Simple Fix For Today's Clutch Fan Running Hot
 

Found this great article which explains why these newer Fan Clutches run hotter and the simple fix.... Basically due to GM reduction the fans are spec'd for 1968 and newer motors where the higher temps are needed for lower emmissions. This fix now has my GTO getting no hotter than 195 degrees.

http://midamericachevelles.com/tech/...tch_adjust.pdf

Excellent information, thank you.

Nice article thanks for sharing. I have had this problem in the past and returned the clutch and exchanged it for the HD unit and it solved the problem and cuts in at the proper point for 180 operation.

Thanks Old Goat 67 for fixing the link

Good stuff,thanks! :cool:

That is best tip I have seen in a while.

Just added to my notes.

Nice....gonna go out and look at my clutch now. Would be great if it works for me. Thanks

Not clear on what direction to spin the coil. THe center pin will rotate either direction when I spin the coil. Should it be clockwise or counter clockwise?? My clutch may just be faulty although it is very new.

Now we need somebody to do this mod (and only this mod) and report back how much it actually reduced your normal operating temps, if at all.

Bart, I did the mod Sunday night and yesterday drove the car around for over an hour and usually it can get up to 210 degrees but it wouldnt go over 195 ish

You want to make the coil tighter so it reacts faster . Mine is clockwise
See pic

Excellent, nice measurable improvement.

Be sure to let us know if you see that same 15 degree difference continue over time.

Hopefully others here will report back with similar results. :)

I don't understand
 

I read the article and I'm a little confused. It says in the top left picture of page 63 in the article that the valve in the center will rotate when you turn the spring to a different slot. But it says at the bottom of that same picture text that the center valve won't rotate. On my severe duty Murray fan clutch I can easily turn the spring and center in either direction, no tention. Not sure it's really doing anything. Oh, the fan clutch only has about 30 miles on it, it's new.

Can someone explain to me how to perform this procedure?

adj
 

i heated the coil to view direction the spring would rotate center pin.
then moved outer spring to get center pin rotated abit to then activate sooner.

I can spin the coil on mine clockwise many times with no tension or resistance. A little suspicious of this mod. Started to do it, but changed mind and replaced the clutch instead. Maybe mine was broken??? I will drive it tomorrow and see if there is any improvement.

Same here. I unhooked the coil and as I turned it and it turns shaft in the center. It pops as I turn it, but no real resistance.

Clutch mod
 

OK, I took my brand new Murray clutch fan back off the car and did this modification. I took a hair drier and heated the coil to see which direction it would rotate the center pin when heated. In my case it was counter clockwise. I took the coil loose from the outside slot it was in from the factory and rotated it CCW just to the left of the casting which the outside coil was located in (total distance moved was only about 3/8"). I then placed some JB weld on it to hold it in place at the new location. The result was that the clutch engages now much earlier and keeps the car at around 180 versus the previous 195. In addition, I called Murray and spoke with their tech department to ask them about this modification prior to doing it. In a nut shell,the tech said that it would work but discouraged me from doing it since"they spend thousands of dollars on research to get this things right"

The only negative so far is that the fan clutch stays on more than normal, is a little noisey, and may rob a little HP. Definately cooler though.

Thanks for the update. I purchased a new Murray clutch and installed it. It appears that Hayden is now Murray. I installed it without any mod. I have not been able to drive the car much due to some other issues, but I see some improvement already. No more belt sqeek!

My fan clutch is a Hayden 2747 which is supposed to be a heavy duty unit. But the coiled spring outer coil has only one slot to put the bent coil end into. I can move it clockwise (looking from the front of the engine) and get a kind of funky grip around the mounting tab. Or I can move it counter clockwise and have it just rest against the mounting tab. The coiled spring will get longer when heated and so the clockwise change would not transfer any movement to the valve at the center. And a change counter clockwise might cause a change in the operation of the valve but the spring would not rotate the valve back to original position when cooled.

So which way is the movement supposed to be? Clockwise or counter clockwise? The article says move to the other slot position and I suppose if you had two possible slots (the pictures show Eaton) it would be obvious. Anybody done this yet on a Hayden?

If you restrict bi-pass coolant flow at heater core and intake to timing cover, forcing more coolant through the radiator. then clearance the divider plate to water pump, you wont need a fan except for stop and go. IMO.

Restrict bypass
 

What do you mean by "restrict bypass coolant flow at the heater core"? Are you saying to block off the water going to the heater core altogether?

This is a Hayden 2747. 1st picture is the stock setting. 2nd picture is rotated to the right, CCW, which I believe shuts the valve right away. Is this the way to go? 3rd picture is rotated clockwise, to the left of stock.
When the coil is heated, in the 3rd picture, it rotates CW, doing nothing as it moves CW away from the tang.
It's not as clear as the article say it is.
What's the answer?
Tony:confused:

BITD i blew a heater hose in my street car around the 1000 ft mark at Commerce. It was dark. Everyone was mad.
Later i replaced my already new hoses, found a pipe plug, drilled a .250 hole in it and screwed it into the heater hose @ the head nipple. Note/ some nipples are already restricted. This takes pressure off both hoses and the heater core. Dont confuse this mod with the race guys where coolant is plumbed back to the front water crossover and on to the radiator. Factory configuration, coolant goes back to the water pump by-passing the radiator.
Then next time the intake is off, tap and restrict the bypass to timing cover. IMO/FWIW.

