12ht Rebuild, just about finished -couple questions?

[watrob]

Hi all, couple questions for the experts:-


I have just about finished a rebuild of a 12ht which came out of a 60's coupled to automatic transmission.


It's going into my FJ40 which currently has a 2H with a manual gearbox and with the matching wiring loom to suit the 2H (I did the 2H install a few years back)


Questions are,


Is the 2h manual transmission flywheel the same as a manual 12ht flywheel? as I cannot use the 12ht automatic flywheel.


Can I fit the EDIC motor from the 2H ip to the ip pump of the 12ht


The 2H uses glow plugs and the 12ht uses a heat screen, question is, the glow plug relay timer on the 2H wiring loom, can it be use on the heat screen, its the same voltage and timer would be the same time in duration length I would guess.


Thanks

 

[niffa]

Im not an expert mate and I cant tell u if the 2h glow setup will work on 12ht but my 12ht doesn't even have the glow screen plugged in. Im in South Australia so it really doesn't get cold enough to need it. It fires up so fast even in winter. If u get sub zero winters then u need it, depends where u are

 

[watrob]

Im not an expert mate and I cant tell u if the 2h glow setup will work on 12ht but my 12ht doesn't even have the glow screen plugged in. Im in South Australia so it really doesn't get cold enough to need it. It fires up so fast even in winter. If u get sub zero winters then u need it, depends where u are

HI,


The glow on the 2H works when you turn the key on, it will auto run the glow cycle for around 5 sec, then turn the key one step further and cranks the starter motor. When the engine it warm you turn the key straight to start.


What I am wondering is can I connect this electrical cable to the glow screen of the 12ht and would it give the glow screen a 5 sec heat if required?


I suppose it comes down to what is the length of time does the glow screen run for compared to the glow plug timer on a 2H?

 

[niffa]

All I know is the glow screen wont even fire up till its zero degrees. Dont know how or why but heard it from lots of different ppl.

 

[niffa]

Cant hurt to try. Well maybe it can, again im by no means an expert take the crossover pipe off and plug it in get someone else to turn the key while you look at the glow screen to see if it heats up. Again tho the 12ht doesn't need glow to start. Before I had my engine rebuilt it was completely stock with 500,000klm on clock I had it for two years and never once saw the glow light come on the dash and it was hooked up then. Since rebuild I never bothered to hook it back up. Motor turns half a turn and its idling. Never known a diesel to fire up quicker than the 12ht. Love it. By the way got any pics of ur build pre and post build?

 

[watrob]

The problem I have is 2H wiring loom, the glow timer turns on when the ignition key is turned to ON, the glow light comes on turns off after about 5 secs, then you turn the key one more time crank the starter motor.


If you turn the key straight to crank it by-passes the glow, if I don't connect the wire to the glow system I think it does not forward power to the start relay and engine management box (which is very basic anyway), its sort of closed loop starting system.


Suppose it comes down to whether the glow screen can handle a 5 sec heat which would occur if I just turned the key to the ON position without actually starting the motor, this would happen when the engine is cold only as there is temp relay sensor in wiring I think?

 

[niffa]

Hook it up that way it'll have power to start relay. I spose u can just crank the engine straight away and not glow it. once winter hits u have glow available if u need it. Still don't know if it'll work but

 

[niffa]

12ht doesn't have any engine management or edic like the 2h

 

[watrob]

I know that 12ht does not have an Edic, but it does have a similar management box that controls things like engine cut on low oil pressure, checks timing of glow cycle and few basic things. Its does not have and neither does the 2H have a proper management system, but they do have a small box that checks the start relay, timer relay, glow plug relay etc.


I have read (some where) that you can add a edic which shuts off the fuel so the your 2H wire system will work properly with a 12ht.


You also have to use the oil pressure sensor from the 2H block on the 12htm because if this management box does not get a pressure reading it thinks the engine has lost oil pressure a makes the Edic turn the fuel off.


The edic was introduced because if vehicle with a 2H in it rolled backwards the engine would try to run in reverse.

 

[roscoFJ73]

The 12HT with its direct injection will rarely ,if ever, need to be glowed in your climate.
My 12HT would fire and run smooth within a second of hitting the starter in Perth.
I didn't even know the glow system wasn't working until an auto sparkie pointed it out to me when he was doing some other work.

