12HT swap (1 Viewer)

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Joined
May 20, 2011
Threads
2
Messages
20
Location
Spain
Hello all

I am doing a 12HT swap into my BJ73.

I am replacing my 50000 kms-since -rebuilt trbo 3B because it is impossible to make it roadworthy here in Spain. Simply too expensive

So, after plenty of thought and Mud reading, I decided to go this way.
So I got an engine from a Mud fellow and now the car is at the shop; 3B has been removed.

20210414_162051.jpg



Here is the 12HT, still in the box. The engine is 340,000 km and has good compression according to the provided videos.


20210325_181002 (1).jpg


Also waiting for the brackets that go beneath the isolators and the frame. BTW, using new isolators, front and rear:

Mounts.png


So now next step would be installing the primary gear, and then setting the engine.
This means brackets will have to be fabricated and welded to the frame.

A few links from Mud where I have found very inspiring information on how the engine should mount:
HELP!! 12HT into HJ60 2H Chassis mounting - https://forum.ih8mud.com/threads/help-12ht-into-hj60-2h-chassis-mounting.1209674/
Build: 2H swap to 1HZ w/turbo in HJ75 Troopy - https://forum.ih8mud.com/threads/build-2h-swap-to-1hz-w-turbo-in-hj75-troopy.1226400/post-13722613 (thanks RhinoRig for your advice)
12ht CONVERSION - https://forum.ih8mud.com/threads/12ht-conversion.236737/
Builds - Billy's excellent FJ73-12HT - resto-modded - n that - https://forum.ih8mud.com/threads/billys-excellent-fj73-12ht-resto-modded-n-that.863291/page-5 (thanks Billyfj7312ht for your advice)
Builds - HJ75 Pick up - https://forum.ih8mud.com/threads/hj75-pick-up.847746



My best choice would be fabricating two brackets just like the one's that can be barely seen in these two images:, attached to the lastest mentioned thread.

https://forum.ih8mud.com/attachments/image-jpeg.1246265/

https://forum.ih8mud.com/attachments/image-jpeg.1246917/

I tried to get these brackets from Toyota to no avail: out of production.

I wonder if ANY HJ75 owner could post pictures of where the brackets are welded to the frame. Just to kave a look of their size and exact point where they should be,.
This would save me lots of work and cost.

I will be updating this thread with the ongoing progress.

I hope this can be of help to other owners wishing to put this engine into a 70 series.

Any advice or information on how to perform this swap will be welcome.

Thanks to all!

Marcos
 
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Hi Marcos,

You have same problem as I had with my BJ75. I solved it few weeks ago like this, see post #245 and please use the translator from finnish to english: https://forums.offipalsta.com/showthread.php?t=159385&page=10

I used some good pictures as a model from this topic ( thanks "coldtaco" ;)): Builds - AK HJ-75 - https://forum.ih8mud.com/threads/ak-hj-75.930702/page-31

My whole BJ75 story: BJ75 SA-1084 - Offipalsta.COM - https://forums.offipalsta.com/showthread.php?t=159385

Hi Jul. Thank you very much!.
This really helps.
Also thanks to ColdTaco for posting his build.

Subscribed to both.
 
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Sure wish I had seen some frame pics like @coldtaco s for the 1HZ. Here are my old brackets that I mutilated to fit the new engine. Not enough metal left, so I made new ones. The angled spacers must have some engineering purpose (like making it more complicated) but it befuddles me as an engineer. Paper towel roll backdrop for clarity 😉
117E6EEB-E141-4997-8447-38FE2B35D276.jpeg
C64BE9C1-A46B-490D-8C99-E1D94EFF5B87.jpeg
6835AA7A-A521-4444-A2C2-2387C549F9EE.jpeg
0780076B-914D-4416-8002-58921234194F.jpeg
 
When I put a HD into a LJ I bought new frame side engine mounts and welded those in.
Yes, that is the first thing I tried.

1619624360336.png


Part numbers 51422-60091 and 51421-60091 are out of production.

Thanks.
 
Updating progress.
I really hope this can help anyone that decides to makes this swap.

Gearbox with 12HT input installed. New OEM isolator inslalled

H55F.jpg


Right side engine bracket mock-up using 3B's. With a little more trimming it will fit perfectly. Engine isolators are brand new OEM too.

RS3BBracket.jpg



Left side, still pending. Will need to set the engine slightly to the right side.

LHBracketPending.jpg


Front view. Chain has no tension, just for safety.

FrontView.jpg


And finally, hood clearance. I told the mechanic to try to get a few extra mm. However I guess it will increase once frame is supporting engine's weight.

HoodClerarance.jpg


Using 3B engine brackets is going to save losts of time.

Will soon see how it fits.

Regards.
 
Hi. New pics on the swap.
Engine mounts from 3B not yet welded, just to show where they are located.
20210607_110934.jpg

20210607_110919.jpg



20210607_110803.jpg

20210607_110817.jpg
 
Update on this build
Long story short, the engine is in and it runs smoothly. Starts at the first turn and makes little smoke.
The most challenging issue was finding the spot for the engine mounts.
As for the engine mounts themselves, we adapted the ones for the 3B but switching sides. After a little trimming they fitted nicely.
Here are some pictures of the result
Top view

20230108_115531.jpg


VSV wiring

20230108_115551.jpg

Compressor housing and steering bar


20230108_115620.jpg

Right side engine mount view

20230108_115648.jpg

Accelerator cable

20230108_115740.jpg



However, we are having an issue with the engine: It randomly cuts off, as if the VSV allowed vaccum to pass the actuator. The VSV is brand new from dealer.
It just cuts off, and then when you try to start, it cranks, takes a spin and then stops. It happens at low engine speeds, as in a sharp turn or a stop.
After a while it will start again, but with a big cloud of smoke.
I have also noticed that with engine off, if I cycle the key between the on and off position (without starting), the vaccuum last only a couple of cycles. After that, there will be no vaccum in the system.

Does the VSV require >= 24 volts to work? I checked the voltage and it only gets around 19

I am not familiar with this engine and its vacuum circuit. I do not know if this is normal.

Regards
 
Last edited:
Problem solved!! Wrong wire.
Tapped a line from ignition switch and now it works as expected
Also replaced front brakes and hoses. Much better now.
 

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