Thermostat or Fan Clutch? - Team Camaro Tech
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post #1 of 14 (permalink) Old May 6th, 19, 08:39 AM Thread Starter
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Thermostat or Fan Clutch?

I'm having an issue where when driving my engine temp is in the normal range of 180 - 185 (I have a 180 thermostat) but when I'm not moving the temps start rising quickly. The other day I ran some errands and hoping from a few close stores I got up to 220 and had to let it cool off. Then started driving and temps would stay in the normal range.

About 5 months ago I replaced my intake but due to weather I've just recently been able to drive the car. I did not put in a new Thermostat and did not have any issues before the new intake.

I was thinking about trying a new thermostat, which I would prefer not to do because I struggled to get the t-stat housing to not leak, but when talking to someone they thought that it was more likely a fan clutch. That would make more sense since my issues have been mostly when I'm not driving.

The fan clutch I have is at least 20 yrs old if not older. When I replaced the intake I also pulled off the fan to gain some access to my harmonic balancer because I changed that due to it slipping and lot allowing me to get an accurate timing. The fan clutch looked a dirty and gummed up some so I tried cleaning it up before putting it back on. I don't know if I goofed something up at that time or not.

What would your thoughts be? Do you think its more likely a fan clutch or thermostat?

Also, with the fan clutch I see a non-thermal and thermal fan clutch on Summit. Is the thermal one recommended? What about a standard vs a heady duty clutch?
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post #2 of 14 (permalink) Old May 6th, 19, 08:48 AM
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Re: Thermostat or Fan Clutch?

If car cools off when driving then there is enough capacity in your radiator to cool the car and your issues are with the fan/shroud not moving enough air to cool at idle. The factory changed the fan on a the BBC from five blades to seven in 1970 due to the five blade fan not moving enough air to cool the 454 (more power equates to more heat).

I ran a 582 big block using a seven bladed fan, thermal controlled fan clutch and a molded shroud to control air flow.

Big Dave
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post #3 of 14 (permalink) Old May 6th, 19, 09:52 AM Thread Starter
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Re: Thermostat or Fan Clutch?

Quote:
Originally Posted by Larger Dave View Post
If car cools off when driving then there is enough capacity in your radiator to cool the car and your issues are with the fan/shroud not moving enough air to cool at idle. The factory changed the fan on a the BBC from five blades to seven in 1970 due to the five blade fan not moving enough air to cool the 454 (more power equates to more heat).

I ran a 582 big block using a seven bladed fan, thermal controlled fan clutch and a molded shroud to control air flow.

Big Dave
Thanks. I'm leaning towards replacing the fan clutch with a thermal controlled one.

This is on a 350 sbc that has had the same fan/clutch/shroud setup for 20+ years with no previous issues.
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post #4 of 14 (permalink) Old May 6th, 19, 10:29 AM
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Re: Thermostat or Fan Clutch?

when the motor get to the 220 degree point....can you spin the fan blade (motor shut off)?

If so the fan clutch is no longer locking up

If fan clutch checks out than the T stat is likely suspect

FWIW I bought my fan clutch from Ricks Camaro (Ecklers) which was cheaper than rock auto (surprisingly), the correct one and Made in USA
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post #5 of 14 (permalink) Old May 6th, 19, 10:39 AM
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Re: Thermostat or Fan Clutch?

Word of caution!

You do not want a HD fan clutch. Those are designed to power a nineteen blade 24 inch fan on a diesel engine and will not release with a car fan. It is like spending forty dollars for a solid spacer. Just because it bolts up and says HD (who doesn't want HD parts) doesn't mean it is for your car.

Big Dave
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post #6 of 14 (permalink) Old May 6th, 19, 10:56 AM
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Re: Thermostat or Fan Clutch?

Quote:
Originally Posted by Larger Dave View Post
Word of caution!

You do not want a HD fan clutch. Those are designed to power a nineteen blade 24 inch fan on a diesel engine and will not release with a car fan. It is like spending forty dollars for a solid spacer. Just because it bolts up and says HD (who doesn't want HD parts) doesn't mean it is for your car.

Big Dave
The Hayden 2747 used on some A/C cars is HD and works great.