 

[watrob]

The 12HT with its direct injection will rarely ,if ever, need to be glowed in your climate.
My 12HT would fire and run smooth within a second of hitting the starter in Perth.
I didn't even know the glow system wasn't working until an auto sparkie pointed it out to me when he was doing some other work.

Thanks,


But my question is will the 2H wire system that has timer connected to the grow plug system also work if I connect it to the glow screen system of a 12ht?

 

[blis]

Thanks,


But my question is will the 2H wire system that has timer connected to the grow plug system also work if I connect it to the glow screen system of a 12ht?

I doubt that... glowplugs are way different from 2-stage heater screen...

Also, the edic cannot be hooked to the 12ht becouse edic is mechanical while 12ht uses vacuum for shutting/ac-up/idle-up

 

[DanS HJ-45]

These guys are right:

There's no EDIC, or possibility of connecting the EDIC to the 12HT. The 12HT is managed via a vacuum idle up, and a vacuum shutoff. That's it. It doesn't include a low oil pressure sensor to shut off the engine.

The EDIC is pretty simple, but the EDIC relay does more than send just an "on/off" signal to the EDIC motor, which is why you can't use it for the vacuum shutoff VSV int he 12HT. One way or the other, you will be modifying the wiring. I'd personally take the IGN wire into the EDIC relay and tap into that for the shutoff VSV. Very simple, and keeps the shutoff VSV on the same fuse as the EDIC would have been.

On the other questions: the 12HT and 2H use the same flywheel.

On the glow screen: you could wire the power to the 2H glow bus bar to the 12HT glow screen, and I'd imagine it would work. The factory wiring for a 12HT glow system is for a large black wire to come pretty much straight from the battery, to each of the glow screen relays. From the two relays, the wires merge back into one wire, which is connected to the post on the glow screen itself. The only "magic" is the control of the 2 relays (which is done by the glow timer). But if you have none of that, apply 12V to the glow screen and it should glow for you--which, as has been pointed out, is not normally required.

Dan

 

[watrob]

These guys are right:

There's no EDIC, or possibility of connecting the EDIC to the 12HT. The 12HT is managed via a vacuum idle up, and a vacuum shutoff. That's it. It doesn't include a low oil pressure sensor to shut off the engine.

The EDIC is pretty simple, but the EDIC relay does more than send just an "on/off" signal to the EDIC motor, which is why you can't use it for the vacuum shutoff VSV int he 12HT. One way or the other, you will be modifying the wiring. I'd personally take the IGN wire into the EDIC relay and tap into that for the shutoff VSV. Very simple, and keeps the shutoff VSV on the same fuse as the EDIC would have been.

On the other questions: the 12HT and 2H use the same flywheel.

On the glow screen: you could wire the power to the 2H glow bus bar to the 12HT glow screen, and I'd imagine it would work. The factory wiring for a 12HT glow system is for a large black wire to come pretty much straight from the battery, to each of the glow screen relays. From the two relays, the wires merge back into one wire, which is connected to the post on the glow screen itself. The only "magic" is the control of the 2 relays (which is done by the glow timer). But if you have none of that, apply 12V to the glow screen and it should glow for you--which, as has been pointed out, is not normally required.

Dan

Hi Dan, with my current 2H I do have the glow plug timer & relay systems installed (I have a OEM wiring loom from a hj47 that had a factory 2H installed which is already running now in my FJ40). Voltage & amp wise should be ok, so if I connect the wire that goes to the glow plug rail on the 2H to the glow screen on the 12ht it should work?


Flywheel sorted as I can use a 2H one.


Is the backing plate the manual bell housing attaches too the same as the one used by the auto transmission?


Now, if I install the low pressure oil sensor from the 2H to 12ht (which I believe can be done) which works that if it sensors low oil pressure by making the Edic motor lever the manual shut off valve on the IP to shut off. The Edic also does this when the ignition is turn off (the same thing as the low oil pressure, it pushes the manual IP lever to shut off). I could send that signal to the switch that operates the vacuum shut off so the butterfly in the inlet manifold, so:-


1. Low oil pressure close the butterfly shuts down the engine.
2. Closes the butterfly when the ignition is turned off shuts down engine.


Your thoughts on this?


Another problem I need to solve is on a 2H the IP manual shut off lever, the edic on start up I believe actually pulls the lever passed the run position for a moment before returning to the run position, I have been told this is like a choke or extra fuel injected, can you confirm this?


