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Update and info needed 2002 BF 225

O

Other Line

Contributing Member
Guys,

Been chasing an overheat issue. I can idle all day long with no issues, but once I hit 4k overheat alarms go off and she goes into safe mode. Got her on the water yesterday, did it twice in a row, then it went for 20 minutes at 4200 RPM, but when I bumped it up to 4800 she alarmed and shut down.
Took the heat gun with me this am. idled for 30 minutes and both cylinder banks read 107ish on the gun.
Pushed her up to 4000 and alarmed within 20 seconds. Facing the motor, left bank read 137, right bank read 184.5!
Idled home with no problems. First thought is a bad t-stat on that side, but I replaced them both less than 50 hours ago. Also, this T-stat " cavity" developed a pencil sized hole from corrosion at 600 hours ( right after I replaced the Mid-Section!). I used MarineTex and it lasted 30 hours, secound fix was with SteelStik and it's been good for about 200 hours.
I am going to put the t-stat on the stove to see when it opens.What temp should it open at? I forgot. If's it works right, I have the following concerns: I got some debris in the cooling passages during the repair, or I have built up the patch Area to much and it's interfering with the t-stat opening.
Thoughts?
 
T-Stat should start to open at approx. 140 F and be fully open at 160 F. It only opens 3 mm.

I wonder of some of that MarineTex got lodge in the water passages when it failed. When you have the t-stat out, try to seal in the end of a garden hose into the opening and turn it on full power, you might get lucky and move it on through.
 
Pulled the t-stat from the hot side, pretty gummed up with salt. Dropped a new one in and ran it for 45 min with no issues. I think I have built up the patch a little too much so there is not quite the space in the cavity as there was originally. So, easier to clog up. Probably pull every 20 hrs or so to inspect
 
I suggest that you also open up the t-stat on the left side. The 137 degrees sounds too low, so that t-stat may be stuck open. When fully up to operating temp, the heads and manifolds should be at about 160 F. It's best to test the temperature after idling in gear for at least 15 minutes.
 
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