaust pipe going to the outdrive is not plugged. Hopefully there is no blockage in any of the water jackets in the block. If this is suspected, is there any other way to clear a blockage in the block, other than removing the head?

 

[veeru]

Re: 2007 Volvo Penta GL-P SX-A drive overheat

how did you go with this. was it muck from an impeller or something from the mucky water.

 

[bruceb58]

Re: 2007 Volvo Penta GL-P SX-A drive overheat

First thing I would do is back flush from the hose going to the raw water pump back towards the drive. If you have power steering in your boat, there is a heat exchanger there that coul dbe clogged.

When you overheat, what are the temps of the manifolds? If the manifolds are cool and the engine is hot, you likely have a blockage in the engine. Best way to check is get an infrared temp gun and point them at the manifolds and at the block near where the temp sender is. This will also tell you that you are not getting fooled by an incorrect temp gauge/sender.

Put the thermostat back in. You need it in there to properly control the waterflow in your engine.