Testing Viscous fan couplings

**PhilipA** · 21st May 2011, 03:58 PM

One of the unresolved issues that many of us face is how to test a Viscous fan.

I have found a test procedure issued by Borg Warner who bought all of the Eaton businesses that made VCs for Land Rover. It is pretty complex band needs a special tacho.

One thing that comes out of it is that a VC is a VC. The testing procedure implies to me anyway that most air temperature controlled VCs work in the same way at the same temperatures and the same revs.

I was researching , as I posted yesterday, whether the 300Tdi fan I have is suitable for my 3.9 V8.
http://www.ets.borgwarner.com/PDFs/S...ins/sb1005.pdf
Regards Philip A

**rick130** · 21st May 2011, 06:19 PM

Thanks Philip,
that's the first definitive test for a fan VC I've seen (and now saved)

Much better than the airy fairy 'tests' in all the service manuals I have.

**rovercare** · 21st May 2011, 06:55 PM

Dont you just warm the car and stop it with your hand if it's faulty

**Pedro_The_Swift** · 21st May 2011, 07:33 PM

yep!, its probably a good idea to use a hand thats already faulty

**Pedro_The_Swift** · 21st May 2011, 07:36 PM

and that link goes straight to the pool room

**Blknight.aus** · 22nd May 2011, 07:09 AM

not all VC's are the same but for approximate numbers and an official testing method that's about as good as you'll get.

One potential problem with this method is having the reflective strip on the fan and the pully, there is the possibility of getting a false reading from the 2 strips coming past at different rates. Prior to applying the second strip to the fan (or hub) test run with just the strip on the pulley then after you've established a base line RPM on the tacho attach the second strip to the fan. If after attaching the second strip to the fan you get a tach count that is higher than the nominated engine speed your getting interference on the photo tacho, try a different aiming position for the tacho or position the strips differently.

In some cases the colour or reflectivity of the fan will throw a photo tacho, You'll need to attach the strip to the hub itself which is likely to have the 2 reflective strips within close proximity to each other and put you right back where you started from. The work around for this scenario is to setup a tacho on the engine proper and then the photo tach on the fan pully, run the engine revs up till the photo tacho shows the RPM's you want and note the tacho speed on the engine tacho (avoid using a piezo injector line mounted tacho for this as the engine will be lightly loaded it may not register accurately). Move the reflective strip to the fan hub and then conduct the test using the engine tacho to set the nominated pully speed.

**rick130** · 22nd May 2011, 08:01 AM

Those reflective strips that come with some of the optical tachos have good glue too.
Pretty sure one is still on the crank pulley of my engine and i stuck it there five years ago

**PAT303** · 22nd May 2011, 02:26 PM

Just use a paint brush

,you blokes think like engineers to much. Pat

**rovercare** · 22nd May 2011, 05:50 PM

Originally Posted by PAT303

Just use a paint brush

,you blokes think like engineers to much. Pat

I still prefer the hand method, it's usually easy to work out why an unmodified vehicle is overheating, nothing like simple method...... Maybe for simple people like I

Thread: Testing Viscous fan couplings

Thread Tools

Testing Viscous fan couplings

Bookmarks

Bookmarks

Posting Permissions