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5.7 GSi Running cold any experience on why?

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Newport Dave

New member
. I have a boat with 2 clean running 2000 Volvo Penta 5.7 GSi's with SM/DP drives. Bought with 800hrs. When I purchased the boat I stripped motor's I did
-caps, rotors, plugs
-Raw water pumps, engine water pumps, belts, and hoses
-thermostats, housings, senders
-manifolds, risers
-filters and fluids
Motors run great, raw water cooled "salt". Port motor runs cold. It has gotten worse over the last 100 hours now won't get over 110 degrees. Changed and checked thermostat it was good but replaced anyway with no change.
No issues but running to Catalina next month.
I want to know if anyone else has has this problem or can offer a solution?

Thanks Newport Dave
 
IS that "cold, the gauge says so" or is that "cold to the touch on the t'stat housing and elbows"??.... An IR gun works well too....
 
sandkicker said:
IS that "cold, the gauge says so" or is that "cold to the touch on the t'stat housing and elbows"??.... An IR gun works well too....
Click to expand...

I have an IR Gun I used when I first bought it, I don’t remember the readings they weren’t this cold. I need to take it out and do it again to get exact t-stat housing and manifold temps.

Thanks
Dave
 
Newport Dave said:
I have an IR Gun I used when I first bought it, I don’t remember the readings they weren’t this cold. I need to take it out and do it again to get exact t-stat housing and manifold temps.

Thanks
Dave
Click to expand...

Thermostat housing likely has a blockage in the small almost hidden passage. It causes enough pressure that "forces" the thermostat to open prematurely, enough so that it over cools.
 
I have heard that this can happen. My thought is the housing and hoses have both been replaced and it seemed to get worse. Then I removed it and checked the housing and replaced the thermostat with no change. I have read that people have removed the thermostat (which I do not suggest) and the engines eventually warm up to at least 140. I order new gaskets last night and I am going to pull the housing again this week to recheck for blockage.
The prior owner could have easily shredded an impeller at some point, and clogged a passage, but I have always associated that with restricting flow and causing heat. Plus I have replaced everything with water flow other than intake heads and block.
Thank you, I am going to recheck as suggested.
 
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