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post #7 of 14 (permalink) Old May 6th, 19, 11:05 AM Thread Starter
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Re: Thermostat or Fan Clutch?

Quote:
Originally Posted by SoCal805 View Post
when the motor get to the 220 degree point....can you spin the fan blade (motor shut off)?

If so the fan clutch is no longer locking up

If fan clutch checks out than the T stat is likely suspect

FWIW I bought my fan clutch from Ricks Camaro (Ecklers) which was cheaper than rock auto (surprisingly), the correct one and Made in USA
Don't know about the fan being able to be spun at 220. I only saw it get to that temp once and don't plan to let it get there again if at all possible.

I'll look at Rick's and see what they have as well. I'm going to hopefully pick one up locally so that I can get it installed before the weekend. I have a car show to make if the weather holds up.


Quote:
Originally Posted by rp930 View Post
The Hayden 2747 used on some A/C cars is HD and works great.
Thanks, my car is an A/C car so I'll look at that model number as well.
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post #8 of 14 (permalink) Old May 6th, 19, 11:15 AM
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Re: Thermostat or Fan Clutch?

fan clutch when cold the blade spins fairly easily but as car warms up the fan engages more. Once car warms up.....is the fan harder to spin?

The fan never really "locks up" when car is at operating temp but should be harder to turn fan blade when it is at operating temp

simple to install, just 4 bolts and the fan blade comes off with it. Swap fan onto new fan clutch. Install back on WP

If it turns out to be T stat, the felpro 35562T gasket, IMHO, seals better than just the flat ones for standard T stat housing. If you have one of those aftermarket housings with the large "O" ring, those are re-usable if the O ring is not compromised.
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post #9 of 14 (permalink) Old May 6th, 19, 11:24 AM Thread Starter
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Re: Thermostat or Fan Clutch?

Quote:
Originally Posted by SoCal805 View Post
fan clutch when cold the blade spins fairly easily but as car warms up the fan engages more. Once car warms up.....is the fan harder to spin?

The fan never really "locks up" when car is at operating temp but should be harder to turn fan blade when it is at operating temp

simple to install, just 4 bolts and the fan blade comes off with it. Swap fan onto new fan clutch. Install back on WP

If it turns out to be T stat, the felpro 35562T gasket, IMHO, seals better than just the flat ones for standard T stat housing. If you have one of those aftermarket housings with the large "O" ring, those are re-usable if the O ring is not compromised.
Thanks for the info. My t-stat is a factory aluminum one but it sits on top of a spacer that has an o-ring. Used the spacer due to clearance from my EFI temp sensor. The top of the spacer and below the actual housing is where I was having most of my issues. If I have to replace it again I'll look at getting the felpro gasket.

Since my fan clutch is so old, I'm probably going to replace that first. I have a feeling that is the issue.
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post #10 of 14 (permalink) Old May 6th, 19, 12:35 PM
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Re: Thermostat or Fan Clutch?

I also had clearance issues with the stock T stat housing when I switched to a Edelbrock manifold with oil fill tube as it would not clear the temp sensor. Got a Mr Gasket taller, swivel, T stat housing. It has the "O" ring
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post #11 of 14 (permalink) Old May 13th, 19, 02:53 PM Thread Starter
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Re: Thermostat or Fan Clutch?

Wanted to let everyone know that it was actually the fan clutch that was issue. I ended up buying a Hayden 2705. Picked it up from Pep Boys for $25. Before my car would get up to about 185 on occasion but now it pretty much sits at 180 now, at least with the limited driving I've done with it. I will say that I do have a 7 blade fan as well.
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post #12 of 14 (permalink) Old May 14th, 19, 11:07 AM
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Re: Thermostat or Fan Clutch?

FWIW the HD clutch will roar.

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post #13 of 14 (permalink) Old May 14th, 19, 02:04 PM
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Re: Thermostat or Fan Clutch?

Are you running a fan shroud?

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post #14 of 14 (permalink) Old May 14th, 19, 06:05 PM
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Re: Thermostat or Fan Clutch?

Was it running hot prior to changing changing the intake? If not, you may want to recheck your timing as you changed balancer. I would use a piston stop and check TDC.
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Thanks,

Jeff


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