Overheating Supra

Hmmm.....

I went out Saturday morning and spun the fan with the engine cold. It spun fairly easily... On a "BBS" similar to the Toyota group run by...ummm.gee, he hasn't posted here in so long, I forgot who he is! one of the members told another member, "If you can move the fan easily with the engine COLD, you have a bad fan clutch..." Now, it seems to me, I have ALWAYS been able to move the fan easily with the engine cold on my Corollas and Celicas with water-pump mounted fans...

So, Ray, qslim, et al...what be it?!?!

Reply to
Hachiroku
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You should be able to spin the fan freely when it is cold. With the engine warmed up, it should not spin.

Reply to
Ray O

Agree with Ray. The viscous coupling is designed to lock up when the engine is up to temp and the fan is needed, which means the coolant can heat up faster.

J
Reply to
Coyoteboy

I parked it two hours ago. The engine is still 'warm', but not hot. The fan still spins fairly easily.

I'll have to see if I can find the bills from the previous owner to see if she replaced the fan.

Is there a quick fix, like adding 'clutch fluid' or something?

Reply to
Hachiroku

After a couple of hours, the clutch is probably disengaged. Take it for a run, get the engine good and hot, shut off the engine, and see if the clutch is engaged. No quick fix for a bad clutch, but swapping it out shouldn't be too hard.

Reply to
Ray O

Im not familiar with the clutch in question but it may be possible to adjust it? Or jam it if you have fairly warm ambients normally, at least until you get a new one.

Reply to
Coyoteboy

Well, I went out for lunch and when I came back I was able to spin the fan fairly easily. But, then again, it's only 2 miles each way.

It's about 25 miles to get home, so it should be good and warm by then. Take a look at this 'dissertation' on Toyota fan clutches:

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An excerpt:

Anyway, I finally just got three of the bolts off the pulley, I need a

2nd 10mm wrench. I also had to take off a couple of belts. I'm using some bike tools as these small bolts are difficult to get to.

Back to the diagnosis, my general conclusion was that the clutch's "grip" loosened as the engine warmed. That oil must be pretty sensitive to temp changes. That is, it should thicken (engage) when the engine heats, not loosen like it appears to. I was able to stop the fan easily when the engine was running and hot (I used a cardboard stick, there was little, if any, resistance). I could even think that with enough air gushing the wrong way, that could stop the fan's motion. So, I've got to get back to that final bolt, then the clutch should just drop down. Huh, nothing ever goes that simply, so I've found.

OK, I have the clutch out and disassembled. The fluid, or what's left of it, looks and feels like thick honey. I can see evidence of seeping around the edges (lots of gooey dirt deposits) despite the tight-fitting o-ring. I will go to the dealer this afternoon for some of the silicon oil which looks a LOT like 10W/40. I can't see needing more than one tube of the oil, unless more has leaked than I think. Right now, there's barely more than a film covering the large internal gear-looking mechanism. I had to buy a 2nd 10mm wrench to get the nuts off (and back on) and also you'll need a large-nosed phillips to undo the four brass screws. Actually, I had to use vice grips on one of the screws that I tore up and will need to replace.

________________________

I have heard of replacing the fan clutch oil before. Now, doesn anyone have any idea how to DO this on a Supra?

Reply to
Hachiroku

Follow up: ride home, approx 24-26 miles, not as warm as the last few days ~85 degrees.

No overheating, parked the car and got out and grabbed the fan and was able to spin it fairly easily. It had a little more drag than when cold, but not a lot.

Reply to
Hachiroku

The fan clutch is probably shot. I've never heard of anyone changing the fan clutch oil, but that doesn't mean it can't be done. Personally, I'd just swap the clutch.

Reply to
Ray O

I had heard of it somewhere before, and also found a link to a guy who did it with his truck.

Of course, I DO have a Celica GTS sitting in the yard doing nothing, and it has a good fan clutch...

I wonder...

Unfortunately, it's raining AGAIN on a weekend, so it will have to wait...

Reply to
Hachiroku

Or, see if the fan will bolt up without the clutch...

Reply to
Ray O

here in so long, I forgot who he is!

the engine COLD, you have a bad fan clutch..."

engine cold on my Corollas and Celicas with

Probably way to late to matter now but anyway.

A cooling systems fluid coupling, clutch or whatever that is working properly should be do the following.

When first starting a COLD engine the fan at first should fully engage and be moving allot of air. So much air its obvious from the driver seat. (My Supra fan makes very loud wind noise.)

Within a short time (temperature dependent) the COLD coupling should basically go to the other extreme and move the least amount of air. (My Supra fan makes almost no wind noise)

If your car is running above normal temperature it would be heating that bi-metal part of the coupling and should be moving allot of air. (I would guess that stick would break things and probably hurt too.)

What I mean is on a cool morning when I start the car it sounds like a dam airplane for say maybe a minute. Then all of a sudden the noise just stops. It's really obvious if your listing.

Symptoms typically show up at the first stop after highway driving. The temperature gauge go up quickly but then go back down when you take off. (like the light turned green.)

A/C system might get really weird too at times.

Oh, and if you stuck a stick in the fan and stopped it. That couplings bad. If the coupling seized so the fan was direct drive it would use a major amount of HP, kill your gas mileage and sound like a airplane big time.

GL Dan

Reply to
Danny G.

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