Hey guys, Thought I'd get a thread started for those thinking of refilling their clutch fans as this is a topic which hasn't really been covered on the forum much in the past. Those who have done it before, what CST rating did you use and how did you find the results? Good post from a2zed here, was hoping we might be able to expand upon it some more: Interestingly, I found that Toyota use three different types on their clutch fans depending on the car: 3000cst, 6000cst and 10000cst Does anyone know what rating the stock zed clutch fan is? Cheers, Martin
As a follow up to this post quoted above. Fuel consumption has suffered a little due to the fan working alot harder than before, this is why I say 6000cst would be better as it will allow the fan to work as it should. The other drawback in using heavier fluid in the zed, the engine bay has very limited flow through. Having the fan pull a million cfm of air through the radiator will only cause a high pressure build up at the rad itself. This is why the Davies Craig fans often do not work. They pull too much air through with nowhere for it to go, so the air basically stalls at the radiator. 6000cst would be my choice.
Eric, can you just elaborate a bit more..... 1. Where do you drill? On the orange dot? 2. What size hole will be needed? 3. How do you plug it after? 4. Also they sell it on EBAY in 60ml bottles, would this be enough? http://www.ebay.com.au/itm/CORE-RC-Silicone-Oil-6000cSt-60ml-/400318855855?pt=UK_ToysGames_RadioControlled_JN&hash=item5d34dcfaaf
I would suggest buying a larger amount as the old fluid didnt evaporate, it leaked out, most likely of the rear seal, unfortunately they are not serviceable like some brands, although refilling will work, it is only a temporary fix IMO.
I don't think its a case of leaking, more about the oil losing its viscous properties after 20 years of use.
on an RB yes, im presuming the clearence is the same. it was a while ago but i think i just had to widen the 4 mounting holes it is slightly thicker from mounting face to blade face
Silicon oil is very resilient in a sealed environment, it is also used in our viscous LSD. If you pick up any number of old Z32 clutch fans you will see fluid witness marks at the back of the fan, it does leak quiet slowly and the marks are quiet faint, but they are there. The rule of thumb for replacement of a viscous fan clutch is 100,000k's (with the water pump) they are not listed as a 100,000k item but that is the best rule of thumb I can find, and or when the vehicle has been overheated. I can only convert that to the o-ring on the back shaft is damaged, as the upper temperature range for standard o-ring material is around 120C. Obviously when an engine is overheated not every o-ring bleeds. Silicon oil is also used in our viscous LSD, it has a very interesting property, it expands quite a bit when heated, this expansion causes the diff plates to bind and give a locking effect. Hence why viscous LSD's are not as snappy as other types of LSD, it has to slip to heat the silicone oil before it bights. The "flash" heating in a LSD over time does lead to the silicon oil losing its properties. Silicon oils operating temperature can be in excess of 200C, so I dont see heat being a problem in a fan clutch. If you can get your engine temp up there you are doing well. Yes you can refill the fan clutch and it will improve its operation, but the simple fact is that it has probably leaked already and it will leak again. I know people like to be hopeful about cheap solution but the simple fact is that if the fan clutch was $50 we would not being having this discussion. I dont want to say that refilling them is a waste of time, because it is not, how long will it last ?, I dont know. Eric is putting up some big numbers, but I do respect his opinion, although 30k is like 2 years of operation for a daily runner, the best indication I have had on fan clutch life is 100k. Cars are a pile of thousands of parts that all have a service life, they are all going to fail at one point or another, some sooner than others, fitting parts that last a fraction of the time of new part only increase the labor component to maintain the car. I realise that my perspection on things is about long term ownership with reliability at the lowest cost, I realise that is not everyone's position and I accept that, people can make up their own mind, some people will be out of the car in 2 years, I dont think I will be and if I spend money on the car I prefer to spend as well as I can, because god knows it aint cheap. It really does come back to labor cost, if you do the work yourself it Is not so bad, but I would not pay someone to fit half worn brake pads as doubling the labor cost is uneconomical. The other aspect is increasing the likely hood that failure can contribute to progressive damages is not something I want to deal with more often when an engine is at stake. Make your own minds up !
I have refilled a few for Zeds. Most are very low and some have had next to no fluid left in them. A couple the fluid has turned to paste ?. I heat the hubs up to get the fluid to run out. Always tap 2 x holes opposite each other. One to fill of course and the other to bleed the air out. I aways drain the old fluid for at least 2 days to a week and heat up with a heat gun a couple of times a day to aid in draining. Is it worth the effort ?. It's a toss up. The fluid cost me less than $4 a hub so apart from a little time it is dirt cheap. That said Car Craze is selling new hubs at a good price. Every one i have done has worked fine afterwards but i believe they should be drained and refilled once a year once they start giving trouble as going by the low fluid levels i have found the obvious cause of failure has been oil loss. Where from ? i believe the rear shaft seal as it is the weakest point and most have been dirty in that area. For $4 a go it's cheap if you feel like doing it and you only need a 1/8 drill bit and a 4mm tap and some grease , a couple of small 4mm bolts and little washers + loctite or aviation sealant for the bolts. One day i will probably put a new hub on but at the moment i don't mind fiddling. The main sypton of a faulty hub is raised temps even at high speed. Of course check coolant level and thermostat operation first as long as radiator is clean also. Cheers Dave
I read one workshop fits a zerk/grease nipple and greases the fan clutch. I wondered if the grease would make the rear o-ring swell to seal ?, but then I thought I dont really want grease flying around my belts or silicon oil for that matter.
I got mine from Caz. Just the aftermarket version... about 3yrs ago now. Nothing wrong with it. Works perfectly. Can hear the air being pushed around. Peter
