Hey all,
I suspect issues with my fan clutch; temperature goes up in stop-and-go traffic, goes back down when I'm driving on open road and stays down unless I stop for a long period or end up in stop-and-go again.
I was going to order a new fan clutch, but I read recently that the OEM ones are the best option, and can simply be re-greased once they start to malfunction.
What grease goes in them? I assume you just open it up and slap on as much as it will hold?
What's going on sir, I did this exact same thing a few months ago and wrote a clumsy if not somewhat detailed exploration of the process for the fan clutches in the 1998 and 99 Montero on the Mitsubishi Facebook group, I'm definitely not a huge fan of that group all of the time so I can understand if people aren't going there immediately for any resources. Nobody on expedition portal has threatened to beat me up yet.
Without knowing if yours is an OEM you might want to check to see if it matches the way the OEM one looks. We have what looks like a bar on the front. I've noticed that some people that I've talked to have tried to service an aftermarket fan clutch and I have no idea what those are in terms of volume. If your fan clutch has that little curly heated element that is common on aftermarket clutches then this probably won't help.
So assuming you have an OEM unit let me walk you through the process.
First, you're going to want some kind of impact or an impact screwdriver to take the screws out they are tiger tight and you will strip them if you aren't careful ask me how I know.
Assuming someone hasn't been there before with a little bit of coaxing you'll be able to pop the unit apart The only thing holding the thing together is age and the vacuum created by the silicon oil.
The OEM silicone oil will probably be yellow or brownish at this point. color doesn't really matter it's just what seems like the manufacturer color it's similar to the ones the Toyota comes in.
Now is a good time to feel the bearing The bearing should be smooth and not crunchy if the bearing is crunchy you'll be able to feel it, there will naturally be some resistance from the silicone oil but just make sure that your unit is actually serviceable and don't try to service one that's bearing is already destroyed.
Second, you going to need to drain it I find that heating it in a oven can sometimes slow the draining because it becomes more viscous at higher temperatures at least with the nature of the silicone oil being used in the fan clutch. The fastest way that I got to drain mine was I used an entire can of WD-40. WD-40 seems to be able to cut through the silicone oil pretty well. But realistically you should try to capture as much as possible to know exactly how much your fan clutch is full.
Be very careful once you take it apart there will be a little tiny plastic step that the fan clutch uses to scrape the silicone oil back into the reservoir. Do not lose this. There will also be an o-ring gasket it will probably grow in size once you remove it from the galley so just be prepared to struggle with it a little bit to get it back into place I would encourage boiling it to try to shrink it a little bit but also realize that it's almost 20 something years old.
I tested four different OEM fan clutches and they all contained anywhere from 18 mL to 25 ml of silicone fluid. I've seen people suggest overfilling them I do not suggest overfilling them because then the lockup is going to be constant. I filled my own with about 23.5ml enough to fill the reservoir. The Toyota guys seem to recommend two bottles I do not recommend two bottles as their fan clutches are bigger than ours.
Go to your local hobby shop or order from Toyota The silicone oil that you're going to need. Don't quote me on the viscosity, I believe the Toyota one is around 6,500 CST and the hobby grade stuff that you can use from an RC car hobby shop will probably be better off being closer to 10,000 CST. This stuff is less than 10 bucks you shouldn't have any issues finding any at a local RC shop. I used 10k cst.
Third, once you clean out all of the old silicone oil load up the reservoir side it's the one with the hole in the center, it's the face. With the silicone oil of your choice. I would use a syringe with the exact amount that you expect to use. if you're being conservative I would encourage 18 but I've gotten about 23 ml on average out of the fan clutches. it could be more if you could scrape every last surface, just fill it to where you have the reservoir filled which is going to be between 18 and 25 ml.
Once put your gasket in place and gently put it all back together make sure that you put your little plastic piece back in the little slot that it's for and put it back together Make sure that you have the gasket seated before you put in the screws otherwise you will destroy the gasket.
There's no torque setting just tight is tight. Hammer them in, lightly, opposite of removal I used an impact on a very low setting and got them nice and tight.
You'll probably notice a stronger lockup with higher CST oil. But bear in mind for the effort it's probably easier to find a newer fan clutch. I don't see many problems with the aftermarket ones myself but if you want to keep it original and you don't have a problem with doing some of the work you can only improve what's in there.
Again this is assuming that the fan clutch is your problem and you're not having other fundamental cooling issues.
Good luck.
