radiator advice for a bj78

[pradoblivious]

Almost 10 years ago, I paid a ton of money for basically the worlds worst engine swap wherein cruisers direct slapped a nearly dead 13bt into my lj78, which lost compression in cy1 a few months later. After a complete rebuild, along with associated rebuilds for the injection pump, injectors and turbo, and just.. years of trying to figure out how to make it run right, it still idles like a car out of a mister magoo cartoon, and struggles to maintain 40mph on the wyoming backroads. When I either get a divorce, or somehow manage to work up the marital capital required, I'll probably do an r2.8 swap, but for now (among other things) I'm trying to figure out what to do about my water temps.

Landcruisers Direct ziptied a 20-amp spal fan in pull-mode onto the back of my 2lte rad because the rebuild didn't leave room for a shroud.

I've since had it re-cored to no real avail. and even tried adding a pair of push-fans to the front of it, which I managed to wedge in between the rad and the A/C evaporator.

Those didn't really make much of a difference. In fact, I think they actually made the system a little hotter by impeading the flow of air through the front of the rad. There's three or four inches of space between the rad and evaporator, so I've been thinking maybe I can fabricate some means of moving the rad forward, and either ALSO fabricating a shroud, or maybe picking up one of those 4-core aluminum rads with the built-in fan and shroud as a complete unit and slipping it in there.

So my question for the peanut gallery is: do I keep the copper toyota rad, which is newly-re-cored and try to figure out a shroud? Or should I go aluminum? If the latter, can anyone recommend a brand or unit that's up to the task of the heat this 13bt of mine puts out?

 

[Eurasiaoverland]

I've never heard a good thing about aluminium radiators. The original brass radiator will be better than a similarly sized aluminium unit.

I think what you are missing is an engine driven fan. How is the water pump pulley secured without a fan?

Also, a rough running engine after a rebuild is not good, has it been compression checked? If the last shop screwed up and the head gasket is leaking, that will cause cooling system problems.

Could you show us how the radiator/cooling system is plumbed in? Is the thermostat known to be good?

I think aftermarket viscous couplings are still available, and fan blades certainly are. Worry about a fan shroud later imo.

 

[hoser]

x2 on getting the engine driven fan working again. I'd add the shroud too. Keep the brass radiator if you can for cool factor but aluminum is actually better because the material is more rigid and so the cooling tubes can be wider for more surface areas. A 2-row aluminum radiator is typically thinner than a 3-row brass radiator and will have better air flow.

 

[JuanJ]

Hello,

I am late to the party.

For the time being, you could keep your radiator.

I have to take a closer look at other 78 Series Prados, but it appears that your radiator and evaporator are farther back than they should. I may be wrong, but the evaporator looks bigger than it should be. Is it factory?

It is worth to check other 78 Series to confirm the location of both radiator and evaporator.

Depending on the proper setup, you might have about an extra inch of space there, enough for a fan and a shroud, without the push fans.





Juan

 

[AirheadNut]

Due to the short engine bay on Prados, there is almost no room between the pulleys on the 13BT and the radiator, certainly not enough for the stock mechanical fan. Modifying the radiator and condenser mounts should be able to gain enough clearance; I've seen where a couple of people have swapped inline-6 engines into Prado engine bays by doing that (a 1HD-T and a BMW M57 come to mind).

 

[pradoblivious]

As AirheadNut says, with the 13bt in the lj78 frame there is actually negative space for the clutch-fan. You can see in this pic how the electric spal fan's motor actually protrudes into the belt's space, fitting in between the power-steering and water-pump pullies.

I've seen the actual 13bt stock configuration and it's kind of wild. It's a tiny little 8 or 10" fan with an absolutely massive shroud setup. You can see in this pic above how the clutch-fan mount (south of the electric fan and north of the rad return hose) is situated at a slight angle to the front of the radiator. I used to think this was a function of my horribad engine-swap, but the 13bt in, eg.. the bj74 is actually like this.
Here's a picture of the stock setup (borrowed from @FJBen's number1 thread...

