5.7 GSi intermittent overheat issue

[avirgo63]

2000 four winns 5.7 GSi (Gray motor) sx drive, first off this overheating issue is intermittent... that being said the only condition that causes the overheat issue is after approx 20-25 cruse 3100-3200 rpm and after dropping off plane to idle the temp begins to climb (keep in mind this does not happen all the time) thats why i'm pulling out my hair... last year replace impeller, t-stat, both bellows(regular maintance), water pick-up hose (outdrive) did notice that the temp started to climb with the muffs on in the driveway this spring, removed hose from raw water pump at t-stat housing and checked volume of water at idle, with hose pointed straight up water flowed out approx 1 1/2 stream 2-3" tall... looked like good volume to me... only thing i have not done yet is the clear hose test, oh and all parts used were genuine oem Volvo Penta. end of season winterization water is drained and pink RV antifreeze is flushed thru motor, pump and outdrive
I love this boat and motor combo... just that i get a little nervious that someday its going to leave me stranded

 

[avirgo63]

Re: 5.7 GSi intermittent overheat issue

nobody has ANY ideas? WOW

 

[Senior B]

Re: 5.7 GSi intermittent overheat issue

My .02 cents is that you have reduced water flow due to manifolds that are getting plugged up. You say that you changed the water pump and are getting good flow through the drive. If you have the engine flush connection on the stbd side, hook up the hose and turn the water on high. Mine has the valve at the motor so I can kill the water there. remove your manifold drain plugs one at a time. with one plug out, turn the water on. Stick your index figer in the drain hole to dislodge all the rust and scale and let the water flush it out Keep sticking your finger in till you feel no more rust. When it's all flushed out on that side, stop the water and re-install the plug and do the same on the other side. Hope this cures your problem.

 

[Don S]

Re: 5.7 GSi intermittent overheat issue

only thing i have not done yet is the clear hose test,

And I would bet you get bubbles too.

 

[avirgo63]

Re: 5.7 GSi intermittent overheat issue

I don't remember seeing a flush connection... but I will take a closer look for one, and will take a closer look @ the manifolds,
Don, you say bubbles? I assume you mean I air leak in the raw water pick-up somewhere
THANKS