Builds 1992 LJ78 build/refresh

[Nas90tdi]

Thanks Don. I know yours is coming along as well from our off site communication.
I am glad to see a larger pool of people working on their LJ's. Things will become easier as the knowledge pool increases.
GTSSportCoupe was getting worn out as the king of all things Prado. We all can start pitching in as we break more and more on our trucks and have to fix them.

Though it serves him right for being Canadian and getting them 10 years before us.

 

[Nas90tdi]

No work on the truck this past weekend. I did take it for a nice long test run and a bit of exploring.
It has really started to run a lot better since I have been driving it more and running fuel treatment through it. Fuel mileage is still crap. About 18MPG. Though a lot of my mileage has been short runs and very little highway driving. I am sure it will be better on a longer run.
I am running 13PSI boost. That has gone a long ways towards controlling the EGT and water temps.
After I get back from vacation in May I will make a decision about how I want to do the intercooler and get that finished up. Then I will start playing with the boost and fueling.

 

[GTSSportCoupe]

Great pictures and looks like fun! Nice to see you getting out in it.

18US MPG = 13l/100km. That's pretty good for short driving around town in one of these. I get closer to 14l-15l/100km in town doing short trips, idling in traffic and bagging on mine. I get 12l/100km with mixed driving. Long trips on mixed highway (some twisty/steep, some high speed) I get 10-11l/100km. Towing a 3500lb camper with truck loaded I get 15-16l/100km.

 

[Nas90tdi]

I decided it was time to tackle the A/C. When the truck came from Japan it had no pressure on the system.
I no longer have my secret stash of R-12, so after talking to GTSSportCoupe about the Red-Tek and a fair bit of research, I decided to give it a try.
Since I had no pressure on the system I had not been able to verify operation of the pressure switches on the system but had jumped the clutch to make sure the compressor worked, or ,at least engaged.

I used Red-Tek Dry12 first. Red-Tek actually suggests not pulling a vacuum on the system before introduction of this. Then I used a can of the Leak Stop 12 to help with any dry orings. At this point the sytem had enough pressure on it to kick in. Everything actually worked. So I started putting a can of Pro 12 in. This is when the leak that undoubted drained the system showed up. At the compressor the high side line was leaking at the fitting. So, I stopped, got that fixed and called it a day while I waited on a couple of more cans of Pro 12 to show up.

I partially charged the system and left the gauge on it overnight to verify it wasn't leaking. All seems to be holding ,so I topped it up.
I find that the system actually cools better with less than the equivalent of the 800 grams the underhood decal calls for. I actually slightly overcharged it at first on accident and it dramatically decreased the cooling capacity.

So, I started pulling small amount out until the cooling capacity peaked. I am getting 39F/4C at the vent at about 55 degrees ambient. Used the oil test Red-Tek provides. While it's a tad bit hokey, it shows the oil in the system to be fine.Summer will actually tell how well it's working, but for the moment, it seems to be working great.

I also installed my low coolant sensor for my Madman gauge and replaced a rattling exhaust cushion.

I have basically 2 more bigger projects and I think the truck will be ready for more regular use.
I am going to have the radiator recored when I pull everything apart to do the timing belt/water pump. I have a Tridon high flow thermostat enroute. And, the intercooler.

Thus far I have been extremely happy with the truck. It runs really well, after turning the boost up the EGT's became far more controllable. I am still getting some temp creep on the coolant. Hopefully the combination of the recore,thermstat and intercooler will solve that last little problem.

 

[GTSSportCoupe]

Nice work! And thanks for the head's up about the pressure. Might drop mine a bit and see what it does for the cooling.

Good plans, can't wait to hear how the cooling mods go.

Don't forget the fan upgrade and servicing the viscous hub. You have to take all that out to get at the radiator anyhow. I looked into it a bit and I believe there are bigger fans from other cruisers that will fit without a spacer. All the Toyota ones of the 80's and 90's bolt on, but what you need is the right offset to clear the crank pulley. I'm almost certain the 2H fan from the HJ60 is a direct fit. Just need to find one to confirm....

 

[GTSSportCoupe]

Also, if your A/C leak continues to be a problem, I'm pretty sure I have more than enough o-rings from my kit for you to re-seal most of your system. I only replaced the o-rings on my compressor and dryer (as they were the only ones leaking). Could send you some.....

 

[Nas90tdi]

Hasn't leaked again, so I am keeping my fingers crossed for the moment.
I remember you mentioning the 2H fan. I would love to find someone that had one we could look at.

 

[GTSSportCoupe]

Hasn't leaked again, so I am keeping my fingers crossed for the moment.
I remember you mentioning the 2H fan. I would love to find someone that had one we could look at.

