GKLCPA

The temperature gauge in my car moves towards the red mark at idle. I can literally watch it move, however at normal speeds it's in the correct position. At idle, the fan does turn on and I recently had the water pump replace when the timing belt was done. Searched this topic, but no one had this specific situation.

What should I check out here?

emarknot

weak fan clutch is my first guess.

lets clarify things...

how long ago was the timing belt done? a timeline would help.
If the t-belt was done say 400 miles ago, this could be from a defective water pump.

if it was 40 miles ago, it could be air in the system.

now if it was around 1500 ago, and NOW, its over heating, I would suggest the fan clutch.

here is why.........
a new fan clutch.....the thing your fan blade is attatched to,......should have a moderate amount of resistance when trying to spin it by hand with the engine off.

a fully locked fan clutch will have a lot of resistance......but if it were fully locked, you wouldnt have this issue.
im suspecting the fan clutch is too weak.

why?
because when you drive, you get the extra airflow, at idle, there is none.


whatever the problem is, when you get it figured out, let us know

GKLCPA

Thanks much for your response.

The T-belt was done about 2000 miles ago.

Question on the fan clutch---are you saying that it possible that the clutch is not spinning the fan fast enough such that it's not cooling properly?

Also, with respect to testing....if the fan clutch doesn't have any resistance when spinning, does that mean its faulty?

Also, is the T-stat pretty much ruled out as a problem?

I'll spin that fan tomorrow and report back here on my findings. Thanks again!

emarknot

the thermostast might be an issue, but I would venture to say.......not in this case.

a weak fan clutch would most likely be the culprit because....

while driving, the fans is spinning, and pulling some air through the radiator, with the added airflow from the vehicle moving.

while at idle, the car has no airflow, other than the fan clutch. so, If the fan clutch isnt doing its job correctly, there is basically no airflow.

a new fan clutch will have a moderate amount of resistance, not too terribly difficult to spin......a locked fan clutch would have alot of resistance.
a weak fan clutch should have easy resistance trying to spin......of course , with the motor not running.


you could always try a t-stat first, maybe it is partially stuck open,

but if this were my car, and my symtoms.......i would do a fan clutch

cf3232

Fan Clutch, not T-Stat. In this situation I am pretty sure of it.

deanshark

Actually this has been talked about MANY times, you must be searching the wrong words.
My moto is "cheapest and easiest first"
Although the fan clutch can be weak and possibly may need to be changed, it might not. The first thing you should check is to see if the radiator is being blocked. There are so many threads showing the stuff that gets in front of the radiator which doesn't let enough air through. This is one of the minor ones; https://www.clublexus.com/forums/ls4...-pictures.html There's more that show alot more crud in there.

People have changed all kinds of parts and spent alot of money trying to figure out why thier car was overheating and then found all the crud in front of the radiator. Checking it only takes 5 minutes and if it turns out to be clogged will save you alot of time and aggrevation of changing parts that don't need to be changed, and it's FREE.

GKLCPA

I like free .

I went out and spun the fan awhile ago and it had moderate resistance and did not just whirl around freely. I ran the car at idle to see if I could recreate the high temp condition and couldn't do so after overheating on a number of previous occasions. The only difference is that the car was in the garage and this is a considerably cooler day than it has been recently. After idling for 15 minutes, the temp gauge was where it was supposed to be.

And, yes, I've been through the deal of throwing parts at cars only to find it was something else. I'll check that radiator at my first opportunity. Thanks for the tip.

qewani1

i have same issue with my LS, will try doing this.

cf3232

Mine did the same thing on idle after just sitting. You have to drive it to get the correct amount of heat generated then when it sits it will overheat. The fact that when you drive it is fine and when you sit it overheats says fan clutch to me.

The post about stuff obstructing the radiator was a good post. Only difference is the guy said it was running tick hotter, not overheating.

deanshark

There have been a boat load of Club Lexus members that have had the problem with all the stuff in front of the radiator and overheating while at idle. Actually someone just posted about the crud about a month ago and it was the worst I ever saw in my almost 40 years of mechanics. The link I posted was just one to show the point, with a picture, of what I was talking about.
If you read it you would notice I said "This is one of the minor ones; There's more that show alot more crud in there."
I'm not gonna do all the searching for him but I will point something out that the problem could be.

GKLCPA

Thanks CF. That makes sense as the times it did it before I had driven a distance previously. I'm definitely going to check that radiator though as I really didn't look down in there to see any blockage. My problem is that I ripped my Achilles recently and I'm on crutches, so getting up and doing something like this takes a bit of "pre-planning". As I indicated above, the fan had moderate resistance and didn't spin freely, so it seemed okay.

BTW, it looks pretty tight in there if I have the change that clutch. I see Lexls has a tutorial on explaining how to remove it, but my car's a 1996. Am I right to assume that it's going to be set up pretty much the same way? Also, is there anything special I should know should I have to put one in?

GKLCPA

Yep. 15-16 years worth of crud down in there is a definite possibility, especially since I've never looked at it. I'll definitely be doing that on my next "vertical excursion" to the garage . Once I do so, I'll report back here on the results.

GKLCPA

Well, checked the radiator today and all clear. I'm going to go for the clutch and it appears that I can pick one up from autozone pretty cheaply. While I'm at it, I'm going to address the radiator hoses and the serpentine belt. None have ever been changed and the last guy I took the car to indicated that the hoses showed some evidence of dry rotting.

emarknot

let us know how it turns out.

GKLCPA

Well, got the clutch in today. The last nut was a bear. Got stripped on me and I had attach some vice grips to get it off. Went pretty quick after I got the clutch off. All of the time was spent fighting with the problem nut. I've not had a chance to test yet.

For anyone who does this, make sure you have two 12mm wrenches and a pickup tool as well as you're bound to drop something working in that tight space. When you get to the last two bolts, loosen one and leave it in so you have the leverage to loosen the last one. I didn't do this and wound up stripping the last bolt accidentally as a result.

I'll touch base once I test. I'm curious how this $ 57 autozone part will work, especially since Autohauz is selling it for $ 160+ and I understand the same part from Lexus is even double that.