Volvo penta 4.3 running cool

[Schadow]

I have a 2000 Volvo Penta 4.3 in a Glastron runabout. My water pump went out last year and the local marina replaced the impeller. Ever since then, the engine will only get up to just over 100 degrees when running, normal is roughly 160 - 190. I believe the gauge is right because I can touch the engine after running and it is clearly not hot. Trying the simple fix, I replace the thermostat and this made no difference. When I installed the thermostat I made sure the spring side was pointed towards the engine block which is how the old one was mounted. I thought this was a pretty simple system, I guess not. What other things can I check?? The engine actually runs pretty well but will back fire some on cold mornings at mid range RPM?s. Not a big deal because I am mostly a summer boater. If I leave this situation can I damage the engine long term?

 

[Woody-jh]

Re: Volvo penta 4.3 running cool

I had similar issues recently, Mercruiser 4.3, but I don't know how to link you to my thread.

Here are some of the things that other folks told me to check. (Don S, Bondo, others)
1. Ignition on. Remove the 12V lead from the temperature relay on the side of the thermostat. Short it to ground and watch the gauge. If the gauge moves to top scale, the gauge is OK and you have a good lead wire.
2. Ignition off.The temp sender could be defective, but unlikely. To check, you have to open the thermostat cover to see the temp. relay (thermocouple). Hook up a voltmeter (ohms scale). One terminal on the +ve terminal, the other on the body of the relay- mine had visible plastic insulation, so I made sure I was on opposite sides. I applied hot air (wife's hot air dryer) to the thermocouple-if the ohms change quickly, the relay is OK.
3. I had an engine rebuild two years ago, and the engine has not run at proper temp since. To my surprise, I found two of the six hoses to the thermostat were crossed, both on the starboard side. When I corrected them (as shown in my manual) everything straightened out- temp gauge responded to normal, water exiting outdrive (on muffs) was the same temp.
Good Luck...

 

[Schadow]

Re: Volvo penta 4.3 running cool

Thanks Woody, good idea on the temp guage. For the hoses, I have my manual at my lake place, will the owners manual show me the correct hose hookup or do you think I need a service manual?