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Thanks for the tips. How do you feel about a hone and rering using the existing cylinder liners??? I am just going out on a limb before teardown and thinking the rings are shot. I found an aftermarket controller I am going to "tinker with" to see if I can get the jatco to work without the factory ecu. I will cover all of this when the time is right in my vlog of course.

I appreciate your responses....
On a sidenote: Do you have a link to a master rebuild kit for these engines that you have used and recommend?? I see the ebay kits but I don't think they are genuine.
Also, when searching I keep seeing grade 1x or 3x liners. I am guessing that designates some sort of tolerance sizing??
If the existing liners are good then I would absolutley hone and reuse them. For parts go straight to an Isuzu or GM truck dealer. There are some online Isuzu truck parts sellers. Do not shag around with any of the ebay kits. The liners and pistons are graded into kits with 4 sizes based on the bore size in the block. If the engine hasn't been monkeyed with then there should be markings on the block deck to say what grade was factory installed. If the engine has been rebuilt then they'll likely be gone but you can measure the bores to confirm.

Have a dig through my recent post history for Isuzu 4BD1T liner tolerance games. The 4BD2T uses different pistons but the same liners and rings.
 

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Discussion Starter · #22 ·
If the existing liners are good then I would absolutley hone and reuse them. For parts go straight to an Isuzu or GM truck dealer. There are some online Isuzu truck parts sellers. Do not shag around with any of the ebay kits. The liners and pistons are graded into kits with 4 sizes based on the bore size in the block. If the engine hasn't been monkeyed with then there should be markings on the block deck to say what grade was factory installed. If the engine has been rebuilt then they'll likely be gone but you can measure the bores to confirm.

Have a dig through my recent post history for Isuzu 4BD1T liner tolerance games. The 4BD2T uses different pistons but the same liners and rings.
I am terrible at finding things on these boards. Do you have a link to that post. I am willing to learn I just need a bit of direction on this platform.
 

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Discussion Starter · #23 ·
If the existing liners are good then I would absolutley hone and reuse them. For parts go straight to an Isuzu or GM truck dealer. There are some online Isuzu truck parts sellers. Do not shag around with any of the ebay kits. The liners and pistons are graded into kits with 4 sizes based on the bore size in the block. If the engine hasn't been monkeyed with then there should be markings on the block deck to say what grade was factory installed. If the engine has been rebuilt then they'll likely be gone but you can measure the bores to confirm.

Have a dig through my recent post history for Isuzu 4BD1T liner tolerance games. The 4BD2T uses different pistons but the same liners and rings.
Btw, thanks for your help. i was wondering if I could just hone and rering these types of motors. I guess we will find out what is going on inside the motor once I tear it down. I just finished up the frame today. I appreciate your patience and help.
 

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Really nice progress.. I admire your drive, organization and follow-through. Great team work too! I think I have too many projects or take on too many things but after seeing what you have going on I think I am just lazy- and you video a lot of these projects!!!
I think the Isuzu will be a good fit. The IDI (if I'm not mistaken) should make for a bit quieter ride.
 

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Discussion Starter · #25 ·
Is anyone still here? Well I had enough time off during the pandemic to work on and finish this project. I even had time to build a trailer for this 7500 pound tank.... Now I am at the point where I have some questions for those of you familiar with the isuzu 4bd2t engines.

So for the motor rebuild I tore it down and found a cracked piston ring which was the reason for the blowby on the motor. The liner had minor scratches in it and the liners were all glazed so I decided to ball hone the liners, rering the pistons, and rebuild the motor with all new gaskets. I also replaced the worn main bearings and inspected the rod bearings which appeared to be in great condition and fell within the specs of the tech manual so I opted to reuse them in the build.

The head and valvetrain were also in great shape with no cracks. I replaced the valve seals and decked the head using a hand lapping technique I have had great success with on over 7 Subaru motors (no more blown head gaskets).

This motor has a tremendous amount of power and torque. I am getting fantastic oil pressure. The rings seated nicely after a 3-4 hour motor break in driving around in a field. I have no oil burning or blow by and the break in oil dump had the normal amount of fuzz/shimmer in it that I can tell (no big metal chunks).So now I am at the point of tweaking and tuning. I have been watching videos on YouTube of 4bd motors and noticed they all have a similar noise on camera but in person they sound different (less dramatic and clackity). Take this video for example
and compare the motor sounds to mine
Now on camera for some reason they sound so loud and ticky and in person they sound normal to me with a slight ticking.

This lead me to read this thread Ticking Noise source and makes me think I should tinker a bit more with valve adjustment. I will be tackling that today. Maybe I am just being paranoid but I do not want a catastrophic failure in the middle of nowhere.

I am also curious about what appears to be a giant heater threaded into the intake?? What are those used for?? I left mine disconnected. I am going to be making a cold air intake today and I am wondering if I should skip that because of this intake heater I am seeing??

