Fan Clutch Affects Tranny Shifts

[LaGrasta]

To help save you a headache, I want to let you in on a recent discovery.

A few years go, my tranny was screaming at every shift point, I reluctantly rebuilt it. But not before swapping out the fan clutch, suspecting it was the roar I was hearing. After the clutch and trans swaps, no change! What a huge spend for repairs unneeded.

Still suspicious of the fan clutch working properly, I was told to move the fan while the engine is cold and if I can turn it, it's a good clutch. Although resistant, I could turn it.

Yesterday, after loosing freon and having it recharged at the same shop that replaced my fan clutch a few short years prior, I again mentioned the screaming tranny and he immediately said he'd look at the fan clutch again. Upon picking up the van, he says they again replaced the clutch, at no charge. I found it strange it again needed replaced, and even stranger they did it for free, it had been nearly 3 years.

I started the van to leave and to my surprise, nothing, not a single roar of the fan. I pulled away and quiet, quiet as it had been 3 years earlier. Now driven nearly 60 miles, it's like a new van, quick on the road, smooth, near undetectable shifts, it even feels fast! I bet my MPG increases.

Not sure what the real story is in my case, but wanted to mention it you guys for your troubleshooting future. If you hear a roar and it seems the tranny is hanging up prior to shifts, replace your fan clutch, with one that works!

[Herbie]

Interesting.

I've got a bit of a scream right now as well. I'm about to have it looked at (after I spend a week working on new interior cabinets). I sort of assumed mine was a bearing or something, since it's RPM dependent (and partially load?). Will also have the fan clutch checked...

[ihatemybike]

Yes, interesting.

Wonder what causes them to fail, as I've yet to have that happen in any of my vans.

[LaGrasta]

My father owns a 1978 Chevy van, since new. …and he is still running his original fan clutch!

[AstroWill]

I had the same thing on my van once, the clutch goes solid and sounds like a freaking freight train going down the road. Makes you think that the transmission isn't getting into OD or something because of the noise it makes. Of course if we had a tach we could see that everything there was just fine. I have only had this happen to one of my vans so far, it was my 99.

[LaGrasta]

…perfect description AstroWill.

[slow buick]

Upon reading this, I'm a little confused.

Upon a cold start, my fan runs.. will engage for most of first gear when I start off and then stop the fan noise after it is partially through second. Has been this way as long as I can remember and we've owned it since new in May 1999.

[AstroWill]

If it does that from a cold start only I would say that is normal, if it does it constantly I would think it would be faulty.

[ihatemybike]

Of course if we had a tach we could see that everything there was just fine.

ScanGaugeII, UltraGauge, Bluetooth adapter and Torque app, all great ways to gain a tach.