I think someone in my club has one. He's not 100% sure what it came off of, but he's going to send me pictures soon.

 

[Nas90tdi]

That is definitely a lot of wasted airspace. Makes the shroud somewhat less effective it would seem with that much unrestricted flow around the fan.
I swapped my t-stat out to the Tridon one this afternoon. Haven't had a chance to test it out yet.
I have to assume the high flow is generated by the amount the valve draws back because the diameter of the opening seems identical.

The picture didn't turn out really well, but it's in now. Not taking it out for another photo op.

 

[GTSSportCoupe]

That is definitely a lot of wasted airspace. Makes the shroud somewhat less effective it would seem with that much unrestricted flow around the fan.
I swapped my t-stat out to the Tridon one this afternoon. Haven't had a chance to test it out yet.
I have to assume the high flow is generated by the amount the valve draws back because the diameter of the opening seems identical.

The picture didn't turn out really well, but it's in now. Not taking it out for another photo op.
View attachment 1679115

I compared mine by boiling them in a pot of water. Have pictures somewhere. If I remember correct the Tridon had quick reaction time and opened more than the other one I had in the pot.

 

[Nas90tdi]

I suspect your memory of that is accurate. After a test drive I can confirm it definitely works differently than the factory one.
I can hit 192F and then drop to 188F is within a few seconds. If I am really running the EGTs a bit higher it hits 194F and then drops rapidly back to 188F. The response time on the factory t-stat was far slower than that. It took it a lot longer to drop after it opened.
The annoying thing, and this is just my anal retentiveness, is the truck moves the temp around all over the place. If I am going downhill it will go down to 179F, or less ,short climb and it's back up to the 190F range. Just regular driving it's all over between 180-192F I am not a fan of an engine changing coolant temps like an RPM gauge. It makes me watch it far too much because it's not stable.
Part of it is I tend to run analog VDO gauges in most of my Land Rovers. They have a bit of a buffer while still reacting plenty fast. The digital Madman gauge is nearly instantaneous, so the fluctuations appear more rapidly. So, I am having trouble getting used to it. Oddly enough, the Madman is big in the Land Rover community and I have fought it for years. But, gauge space isn't at a premium without hacking up the dash or putting crap all over it, which I don't like.
That does make verifying how the t-stat is working really easy however.

 

[malteser]

I think someone in my club has one. He's not 100% sure what it came off of, but he's going to send me pictures soon.

Here is a picture of a 2H one on ebay. Looks like the right offset to me. Ad says its 445mm in diameter. Would have to measure the shroud on the LJ78 to see if it's a match. I did trim the blades on my Isuzu fan to better fit the shroud in my LJ78. In retrospect I wish I'd left it full diameter. The LJ78 frame is so strong they don't seem to twist or flex enough to move the fan in the shroud. And I've had two wheels off the ground on a few occasions; had to use the e-locker to move...LOL. I have heard fans hit in the 40 and 60 series on a number of occasions while wheeling with the club.

Toyota Landcruiser 2H Diesel, Cooling Fan 16361-68010 | eBay

And my old LJ78 one:
View attachment 1678761

Here is how pathetic they look in the shroud:
View attachment 1678762

That is exactly what I'm looking for aswell!

I made some research to see if it would fit directly and came across these photos, maybe you could compare these dimensions with the original one you have already removed (since ours still mounted)

 

[GTSSportCoupe]

That is exactly what I'm looking for aswell!

I made some research to see if it would fit directly and came across these photos, maybe you could compare these dimensions with the original one you have already removed (since ours still mounted)

I threw away my original one a long time ago so cannot measure. I know the 2H one will bolt on. It's just the offset and outer diameter to check. Anyhow, maybe we should not side track this thread too much from Nas90tdi's build. I will be getting a 2H one soon and will try it out and take pictures for you guys. I'll post in a new thread.

 

[ALEXY]

[QUOTE="Nas90tdi,
I can hit 192F and then drop to 188F is within a few seconds. If I am really running the EGTs a bit higher it hits 194F and then drops rapidly back to 188F. The response time on the factory t-stat was far slower than that. It took it a lot longer to drop after it opened.
The annoying thing, and this is just my anal retentiveness, is the truck moves the temp around all over the place. If I am going downhill it will go down to 179F, or less ,short climb and it's back up to the 190F range. Just regular driving it's all over between 180-192F I am not a fan of an engine changing coolant temps like an RPM gauge.
.[/QUOTE]

I had a similar behaviour before I topped the fan clutch ( which I found to be almost void of silicone oil).
Still temperature goes up and down, but not quite so scary fast.
on regular driving without hills stays at same coolant value, just egt plays.

