99 4runner overheating while sitting
 

Before anyone says it.. I searched... and found a couple threads but nothing definitive.

my 99 has 170,000 miles on it. Recently (last 2 months) it has started overheating when sitting still.. if I rev it up the temp goes down.. I have never let it boil over but its worrying me.

Checking around I believe the clutch fan is going out.. It does not comepletely freewheel but not as much as I have seen on other cars.. my question is :

Radiator is clean, coolant is good, no leaks.. I dont believe it to be the t-stat because usually those cause overheating at revs...

has anyone else experienced this? What did you find?

My buddies Tacoma did that. Just sitting there it would over-heat like mad. He got a new thermostat, now it works fine.

yeah the fan clutch thing seemed a little odd. yeah they do go bad but not often at all in these yotas from what i have seen and heard. i would lean towards something else.

Guess I will start with the Tstat... I am sure its cheaper than the clutch anyways... thanks for the info...

One thing you may want to consider to troubleshoot this problem is to get a probe mounted thermometer (they cost about $6) and stick it down in between the fan shroud and radiator while the truck is running. Once the truck is warmed up you should see 160 to 170 degrees or so in the middle of the radiator. (The fan will pull some air even if your clutch is shot...) If you are seeing less than this when the temp guage starts to indicate that the truck is overheating, the thermostat might be bad. (Your radiator could also be having problems if this is the case - mine did....plugged...) If you are seeing greater than around 190 to 210 degrees AND your fan clutch is not engaging, then the clutch might be bad (look for oiling, dirty deposits on the shaft between the fan clutch and motor....) I am assuming that you already checked coolant level, etc...

thanks for the advice, yeah I am going to do a new Tstat, flush, and new coolant... I have no idea how old it is, so its just good practice, felt around on the radiator and its even heating... dont believe its clogged... I will report back my findings.. going to do axle seals and maybe rear shocks all at the same time... now to decide on what shocks...

The folks at Jaos are nasty
 

I bought a Jaos bull bar for my 01 4Runner on Ebay I got it for 400 bucks with no instructions and Jaos will NOT even sell them to me ???
SO I will not buy any more of their products unfortunately you burn me and I burn back (sorry J Burtman) I was going to order A LOT of stuff from you but got the hand so I am moving on !

Does anyone have directions for this bar or does it go in da trash ??

Thanks !


Bob:pop:

I have no idea where this came from... but lets keep on topic please.

Ok so this was a moderately productive weekend... changed the oil, changed the Tstat, flushed, filled the radiator with new coolant., seafoamed the vacuum system (man thats a lot of smoke..) Replaced the axle seal that was leaking... Cleaned the brakes up (no-longer have the pulsating pedal..).

TRUCK STILL GETS HOT!
I think its the clutch fan at this point, after sitting idling for 15 min or so.. its starts climbing... and wont stop until I drive the truck.. when I rev the engine up I can't hear the fan ... I should be able to hear the fan engage when it gets warm... Just like when you start it up when its cold... it does not slip for the first 30 sec or so... sounds like a jet... then goes away.. it should do the same thing when the temps start climbing... yesterday I could hear detonation when the temps were up... as soon as they came down everything was fine..

Just food for thought...I threw $90 at a fan clutch that did not correct my overheat problem....if you do not see oiling/dirt on the fan mounting shaft, the problem may not be the fan clutch. If the radiator is not flowing air or coolant through it properly, the fan clutch "control" will not get hot enough to cause it to lock up....you might want to check your air temps....

Thanks for the input, I checked the radiator / condensor thoroughly this weekend, its pretty clean.. the flush was clean... I will check the fan next... 90$? wow... almost rather switch to electric for a little more... wonder if the alt could handle it?

Sorry - I should have been more specific....the outside of my radiator was not plugged - it was internally...and flushing came out perfectly clean. I did not figure it out until I stuck the thermometer into the air stream. The blockage was approximately 50% of the core right in the middle of the radiator. The PO did a good job of maintaining but something caused the radiator to plug...

good to know, that may be the next test... It takes sitting in traffic for 15~20 min for it to start to get hot... so its not a huge issue as we dont have much traffic where I leave... the occasional deer / cow in the road ... but not traffic.. But I do want to fix it... I know a radiator shop that can back flush my radiator cheap if I yank it... that may be the next thing...

That's what mine was doing too but would only take about 10 minutes to overheat - if I turned the heater on full blast it would cool it down. Except..... when towing my boat. I was toast until I replaced the radiator....