LJ78 Prado BIG Cooling Fan Upgrade (1 Viewer)

[GTSSportCoupe]

I think everyone knows the LJ7x's and KZJx's have temperature issues under load, which can lead to localized boiling/cracked heads. Many of you also know I've done a huge amount of work to improve my LJ78 to the point where I don't have these issues. My truck runs cool and good 99% of the time, but when I'm towing my 16' camper trailer up 8% grades in 30C weather in summer, the engine still builds heat.

One of the first things I did was replace the fluid in my Viscous fan clutch, and I also tuned it to come on earlier. (I followed these instructions: https://forum.ih8mud.com/threads/blue-fan-clutch-mod.102633/). I also will be putting in Evans waterless coolant to prevent any localized boiling from ever happening again no matter how hot I get the motor.

However, I've been meaning to source a fan upgrade, as the factory Prado fan is really quite small for the size/weight of the vehicle. Turbo engines need more cooling just like a V6 would compared to a I4.

So finally I found a fan upgrade. It is from a Toyota Truck/4Runner with the 3.0l V6 engine. I've gotta say, this is the biggest and best designed Toyota fan I've seen. The one I bought has damage to one blade (got it cheap), but I don't think it will matter much at all. I tried installing it last night, and it fits perfect to the viscous clutch, and fan shroud. The only issue is the offset is wrong, and it interferes with the crank pulley. So today I plan to make a 13/16" spacer for the fan hub. I'm pretty certain this fan is the same one that TRD includes in its 1FZ-FE 80 series supercharger kit also.

I imagine this will make an EPIC difference to the cooling of the Prado.

Fan comparison. LJ78 on the left, Toyota 3.0 V6 truck on the right:

LJ78 fan in LJ78 shroud:

Toyota V6 fan in LJ78 shroud:

Fan blade comparison (LJ78 first, then V6 second):

Need a 13/16" spacer because the plastic part has a different offset. I've used my OEM LJ78 viscous fan clutch here (the V6 one is even shorter):

 

[Gun Runner 5]

If all else fails, try this one. Might require a larger shroud and some minor modifications.

 

[GTSSportCoupe]

If all else fails, try this one. Might require a larger shroud and some minor modifications.

I'll take it if it comes with the turbine engine attached...haha!

 

[Gun Runner 5]

I'll take it if it comes with the turbine engine attached...haha!

I'm sure that part could be negotiated. : )

 

[GTSSportCoupe]

Finished my adapter on the lathe/mill today. Should get everything together tonight or sometime this weekend. I'm pretty excited.

 

[ForealBoreal]

I love how you are taking your prado and making it reliable.
Hats off to you and keep up the good DIY mods!

 

[GTSSportCoupe]

I love how you are taking your prado and making it reliable.
Hats off to you and keep up the good DIY mods!

Thanks man. To be honest, with all the complaining of Prado's and their over heating 'crap' engines, I'm suprised no one has tried this yet.

Here is the concentric spacer machined up today. I'll try it out sometime this weekend. Can't wait to tow; bring on the heat!

 

[ForealBoreal]

Hope you rebuilt and put new fluid in that puppy! Looking SLICK

 

[Postoy]

Wanna make another adapter? I'm super interested in doing this to mine.

 

[GTSSportCoupe]

Hope you rebuilt and put new fluid in that puppy! Looking SLICK

Yup, did that last summer. Put heavier silicone in it, and adjusted it to come one earlier.

Wanna make another adapter? I'm super interested in doing this to mine.

Could do. I'll let you know how/if it works out first tho, haha.

 

[GTSSportCoupe]

Despite coming down with the flu, I pushed through and installed the fan today. Went according to plan for the most part. The fan is very tight to the shroud at the top. I probably should have shifted the shroud up a couple mm. Other than that, it seems to work very well!

 

[VI Cruzer]

If that works out I would be very interested in incorporating the mod also. You may be able to sell a few of those adapters!!
NIce mod!

 

[GTSSportCoupe]

If that works out I would be very interested in incorporating the mod also. You may be able to sell a few of those adapters!!
NIce mod!

I'll definitely let you guys know how it works out over the next while. Only real issue I foresee is how tight the fan is to the shroud, but I suppose it could be trimmed with out too much hassle.

Not sure if I can make you guys adapters or not (I work at the University, and they are touchy about what we use the shop for), but I'll look into it. At the very least I'll put together a drawing and post it up here. Then you guys can have your own made if you want.

 

[Postoy]

Nice work again GTS! Interested to hear how this helps your cooling. Especially when you tow.

 

[Postoy]

Have you ever thought about just running a good electric puller fan? my thought would be quieter cooling and free up some HP from the mechanical fan.

 

[GTSSportCoupe]

Have you ever thought about just running a good electric puller fan? my thought would be quieter cooling and free up some HP from the mechanical fan.

Yup I have. Pradocruzer did that with good success (he has pics on the forums here somewhere). The only reason I have not, is my truck is real tight in front with A/C condensor, trans oil cooler, and intercooler. That and I've already loaded my alternator pretty hard and don't want to push it to much. It is only 55amp.

 

[Postoy]

I think I have seen Pradocruzers, His is mounted in the front as an addition to his mechanical fan is it not? I'm talking about replacing the mechanical fan with and electrical puller (not pusher) fan.

 

[GTSSportCoupe]

I think I have seen Pradocruzers, His is mounted in the front as an addition to his mechanical fan is it not? I'm talking about replacing the mechanical fan with and electrical puller (not pusher) fan.

My understanding is that electric fans have a real hard time matching a clutch fan. With a clutch fan we are talking a few hp of air movement (1000's of watts). Hard to make electric fans match that when they are 100's of watts at most.

 

[Trinidad]

I certainly would not have thought about using a larger fan. Good thinking and implementation of the idea. Looking forward to your feedback after your testing of this mod.

 

[GTSSportCoupe]

I certainly would not have thought about using a larger fan. Good thinking and implementation of the idea. Looking forward to your feedback after your testing of this mod.

Thanks! Will let you know how it works out.