 

[Nas90tdi]

That is one of the items I haven't gotten to yet. But, mine doesn't have much resistance. I suspect it may be dry as well.
Thanks for all the suggestions guys.

 

[SNLC]

Just an FYI....

Every tropical spec Cruiser (that is 25yrs old) I have seen has no fan clutch, they run a direct drive fan. Everyone of these including mine runs very cool under all conditions.

You can get a re-seal kit for the A/C compressor for about $30, I just got one from Toyota. A lot of A/C shops still have R12. I found one locally and am having my A/C system recharged with the R12 after the compressor is re-sealed.

Cheers

 

[Nas90tdi]

I was actually wondering about that. I am assuming the fan clutch is present for some sort emission compliance and to relieve a small amount of drain on the engine. Though, I have always felt that was negligible. Certainly not on par with an AC for instance.

Ian, is that the factory set up on the Latin American trucks ,or, do they modify them to be direct drive?

 

[GTSSportCoupe]

I was actually wondering about that. I am assuming the fan clutch is present for some sort emission compliance and to relieve a small amount of drain on the engine. Though, I have always felt that was negligible. Certainly not on par with an AC for instance.

Ian, is that the factory set up on the Latin American trucks ,or, do they modify them to be direct drive?

Don't do it!! Way over kill for our climate, and will draw too much power from the little diesel. I've heard of people doing this, and the noise of the fan roaring all the time is too much. Not only that, but the cost to fuel economy is very noticeable. Would likely make your engine run too cold in winter too, which means a dirty diesel burn and the engine would never be up to proper operating temperature.

I watched a youtube video a while back on how the viscous fan hubs work. They are quite a little feat of engineering, and not junk at all. They put the power to the fan when it's needed (rad hot), and remove the power when it's not needed (rad cool).

Upgrading to a heavier weight silicone oil will transfer more power between the clutch surfaces. I went to 10,000cst and just used silicone oil from a RC hobby store.

Also, the little hole is adjustable in the LJ78 viscous hub. A few of us have adjusted it so that it 'turns on' at a lower temperature. I have compared the LJ78 viscous hub to earlier land cruiser ones, and it is a superior design with more clutch surface, more adjust-ability and more heat sink fins. I tried an aftermarket one before and it was garbage.

By changing the oil in your viscous hub and upgrading to a fan matched to the size of the vehicle, you'll be in good shape. Especially if you get your radiator re-cored at the same time.

Just my two cents....

 

[Nas90tdi]

Funny Nick. I was just curious.
I have already ordered the silicone oil to change mine out. I certainly think it's a worthwhile project.
I have had both and I agree a direct drive fan can be a tad noisy. I don't find it to be that annoying. I need to come up and let you drive my Defender sometime. You think a little fan spinning is noisy. My Defender is quiet as a tomb compared to some I have had or ridden in. You would think you had jumped into a combine if a little fan noise bothers you. Especially one of the exposed metal floor soft top ones. I have lots of sound deadening in mine.
I do enjoy a quiet vehicle though, so will be doing the fan clutch mod.

I think the viscous fan is definitely a feat of engineering. They are an ingenious little device. And, if I can make mine work the way I want, I will be happy with it.

 

[Nas90tdi]

Last night I pulled the fan clutch out to replace the fluid.
Left it draining overnight. This morning I reset the temp on front half. I set it to 95F half open and then cycled it through a few times. It appears to start opening around 91F and is fully open at 113F
I refilled using the 10K fluid to just below the drive plate. Which is also about the time it begins to creep up to the top on the edges.

I used a cast iron skillet out of my camp kitchen. This made the temp much easier to control. A SS pan will fluctuate quickly and cause you to be continually trying to adjust the water temp. Whereas the cast iron will heat up very slowly and then drop slowly.

I also put the other half on a wire rack and heated it up when I put the fluid in. Getting the entire clutch body warm made the fluid flow a lot better.

First impression driving it are phenomenal. Nick told me it would be a worthwhile endeavor. And, while I completely believed him, I didn't expect it to be so clear cut.

I drive the exact same route with all my testing so I have a baseline on everything. I have 2 areas of this route that if I let my EGT's climb to around 1200F I would see 203F on my coolant temp. Today I saw 192F in both those locations. I even went back to one of the hills just to make sure.

I used the info found here:Blue fan clutch mod

There are about 45 pages spanning almost 12 years there. With wildly varying theories and directions. At Nick suggestion I just ignored most of that and went with the original posters directions with the exception of the silicone fluid viscosity. This seems to have worked out very well.