okay, im stumped here. i have a 99 4runner 3.4 v6, just recently it has started running hot. i just flushed the cooling system a few months ago, and the original coolant seemed to be pretty clean. it just started overheating, now it usually takes about 25-30 mins to get hot. i have replaced the thermostat, cap, and bled the cooling system. now it once it starts getting hot i can turn the heat on and rev the motor and the needle drops. im thinking maybe the water pump? also i noticed that the coolant backs up into the resevior tank. also, im thinking it might possible be the fan clutch. how can i test this? my truck has only 81,000 miles so im thinking the water pump should still be good. any ideas?
help! 99 4runner 3.4 overheating problems
May 13, 2004
3 Replies
When does it overheat, fast slow, hot weather or cool, high or low engine RPMs, engine working hard (like climbing a hill) or just running normally?
Fan clutch testing:
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Did you test the old and new thermostat to see if they were working or not?
The fan clutch, becomes ineffective after a certain speed. If it still overheats after replacing the water pump, the next obvious source could be the radiator itself. I've seen a radiator go after 3 years in my friends Durango. We went though the same scenario, until finally changing the radiator. It has not overheated since.
Good Luck!
JW
RPMs, engine working hard (like climbing a hill) or just running normally?
it overheats when im driving, usually takes about 15-20 mins. whats odd, is that it doesnt go completely hot when im sitting at idle. it needs to actually be driven to overheat, and also if im driving i can turn the heat on and rev the motor and watch the temperature fall. im thinking about just taking it to have the water pump and timing belt done, since im due for it in another 9k miles, but would rather just fix whats wrong until then. i'd like to rule out the radiator since the coolant seems pretty clean when i first purchased it from the original owner a few months ago.
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