my biggest fan (clutch)

[norm]

I do not wish to pit diesel guy against diesel guy here, but I think I need a new fan clutch, and would like to know what you all like about the ones you have used - benefits, cost, etc... I am going to begin my engine mods with cooling and gauges, and move out from there.

[john8662]

I have already done the 97 cooling mods on my 95. I installed Robershaw 180 degree stats in the dual stat crossover. I have noticed that even though I have the cooling mods I can't keep the temperature right at 180 where I want it, with A/C on and a 100 degree outside temperature, it still gets to about 190 degree on the guage. I notice that the temps cool down when the temp on the guage reaches the 190 mark with the A/C on and cools off really really quick when the fan clutch engages and roars to life. So, I have really determined that the fan clutch just needs to be recalibrated to 180 degress to match the stats. The fan clutch that Kennedy sells I think is going to the be final cooling upgrade. As this clutch engages earlier with my configuration. I think that it would really work well for the 195 degree stats too, as the stock clutch still engages late for that temp too. So, you're on the right path. New clutch and fan blade (the newer fan has more blades, perfect match with the new clutch) and the cooling mods.

[Scooby]

The severe duty fan clutch Bill Heath sells (Hayden) is a more precise unit than stock, and will cut in sooner and pull much more air. It should be the ticket to keeping you cool.

[Cooperrw]

I agree about the new fan clutch, after installing the 97 cooling mods I noticed the fan kicking in sooner which leads me to believe it is a big reason I can keep engine temps below 200 degrees even on 120 degree days. smile.gif

[AndyL]

Originally posted by john8662:
I have noticed that even though I have the cooling mods I can't keep the temperature right at 180 where I want it, with A/C on and a 100 degree outside temperature, it still gets to about 190 degree on the guage. Those dash gauges are horribly inaccurate. On my 99 the gauge and the PCM temperature sensor are off about 10 degrees at 160 and about 5 at 190.

[john8662]

Andy, yeah the guages are probably off, but I just notice that if I had a fan cluch that would engage sooner that I would have the engine running cooler, instead of waiting until the OEM clutch engages. Because during the summer on a hot day, you couldn't tell I had 180 degree stats installed, because it would run about the same as it did with the 195's in it. Thats why I want the lower engaging clutch..

[AndyL]

You are definatly correct, the thermo temp and fan clutch temp have to match for it to work properly.

[Billman]

AndyL

Being off 5* at 190 is only 2-3% inaccuracy. That's pretty good if you ask me. I've never found my factory gauges to be that far off.

I tried 180 thermostats but immediately went back to 195's. No difference in cooling, and it ran more efficiently.

The intercooler helped as well...

[autocrosser]

Using the stock fan with a earlier engaging clutch isn't the complete answer. I have adjusted the spring on my clutch to make it kick in around 195 deg but that still won't keep it cool enough going up a long steep mountain pulling 8,00lbs. I blew water out last year and it showed 220 all the way up. I suspect the coolant expanded and overfilled the reservoir causing coolant loss. I didn't have a problem until I came down the other side and had gone about 3 or 4 miles. the temp gauge suddenly went full scale. I guess I'm lucky I didn't blow a head gasket.

I think the heavier duty fan and the proper clutch to go with it is the only answer. I'm had a great improvement in cooling with the tricked clutch but it doesn't work when you really need the added cooling capacity.

[jspringator]

I have had good luck with Heath's severe duty fan clutch. However, I drive hills by the pyrometer, so when it gets into yellow, I back off! I suspect this driving style is the major cause of my absence of cooling problems.

[damork]

I updated to the 97 cooling system, installed Robertshaw 180's and the cooling system stays rock solid at 180. For some reason, the new fan clutch I got from GM works just fine. I also went with the Duramax fan while I was at it.

[BBCB]

I updated to Kennedy's fan clutch last summer - and have been very happy with it.

For me, in Houston, it was night and day for temps in traffic and as an added benefit, the A/C seems to work better now as well. Still I'd like to be sure I was getting the most cost effective output of my cooling and A/C system, but I'm still on the fence regarding the fan upgrade. When I purchased the clutch, the vote was still out on whether the DMax fan was a valid upgrade or just a case of bigger is better. Kennedy suggested I wait until a verdict was in. I really appreciated John's honesty.

In the meantime, I just found this on ebay: New Dura Max Radiator Fan Modified For The 6.5 Diesel (http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33600&item=2479591731&rd=1) anyone have opionins on this? Do quantitative statistics exist showing where the Dmax fan is better than stock?

BBCB

[Kennedy]

The Dmax blade will move SLIGHTLY more air than the 9 blade steel unit in some cases, and SLIGHTLY less in others.

It has to do with static pressures. I believe that what happens is the plastic blade "folds under pressure" or has a minor "flex fan" effect whereas the steel blade is more the torquer of the two...

I'd recommend the steel one...

[Kennedy]

Originally posted by BBCB:
I updated to Kennedy's fan clutch last summer - and have been very happy with it.

For me, in Houston, it was night and day for temps in traffic and as an added benefit, the A/C seems to work better now as well. Still I'd like to be sure I was getting the most cost effective output of my cooling and A/C system, but I'm still on the fence regarding the fan upgrade. When I purchased the clutch, the vote was still out on whether the DMax fan was a valid upgrade or just a case of bigger is better. Kennedy suggested I wait until a verdict was in. I really appreciated John's honesty.

In the meantime, I just found this on ebay: New Dura Max Radiator Fan Modified For The 6.5 Diesel (http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33600&item=2479591731&rd=1) anyone have opionins on this? Do quantitative statistics exist showing where the Dmax fan is better than stock?

BBCB As for quantatative statistics, here is what I have learned in dealing with Borg Warner both directly and now through their main distributor:

1) The OE fan clutch for the 6.5 has a cut in air temp spec of 195

[More Power]

The 21" 9-blade composite Dmax fan looks way cooler. tongue.gif

MP

[Billman]

And quieter.

Which may prove JK right...

[BBCB]

John, thanks for the information and clarification... now I can start looking for other things on Ebay... ;)

[norm]

Thanks, men, for all the posts. Good info to digest. Now that I have some help on cooling mods, it looks like the freeze plugs have started to seep... (more work) :D