How is it suposed to work>? when i start my car from cold it is running full speed(at engine idle) and sounds very whoosy. It is behaving completely different to my van which also uses a viscous fan set up.
viscous fan
- Thread starter Finnon
- Start date
sounds like your fan clutch is starting to lock up.....try moving the fan back and fourth. (with the engine off) haha if its hard to move, get a new clutch!
There is a good post on Mkiiitech.com, but my link doesn't seem to be working any more. Is that site down?
it is stiff ish to move, i can feel some resistance. Not loads though. should it spin quite freely? if so then i need a new clutch for deffo
I wish the link to mkiiitech worked, the fan clutch is really easy to rebuild, but all the information was over there. The person who wrote the article used silicone shock oil for R/C cars, as it's cheaper than the stuff from the dealer, and can be obtained in the correct viscosity. There's some small parts and springs in there, iirc, so you need to be careful when taking it apart.
Off topic: Anyone know what happened to mkiiitech? There was a lot of really good info over there, and I'd hate to see it lost.
Off topic: Anyone know what happened to mkiiitech? There was a lot of really good info over there, and I'd hate to see it lost.
TooGoode said:
Assuming the engine is cold it should be hard to move. It should also engage after a cold start and then settle down to a lower speed. The article cuel mentioned (thanks
) on MKIII tech provides both testing and rebuilding instructions. Unfortunately the site has been down for some time but it might be accessible using the waybackmachine:http://tinyurl.com/f754
hmmm well ive cleaned the air filter today so im gonna re oil it and take it for a run. After that ill see what the fan does. if its still stiff etc then ill assume its knackered.
Oh and ill do that way back thing and have a look see i fi can find that article on the viscous coupling
ta guys
Oh and ill do that way back thing and have a look see i fi can find that article on the viscous coupling
ta guys
Try this: With a warm engine raise the RPM from idle to around 2500 while listening to and watching the fan. It should slow down. You can use a timing light to see it but the speed change should be obvious, especially if done under fluorescent lighting.
The proper way to test the coupling is to insert a long thermometer between the radiator and fan shroud then block the front of the radiator with cardboard or plastic. The coupling should begin to engage around 175 F and be fully engaged by 200 F. It should be fully disengaged by around 160 F. If it doesn't do this it needs to be split and refilled. I authored the article cuel mentioned about clutch rebuilding. If you can't find it let me know. It's not difficult to do.
The proper way to test the coupling is to insert a long thermometer between the radiator and fan shroud then block the front of the radiator with cardboard or plastic. The coupling should begin to engage around 175 F and be fully engaged by 200 F. It should be fully disengaged by around 160 F. If it doesn't do this it needs to be split and refilled. I authored the article cuel mentioned about clutch rebuilding. If you can't find it let me know. It's not difficult to do.
ok mate will do, Ill have alook for your article in a bit as im about to get some tea. I wonder if the fluid(?) i need is available in the uk. I should imagine it will be.
Ill take it for a spin later and see what the fan does with a warm engine.
Ill take it for a spin later and see what the fan does with a warm engine.
hmmm i drove it for a few mioles just now and the fan once warmed up spins quite freely. about 1 revolution if i give it a quick spin. bit dark to tell if the speed changed as mentioned before when i brought the revs up a bit.
edit:
Would it be like say when watching an old western movie and the coach wheels look funny when there spining. If you get what i mean? the speed change in the fan i mean
edit:
Would it be like say when watching an old western movie and the coach wheels look funny when there spining. If you get what i mean? the speed change in the fan i mean
jetjock;876008 said:
JJ would you mind posting that information here? It's one of a bunch of little things I'd like to take care of...
1) Remove clutch and inspect the bearing. If it's shot you can't go any further. Shaft/flange wobble means a new clutch because the bearing is not easily serviceable. Fwiw a bad clutch bearing can quickly kill a water pump and vice versa. It's why they're usually replaced together.
2) Remove screws holding clutch halves together. They can be tight. Separate the halves being careful not to damage the O ring. There aren't any springs or small parts that'll come flying out so don't worry about it.
3) Drain what remains of the old fluid and clean. There aren't many solvents that cut silicone oil well but do what you can.
4) Inspect the control valve. It's a metal strip that uncovers two ports as the thermostatic coil twists the shaft it's on. A simply device really. If you want to test it place the half with the coil down in a pan of water with the water just covering the coil but keep the coil off the bottom of the pan. Heat the water while measuring it's temp. The ports should begin to uncover around 160 F and be fully uncovered by 200 F. A little "sticktion" in the mechanism is normal. If the thing needs calibration the holes are elongated. You'll see what I mean when you're in there. You can also heat the coil with a hair dryer just to see if it's working.
