Replacing Original Fan Clutch Oil

[bpenn1980]

If you read my recent post about my temp gauge mod you know that I discovered my truck is running slightly hot which concerns me because in a few short months its going to be getting much much hotter here in Southern California.

My first step toward lowering the temperature is going to be replacing the original 3,000cst silicone oil in my fan clutch with a combination of 6,000cst and 10,000cst oil. I will also be measure the temp at which to clutch plate opens to make sure the spring is still operating at spec. I should mention I dont really know what spec is, but if it doesnt open by 120 degrees I'll be bummed. I'm doing all of this because I didnt want to buy a new blue fan clutch, so wish this cheap bastid luck!

The fan clutch is off the truck and sitting on my desk so I'll be tearing it apart, checking temp of spring activation and allowing to drain overnight before I refill with heavier oil and reinstall tomorrow. I'll post pics as I get into it.

 

[bpenn1980]

Never can be easy, 2 questions

1) I thought original fan clutches werent adjustable?? Mine sure as heck looks adjustable. (see below)

2) Since I'm only used to seeing pics of moded BLUE fan clutches, how high should I fill the original when I fill it up. Pic below shows current level.

 

[bpenn1980]

I've been slowly simmering clutch in my frying pan for the last 45 minutes and here are my temperature measurements for the clutch plate:

Small Hole:
Closed = 120 degrees
1/2 Open = 125 degrees
Open = 130 degrees


Boot Shaped Hole:
Closed = 150 degrees
Toe Open = 160 degrees
Open = 180 degrees

 

[landtank]

if this was the blue clutch I'd say that the timing was where you would get some overheating in 100* weather for sure. The small hole half open temp was where mine was when my truck was overheating.

I'd adjust it so the small hole half open was 95* and put in some 5k oil from a hobby store and see how it performs. I would also fill it to where it just comes up the underneath side of the disk jyst as I do on the blue clutch.

 

[bpenn1980]

For research reasons I decided to not adjust the clutch plate temperature at the same time as adding new oil. I wanted to see what would happen with only new thicker oil.

I added two full Toyota tubes of silicone oil. The first tube was 10,000 cst and the second tube was 6,000 cst, so I have a combined value of 8,000cst in there right now.

I reinstalled the fan clutch to truck and took a drive this afternoon. No change at all in city driving.

After running my errands I took the clutch off again and this time reset the small hole to 1/2 open at 105 degrees. Took it for a spin and temps were definitely lower and I noticed a whirling noise from the fan while driving from time to time. Unfortunately my second drive was after daylight and ambient temps were much lower, so I'll update you guys later this week if the lower temps stick.

 

[landtank]

it's the temp timing that gets the clutch to start, so to speak. It's the fluid thickness that determines how hard it pulls once it starts. 125* was where mine was when the truck was overheating very badly.

 

[bpenn1980]

it's the temp timing that gets the clutch to start, so to speak. It's the fluid thickness that determines how hard it pulls once it starts. 125* was where mine was when the truck was overheating very badly.

Thats what I was thinking, and I'm probably wrong here and not understanding this properly, but the ambient temp here in the summer time gets above 95 all the time but it only gets above 105 on the hottest days. Dont know how much engine temp adds on top of ambient temp to the fan clutch though

Anyway, if it doesnt work I'll just take it out and readjust down to your 95....which is probably where I should have set it the first time!

Thanks for the write up Landtank, and for the Front end inspection, I used that too

 

[Bear80]

I don't recall how much I filled mine with but it's fairly easy to pour all the old fluid into a measuring container. Then add slightly more than what came out, worked well for mine and the four other's I've done.

 

[landtank]

Dont know how much engine temp adds on top of ambient temp to the fan clutch though

that's going to be relative to how well your radiator is transferring heat. This is one of the reasons I wanted to come up with a way to be sure the clutch was working such that if you are still running hot it would most likely be the rad.

 

[bpenn1980]

that's going to be relative to how well your radiator is transferring heat. This is one of the reasons I wanted to come up with a way to be sure the clutch was working such that if you are still running hot it would most likely be the rad.

I'll find out sometime in the next couple months. I'm going to be doing a round of PM's that will include the PHH. I'll have the radiator out and assessed/repaired/replaced by a shop at that time and see how my temps change after reinstallation.

 

[Mike Fish]

If you read my recent post about my temp gauge mod you know that I discovered my truck is running slightly hot which concerns me because in a few short months its going to be getting much much hotter here in Southern California.

My first step toward lowering the temperature is going to be replacing the original 3,000cst silicone oil in my fan clutch with a combination of 6,000cst and 10,000cst oil. I will also be measure the temp at which to clutch plate opens to make sure the spring is still operating at spec. I should mention I dont really know what spec is, but if it doesnt open by 120 degrees I'll be bummed. I'm doing all of this because I didnt want to buy a new blue fan clutch, so wish this cheap bastid luck!

The fan clutch is off the truck and sitting on my desk so I'll be tearing it apart, checking temp of spring activation and allowing to drain overnight before I refill with heavier oil and reinstall tomorrow. I'll post pics as I get into it.

If you read my recent post about my temp gauge mod you know that I discovered my truck is running slightly hot which concerns me because in a few short months its going to be getting much much hotter here in Southern California.

My first step toward lowering the temperature is going to be replacing the original 3,000cst silicone oil in my fan clutch with a combination of 6,000cst and 10,000cst oil. I will also be measure the temp at which to clutch plate opens to make sure the spring is still operating at spec. I should mention I dont really know what spec is, but if it doesnt open by 120 degrees I'll be bummed. I'm doing all of this because I didnt want to buy a new blue fan clutch, so wish this cheap bastid luck!

