Blue fan clutch mod...Thread has gone to hell, read at your own risk (1 Viewer)

[landtank]

Cattledog, I'd be curious if you were in a similar idling situation if you got better cooling by opening the hood. CDan had a situation where he was running hot when idling and it was resolved by opening the hood. He actaully saw his temp return to 185*F.

If that was the case then it would seem that louvering the hoods would be next in line to get complete control of the operating temps.

I still have no AC so I can't recreate that situation.

 

[Tools R Us]

Kevin, this goes directly to the difference between our perseptions of how the clutch works.

Since I beleive that the second set of diagonal holes provides the drive and they open after the first smaller holes than having the smaller holes at 115* would be starting too late.

By moving the smaller holes down to 95* the larger ones come in later around 110* or so, I haven't measured that though. If I get some time later on this weekend maybe I'll pull my clutch and see.

Knowing where the valve is full open would be a good data point. On the way home last night it was ~84F and sprinkling, the fan output air temp was 125-135F at 65-75mph. Under those conditions you probably don't need much if any fan.

With the stock fluid the clutch is pretty wimpy, by advancing the valve it gets to the bigger openings sooner, but even wide open they are weak. When thicker fluid is added the fan actually moves air, so it probably doesn't need as much valve advance. I bet that mine with the 10K cst moves more air on the first step than a stock blue hub with the valve fully open. Looking forward to cooler weather data, maybe able to retard the timing so that it freewheels when highway cruising in cool weather and still kicks in hard when it sees a heat load?

 

[landtank]

The one thing I noticed is that while the truck warms up it does so as usual until it gets close to operasting temp andf then it kind of eases into it. That last needle width takes like 15 minutes of driving and this is at 80*+.

If during the winter months I see that the truck never really warms up then I 'll know what to do, but I don't think that will be the case.

 

[Cattledog]

Cattledog, I'd be curious if you were in a similar idling situation if you got better cooling by opening the hood. CDan had a situation where he was running hot when idling and it was resolved by opening the hood. He actaully saw his temp return to 185*F.

If that was the case then it would seem that louvering the hoods would be next in line to get complete control of the operating temps.

I still have no AC so I can't recreate that situation.

Sure, I can give that a try. I will let you know on the next hot day.

Anyone thought about venting the splash guards in the wheel wells? I have no idea if they are a high or low pressure zone at speed, but at 5 mph who would care. I noticed alot more air moving out of the wheel wells after the fan clutch mod.
I understand reasoning why some may want to vent the hood, but IMHO it is not a practical, diy or cost effective mod. It would be simple to remove the guards for a quick test.

 

[LandCruiserPhil]

Sure, I can give that a try. I will let you know on the next hot day.

Anyone thought about venting the splash guards in the wheel wells? I have no idea if they are a high or low pressure zone at speed, but at 5 mph who would care. I noticed alot more air moving out of the wheel wells after the fan clutch mod.
I understand reasoning why some may want to vent the hood, but IMHO it is not a practical, diy or cost effective mod. It would be simple to remove the guards for a quick test.

The splash guards have been removed from my junk and additional metal cut from the fender skirts for clearance of the remote reservoir shocks. Does it help? My guess is a little, you can feel the heat standing next to the front fender. The hottest area under my hood is the back corner above where the exhaust dumps. It seems to get trapped up there with no where to go. At one time I thought about mounting a carb fan from a 60 series to dump the heat from that area but I didnt think the fan would hold up being mounted above the exhaust manifold. On a SC exhaust temp can get in the 1400* range .

Venting the back of the hood would help the most with underhood temps. The down side is the inside air vent is picked up from the cowl and driving with the window down would suck all the hot air into the cab making not worth it here in AZ.

 

[clownmidget]

Man, this is a lot of reading - especially to do when I'm supposed to be working

So my questions/comments are kind of like Turbocruiser's in that I'd like to know what the advice/consensus would be for oil weight for a turbocharged truck that resides at near sea level where ambient temps go over 110-deg F but frequently gets driven to snow and temps below 20-deg F during the winter. Should I just stay with the stock oil or do I need to have two fan clutches - one for extreme high temps and a stock one for general duty?

