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Runs hot..

I have a 98 4.3 V6 4x4.. It runs just fine and the temp gage always stays a little under midpoint when I'm driving. The other day I was sitting in the parking lot waiting for my wife to finish shopping and noticed the temp gage was almost to the red zone. I quickly turned off the truck and waited for her return, as soon as I started the truck it cooled back down to it's normal temp. After it cooled down, I check the fluid level and it was full to the top. Today I stopped on the way home from work at a Mc Donald's drive through and then parked to eat my burger. Again the temp started to rise. I let it go and it just about got into the red zone. I finished eating and got back on the road and the temp immediately went back to the normal range. When I got home I tried to spin the fan blade and it did have some resistance to movement. So it must be working somewhat.

- I sort of ruled out the thermostat as it keeps the temp at the normal level most of the time.

- The radiator isn't leaking and must be doing it's job. But maybe not good enough?

- I have no idea how much restiance the fan should have when hot. Is there a measurement I could make to test that, or should it be locked tight when hot?

Anyone have any suggestions, other then not eating fast food.. LOL

Joel

Reply to
Joel
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Reply to
Roger Brown

i had the same problem with my 99' 4runner. i replaced everyting, themostat, cap, water pump, flushed the coolant twice. it only had

79k miles on it and the radiator ended up being clogged. they pressure tested it and could never tell the radiator was bad. but it had the same symptoms it would overheat while at idle or stopped and it would cool down while moving or if the heater was turned on. i would just replace the thermostat 1st, since its the easiest thing to replace, but im thinking its the radiator, or possible air trapped in the coolant.
Reply to
stkd16z6

check the cooling fins on the radiator, probably a bunch of them loose esp near the bottom. When you drive, the ram air provides extra cooling, when you idle while stopped, the rad is not getting cooled enough by the fan alone. when the temp is up, just open the hood and the fan should be turning full speed, if not then check it out, fuse ? Else take it to a rad shop for test or just change it if it's over 5 years old. Not worth letting it die back in the bush somewhere.

regards

Reply to
Guylaine J. Parisien

I used this a few years ago to determine if the radiator was clogged. Start the engine from cold. After just a few minutes, start feeling the front of the radiator for variations in temperature. The radiator should warm up all over pretty evenly. If you feel a lot of cold areas, and some warm areas, the radiator is probably clogged.

Reply to
Offen Rong

I had the same symptoms and did the same things you did when my '82 Toyota Pickup would overheat, then suddenly cool down when driving it. My fix was to finally have the radiator rodded out and pressure checked.

Then it worked fine.

Reply to
Yoboslayer

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