Volvo Penta 5.7 Overheating

Ryleighg21

Recruit
Joined
Jul 28, 2015
Messages
1
Looking for help, our 03 Chap. Bow rider is overheating. We have had it recently serviced, impeller changed, thermostat checked, oil change and so forth. It doesn't heat up till we get over 25 mph, and around 4000 Rpms. Any suggestions greatly appreciated.....
 

BRICH1260

Lieutenant
Joined
Jul 6, 2011
Messages
1,342
It could be several things from water supply to water distribution. I would pull the pump hose going into the Tstat housing while running and make sure your water supply to the Tstat is good. This would eliminate pickup, hose blockage and pump issues. then I would take the Tstat housing off and inspect the housing for blockages and test the thermostat. The general problem will come from one these components not functioning properly
 

Tretatt

Seaman Apprentice
Joined
Jul 28, 2015
Messages
38
I have a Volvo Penta 4.3GL inboard outboard boat engine. I was on the lake and my motor started to get hot; around 200 degrees. I stopped the boat and put the blower on for about 10 minutes. Started it back up again and started going. The temp came up to about 200-210 and I shut it down. I think the hottest it got was 225. Is this too hot, and is my impellar bad? If I replace the impellar, do I have to relocate the raw water pump? The pump was not leaking at all. And if I do have to replace the impellar, how to I flush the engine so not if the impellar parts are stuck in the motor or stuck against the thermostat. I am a new boat owner. Please any advice will be greatly appreciated!!
 

internetdel

Cadet
Joined
Nov 11, 2015
Messages
13
Put your hands on the exhaust risers. If it's really hot, the water jackets in your exhaust risers are restricted. I replaced the exhaust risers (recommended every 6 years) after having overheating problems at 10 years. Worked perfectly afterward. You can get good aftermarket risers at http://www.michiganmotorz.com/ and they are easy to change if you have a little room around your engine.
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,923
Tretatt, you should start your own thread.

Ryleighg21. Welcome!!
Salt or fresh water?
Usually an overheat at high RPM's is a constriction in a riser or manifold.
Possible the new impeller is bad?​
You start it without a hose or out of the water?

Running in shallow water, will pick up sand or mud and it can settle in the block or manifold causing it to overheat.
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,923
Tretatt.
The blower has nothing to do with overheating or cooling the motor.
It's function is to remove explosive fumes from the bilge before starting.
No relocation when changing the impeller.
Inspect the impeller and if there is any vanes missing look downstream from the pump, the thermo housing might have the pieces or any constriction points.
The pump doesn't have to be leaking if it's bad.

Flushing the motor won't push the impeller pieces out.
Usually they need to be taken out by removing the hoses and inspecting the lines.
 
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