Archived Viscous Fan dripping oil?

[Joe Mc]

I've had my truck down for a about a month working on restoring the frame and some other things. I noticed oil working it's way down one of the fan blades which ended up on the bottom of the fan shroud the other day. I had the fan assy off about 3 weeks ago while replacing the crank seal and it's been back on the engine for about 2 weeks, I cleaned the assy so I know this oil is new and for certain coming from the clutch fan. The truck has not been run since well before I started my projects.

I plan to have it back on the road next weekend, so while it's down I'd rather address this clutch fan issue if indeed it is an issue. My gut is telling me "oil leak at clutch fan, a little wobble (1/8th") back and forth by hand = get a new clutch fan".

So, go with my gut or do you all think it'll be OK? From your previous experience???

 

[DavidC]

Get a new clutch. If it does not detonate it will throw oil on the engine bay area creating a mess.

Dave

 

[DavidC]

Not to bad at Genos, $140.00 and they have the wrench kit for $40.00 if needed.
http://www.genosgarage.com/product/52028615_ramcummins_fan_clutch/fan-clutch

Dave

 

[petersonj]

I had the fan assy off about 3 weeks ago while replacing the crank seal and it's been back on the engine for about 2 weeks, I cleaned the assy so I know this oil is new and for certain coming from the clutch fan.

If the fan assembly was stored laying down flat while it was off of the engine, it may have caused the leak. These fans need to be stored in the upright position. Maybe yours was stored properly and it just decided to leak anyway.

-John

 

[Tuesdak]

Replace it. Agree with storage issue said above. It's lost some of it's working fluid and will not lock up when needed most risking overheat of the AC system and engine. Note fan clutches normally loose 200 RPM per year and are done at 5 years - Spring thermal is down 1000 RPM while ECM controlled can compensate somewhat.

 

[JR]

Note fan clutches normally loose 200 RPM per year and are done at 5 years

You mean to tell me my 18 year old fan has died 3 times over :-laf

 

[Tuesdak]

You mean to tell me my 18 year old fan has died 3 times over :-laf

Dead isn't correct as they 'fade away' if they don't die by bad bearings. I wish I could find where I read that years ago on a supplier site. The silicone fluid breaks down as well as clutch wear. It matches our experience with 'obsolete' spring thermal fan clutches in Arizona's heat where replacing a 5 year old clutch improves AC performance. Add to it OEM's preference to keep the fan off as long as possible for NVH and MPG by setting the turn on temps about 15 degrees too high.

I can't put to words how much better the ECM controlled electro-viscous clutches are for AC. It eliminates the dealer's 'wait 30 min for max AC performance' excuse as the fan clutch needs a warmed up engine to get hot enough air to move the spring and turn on. Cold radiators cool the hot AC condenser air back down...

Regardless the fan clutch is the most abused (by running forever past's it's best if used by date.) and least understood part on a vehicle.

Edit: Sources:

http://www.haydenauto.com/upload/HaydenAuto/Documents/Cat_Hayden/Hayden Fan Clutch Design Types.pdf

"The biggest problem is that fan clutches wear out over time, losing about 200rpm each year. After twenty years you'll have a Corvette that overheats..."
https://books.google.com/books?id=S...&q=fan clutches lose 200 rpm per year&f=false

http://www.centuryperformance.com/cooling-system-basics.html

 

[JR]

I have no doubt they lose their performance over the years, perhaps if I lived in a hotter climate my original fans deficiencies would be more noticeable. I regularly tow up to and over my GCWR with AC cranked with no over heating issues. I've touched 202-204 a couple of times pulling long grades but can hear the roar of the fan as it locks and temps will either level out or drop depending on load. A hot day here is 90 degrees and don't see too many grades over 4-5% so I'm sure that plays into the equation alot.

I've never had any complaints with my trucks AC (I actually freeze people out on a regular basis) but almost all of my driving is on open roads so the fan is not needed nearly as much. I'm almost never in stop and go traffic. Again, geography likely playing a big role in performance.

