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How to check Fan Clutch on 1988 Cherokee?


 
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beaumecxxx
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Joined: 21 May 2006
Location: Vancouver, Canada

PostPosted: Mon Jul 10, 2006 10:56 am    Post subject: How to check Fan Clutch on 1988 Cherokee? Reply with quote

Hi all. I have posted a couple of comments on this great site.

Does anyone know how you can determine if the viscous fan clutch is working correctly on a 1988 Cherokee?

I am now having overheating problems on my 1988 Cherokee (4.0 manual transmission, basic Cherokee with no Air Conditioning). In normal street driving engine cooling all is ok.

When I go into low speed mountain crawling (usually in 4 Low) at about 8-10 MPH my engine overheats after about 20 minutes.

My radiator was replaced new 18 months ago (after accident). All components seem to be in OK working order. I have the pressure bottle clsoed cooling system. Coolant is very clean, when it spews out in great balls of steam Very Happy

There is no auxiliary electric fan, just the main fan with viscous fan clutch. I was wondering if the fan clutch might be defective? How can you determine if the fan clutch is working???


I was thinking of installing an auxiliary electric fan, but is this the only option? I first want to be sure that my Cherokee is working properly (as per factory design) before I start modifying the system.


Thanks to all

Beaumecxxx
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ThePhantum
Pissed-Off Admin
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Joined: 23 Jan 2004
Location: I knew it...I'm surrounded by Assholes!

PostPosted: Mon Jul 10, 2006 8:46 pm    Post subject: Reply with quote

There's a long, drawn out procedure for the official test involving drilling a hole in the shroud, a thermometer, tach, timing light and blocking off airflow to the radiator...

The easy way to tell is with the engine cold, spin the fan by hand. If it free wheels or spins more than 3-4 times replace the clutch.
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beaumecxxx
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Joined: 21 May 2006
Location: Vancouver, Canada

PostPosted: Tue Jul 11, 2006 8:35 am    Post subject: Reply with quote

Hi Phantom, thanks for your reply.

I noticed that when the engine is cold the fan spins with a little resistance. But I did not really pay attention to how many turns it made. I will check today.

I did check to see if the fan speeded up between idle and reving to about 1500-2000 RPM.... and I must say I did not get the impression the fan was speeding up much. Speed seemed fairly constant, i.e. same at idle and reving.

Looking online I found this test for the fan clutch:

1. Cold engine: fan should spin somewhat with low resistance
2. Hot engine: fan should show much more resistance to spinning

I also read that you could rebuild the fan clutch by simply refilling the clutch with oil (90 wt). Apparently the main cause for fan failure is progressive loss of oil. I saw some photos of fan clutches being opened up, refilled and closed....

I like the idea of finding solutions by myself.... makes owning a Cherokee much more fun Mr. Green

Cheers

Beaumecxxx
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plym_46
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Joined: 16 Apr 2006
Location: central ny

PostPosted: Tue Jul 11, 2006 3:21 pm    Post subject: Rule of thumb for over heating Reply with quote

Hot at speed = poor coolant circulation, blocked flow or pump not up to snuff.

Hot at low speed or idle= poor or blocked airflow, fan, slipping belt, or restricted flow to or through radiator.

I am having a problem with noise from my fan clutch. Can your post link/s to the website/s you found dealing with fan clutches?????
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Titan4u2c
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Joined: 03 Dec 2005
Location: Clayton, NC

PostPosted: Tue Jul 11, 2006 6:01 pm    Post subject: Reply with quote

Hey guy, you do know that if you are running solely on the main clutch fan that after a few minutes of "crawling" it will of course overheat? That is why the aux elec fan was installed to help pull in more air to cool the engine. SO even if your main fan is working properly, she will still overheat so check into the elec. one as soon as possible if you want to continue to wheel. Some good ideas are to install it on a relay with a toggle so you can control it manually in case you cross deep water you can turn it off. And to wire it into the temp switch to cut on at a certain temperature. Hope this helps, good luck.
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935speedxj
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Joined: 08 Oct 2004
Location: pittsburgh pa

PostPosted: Sat Jul 15, 2006 10:07 pm    Post subject: Reply with quote

Titan4u2c wrote:
Hey guy, you do know that if you are running solely on the main clutch fan that after a few minutes of "crawling" it will of course overheat? That is why the aux elec fan was installed to help pull in more air to cool the engine. SO even if your main fan is working properly, she will still overheat so check into the elec. one as soon as possible if you want to continue to wheel. Some good ideas are to install it on a relay with a toggle so you can control it manually in case you cross deep water you can turn it off. And to wire it into the temp switch to cut on at a certain temperature. Hope this helps, good luck.


hey there titan that is not all true well if you are stock it may be .... never did overheat .... an all i have done to it is a 180 stat an 3 core rad.... crawl for hours on this an never overheat.... an i dont have a electric fan.... well i do but the darn thing never did work headbang
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