Many aluminum intakes need the front water crossover opened up and gasket matched in the same manor as intake runners.

Old Tin Indian - Your 2747 is a little different than mine. You could rotate CW or CCW 180 degrees to get a different setting. Maybe that is correct and maybe not - don't know. But my 2747 does not have a slot cut into the 180 degree opposite tab so I'm forced to try either if the two changed settings you show. And I'm with you in that neither is likely to work as the tang on the coil is not restrained in a slot. Move it one way and the coil expansion will only change the coil length and not move the valve. Move it the other way and it may move the valve but will not return the valve to the cold position. Apparently the article only applies to Eaton clutches. Dang - I wanted to try it.

http://forums.maxperformanceinc.com/...od+heater+core

I recalled reading this a number of years ago.

Yes the brass cores will leak if "abused". I learned after a couple of changes back in 64 and 65. If you rev it high with the thermostat closed (i.e. it's cold and the car wants to stumble with the choke still closed so you rev it and dump the clutch to get going) the pump pressure will blow the heater core. Back in the day Olds had a service bulletin listing an Olds part number for a restrictor nipple at the manifold. I put one in replacing the 90 degree bent pipe that Pontiac used. Looked strange but it worked. The hole drilled in a piece of round stock and inserted in the hot hose would also work but back then I didn't have good access to the tools to do that. And had a buddy working at an Olds dealer so that was a cheap easy fix. No more blown heater cores.

thanks for replying pfilean. i'll probably put it back in the center and massage the divider plate a little more. i think i have it set at around .050" impeller to plate. i'm going to bring it down to .025-to-.030". this is so frustrating.
by the way, love the bubble-top.
tony

This modification made a believer out of me and you do not need to relocate the spring tab a whole lot, a little goes a long way. By moving the spring tab CCW about an 1/8" I dropped my cooling temps a least 10 degrees.
I popped the spring out and cut a new notch using a small cut off wheel to the left of original and reinstalled spring.
At start up you can hear the difference with a slight roar.
Tested during a hot day at the track yesterday with temps in the 90's.
In the past while idling in the staging lanes my temps would creep close to 200 deg.'s. Never hit 190 yesterday with 185 T stat.
Attached is a pic of my modification, not the clearest but hope it helps

I thought I posted here yesterday but for some reason it’s not here? Anyway what I said was that when the spring is heated it will try to unwind due to thermal expansion and that’s the direction you want to turn it to get the valve to open sooner. Also, there is no preload on the spring or valve.

Alright I did some testing on this yesterday. This is on a Hayden Severe Duty clutch. If you lift the spring out of the slot you can turn it about 90 degrees (counter clockwise in my case) before you feel a stop and if you turn it back to the original position you can feel a stop there as well. So apparently mine has a 90 degree sweep valve. I placed the spring back in the original slot and got out the heat gun and the temp gun. At about 170+ F it had turned about 45 degrees. At about 200+ it turned an additional 10-15 degrees. I heated it up some more and it may have moved slightly but not much, never reaching the complete 90 degree turn. Keep in mind these are air temps not coolant temps.

When it cooled I lifted the spring out of the slot and let it rest against the edge of the tab (counter clockwise). I hit it with the temp gun and the movement was the same plus the additional amount that it was offset by not being in the original slot. It did move nearly all the way 90 degrees to the stop when heated to 200+. When it cooled the valve stayed in the same position but the spring contracted and moved away from the tab leaving a gap as there was nothing to capture it there. I wondered if when on a running engine the fan rotation and clutch when cold would rotate the valve and return the spring to the resting location against the tab but I did not test this. Instead I made a little clip to retain the spring against the side of the tab. Hope that helps.

85*
http://i284.photobucket.com/albums/l...psfkwzsrj5.jpg

170* +
http://i284.photobucket.com/albums/l...pswo3j63jt.jpg

200* +
http://i284.photobucket.com/albums/l...pst7zq4rj2.jpg

Lifted spring out of slot, same 200+
http://i284.photobucket.com/albums/l...pskcy1vvoz.jpg

Spring cooled down.
http://i284.photobucket.com/albums/l...psg0fvmjgq.jpg

Fixed.
http://i284.photobucket.com/albums/l...psnfw0tcw7.jpg

Very cool idea quicksilver!!! I like that.

Quicksilver I like your approach. Great thinking. Keep us posted on how it helps (or not) on the road.

Quicksilver - how did it work?

Inconclusive. I dont have any cooling problems with the car moving, rather my temps creep up idling with the A/C on and I just dont think this is the fix. I've been running a 180 t-stat to see how my carb and intake like that but if/when I go back to a 160 I think that would be when I would see an effect from this mod.

The mod worked for me! Temps went from 190 to 170 just from the spring relocation. Here's the play by play:

http://forums.maxperformanceinc.com/...664082&page=21