Any thoughts, elbow jabs, patronizing, or other comments are gladly welcome. :) This platform is new to me and I had to learn about it fast through self education, this forum, and advice from others so forgive me if I do not understand all aspects of this motor yet...

Pics for attention of course....

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Your 'heater' in the intake might be a heater for starting in cold weather, injects raw fuel in intake manifold and ignites it with spark plug.

Ed in CO.
 

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Discussion Starter · #29 ·
Your 'heater' in the intake might be a heater for starting in cold weather, injects raw fuel in intake manifold and ignites it with spark plug.

Ed in CO.
I applied 12v to it and it gets hot like a burner on a stove so I am not sure what it is supposed to do. I have glow plugs and a hydronic diesel heater plumbed into the engine block and heaters in the cab so I have cold weather starting covered. Run the hydronic heater for 15 minutes and I don't even need to use the glow plugs...
 

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I think what you're calling a 'heater' in the intake is a voltage dropping resistor-to reduce the voltage to the glow plugs to keep them on during engine warm up. It was powered by a relay that was commanded on by the ecm in the Isuzu trucks. A side effect of that resistor is a lot of heat-so they put it in the intake to further help with warmup. I use mine; I have a toggle switch to control the relay. It does help the engine run smoother when cold. I usually only keep it on for a minute or so. Hope that helps. Joe.
 

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Discussion Starter · #31 ·
I think what you're calling a 'heater' in the intake is a voltage dropping resistor-to reduce the voltage to the glow plugs to keep them on during engine warm up. It was powered by a relay that was commanded on by the ecm in the Isuzu trucks. A side effect of that resistor is a lot of heat-so they put it in the intake to further help with warmup. I use mine; I have a toggle switch to control the relay. It does help the engine run smoother when cold. I usually only keep it on for a minute or so. Hope that helps. Joe.
That makes total sense. I have it disconnected right now because the motor has bare bone for electronics. I do have the glow plugs connected to a timer though so I guess that helps. This motor fires up really nicely with the new piston rings and the liners deglazed...
 

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Pretty cool piece of machinery. I have always been curious, how fast will it go?

Randy
 

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Discussion Starter · #33 ·
Pretty cool piece of machinery. I have always been curious, how fast will it go?

Randy
Hi Randy. Thank you! Building him was a tremendous amount of work solo. I am not quite sure. We have only had 1 driving session in an open muddy field. We did get up to 20 mph about halfway through 3rd gear with the transmission in NORMAL mode. Someone in the snowcat forums did some calculations and they think I will hit 40 on packed snow flat out with no incline/decline in 4th gear with OVERDRIVE mode on. I have my doubts. I am thinking it will be a really harsh scary ride at that speed. I am not sure rock quarry belts were designed for those speeds either.

Once we get a bit of snow, even if it is a few inches to places we normally frequent I can get back to this post with some actual data. The driving we did do was just to get the feel, make some adjustments, and break in the motor/seat the piston rings. I do know the acceleration is pretty dramatic surprisingly.

Here is the link to the first episode of the new series we have started for the entire winter setup.
 

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I think what you're calling a 'heater' in the intake is a voltage dropping resistor-to reduce the voltage to the glow plugs to keep them on during engine warm up. It was powered by a relay that was commanded on by the ecm in the Isuzu trucks. A side effect of that resistor is a lot of heat-so they put it in the intake to further help with warmup. I use mine; I have a toggle switch to control the relay. It does help the engine run smoother when cold. I usually only keep it on for a minute or so. Hope that helps. Joe.
I don't have that on my 4BD1T, but I think it's called QOS or something similar on the 4BD2. My 4BD1T has normal glow-plugs which I've never bothered to hook up but an IDI in the snow you'll definitely want them.

I had a blizzard come through this time last week. It was crazy seeing snow this low this late in the spring. We'd had nothing down low all winter.
 

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Discussion Starter · #37 ·
I don't have that on my 4BD1T, but I think it's called QOS or something similar on the 4BD2. My 4BD1T has normal glow-plugs which I've never bothered to hook up but an IDI in the snow you'll definitely want them.

I had a blizzard come through this time last week. It was crazy seeing snow this low this late in the spring. We'd had nothing down low all winter.
Yeah I have the glow plugs hooked up and also have a hydronic diesel heater plumbed through the coolant lines on the engine and the heat radiators in the cab...
 

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Discussion Starter · #38 ·
I forgot I made this thread but wanted to update it with this years snowcat trip that turned out really well.

4bd2t just ticking along and having some fun.... I did install a transgo shift kit at the end of last season and rebuilt the 250k mile jatco jr403e transmission since it blew the planetaries at the alpine snowcat jamboree last winter....

I have a few things I want to fix like a pesky pinion seal leak that will require a speedi seal since the surface of the pinion is pitted...

A constant amount of upkeep but really really fun to drive as you can see from my latest vlog....

 
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