GKLCPA

My car has recently begun overheating either at idle or when I'm not a full speed on the highway. My heat also seems to take longer to kick in. I tested my fan clutch by sticking a newspaper in the blades and was able to bring the fan to stop. I replaced my fan clutch in 2011 with one I got from autozone. About the same time, I replaced the thermostat. Since then, I've put less than 10,000 miles on the car and have had no overheating problems until the recent cold spell. I've checked the front of the radiator for blockage. Here are my questions:

1) How likely is it that a fan clutch would go bad in so short a time?
2) Can a bad fan clutch bracket cause a overheating problem? What are the symptoms of a bad bracket?

LScowboyLS

a bad fan clutch bracket usually just causes noise

a fan clutch could go bad in 2 years if it was a junky one - the OEM fan clutch can last 15 years

a bad fan clutch can cause overheating, but so can many other things - is the electric fan running? - is the condenser free of debris?

YoshiMan

Were the Thermostat and Clutch Aftermarket ones? If so, that could be your problem.

I'm a Firm believer in utilizing aftermarket whenever we can, but the Thermostats and fan clutches are usually laughable compared to the originals.

You can get nice "Aisin" branded fan clutches on the internet for pretty decent prices, which are the exact ones which would come from the dealer.

As far as overheating, i would check to make certain the system is bled and filled properly, check radiator for leaves/blockage on the outside (mine had a bunch of cotton or something built up behind the A/C condenser, damn trees!) then start looking deeper if that doesn't help.

Thermostat could be sticking, and the fan clutch may have worn out already and may not be pulling enough air.

GKLCPA

The electric fan in front of the radiator is not running. I thought that only ran when the airco was on? I checked for debris and cleaned out. There wasn't enough to cause any blockage

GKLCPA

I'm not sure at this point what it might be. As it turns out, my newspaper fan clutch test might have been conducted incorrectly. After reviewing a youtube video, I redid using only one page of a rolled up newspaper (I used about 3-5 pages initially) and was able to stop the fan only once in a few tries. Moreover, at idle after a highway drive, the temp needle is only slightly above the 3rd bar and it's not overheating now. While I was in the engine bay, I noticed evidence of a cooling leak around the upper hose on both ends and I tightened the hose clamps.

The main difference is that today was a bit warmer than the past couple of days. I'm thinking that I should just have a coolant flush/refill done on the off chance there's blockage in the radiator and.or the coolant having lost its potency. I've had the car 7 years and never have had that done, so it's overdue anyway. Thoughts?

GKLCPA

Also, I'm definitely going to swap out the thermostat and fan clutch with some better quality products. What brand of thermostat is recommended?

Mugen_1

You can buy an OEM Toyota thermostat for $17+ shipping:

http://www.lexuspartsnow.com/oem-lex...hermostat.html

LScowboyLS

I would look at the sensor in the bottom corner of the radiator as suspect, it controls the electric fan, which is supposed to come on with the A/C or anytime the temperature exceeds a preset point (195 F if I remember right) but in any case, if it is overheating, then you have definitely reached the temp where it should be running!

GKLCPA

Is this the sensor I need to replace?

http://www.partsgeek.com/catalog/199...an_switch.html

Is there also a relay that needs to be replaced?

GKLCPA

Great. Thanks for the tip.

LScowboyLS

first of all, i would stick with OEM parts, not aftermarket - they are not that expensive online

I will look up the part and post a link in a few minutes

LScowboyLS

well a bit more expensive than I thought - $63 on ebay for the factory part, you could get the aftermarket part for a test, for sure, since it is about $18

the correct Toyota part number to cross over is 89428-33010

GKLCPA

Thanks much! Is there a relay for that fan also or do I just need to deal with the sensor?

LScowboyLS

there is a relay but it pretty much never fails on LS400

python

iTrader: (4)

my relay failed a few years back, its located in a weird place up front in the bumper somewhere (92). also I have the original fan clutch at almost 200,000 and I notice my electric fan coming on more than usual...something isn't right.