And the final pieces to solve are:-


I don't need the auto transmission kick down and vacuum pipes as I have a manual transmission - there gone.


Don't need the idle up vacuum pipes as I have a sports tube - no air-con, there gone.


Now I need the vacuum pipes & switch for the shut off butterfly in the intake manifold - kept


That leaves me with two vacuum pipes going into the IP near the throttle cable butterfly, what do they do?


And there is a sensor/vacuum switch just to the right of the oil sensor which has two vacuum pipes going to it, what do they do. I have a feeling that this needs to be removed and this is where I place the low pressure switch from the 2H?


Finally, can I remove the two vacuum pipes from the variable power steering pump? or are these interconnected to the two vacuum pipes going to the IP beside the throttle cable, does this do idle up when extra pressure is exerted by the steering pump requiring idle up?


Ok, I think that enough for now, my head hurts!!!!!!!

 

[blis]

I believe the 2 pipes goings to IP are for boost compensator, other one should provide manifold pressure and the other i'm assuming should go to free air...

 

[watrob]

Found a photo showing the following. Have read the FSM, but having trouble finding what the sensor on the right of the oil pressure sensor is and also the switch sensor that has the two vacuum pipes attached?

 

[DanS HJ-45]

Hi Dan, with my current 2H I do have the glow plug timer & relay systems installed (I have a OEM wiring loom from a hj47 that had a factory 2H installed which is already running now in my FJ40). Voltage & amp wise should be ok, so if I connect the wire that goes to the glow plug rail on the 2H to the glow screen on the 12ht it should work?

I believe so. The glow screen won't need to be used much at all, so the GP setup from the HJ-47 should be more robust than the glow screens will require.

I think.

Is the backing plate the manual bell housing attaches too the same as the one used by the auto transmission?

No idea, but I'd be willing to bet that they are different.

Now, if I install the low pressure oil sensor from the 2H to 12ht (which I believe can be done) which works that if it sensors low oil pressure by making the Edic motor lever the manual shut off valve on the IP to shut off. The Edic also does this when the ignition is turn off (the same thing as the low oil pressure, it pushes the manual IP lever to shut off). I could send that signal to the switch that operates the vacuum shut off so the butterfly in the inlet manifold, so:-


1. Low oil pressure close the butterfly shuts down the engine.
2. Closes the butterfly when the ignition is turned off shuts down engine.


Your thoughts on this?

I've given this a good deal of thought, because one of the features I like best about the 3B/2H/EDIC system is the low oil pressure shutoff--and I wish I could do the same on future projects (specifically 1HZs, which are similar to the 12HT in that there's a simple on/off wire that controls either the fuel cutoff, or the vacuum shutoff).

You can't simply wire it up that way. You'd need some sort of logic box to make it work well. When the engine is stopped, the oil pressure is 0. So, it would prevent the engine from actually starting until the oil pressure rose, which can take a good amount of time sometimes. The EDIC system deals with this by having a timer, so for some period of time, after you select the start position, the EDIC ignores the low oil pressure shutdown signal from the oil pressure switch. You'd need to build or acquire a "logic box" that would work along those same principles. The 3 wire connection between the EDIC relay and EDIC motor doesn't ever make an "off signal" that easily equates to a simple on/off wire. It is controlling combinations of those 3 wires to command the EDIC motor to move to the various positions--which is why you can't readily use the EDIC relay to control a 12HT (or 1HZ, etc...)

Another problem I need to solve is on a 2H the IP manual shut off lever, the edic on start up I believe actually pulls the lever passed the run position for a moment before returning to the run position, I have been told this is like a choke or extra fuel injected, can you confirm this?

Yes, the positions that the EDIC motor will command are OFF, RUN and OVERINJECT. But none of that matters for a 12HT. The 12HT doesn't require, nor desire over inject to start.

Don't need the idle up vacuum pipes as I have a sports tube - no air-con, there gone.

Not so fast there. See below.

And there is a sensor/vacuum switch just to the right of the oil sensor which has two vacuum pipes going to it, what do they do. I have a feeling that this needs to be removed and this is where I place the low pressure switch from the 2H?


Finally, can I remove the two vacuum pipes from the variable power steering pump? or are these interconnected to the two vacuum pipes going to the IP beside the throttle cable, does this do idle up when extra pressure is exerted by the steering pump requiring idle up?