 

[GAmes]

If the fan assembly was stored laying down flat while it was off of the engine, it may have caused the leak.

I don't think so. I just bought a low mileage fan and clutch from a '96 a couple weeks ago. It still has the factory sticker on it stating to store it flat. I also disagree with the deteriorating with age. I found this one works perfect last weekend while towing my 5er in the TX hill country. Temps were in the 90s, A/C on the needle never passed the 190 tick.

 

[BigPapa]

Note fan clutches normally loose 200 RPM per year and are done at 5 years - Spring thermal is down 1000 RPM while ECM controlled can compensate somewhat.

You mean to tell me my 18 year old fan has died 3 times over :-laf

I was thinking the same thing, JR. Mine is 20 years old and I can still tell when it kicks in and out, right when it should.

 

[cerberusiam]

Comparing apples to oranges, the 3rd gen fans are radically different from a 2nd gen and fail a whole lot more often. They are an electronic over viscous, lot more moving parts and will move more air than a straight viscous fan.

 

[Ozymandias]

A lot more Air.... It's like a hurricane under the bonnet....
The 3Gen Fan has easy doubles its size compared to the 2Gen.
I saw them both side by side at BDs Workshop.

 

[Joe Mc]

Ordered clutch and wrench kit. Thanks.

 

[Joe Mc]

Late thought, after I spent $180 + for new clutch and tools: If the clutch needs to be stored in the upright position, what's shipping while (I'm sure) being flat in the box and bounding around on a UPS/FedEx/USPS truck going to do to it? Just saying???

 

[DavidC]

Post # 9 Joe

Dave

 

[GAmes]

Not to take business away from Genos, but the wrench isn't that important. Remembering the big nut is left hand threads, a couple taps on the side of the flat with an air chisel will break it loose, then it will easily spin off. If you don't have an air chisel, a long flat screwdriver and a hammer will do the trick as well. Prior to replacing a clutch I cut a small groove into the edge of the flats with a dremel cutting wheel for when it is time to remove it.

 

[Joe Mc]

Installed, wrench from Geno's was an awesome purchase, even if: 1-I'll only use it once (hopefully at least on my truck) and 2-Had to use a cheater device to get more leverage on the nut to loosen the fan/clutch assay. The benefit other than new vicious unit, I was able to get better clean-up on the fan and refinish to stock appearance. Job done. Oh BTW when I opened the box from Geno's that contained the assay and wrenches even though the clutch box had arrows facing up it was placed in the box flat… no oil was present on the inside of the box or bag that contained the new unit.

 

[DavidC]

Glad to hear it all worked out well Joe

Dave

 

[GAmes]

If the fan assembly was stored laying down flat while it was off of the engine, it may have caused the leak. These fans need to be stored in the upright position. Maybe yours was stored properly and it just decided to leak anyway.

I'm of the opinion it would have leaked either way.

 

[petersonj]

GAmes, great photo! It makes it clear how the viscous hub should be stored, but raises the question others have mentioned: how does one guarantee that the unit has been stored in this position from when it left the manufacturer to when it was installed in a vehicle? After doing research I could not find anything conclusive as to why a failure (leakage) could occur if stored in other positions.

So, I am left to drawing my own conclusions which, of course, is my own opinion. It could be that since the fan clutch is a fluid coupler and since the reservoir for the fluid is in the part that should be face down, the fluid would be kept away from the dynamic seal (less likely to leak during shipping). It wouldn't mean that the fan clutch would leak if stored otherwise, just that it would have the best chance of not leaking by being stored as instructed.

Once the fan clutch has been installed in a vehicle it would be in the position as was designed for the rest of its useful life. If the fan and the fan clutch are removed as an assembly, the additional mass could affect whether it may or may not leak at the dynamic seal by the method of storage. It may be that this is why the recommended storage as an assembly is to store it in the same position as the installed position in a vehicle.

In the end what really matters is whether or not fluid leakage has occurred. As in your case, it did occur and you did the wise thing and replaced it.

-John