See how much smaller the fan-end of the shroud is compared to the size of the rad? The shroud is this massive foot-long expansion chamber that expands to fit the size of the face of the rad. The fan itself, even though it's canted at an angle, doesn't impact the rad because it's actually such a small diameter that it just doesn't extend that far. Also it sits back a good 4" from the face of the rad itself.

For comparison, here's a different angle of my current setup, where the fan motor is literally extending into the middle of the power-steering belt. Even if I delete my condenser, there's not a lot of hope I'm going to be able to get the stock configuration going, and the angle of the fan-mount complicates the notion of getting a 4runner fan or similar goin on in there.

 

[Eurasiaoverland]

As AirheadNut says, with the 13bt in the lj78 frame there is actually negative space for the clutch-fan. You can see in this pic how the electric spal fan's motor actually protrudes into the belt's space, fitting in between the power-steering and water-pump pullies.
View attachment 3991145

I've seen the actual 13bt stock configuration and it's kind of wild. It's a tiny little 8 or 10" fan with an absolutely massive shroud setup. You can see in this pic above how the clutch-fan mount (south of the electric fan and north of the rad return hose) is situated at a slight angle to the front of the radiator. I used to think this was a function of my horribad engine-swap, but the 13bt in, eg.. the bj74 is actually like this.
Here's a picture of the stock setup (borrowed from @FJBen's number1 thread...

View attachment 3991150
See how much smaller the fan-end of the shroud is compared to the size of the rad? The shroud is this massive foot-long expansion chamber that expands to fit the size of the face of the rad. The fan itself, even though it's canted at an angle, doesn't impact the rad because it's actually such a small diameter that it just doesn't extend that far. Also it sits back a good 4" from the face of the rad itself.

For comparison, here's a different angle of my current setup, where the fan motor is literally extending into the middle of the power-steering belt. Even if I delete my condenser, there's not a lot of hope I'm going to be able to get the stock configuration going, and the angle of the fan-mount complicates the notion of getting a 4runner fan or similar goin on in there.



View attachment 3991155

Wow, I didn't realise just how cramped the Prado engine bay is, have they got the engine as close as possible to the passenger compartment bulkhead, or is there a big gap? I'm guessing there is quite a gap as the 13B is not really a long engine at all. It does have a very long input shaft and deep clutch housing, however, so my guess would be the whole engine and transmission is further forward than it should be.

Just for interest. if you think the BJ74 has a big shroud, check out the BJ60 - it's pretty much half of a 44 gal drum - this one has a fixed fan (no VC) and if you look at the water pump pulley you can see how tall it is to project the fan forward into the tunnel of a shroud. But the engine is tight against the bulkhead and entirely behind the front axle... meaning it's technically a mid engined car!

 

[coldtaco]

Having the inlet/outlet on the same side is not an efficient design. My 2H rad is that way. When I got a custom made aluminum radiator made for my 2H/12HT I had the manufacturer extend the inlet pipe in the top header tank to the filler cap, this trying to force a more of a cross flow, like the HZ radiator are.

 

[pradoblivious]

Having the inlet/outlet on the same side is not an efficient design. My 2H rad is that way. When I got a custom made aluminum radiator made for my 2H/12HT I had the manufacturer extend the inlet pipe in the top header tank to the filler cap, this trying to force a more of a cross flow, like the HZ radiator are.

I've often wondered about that. In my current setup, when things get hot the hose-side of the radiator is WAY hotter than the far-side. Who made your custom rad? Would you recommend them?

 

[coldtaco]

I've often wondered about that. In my current setup, when things get hot the hose-side of the radiator is WAY hotter than the far-side. Who made your custom rad? Would you recommend them?

PDI maybe? can't remember, you would need to look through my build thread. Mine is aluminum and so far it has held up wonderfully. the attention to detail, great welds. I think it was actually made in the US since they have a US based shop. they build radiators for race trucks, vehicles. Just be sure to include a drain in your spec sheet

 

[mjw4]

Another option for aftermarket radiators is PWR. I've check their site out and they have loads of options and I think they may also do custom dimensions.

