Frying rave valves

[doochallenger]

Got a serious overheating problem with a 787/800 motor in a 97 challenger 1800. Had it out a couple weeks ago and engine died and wouldnt turn over. Pulled cylinders to find parts of rave on top of piston and in bottom end. Red plastic and hard plastic with bellows both melted to spring. No damage to rings or piston, vacuumed out bottom end and put in new raves. Ran on hose to get good flush and make sure flowing. Went to lake over 4th and it ran well. Checking things out afterwards, both plastic parts on both raves had melted again. This time no rave parts in motor, whew, but exterior flange proximate threads gone on one. I just ordered 2 used raves but dont want to keep frying them. Any ideas how I can check cooling as it flushes just fine on the hose, both top and bottom connects. No beeps for overheating. Sure wish I had a temp guage. Also, this same motor wont tach over 6 while the other goes over 7 and never overheats. Not sure if overheating and low rpms are related. Suggestions??

 

[kustomkarl]

I would swap the tech wires to see if the tech guage really works... or if the engine is not revving correctly. Check the temp guage to be sure it is working properly. It sounds like it isn't getting cooling around the cylinders. Is the "Tell Tail" working? Check the water flow regulator for any blockage and the elbow fittings too. The fittings should not get mixed up as they do a specific job where they are located. They have the orifice size stamped on them. Here is some information on the water flow regulator.
The water flow regulator has been calibrated at the factory and should not be tampered with or modified in any way.
CAUTION: Strictly adhere to the calibration procedure or otherwise serious engine damage will occur.
If engine does not maintain RPM or the engine is experiencing poor performance, the water flow regulator valve might be out of adjustment. The normal adjustment as done at the factory is as follows: On the top of the water flow regulator valve locate the red plastic adjustment screw. Mark the location of the screw with a dab of paint for reference. Turn the screw clockwise (tighten) until the top edge of the screw is flush with the top of the black cap. Turn the screw 2 clicks counterclockwise (loosen). This is the factory spring setting. The bottom tapered screw should be screwed in just snug.

This Regulator valve plays an important part in cooling the engine. Each fitting is a special size and controls the flow of water to the different part of the engine depending on the rpm. Never mix up the fittings or you'll have problems with over heating and maybe seizure.

I hope this helps.

Karl