We usually run our 1977 454 v-drive at cruising speeds running 1800 rpm happily for hours on end at 175F. We have had overheating issues in the past at higher rpms (eg 3000 rpm) that I thought I had fixed by replacing the raw water pump and having the heat exchanger checked and serviced.
Yesterday while running at 3000 and then attempting to accelerate above that the rpms started dropping as I applied throttle and then stumbled. I dropped into idle and checked the temp at the engine block - 200F at the thermostat housing but not boiling over. I tried to accelerate again before allowing the engine to cool down and rpm increased too slow for the amount of throttle I was giving and it felt rough. Shut it down, checked temps at exhaust elbows at 136F (so raw water pump is working well), temp at v-drive is 115F (first thought was that the clutch was slipping - had just changed ATF). Again temp at thermostat 200F.
After letting the engine cool for a few minutes running at idle speed I again accelerated up to 3000, ran smooth no problems, so I assume not a tranny problem? (I didn't stay at 3000 for long as I did not want to run up the temp again.)
So what could it be? Plugs are due for changing, so maybe it's as simple as that?
Engine is running rough at 200F because that is too hot a running temp ie. I have new cooling problems to resolve? Maybe my heat exchanger needs replacing?
Tranny problem related to my recent ATF change?
Fuel flow problem at tank pick-up? (I don't think its the fuel filters as they were both changed 60 hours ago)
Thanks,
Dave
Yesterday while running at 3000 and then attempting to accelerate above that the rpms started dropping as I applied throttle and then stumbled. I dropped into idle and checked the temp at the engine block - 200F at the thermostat housing but not boiling over. I tried to accelerate again before allowing the engine to cool down and rpm increased too slow for the amount of throttle I was giving and it felt rough. Shut it down, checked temps at exhaust elbows at 136F (so raw water pump is working well), temp at v-drive is 115F (first thought was that the clutch was slipping - had just changed ATF). Again temp at thermostat 200F.
After letting the engine cool for a few minutes running at idle speed I again accelerated up to 3000, ran smooth no problems, so I assume not a tranny problem? (I didn't stay at 3000 for long as I did not want to run up the temp again.)
So what could it be? Plugs are due for changing, so maybe it's as simple as that?
Engine is running rough at 200F because that is too hot a running temp ie. I have new cooling problems to resolve? Maybe my heat exchanger needs replacing?
Tranny problem related to my recent ATF change?
Fuel flow problem at tank pick-up? (I don't think its the fuel filters as they were both changed 60 hours ago)
Thanks,
Dave