I personally don't have experience with them, but @Rigster put one in his 76. So he'd have some info on quality and performance.

 

[coldtaco]

Another option for aftermarket radiators is PWR. I've check their site out and they have loads of options and I think they may also do custom dimensions.

I personally don't have experience with them, but @Rigster put one in his 76. So he'd have some info on quality and performance.

PWR sound like the one I have.

 

[pradoblivious]

I see cruiser parts sells a drop-in aluminum replacement for the lj78. Anybody have any experience with this rad? Anybody know if I can get a shround with fans with it? Aluminum Radiator LJ78 LJ77 LJ with Automatic Transmission [16400-54850-A] - $449.99 : CruiserParts, Toyota Land Cruiser Parts, Service & Restoration - https://shop.cruiserparts.net/index.php?main_page=product_info&products_id=78051

 

[AirheadNut]

I’ve got a similar radiator, only it’s the cheapest one I found on eBay a couple of years ago. Been fine so far, fitment wasn’t quite perfect where it mounted to the core support and I had to modify the mounting tabs but it has cooled just fine. I made my own custom fan shroud, currently working on modifying that to be a little lower profile since my new engine mounts about 2” further forward than the old one.

 

[BC40]

My guess is the temperature issues are a symptom of problems with the poor running and may be fueling or timing or turbo. Something was set wrong in the rebuild. You should not have trouble maintaining 40 mph as stated in the first post. Do you have an EGT gauge? What does it show? How about a boost gauge? A 13bt should not be putting that much heat to the cooling system at moderate speed and load. IMO

 

[pradoblivious]

My guess is the temperature issues are a symptom of problems with the poor running and may be fueling or timing or turbo. Something was set wrong in the rebuild. You should not have trouble maintaining 40 mph as stated in the first post. Do you have an EGT gauge? What does it show? How about a boost gauge? A 13bt should not be putting that much heat to the cooling system at moderate speed and load. IMO

build thread here I recently replaced the egt probe and moved it pre-turbo (pics in the link). From what I can tell, my egts read about what everybody else's do (too danm high). I have boost, oil pressure, and third-party water-temp gauges. I make about 8psi of boost wide-open. After 10 years, a swap, two engine rebuilds, turbo, ip, injector rebuilds and etc.. I think my power problems and rough-running issues are likely not to be found in the engine-bay. I'm pretty sure the a440f was a mistake on this motor. It just eats too much power and torque in the converter. Also I think my torque converter might be bad, and obstructing my idle. Except for the ENTIRE FRONT END which is all brand-spanking new now, the drivetrain is one of the very few systems I've ever had to dig into. I think this truck wants an h55, but as a married man, I am stuck with this trans for the moment. It would be a huge win if I could get the water temps down far enough to run the a/c compressor. Texas sucks hard without a/c

 

[Guyute]

build thread here I recently replaced the egt probe and moved it pre-turbo (pics in the link). From what I can tell, my egts read about what everybody else's do (too danm high). I have boost, oil pressure, and third-party water-temp gauges. I make about 8psi of boost wide-open. After 10 years, a swap, two engine rebuilds, turbo, ip, injector rebuilds and etc.. I think my power problems and rough-running issues are likely not to be found in the engine-bay. I'm pretty sure the a440f was a mistake on this motor. It just eats too much power and torque in the converter. Also I think my torque converter might be bad, and obstructing my idle. Except for the ENTIRE FRONT END which is all brand-spanking new now, the drivetrain is one of the very few systems I've ever had to dig into. I think this truck wants an h55, but as a married man, I am stuck with this trans for the moment. It would be a huge win if I could get the water temps down far enough to run the a/c compressor. Texas sucks hard without a/c

Little confused on the build thread link. So excuse me if this was addressed but, did you regear? The autos do rob power. Doing the Sumo 10% underdrive hi range gears definitely helped my use case (A442F, 33s... blah blah).

Not terribly expensive. Believe if you are just doing the hi range you don't need to clearance the case. Definitely need to machine it if you're doing the low range at the same time.

Gear Yumms (check part #'s for your rig).