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Discussion Starter #1
I have been trying to cool my 1993 6.5L diesel and I keep killing fan clutches. I have the Ho water pump, 180 degree t stat, aluminum KKS radiator, 9 blade 21" duramax fan, and I was using the hayden sever duty fan clutch. The system cools great when the fan clutch works. I had one of the online vendors overpriced fan clutchs that lasted a few years. It went bad. I had a hayden clutch go bad after a year and the truck ran hot. I replaced it with another hayden fan clutch and it died after a few days. In the interim, I have replaced the last bad clutch with an ac delco fan clutch. It is working but its engagement temp is too high for my taste. It is also slipping too much at high RPMS. I want the max cooling when I am ideling and and WOT. Electric fans will give me good idel cooling but poor WOT cooling.

To solve this problem I have looked at using a race fan and spacer. The issue is the biggest I can get is a 6 blade 19" fan. I want to use the dmax fan with a spacer. I have asked a retired machinist to make me a spacer that I can bolt the dmax fan to and bolt that to my water pump. We talked about it and he is going to turn it from a single piece of aluminum. It will have threaded holes and a centering shoulder for the fan. It will have a flange with room to put the nuts on the water pump shaft. It will also have a hole to center its self on the water pump shaft. He is going to measure and record the dimensions of the prototype.

The reason for my post is to see if anybody else wants a fan spacer. I think it will outlast any fan clutch. It will also be much lighter than a whole fan clutch assembly. I think the parasitic loss from the fan will be partially balanced out by the reduction of rotating mass. If enough of you guys want one he is willing to make a batch. I trust this machinist on his ability to design the part to be strong enough and balanced. He was doing aerospace work before. I told him it will probably see max 7000rpms at the pump pulley and he is confident the part will hold and be balanced.
 

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I've never heard of slipping fan clutches for these trucks, mine has been siezed for the last 7 years, if any.
 

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I've never heard of slipping fan clutches for these trucks, mine has been siezed for the last 7 years, if any.
I wish mine would fail in the fully engaged mode. I would just leave it on. I don't know why I have bad luck with fan clutches. That is why I am having a spacer made. It will be a bolt on replacement.
 

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I picked up the spacer yesterday and installed it this morning. Even though it is raining I did my best to test its cooling capabilities. It moves significantly more air and the cooling high idle cooling is greatly improved. So far so good, the only downside is the noise. It is louder but the improved cooling is very noticeable. If it is cooling too much in the winter, I might swap it out for a fan clutch. Probably the AC delco I just bought to replace the dying hayden clutches.

The par turned out pretty good for a prototype. The round stock was too small to make threaded holes for the fan but it it does have notches for the bolts. The shoulder in the center does the centering of the fan. If we started with 4.5 or 5 inch stock it would have had enough meat for threaded holes. The hole on the water pump side centers the spacer on the pump pulley. The fan assembly is also at least 10 lbs lighter.
 

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Discussion Starter #5
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Even though it’ll be noisier than using a fan clutch I bet it’ll be great when towing heavy.
 
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If I can suggest something on your design, nylonlocknuts are great against vibrations so they won't come un-done. And slightly shorter bolts for a great finished look.
 

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If I can suggest something on your design, nylonlocknuts are great against vibrations so they won't come un-done. And slightly shorter bolts for a great finished look.
That is the plan. All I had on hand was 1/4 stainless bolts left over from another project. I just picked up some 5/16 bolts with nylocks for this project. I could not resist testing it so I used what I had on hand.
 
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What would it to take to have one of these built for a guy?

Sent from my LG-LS993 using Tapatalk
 

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Discussion Starter #10
It would take a piece of 5 inch aluminum round stock. So far I have not been able to find a good source. He made the part from a piece of 4 inch scrap he had left over. Buying it new is expensive. If I can find what I need as scrap, the cost becomes much more reasonable.

As far as performance goes. This think is exactly what I wanted. My AC runs cooler, my oil temps are down by 20F, my coolant temps are lower, and it does not go above 210F when I am giving it hell. It has much better idle and high idle cooling. As far as noise goes, it is not too bad until you get over 2500rpms. Below 2000rpms it is no louder than the turbo. With all that said, I will be swapping it out for my fan clutch in the 2 or 3 months of the year when the lows are in the 40's and 30's. Also, my 96 and 97 are cooling just fine and I probably wont install one unless the need arises. I do like the idea of having the part on the truck as a spare for long trips. It is small and light. If a clutch goes bad you could swap it out on the side of the road and get going again in no time.
 
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