1988 OMC Cobra 30

"I have a 1988 FourWinns with

"I have a 1988 FourWinns with the Cobra 3.0 and it has been reaching 240+ degree when first starting but will eventually cool down if I idle it at high RPM's for a minute or so. I replaced the impeller and thermostat with 160 degree but the temperature with the muffs on in the driveway is 185 degree. Do you guys know if this is normal operating temperature, it seems kind of high to me? Shouldn't it be running at or below 160? The engine's water pump is the only thing left that I can think of, is there something else I should be looking at?"

"Should normally run at around

"Should normally run at around 160 (assuming you put a 160 t-stat in?) You could have wear in the drive water pump. At slow rpm it acts like a displacement pump and then when the rpm's increase it's more like a centrifugal pump. You could have wear in the SS liner. Should get a water pump kit and replace all the pieces to be sure. It's very rare for the engine mounted pump to go bad. Take the input hose off the t-stat housing and pointing it up slightly above the engine (put a bucket under) see how much water flow you have when you start it at idle speed. (Should be between 2 to 4 inches of water)
This test has to be done in the water, not on muffs."

"Bob, thanks for the reply. I&

"Bob, thanks for the reply. I'm not sure what the drive water pump is or the SS liner, could you specify to me or do you have pictures? Is it possible that the idle mixture needles have been adjusted and causing the engine to be running rich therefore causing the high temp? I know my wife's father did some adjusting on these before I did a tuneup."

"Sorry...when I say drive wate

"Sorry...when I say drive water pump that should be the one you put the new impeller into as opposed to working on the engine circulating pump. This is a parts drawing so you have replaced 15 but sometimes 16 wears or gets damaged, even the housing 20 can crack and sometimes guys mess up 18 the rubber gasket so it doesn't seal right.

"

"I actually replaced all of th

"I actually replaced all of these items 15,16,18, 20 and checked to make sure there was no leaking and that the impeller is turning by putting a mark on it. Every since my father-n-law adjusted the carb it has been running hot, that's why I was wondering about it running too rich although the boat seems to run okay. My neighbor had mentioned to me that he once had a tractor that was running too rich and caused it to run hot, I had never heard of this until he said so."

I've heard of timing being

I've heard of timing being off can cause it to run hot but your saying it's going up to 240! If it was running that rich have noticed any fuel evidence in the water from the exhaust? I would still do the water flow test by removing the t-stat input hose.

"Hi Bob, I haven't noticed

"Hi Bob, I haven't noticed any fuel in water from exhaust but will keep an eye on it. I will try the thermostat input hose and see how much water flows next time I'm at the lake, thanks."