5) You'll need 3000 centistoke silicone oil. Get it on ebay or a hobby shop, it's used for RC cars. I like the Mugen brand but any 3000 cst silicone will do. It comes in 50 ml bottles (which is exactly the amount needed) for around 6 bux. Btw don't buy an oil that's sold by "weight", only buy one sold by centistokes. All Japanese RC oil is sold by centistokes, Mugen included.
If they don't have 3000 cst buy what thay have and use a viscosity calculator to mix 3000 up. GE Silicones has a nice one on their site but damned if I can find it at the moment. You plug in the centistokes of what you have and what you want and it coughs up the percentages to mix. I'll keep looking for it and edit later.
6) Pour the 50 ml of 3000 cst into the half where reservoir is. Iirc that'll be down behind the coil but it really doesn't matter where it goes as long as you get it all in. Clean then swipe the O ring with a bit of oil and put the thing back together. Torque the screws good. I recommend threadlocker. Inspect and clean fan. Install fan to clutch and install the assembly back onto engine. Be happy.
A few other comments: The clutch is designed to run the fan at about 40% clutch speed at idle to provide cooling at slow speed. It'll drop off as rpm increases and only speed up again as the coil heats up. When in doubt the clutch can be tested on the car as I mentioned earlier.
For the curious some info and specs from Hayden about clutches:
http://tinyurl.com/2cceed
Edit: Forgot to mention. The old oil had to get out somewhere right? It's usually through the shaft seal. Some people add a capful of seal sweller to the oil during a refill. Lacquer thinner works. I've used power steering or transmission seal sweller but any similar product will do. Than again I've done clutches without adding anything and they lasted for years so don't fret over it.
2) Remove screws holding clutch halves together. They can be tight. Separate the halves being careful not to damage the O ring. There aren't any springs or small parts that'll come flying out so don't worry about it.
3) Drain what remains of the old fluid and clean. There aren't many solvents that cut silicone oil well but do what you can.
4) Inspect the control valve. It's a metal strip that uncovers two ports as the thermostatic coil twists the shaft it's on. A simply device really. If you want to test it place the half with the coil down in a pan of water with the water just covering the coil but keep the coil off the bottom of the pan. Heat the water while measuring it's temp. The ports should begin to uncover around 160 F and be fully uncovered by 200 F. A little "sticktion" in the mechanism is normal. If the thing needs calibration the holes are elongated. You'll see what I mean when you're in there. You can also heat the coil with a hair dryer just to see if it's working.
5) You'll need 3000 centistoke silicone oil. Get it on ebay or a hobby shop, it's used for RC cars. I like the Mugen brand but any 3000 cst silicone will do. It comes in 50 ml bottles (which is exactly the amount needed) for around 6 bux. Btw don't buy an oil that's sold by "weight", only buy one sold by centistokes. All Japanese RC oil is sold by centistokes, Mugen included.
If they don't have 3000 cst buy what thay have and use a viscosity calculator to mix 3000 up. GE Silicones has a nice one on their site but damned if I can find it at the moment. You plug in the centistokes of what you have and what you want and it coughs up the percentages to mix. I'll keep looking for it and edit later.
6) Pour the 50 ml of 3000 cst into the half where reservoir is. Iirc that'll be down behind the coil but it really doesn't matter where it goes as long as you get it all in. Clean then swipe the O ring with a bit of oil and put the thing back together. Torque the screws good. I recommend threadlocker. Inspect and clean fan. Install fan to clutch and install the assembly back onto engine. Be happy.
A few other comments: The clutch is designed to run the fan at about 40% clutch speed at idle to provide cooling at slow speed. It'll drop off as rpm increases and only speed up again as the coil heats up. When in doubt the clutch can be tested on the car as I mentioned earlier.
For the curious some info and specs from Hayden about clutches:
http://tinyurl.com/2cceed
Edit: Forgot to mention. The old oil had to get out somewhere right? It's usually through the shaft seal. Some people add a capful of seal sweller to the oil during a refill. Lacquer thinner works. I've used power steering or transmission seal sweller but any similar product will do. Than again I've done clutches without adding anything and they lasted for years so don't fret over it.
Nope. I'm sure I'm not the only one paying attention. Never tried to rebuild one myself, but now that I have a good idea of what is involved, I'll rebuild my old one at the shop(been thinking about switching back from the e-fans anyway). My brother-in-law does R/C cars(and helicopters, boats, planes, trucks), so I have plenty of oil around, in multiple flavors. I can get him to pick up the 3000 cst. on the weekends at the track.
just thinking my mate is right into rc cars so ill be able to get him to buy some for me. Thats if it goes wrong.
Thank you for the information! Not a waste by any means. I'm sure it'll be fairly easy to see what is going on, once I crack it open - no way would I have known the correct cst to use, though