I can say that with the blue clutch in stock form I've only been able to get my coolant temp to 223-deg - and only briefly at the very end of the climb. This was with the egt's at 1500-deg, air temp at 105-deg running 85-mph with about 500-lbs of people, 1000-lbs of gear, a 15-cubic ft rooftop box on the climb up out of the Colorado R basin on I-40 - about a 4 mile climb with a few thousand feet elevation gain. Funny thing is the stock temp gauge on the cluster never went above just a hair above middle (not modded...).

I've done like Phil too and removed all the fender skirts and along with the body lift and suspension lift you can really feel the hot air getting pushed out. I still think hood vents are in my future though.

 

[landtank]

Going with the 6K oil may or may not get it done depending on where your clutch is at. I've logged enough to know that there is a descepency between the clutches that will influence their performance.

I personally would do the timing and oil but if you would want to attack it slower than get 2 bottles of the 6K and swap out the oil and see how it performs.

The oil from CDan is 8.83 a piece so it's not a huge investment and I'd think if the oil wasn't enough then a timing tweek would be next and the oil would still be useful.

Currently there are 2 modified clutchs with both the timing and oil, there will be a third shortly. So we might get more info soon.

 

[SUMOTOY]

General Comments

LT et. al.
Venting the splash guards will definitely help at speed because a spinning wheel is a low pressure zone by definition. I don't think it will help much in trapping the underhood heat, because it's up high that's the problem. I'd also be very careful doing this on the DS, since you have more exposure of the coil to water splash.

LCP
Place the vents outbound of the HVAC intake is key to adding vents. I'll also say doing this presents a problem, since the hood structure would dictate that the first vent opportunity you have is 12in forward of the rear hood line. Practically speaking, if you look at the pics of my install on the ABC IV, those vents have less than 2mm clearance to frame interference, rearward and side to side. The hood bracing runs 4in in from the fore aft edge and 15.5 inches from rear hood line to vent to fit the narrow portion of those vents I installed.

IOW they are mounted as far back in the hood without cutting the frame, and as far outbound without cutting the frame. That creates a lot of limitation in terms of placement. I can say they certainly do their job extremely well, and I highly recommend this modification to an 80 that sees extreme duty towing or wheeling, electric aux, main or mechancal fan. The amazing part is 5minutes after shutdown, those vents are still letting alot of heat out of the bay.

Scott Justusson

 

[clownmidget]

Thanks Rick. I've already got my timing advanced (compared to stock) to about 6 or 7-deg in diagnostic mode. Guess I'll read more...

 

[landtank]

Thanks Rick. I've already got my timing advanced (compared to stock) to about 6 or 7-deg in diagnostic mode. Guess I'll read more...

I not referring to engine timing but the clutch timing.

 

[clownmidget]

yeah, that's why I have to read more...


eight pages

 

[landtank]

yeah, that's why I have to read more...


eight pages

F-that, send me your clutch and I'll hook you up

 

[Tools R Us]

I agree with Rick, start with 6K and see how that affects your truck. The viscosities are mixable, so you can tune the clutch by adding some thicker or thinner to it anytime.

 

[landtank]

Since it was asked about having me provide this service:

The cost would be $60.00

You would mail me your clutch:

I would:

1. adjust it

2. Clean and replace the oil with OEM 6K

3. mail it back to you USPS (continental US)


At some point if the OFNA oil proves to be an acceptable substitute the cost with that oil would be $40.00

 

[Tools R Us]

Rick, Just filled the second tank and the results are consistent. I don't keep track of my mileage, only the mileage where the light first flashes and then is on constant. Tossing out wheeling and highway trips, a normal fill is around 230-240 miles. On this tank the light was on solid at 249 and filled at 259.1 taking 21.8 gallons, raw data uncorrected for the tires, etc. So if anything it's getting slightly better mileage, the motor must like the more consistent temps, is running more efficiently to over come the slightly increased drag from the fan?

IMHO this mod is a great improvement for non supercharged trucks, even with the 10K cst fluid, probably thicker than needed but don't see a downside. It's simple, easily reversible, inexpensive, uses reliable proven stock parts and results in consistent, even cooling, without having to add systems or cut up the truck.

