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Overheat (?) problem. How to tell if fan clutch is bad?

 
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Doc
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PostPosted: Fri Dec 15, 2006 4:25 am    Post subject: Overheat (?) problem. How to tell if fan clutch is bad? Reply with quote

I have an '89 Toyota Cressida and the temp guage has started indicating
a hot condition. It'll run way up to hot and then dip. Sometimes does
it at speed but usually more at low speed/idle. In that respect it acts
like you'd normally expect in an overheat situation, however I put in a
brand new radiator less than a month ago. When it started doing this I
replaced the thermostat, still does it. The engine has about 30k miles
on a complete rebuild. Water pump seems tight, belts are snug. If I
keep the engine RPMs at around 2500 when standing still, it's usually
okay.

The belts are snug, but would a fan clutch cause this kind of
condition? How can you tell if the fan clutch is bad? There seems to
be a fair amount of air moved at a low speed, but I notice I don't feel
particularly more blow back from the fan when I rev the engine.

Other than a bad temp sensor or the guage itself, if the car is
actually overheating, what else could cause it?


Thanks for all input
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Guest






PostPosted: Fri Dec 15, 2006 4:36 am    Post subject: Re: Overheat (?) problem. How to tell if fan clutch is bad? Reply with quote

Hi,
My '89 Corolla behaved like this for a while-- when I was in low-speed
traffic and/or idling, the temp gauge would nearly max out before the
fan would kick in and lower the temp.
My mechanic changed the "fan switch" and it solved the problem. Is
your car's fan kicking in at the temperature it's supposed to?


Doc wrote:
Quote:
I have an '89 Toyota Cressida and the temp guage has started indicating
a hot condition. It'll run way up to hot and then dip. Sometimes does
it at speed but usually more at low speed/idle. In that respect it acts
like you'd normally expect in an overheat situation, however I put in a
brand new radiator less than a month ago. When it started doing this I
replaced the thermostat, still does it. The engine has about 30k miles
on a complete rebuild. Water pump seems tight, belts are snug. If I
keep the engine RPMs at around 2500 when standing still, it's usually
okay.

The belts are snug, but would a fan clutch cause this kind of
condition? How can you tell if the fan clutch is bad? There seems to
be a fair amount of air moved at a low speed, but I notice I don't feel
particularly more blow back from the fan when I rev the engine.

Other than a bad temp sensor or the guage itself, if the car is
actually overheating, what else could cause it?


Thanks for all input
Back to top
Guest






PostPosted: Fri Dec 15, 2006 4:59 am    Post subject: Re: Overheat (?) problem. How to tell if fan clutch is bad? Reply with quote

He's asking about a "fan clutch" which means he doesn't have electric
fans
..
johnyang97@gmail.com wrote:
Quote:
Hi,
My '89 Corolla behaved like this for a while-- when I was in low-speed
traffic and/or idling, the temp gauge would nearly max out before the
fan would kick in and lower the temp.
My mechanic changed the "fan switch" and it solved the problem. Is
your car's fan kicking in at the temperature it's supposed to?


Doc wrote:
I have an '89 Toyota Cressida and the temp guage has started indicating
a hot condition. It'll run way up to hot and then dip. Sometimes does
it at speed but usually more at low speed/idle. In that respect it acts
like you'd normally expect in an overheat situation, however I put in a
brand new radiator less than a month ago. When it started doing this I
replaced the thermostat, still does it. The engine has about 30k miles
on a complete rebuild. Water pump seems tight, belts are snug. If I
keep the engine RPMs at around 2500 when standing still, it's usually
okay.

The belts are snug, but would a fan clutch cause this kind of
condition? How can you tell if the fan clutch is bad? There seems to
be a fair amount of air moved at a low speed, but I notice I don't feel
particularly more blow back from the fan when I rev the engine.

Other than a bad temp sensor or the guage itself, if the car is
actually overheating, what else could cause it?


Thanks for all input
Back to top
Hachiroku ハチロク
Guest





PostPosted: Fri Dec 15, 2006 5:31 am    Post subject: Re: Overheat (?) problem. How to tell if fan clutch is bad? Reply with quote

On Thu, 14 Dec 2006 14:25:48 -0800, Doc wrote:

Quote:
I have an '89 Toyota Cressida and the temp guage has started indicating
a hot condition. It'll run way up to hot and then dip. Sometimes does
it at speed but usually more at low speed/idle. In that respect it acts
like you'd normally expect in an overheat situation, however I put in a
brand new radiator less than a month ago. When it started doing this I
replaced the thermostat, still does it. The engine has about 30k miles
on a complete rebuild. Water pump seems tight, belts are snug. If I
keep the engine RPMs at around 2500 when standing still, it's usually
okay.

The belts are snug, but would a fan clutch cause this kind of
condition? How can you tell if the fan clutch is bad? There seems to
be a fair amount of air moved at a low speed, but I notice I don't feel
particularly more blow back from the fan when I rev the engine.

Other than a bad temp sensor or the guage itself, if the car is
actually overheating, what else could cause it?


Thanks for all input

7M-GE Engine...NOTORIOUS for blowing through Fan Clutches.

You can buy one on E-Bay for $20-25 Buy It Now...the SAME fan clutch I
paid $80 for at AutoZone.

And believe me, when you replace it, you'll KNOW it's working! Sounds like
a B-17 taking off!

If you can spin the fan with the clutch COLD then it is probably bad.
There should be some resistance cold, little resistance when somewhat
warm, and more resistance again when hot. What I did was I drove my Supra
until it started overheating, stopped the car and shut the engine off.
(Since this is not an electric fan there's not much danger of losing a
finger...). I spun the fan and it spun freely. I was well over what was
normal for the engine, so there should have been some resistance.

When I explained my overheating problem in a Supra forum, they all said to
check the fan clutch.

Good Luck.
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