DIY Viscous clutch fan rebuild

[Pagie]

I have to do this now so is it one or two tubes?

[laidlaym]

So my NM 3.2 overheated yesterday. It only took a few hundred metres up a hill accelerating hard with an empty medium weight trailer on. I stopped as soon as I could safely.

With the motor stopped I could spin the fan freely.

Time for viscous clutch attention??

[chrisfarru]

I'm sorry for the late reply. I only used one tube of 18ml Toyota oil and I can confirm that my viscous coupler is working as good as ever.

[Ocean]

So my NM 3.2 overheated yesterday. It only took a few hundred metres up a hill accelerating hard with an empty medium weight trailer on. I stopped as soon as I could safely.

With the motor stopped I could spin the fan freely.

Time for viscous clutch attention??

Certainly if it was spinning freely, and was certainly warm enough to be resistant to spin, absolutely try Chris's excellent instructions on how to reco it. Other wise buy a new one, shop around you will get one for under $300. At the same time double check all the other key elements to the cooling system.

The visco should not free spin when the engine is up to temp, in fact well before

[Pagie]

Thanks very much.

[chrisfarru]

So my NM 3.2 overheated yesterday. It only took a few hundred metres up a hill accelerating hard with an empty medium weight trailer on. I stopped as soon as I could safely.

With the motor stopped I could spin the fan freely.

Time for viscous clutch attention??

Look at the videos I posted. If it's free spinning after switching the engine off (engine warm) the coupler needs servicing. The second video shows how the coupler should behave.

[Pagie]

I tried to get the oil from Toyota yesterday and they had run out. So this morning I rang Mitsubishi, they told me that the unit could not be fixed and would have to be replaced. I got two tubes today from another Toyota place.

[BruceandBobbi]

Another silly question. When the vehicle is at operating temperature and you are driving on a motorway at 100K should the fan be operating?

Next stupid question when the vehicle is at operating temperature and the motor off should you be able to turn the fan by hand?

[Ocean]

Another silly question. When the vehicle is at operating temperature and you are driving on a motorway at 100K should the fan be operating?

Next stupid question when the vehicle is at operating temperature and the motor off should you be able to turn the fan by hand?

Yes

and

Yes

When it is up to Op temp it is still possible to spin the fan by hand, your should notice it is more rigid than when it was first cold. It can be hard to pick this. The key is that when at Op temp and the engine is turned off you will see the fan stop instantly and not continue to rotate.
If you start the engine when cold and turn the engine off after say 30 or slightly more seconds of running a good fan will still pin less than 4 revolutions more.

If in doubt reco it or replace it. My old one behaved like the above so I thought it was some other part of the cooling system after replacing most other components with still no fix to the problem, I decided to tackle the visco and ended up replacing it and the problem was fixed.

[Pagie]

I have done mine, one 18ml tube. Not had a chance to get it hot on a big hill yet. Will report soon.

[Pagie]

Well, it was easy enough to do but it did not work. It still spins after engine stops. Maybe I need to try again and put more oil in.

[chrisfarru]

Well, it was easy enough to do but it did not work. It still spins after engine stops. Maybe I need to try again and put more oil in.

Did you put that black plastic flap in the spot indicated?

[Pagie]

Yes, I put the plastic wiper or whatever it is back. Maybe I need to put more oil in. Could some of the clutches have bigger cavities than others? I checked that the bimetallic strip worked with a heat gun. It does seem to work a little as it does cool down quicker than it used to. But when hot it runs on for at least 30 seconds.

[farcanal]

Seems like this repair is a bit of "hit and miss"....works for some , not others.
My fan definitely spins after turning off the engine (NP 3.2 diesel) but I also have an electric thermetic fan...I guess all models have these as well?
I suppose I could give it a shot and just replace the hub if I don't fix it.
Overheating doesn't seem to be an issue with my car.

[kawamk]

O-ring size

Hi Chrisfarru,

Hi to all members

I am a new member of this large family and my recent situation with cooling fan made me google out and find this forum, and this knowledgeable chat respectively.

I want to say thanx and bravo for this eloquent, detailed effort provided by Chrisfarru, I find this very helpful for us enthusiasts

I have Montero Sport 2004 2.5td 4d56 engine and the problem is rather irrelevant, because what is annoying me is too long, like fifteen minutes, at 50F area temperature, to elevate the temperature gauge pointer. After that is ok, like beneath the middle on the scale ( only when I was driving on the highway for more than a twenty minutes over 100mph the pointer reached half of the scale so I figured out that it was possible to do that).
So after I watched those two videos you have provided up there in the beginning of the statement, my fan is continuing to spin after the engine is stopped, but the engine temperature is OK, the temperature gauge that once have reached the near-to-middle-position on the scale, it stays like that on the highway, in river crossing, in hill climbing..there is no overheating Why?
There could be three possibilities, figure it out,
-No thermostat
-Stuck valve in fan`s clutch
-Both
So I'm planning to open the thermostat housing, open the clutch and check it out. Since you have great experience on this problematical situation, could you happen to know, or remember what are the sizes of that O-ring that is sealing the two halves of the fan clutch, or the sizes of that groove (inside diameter and depth), where this o-ring is situated?
The thing is, it's a one day job for me so I'm trying to be prepared for those challenges that are visible

Cheers