Engine running cool??? <kinda>

[hckrphil]

I have a 2000 Wellcraft Martinique 3000 with twin Volvo Penta 5.7GS motors.

The starboard motor gets up to temp relatively quickly, no issues. The PORT motor never really ever gets up to temperature.

Recently, port motor DID overheat on me (set alarm off, i looked down and noticed the temp gauge pegged at 250!!!!)........ I tore the top of the motor down, heads machined, new gaskets, new circulatory pump, etc.

After re-assembly, upon running the motor, it still doesn't get up to temperature. Read somewhere else, the person had a Volvo 4.3, another user had a Volvo 5.0..... they both were experiencing the same issues, ended up being in their thermostat housing, the "bypass" was plugged.........

Does anyone know what this looks like? Supposedly you remove the housing, remove the thermostat, and its a small quarter inch hole? I am headed to the boat tonight, would love to tear into that and see if its something as simple as a plugged bypass hole.... Supposedly its hard to see? Need to use a clothes hanger?

Thoughts?

I've attached a pic of my thermostat housings prior to when I cleaned them up (they look nasty). They are all cleaned up now, but apparently one may be plugged up?

Thank you!
Phil

 

[hckrphil]

Found the attached file in another post on here........... going to give it a whirl tonight....... hopefully that is my issue

Phil

 

[hckrphil]

OK, think I have the running cool thing fixed. I took off the thermostat housing, and cleaned out that tiny bypass channel.... It was tough to get a close hanger through there, but I was able to wiggle it through.... I didn't see anything major come out, but I'm guessing the entrance to the holes were caked over with corrosion.

Put it all back together and fired up the motor.... After idling for about 5 mins or so the temps started to rise and it rose all the way up to 175.


After sitting at 175 for about 5 minutes or so, all of a sudden the temp dropped down to about 160-165ish (thermostat must have opened).


I let it idle for another 10-15 mins, temp never moved after that.....

Victory???? I'm hoping!!!!

Phil

 

[further]

Looks like it. Had the same issue with mine multiple times.

 

[wkb2460]

165ish is about right for your engine.

 

[rkilpa]

Hey......I was that guy with the 4.3!

You will know if you were successful when you are running on plane, not at idle. If the bypass passage is plugged, the cold water coming into the TS housing will be forced into the block instead of bypassing the block and will cause your thermostat to be forced open from the increased water pressure. With the TS pushed open, the TS housing will not circulate warm water back into the engine and will cause your temperature to drop from constant cold water being introduced to the block.

If you didn't see any pieces of impeller being pushed out when you used your hanger in the bypass passage, you might have just moved the blockage around a little creating a little opening.

The opening can't easily be seen. I went in from the intake side and pushed a wound copper wire (solid electrical wire wrapped into a braid) through the passage until I saw it exiting into the large chamber. I passed the wire through to the chamber several times and didn't get anything out. I almost quit trying figuring there was nothing in the passage. After a couple of more strokes a piece of impeller finally push out. So just because you see the hanger go all the way through doesn't mean you cleared your blockage.

How did the gauge read when you were on plane?