Today I experienced the overheat lite buzzer sounding after 30 minutes @ 2800 so I shut down the engine for 30 min then attempted to start and it took 3-4 try's so I advanced the throttle after 10 seconds buzzer shut off and lite went out and I have been motoring @ 2000-2200 for 1.5 hours with no buzzer it lite's coming on? I can't figure this one. Changed impeller, thermostat and did a visual on heat exchanger from both ends with end caps off inserting a coat hanger in all the holes no sediment or blockage so replaced all gaskets and topped off antifreeze. Water flow out exhaust is present. Changed primary fuel filter on engine no leaks and cleaned raw water strainer? IdeasCould also be a fuel delivery problem. Filters, pickup tube end screen, plugged fuel tank vent..
YOu may not be looking at the mixing elbow. The internal passages are about 2" dia. for the 2GM (which I think you have). You don't need to cut in half to inspect for corrosion but you do need to check the archives here for the correct procedure to remove this little beast. It involves both LH and RH threads. A bit of homework, but will save BIG $$$$$$$$$$$$$.Is it approximately 4 inched in diameter and how do I inspect for corrosion
A close of my old photo shows Kloudie has perfect recall (and that's scary ) on the location of the left and right hand threads. Be sure to use a parting compound when re-assembling these parts as they should be pulled apart and checked periodically.Not 100% sure, but I think the elbow has left hand pipe threads and the part that bolts to the engine has right hand pipe threads..
......................... remember the long past stuff like it was yesterday but the recent stuff, not so much.Ralph, Laughing .. I can remember stuff about engines and cars and motorcycles and airplanes but I can't remember my name sometimes! ..
There's no doubt about it, carbon in the mixing elbows is just one step short of turning into diamond. I once tried an oven cleaner called "Oven Off" and had very limited success. Nothing else other than hours of scratching away at it seems to accomplish very little if anything. At that age, I'm sure you were in the market for a new elbow.Well, after reinstalling the exhaust adapter, elbow, and hose I was again unable to get above 2800 RPM like "hunter_healer".