Clutch fan vs. Electric fans

[FRMLPLR]

We are having some record heat this week, and have noticed clutch fan really robbing the power when locked. Never has exceeded the 210* mark, but sure pulls on the motor. Sound reminds me of the old 2.8l and 4.3l V-6's. Has anyone looked into changing to electric fans?

[sacmandmax]

frmlplr..It got up to 113 deg. here in sacramento. I know what you mean when the fan comes on, NO POWER. Maybe an electric fan conversion like i have on my KW. that way we can turn it on as needed

[SoCalDMAX]

FRMLPLR,

I did. I spoke to John Kennedy about it. I'm paraphrasing here, so don't quote this as gospel.

I asked what he thought of the idea (since he's forgotten more about diesels than I've yet to learn) and mentioned that I'd had great success converting my Mustang over, expecially with A/C performance at a stoplight.

The answer was, the stock fan is about the best that GM has put out, especially on a diesel. It's very high flow for the noise level and has to pull air thru a tranny cooler, radiator, intercooler and A/C condenser.

An electric setup would need to turn on at the same temp as the clutch (which gets air temp immediately from any of those heat suorces) and would have to be a large dual fan setup. I looked at one made by Flex-a-lite and it looked like it had the CFM to do the job, but it cost close to $400, and drew something like 60amps.

Our alternators are 105amp, and that's peak. They're not designed to put out max or near max current for long periods. With all of the other loads (trailer battery, trailer brakes, fuel system, entertainment, lights, etc) the alternator would cook itself in a short while.

So add in the cost of dual alts. $300 or $400? Now you're up to nearly $800 invested into something you had to rig up and install yourself. And if the thermoswitch isn't set properly or in the exact right location, it's not going to work as well as the stock fan did. And that's under warranty.

I dropped the idea for the Dmax, I'm not so sure that it would be that much more efficient than what's on there, but of course I'll listen, especially to an engineer with a background in thermodynamics. ;)

I'm still impressed with what it did for my Mustang. It warms up very fast, stays rock solid at 180* regardless of outside temp or load, etc.

What I am seriously considering doing is what Billy14 suggested, moving the tranny cooler down for better airflow. If I experience a need for more cooling (haven't yet), maybe add a medium size pusher fan on the front.

Regards, Steve

[FRMLPLR]

Sacmandmax

We went throught there on friday on way to Nor-Cal rally in Napa over the weekend. Not a bad event, but they have a long ways to go. Wouldn't be a bad place for others on the forum to meet. Dmax's were outnumbered 25+ to 1. Had pulls on Sunday afternoon, we didn't stick around though. Local guys from our pulling club (www.vtpapullers.org) were there. You would like to see Dan Coehlo's 2 axle freightliner!!! Same guy who pulls with a early 60's vette!! :D :D

[FRMLPLR]

Steve
Knew I wasn't the first to think of this!! Like the idea of extra air from the front, keeping the clutch from running as much. Just picked up an "X-monitor" and waiting on AFE air box. Have a 28' tilt bed that will top out at 16K+ with both tractors on it, and don't to be worried about the heat. This is why the site is the best I have found. Sharing of info and no attitudes!!!

Thanks
Scott

[Kennedy]

You guys do realize that a viscous coupling (fan clutch) will only pull a fixed amount of torque when engaged don't you?

Try 50 lb/ft at the most extreme, and that may even be overestimating it...

[SoCalDMAX]

I haven't experienced any elevated temps yet.

I'd suggest for simplicity's sake, try to move the tranny cooler down a little and install the largest pusher fan that will fit in front of condenser, behind grille.

Regards, Steve

[Dave]

Towing near my max Combination weight rating the clutch fan would stay engaged all the way up any real grade. With the jucie the clucth fan is engaged about 50% less. Even when engaged it is not as loud, due to the viscus clutch not looking as tight I believe.

On the Chevy the trans cooler is in a bad place. it apears 50% of it is block by the chevy power bar. I to am looking at moving it for better air flow.

[Kennedy]

I would be really careful about moving things around up there. I recently had a customer with a problem with my 6.5 recalibrated clutch. Sent him a new one, and it did the same thing. Further investigation showed that he had moved his horn form the middle of the grille area, and upon returning it to the factory location, all was well again...