The fan clutch is off the truck and sitting on my desk so I'll be tearing it apart, checking temp of spring activation and allowing to drain overnight before I refill with heavier oil and reinstall tomorrow. I'll post pics as I get into it.

My company is the only one in Australasia who actually makes "Viscous Fan Clutch Oil". 99.9% of all fan clutches use 10,000 CST (centistoke). Using 3,000 / 6,000 CST's is a waste of time .
Here in New Zealand there are some Auto Parts companies who import rubbish fan clutch oil from Taiwan, which includes ethylene glycol in the mix.' which then makes it poisonous.
When you dis-assemble your unit, clean everything out and lay the two halves on the bench. One half is (cup like) able to accept the 'Oil' and the other half is usually flat. Fill the the 'cup' side with the 10,000 CST oil, but do not overflow it and contaminate the sealing flange. Clean the oil seal with solvent, brake clean will do, and replace it in the 'cup' side, run some gasket sealer around the flange and assemble. Job done. I have been making and selling this product for over 20 years and have never had a customer come back to complain that it does not work.
12 years ago I bought a 1995 Toyota Land Cruiser with a 1HD-FT motor with 165K on the clock that had been abandoned in a farmers barn for over 6 years. First thing I did was change all the fluids and refill the fan clutch. Today she has turned over 425K and runs as smooth as silk.
Mike
glueman@engineeringadhesives.co.nz

 

[awmancomeon]

This thread never completed... You say most all fan clutches are 10,000 weight.. OK, good. Im not sure exactly how much to put in, so with the basin side flat I pour in the oil until the holes are just filled? This is the 1/4 inch or so sized holes in the circle...
I put in 10,000 and it is engaging too much, maybe I put in too much. I can remove some, or put in 6,000 weight oil.
yes, I know it is old thread, but very little info out there on rebuilding these..

 

[mudgudgeon]

This thread never completed... You say most all fan clutches are 10,000 weight.. OK, good. Im not sure exactly how much to put in, so with the basin side flat I pour in the oil until the holes are just filled? This is the 1/4 inch or so sized holes in the circle...
I put in 10,000 and it is engaging too much, maybe I put in too much. I can remove some, or put in 6,000 weight oil.
yes, I know it is old thread, but very little info out there on rebuilding these..

Find the Landtank thread on the blue fan clutch modification.
All the good info is in the 2nd quarter - ish of the thread. Gets a bit off track towards the end

 

[77mustard40]

Here it is, link from FAQ thread

Blue fan clutch mod...Thread has gone to hell, read at your own risk

History: On my first drive this summer after replacing my transmission I was having an overheat condition with the truck. On the following weekend while towing a camper it was real severe in the 230* range. After returning I was able to confirm that my Blue hubbed fan clutch was to blame...

forum.ih8mud.com

 

[TomH]

... but very little info out there on rebuilding these..

Seriously?

Try this search:

Google Search

 

[awmancomeon]

Here it is, link from FAQ thread

Blue fan clutch mod...Thread has gone to hell, read at your own risk

History: On my first drive this summer after replacing my transmission I was having an overheat condition with the truck. On the following weekend while towing a camper it was real severe in the 230* range. After returning I was able to confirm that my Blue hubbed fan clutch was to blame...

forum.ih8mud.com

Thanks. Im looking now, all 51 pages...
Also, you guys talking about 95 or 105 degrees... Your engine water temps run at 190 degrees, hot is over the boiling point (212) at 220 degrees. The ambient temps are not the important numbers, the temp of the air behind the radiator is. Water pouring into the top of the radiator will be 190 degrees, and get much cooler at the bottom of the radiator. 95 or 105 degrees at the front matters little if the fan is not working. The fan clutch gets hit with hot radiator air from the middle of the radiator mostly as the air from the top might scoot over the fan and the cooler air from the bottom might scoot under the fan clutch (which is dead center).
If rad is 190 at the top and 140 at the bottom then avg it to 165 for the temp hitting the fan clutch, but better to measure it. However it measures out it will be much higher than your 95 or 105 ambient temps. Add in the heat from the A/C unit also, and if the motor is running hot then water temps can get higher than 190. 190 is typically where the thermostat is fully open, so if the engine gets hotter the water will get hotter going into the rad too.

 

[awmancomeon]

I rebuilt my Nissan FC with 10000cst oil. I may have poured to the tops of the holes not the bottom. It works great, It might run faster/more than it is supposed to. I assume 10000 is correct for this clutch. MPGs are about normal, so there is no dreaded parasitic drain from too much fan at least. Eventually the oil will degrade and allow the water temps to stay at 190, but for now temps are mid 180's, and best part if trans runs cool.
$15 worth of hobby oil vs $180 for OEM clutch... hey HEY hey.

 

[bpenn1980]

fwiw I still have this fan clutch in there with the same oil and same temp setting. I replaced the radiator about 5 months after this post back in 2008 (koyo c1917) and havent had any issues since and have driven it all around socal city/deserts/mtns. Fan clutch still pulls air hard on first start up, so seems to be working.

That said, anyone else should just do what landtank says regarding temp/oil. I'm just a slow learner.

 

[awmancomeon]

So, I am in US and you guys are saying US vehicles FC will use lighter oil. I have read other US hobbiest use 10000cst also. I have really never heard anyone use 3000 and have it work. Based on what I used in mine I cant imagine 3000 working other than to just spin the fan a little..

 

[flintknapper]

So, I am in US and you guys are saying US vehicles FC will use lighter oil. I have read other US hobbiest use 10000cst also. I have really never heard anyone use 3000 and have it work. Based on what I used in mine I cant imagine 3000 working other than to just spin the fan a little..

I run 20K cst in mine (Texas weather).