I've got an '88 Ebbtide with a 5.0L (Chevy) engine mated to a Cobra outdrive. Earlier this year, I toasted the upper unit due to a bad lube fill (yes, I know). I replaced the upper unit, and since then I have been fighting overheating issues.
After the upper was replaced, the temp would spike very high - about 220*, but it then would immediately drop down to 180* to 190*. That is still too high, but it seemed manageable.
I decided to address the temp issues this weekend. I replaced the raw water impeller in the upper, replaced the seals at either end of the water tube between the upper and lower units, and installed a new 160* thermostat. Of course, all new gaskets were used and were properly sealed. After the work was complete, I ran it on muffs long enough to reach operating temp, which stabilized at about 163*.
While I thought that might fix the mild overheating issues I was fighting, now things are actually worse. The temp spikes high (240*) after a small amount of use, and it does not go back down. I had to anchor off for a while to get the temp to normalize, and then the engine would not start. I'm guessing this was due to heat sink causing internal engine components to expand.
After things cooled down (<140*), I was able to start the engine while I was still in the river. I let it idle for a few minutes, and the temp slowly climbed to normal operating temp (165*). It then slowly climbed to 180*, after which the temp gauge needle jumped dramatically towards another overheat. I killed the motor and came in to call it a night and type this out.
While it's still in the water, I'm gonna run it with the inlet hose disconnected from the stat housing to check the flow. I'm guessing that the water flow will be substandard.
My question is this: assuming that the flow of cooling water is compromised, what do I check next? With a new impeller and stat, I thought I was on the correct path. Is there something else in the lower unit that I should be investigating? What am I missing here?
I'm at a bit of a loss here, so I'll entertain any suggestions. Thanks in advance!
After the upper was replaced, the temp would spike very high - about 220*, but it then would immediately drop down to 180* to 190*. That is still too high, but it seemed manageable.
I decided to address the temp issues this weekend. I replaced the raw water impeller in the upper, replaced the seals at either end of the water tube between the upper and lower units, and installed a new 160* thermostat. Of course, all new gaskets were used and were properly sealed. After the work was complete, I ran it on muffs long enough to reach operating temp, which stabilized at about 163*.
While I thought that might fix the mild overheating issues I was fighting, now things are actually worse. The temp spikes high (240*) after a small amount of use, and it does not go back down. I had to anchor off for a while to get the temp to normalize, and then the engine would not start. I'm guessing this was due to heat sink causing internal engine components to expand.
After things cooled down (<140*), I was able to start the engine while I was still in the river. I let it idle for a few minutes, and the temp slowly climbed to normal operating temp (165*). It then slowly climbed to 180*, after which the temp gauge needle jumped dramatically towards another overheat. I killed the motor and came in to call it a night and type this out.
While it's still in the water, I'm gonna run it with the inlet hose disconnected from the stat housing to check the flow. I'm guessing that the water flow will be substandard.
My question is this: assuming that the flow of cooling water is compromised, what do I check next? With a new impeller and stat, I thought I was on the correct path. Is there something else in the lower unit that I should be investigating? What am I missing here?
I'm at a bit of a loss here, so I'll entertain any suggestions. Thanks in advance!