This is all related. the Power Steering controls an idle up vacuum system. It's set up so that you can't stall the engine at very low RPM from the Power Steering. I wouldn't remove that system if I were you. It seems pretty smooth and transparent on ours, and with as touchy as the 12HT is at low RPM, its nice to have it give it the bump rather than trying to do so with your foot. But, if you don't care about the idle up system (which from the factory is actuated by AC or PS--and obviously you'd just have PS), then you could remove it entirely.

Found a photo showing the following. Have read the FSM, but having trouble finding what the sensor on the right of the oil pressure sensor is and also the switch sensor that has the two vacuum pipes attached?

The plug to the right of the oil pressure sender (the green one) is the coolant temp sensor for the glow timer system.

To the right of that (with the vac hoses) is part of the idle up system. (discussed above)

Dan

 

[watrob]

Hi Dan,


Ok, I can use the Green coolant temp sensor on the 12ht in the same way that the 2H has the same sensor but situated up onto of the head above the first piston between glow plug & injector on the 2H, that solves that problem.


I can leave the switch/sensor with two vacuums tubes intact.


Now below the oil pressure sensor about 6 inches to the left on the block the 2H has a oil pressure sensor for edic shut off on start and or low pressure to shut off the engine, I am hoping that when I check that the same hole is there on the 12ht?


So that now leave me to sort out the 3 wires to edic motor, if the first wire makes the edic activate to over inject until such time the oil pressure comes up then the second wire pushes the edic to the run position and the third to off.


Now I need to measure if any of these three wires has a 12volt constant supply when the ignition is in the on position and when the ignition is turned off so are the 12 vots, I can then connect that to the SVS (which opens the butterfly in the inlet manifold) ?

I have attached a photo of the oil pressure sensor for the edic control on 2H, just need to check if the 12ht has bolt in this position?
Robert

 

[DanS HJ-45]

Now below the oil pressure sensor about 6 inches to the left on the block the 2H has a oil pressure sensor for edic shut off on start and or low pressure to shut off the engine, I am hoping that when I check that the same hole is there on the 12ht?

I believe so. Ours seems to have that hole (with a plug in it).

So that now leave me to sort out the 3 wires to edic motor, if the first wire makes the edic activate to over inject until such time the oil pressure comes up then the second wire pushes the edic to the run position and the third to off.

Nope. I'm not communicating clearly or something. The EDIC motor doesn't work like that. If you apply 12V power to the EDIC motor, it will continually run. Here's a simple explanation: The EDIC relay applies power to two of the three wires. Depending on which two wires that is, the EDIC motor will move to the position commanded. Once that happens, the wiring is such that it then shuts off the EDIC motor. So it's not constantly running.

Does that make any more sense? You could make your EDIC motor control a toggle switch, which would then be switched on and off by the EDIC motor arm, but otherwise the wiring is simply very different then what you need for the vacuum shutoff VSV.

Now I need to measure if any of these three wires has a 12volt constant supply when the ignition is in the on position and when the ignition is turned off so are the 12 vots, I can then connect that to the SVS (which opens the butterfly in the inlet manifold) ?

Again, no--it doesn't work that way. Constant 12V will just make the EDIC motor run, and run, and run....

And the vacuum shutoff actuator is in the "run" position, UNLESS you apply vacuum to it. That said, the VSV is such that when power is applied to it, the vacuum is routed to the atmosphere under the hood. So, when you turn the key off, the VSV switches and routes vacuum to the shutoff actuator.

Dan

 

[watrob]

Hi Dan,


Attached is a photo of a 12ht, I am lucky, your right I can install the oil pressure from the 2H into it as it has a plug installed, that solves that problem.


I thought the VSV worked that when power was applied the switch allowed vacuum to the actuator which then pulled the butterfly open, when power is cut the butterfly closed.


I understand the edic thing, there is no constant power on any of the three once they time thru cycles, over inject, run & stop.


Now I am still a little confused by your last paragraph, are you saying this:-


Your saying that vacuum is being vented to the atmosphere all the time your driving around while theirs power on the VSV switch, when you turn the key off the switch then closes and routes the vacuum to the shutoff actuator which pulls closed the butterfly.

After spending most of my life chasing vacuum leaks why are we venting why driving around? This is the part I cannot get my head around? I get the applying vacuum to the shutoff butterfly, so where does this vent pipe go - to the air intake filter.

I am missing something, when you say venting your meaning air is being expelled right?