View Full Version : Engine temperature issues

11-10-2011, 03:11 PM
I’m helping a friend troubleshoot his 2003 SN, 330hp Excalibur PCM engine, 1600 hrs. I know, trade it in for a MC:D.

Two issues:

1. Engine temperature gauge is erratic…first, it would only show about 100-125 degrees until we cleaned out some thick black residue that was in the engine block where the engine temp gauge sending unit screws in; now, the needle slowly moves from 100 to 180 back & forth; it doesn’t seem to matter if it is at idle or 34 mph.

2. After about four passes through the course, the ECM puts the engine in reduced RPM mode and shows an overheat code on the dealer’s computer. Strangely enough, nothing feels hot on the engine, exhaust risers, etc.

So far, we replaced the impellor, thermostat, both sending units (engine temp gauge and the one to the ECM) and the water recirc pump one at a time...no changes:(.

As mentioned above, when we replaced the engine temp gauge sending unit, we used a small screwdriver to remove some thick black residue from inside the engine block where the sending unit screws in. So, it appears there is sediment built up in that area or maybe the whole engine or an old impellor fin got stuck there and melted? Once we removed the black stuff we could reach, the engine temp gauge worked better, but now swings btwn 100-180 degrees.

I guess the two issues could be related if some of the water passages in the engine block are not totally clear? Is there some way to flush the engine water passages without tearing the engine down?

Any other thoughts? Tks, mac

11-10-2011, 05:44 PM
check exhaust hoses...the may be blocked...cloaked has some good picks