Disclosure; stock cooling system with early blue hub, stock valve setting, fluid replaced with 10,000 cst.

 

[landtank]

Thanks Kevin, I saw a similar MPG increase while on vacation and towing the trailer. The return home was when I finally got the truck to maintain it's temp and it drove much nicer with less downshifts than on the way out. FWIW, my house and the spot down the Cape are near identical elevations so both ways should have been about equal.

 

[Cruiserdrew]

THis has been a most interesting discussion, and I thank the participants/mad scientists. I am coming up on a planned 100k maintenance which will include a new radiator and fan clutch (as well as a HG!).

To summarize Landtank's current best thinking on this, The move to make is stock timing (of the fan clutch lock up) with heavier oil right? I have to make a parts order with the Dan and want to get this right. So, new clutch, drain out the new 3000 cst oil, add 2 tubes of 6000 cst oil, and call it good? I may do the adjustment for grins, but I have a ton of other projects, so if avoidable, I'm avoiding it!

I guess the real question is how important is the fan clutch timing adjustment?

Two years ago, I added 1 tube of 3000, and one tube of 6000 to my FJ60's fan clutch and it worked fine for a year until I bought a new one.

I also have a lower mileage oil style 80 series fan clutch-would it make any sense to run thicker oil in that? Right now it's a spare that goes in my parts box.

 

[landtank]

The timing thing was needed for me was to first, get the clutch to start to work, and then further adjustment was to get the 3000 oil to perform at it's best.

If I'm going to do this for anyone I'm going to do both as I know this will provide excellent results and they will be happy with it.

From my testing the clutches are coming through with some varience to the clutches timing. How the clutch you get responds to just the thicker oil I have no idea. It's going to be better than stock, and maybe as good as doing both. But in the time it takes to drain the oil out of the base of the clutch you could have the control side cleaned and adjusted and be reletively sure t will perform as others have.

 

[Tools R Us]

...So, new clutch, drain out the new 3000 cst oil, add 2 tubes of 6000 cst oil, and call it good? I may do the adjustment for grins, but I have a ton of other projects, so if avoidable, I'm avoiding it!

I guess the real question is how important is the fan clutch timing adjustment?
...

The fluids are mixable and the resulting viscosity is determined by the percentages of the fluids. On a new clutch I wouldn't waste all of the new fluid and take the time to clean it all out. Just remove about 15 ml and add a tube of 10,000 cst will net about 5000 cst, or if your want thicker, remove about 30 ml and add two tubes for about 7000 cst.

I cleaned mine and added ~55 ml of a non Toyota 10,000 cst fluid, it appeared to about the same level as the factory fill, but it's hard to tell. Rick has run them with two tubes (36 ml), they operate correctly, some have run them with four tubes (72 ml) and still had the valve work correctly. So the fill doesn't look to be that critical as long as it's not overfilled so the reservoir overflows causing it to stay on all of the time. I prefer more fluid so the circulation time is longer, may cool the fluid better extending it's life, no data, just my thought.

I see fan output air temps of ~110-125F at speed and 150-165F when stopped. Shift neutral on the highway and rev it I hear little or no fan noise, stop at a light, it heat soaks due to the loss of ram airflow, the fan output air temp raises but the other temps now stay stable. Accelerate from the light, there is big fan noise, the fan output air temp drops quickly and with a few blocks the fan noise goes away. IMHO the fan is doing a good job of reacting to heat loads, providing much improved airflow and keeping temps stable with the stock valve setting.

With the stock thinner fluid, advancing the valve gets more fluid into play sooner, but even full open it doesn't pump enough air when the truck is pushed hard. With the thicker fluid MUCH more air is pumped, so advancing it is less or may not necessary. I am thinking about 115F or so would allow the fan to freewheel when low load highway cruising and still react quickly to loads.

Two data points I would like to see are; What temp is the valve fully open at and what is the fan output air temp with the truck at speed and the coolant at 200F+? It maybe better to go at valve adjustment from that end, making sure that the valve is fully open in an extreme heat load?

 

[alkaline747trio]

With complete disreguard to what has been said already due to lack of time to read, could one drain the fluid in their stock original hub and replace with 6k stuff and expect better operation?