Any fan clutch mods?

[HenryKrinkle]

My fan clutch is not engaging when hot. I know many people have had great results from the ZJ HD clutch (Napa 272310). Unfortunately, no stores have an HD fan clutch from a V8 1997-98 ZJ for at least 2-3 days.

What can I do to my current fan clutch to make it engage and spin faster to keep my temps down (currently 90*F outside too)??

Any help is much appreciated....

ETA: Oh yeah, I found some silicon oil from my old R/C hobby- a few ounces of it - intended for R/C shocks. Is there any way I can refill the clutch temporarily?

 

[ericfx1984]

why not go electric? ehall has a nice write up

 

[badron]

First check to see what kind of clutch you have. It's not a silicon if it has a spring in the center. If so equipped. Losing/tighting this spring by 1/2 turn may help. I have read that this has also locked up the clutch. Just fine for short time us in my book.
The stock clutch works just fine for most DD.

 

[in4aride]

smack it in a few good whacks with a mallet. keeps it constantly going. end of problems

 

[HenryKrinkle]

It is very thin and has a spiral at the front/center of it- I assume this is the spring.

So I should pull the clutch and then what? Tighten or loosen the spring and by how much? I assume it fits into a slot that keeps it wound?

Thanks....


Also, I have a newish Gator belt and keep it tight, so I'm not worried about slippage should the thing end up locked tight.

 

[lazyxj]

What can I do to my current fan clutch to make it engage and spin faster to keep my temps down (currently 90*F outside too)??

Drill a couples holes through the old fan clutch and bolt it together.
It will give you chance to see how loud the HD ZJ clutch is.

My XJ is a DD and the noise the HD ZJ clutch made drove me nuts and slightly cut the mileage on freeway runs. Took it off after a couple of months and replaced it with a stock clutch.
A XJ cooling system, in good shape should be adequate without changing the clutch.
Check out the long but interesting cooling thread below. Pay particular attention to Goatman's responses. You will not find another person on this forum with more experience and good information.
http://www.naxja.org/forum/showthread.php?t=1009479

 

[cruiser54]

Drill a couples holes through the old fan clutch and bolt it together.
It will give you chance to see how loud the HD ZJ clutch is.

My XJ is a DD and the noise the HD ZJ clutch made drove me nuts and slightly cut the mileage on freeway runs. Took it off after a couple of months and replaced it with a stock clutch.
A XJ cooling system, in good shape should be adequate without changing the clutch.
Check out the long but interesting cooling thread below. Pay particular attention to Goatman's responses. You will not find another person on this forum with more experience and good information.
http://www.naxja.org/forum/showthread.php?t=1009479

I took mine off, too. Put it on my son-in-law's XJ.

FWIW, when I used to do road service on big trucks, the common practice was to run 2 drywall screws through the fan clutch to get the guy rolling.

 

[lazyxj]

I took mine off, too. Put it on my son-in-law's XJ.
FWIW, when I used to do road service on big trucks, the common practice was to run 2 drywall screws through the fan clutch to get the guy rolling.

I will have to remember the drywall screw trick.

The HD ZJ clutch is fine for a XJ that's primarily a trail rig but if you have a semi-nice DD, with a quiet muffler, the constant fan noise is annoying on the street and even worse at higher speeds. It provides cooling even when it is not required.
Spinning the fan at high speeds, all the time, is a waste of expensive fuel. Most of the time, at freeway speeds, the fan does not need to be engaged at all.

 

[Ed A. Stevens]

It is very thin and has a spiral at the front/center of it- I assume this is the spring.

So I should pull the clutch and then what? Tighten or loosen the spring and by how much? I assume it fits into a slot that keeps it wound?

Thanks....


Also, I have a newish Gator belt and keep it tight, so I'm not worried about slippage should the thing end up locked tight.

The center of the thermostatic spring fits into a stud with a slot that is part of the fan clutch. The spring twists this stud as the air temperature gets warm, advancing the lockup of the fan clutch. These are typically set for ~200 dF from the manufacturer.

The adjustment is to pull the spring off the slot on the stud and then tighten the stud one-half a turn before sliding the spring tang back on the stud. Each half turn is good for a few degrees of change in the fan clutch lock up temperature. Usually no more than three turns is needed to pull the lock up temperature down below 185 dF (below the temp the thermostat remains fully open, as any lower temp setting is just wasting power).

The spring expands when heated and grows in length. Look at the spring and identify the direction it turns the stud as the spring length grows. When you pre-load the static adjustment for the fan clutch turn the stud in the direction it will twist as the spring grows longer.

If you twist the fan clutch stud too far it will eventually lock up the clutch well below the thermostat operating temperature (not a great use for an expensive fan clutch).

Test your results with an IR thermometer and your ears. You will hear the clutch lock up as the airflow noise increases, and you can monitor the lock up temp at the thermostat. The temp readings may not be exact, but the relative change in monitored temperature will reflect the improvement.

Read through that cooling thread. The recommendation on who's comments to trust are valid. The stock XJ cooling system will keep the engine cool in 4-lo on 120 dF days (keep the radiator clean, inside and out).

 

[lazyxj]

The recommendation on who's comments to trust are valid.

Ed
Wow!, voice from the distant past. I have not seen a technical post by you in many years, except in the land use forum.
Welcome back.