Cummins 4BT & Diesel Conversions Forums banner

1 - 20 of 24 Posts

·
Registered
Joined
·
13 Posts
Discussion Starter #1
Hi guys I thought I would get a thread started for my build since I will be sourcing a 4bt mechanical at some point in the future and may need help. I am not after a ton of power but rather reliability being the key factor. This a common swap in a snowcat community and I am here to learn.

I have a YouTube channel with a vlog that has been going pretty steady for a few years with various builds starting with a built 2005 STI, a Mattracks Equipped and built 2005 BAJASTI, most recently a 1998 LMTV with a mechanical Cat 3116 (still in progress) and now moving into a Thiokol Spryte snowcat restomod from the ground up (complete teardown and rebuild).

I am terrible about keeping up with these threads but wanted to keep this bookmarked here so I can check in more so once I have the 4bt in my hands.

Thanks.
 

Attachments

·
Premium Member
Joined
·
29 Posts
Hello, and welcome to the forum though I'm a quite new myself. I checked out your youtube on this machine. Will be watching here for updates especially when you get to installing your 4BT. I will be interested in where you source it. The mechanical engines seem to be getting harder to find or perhaps I don't know where to look.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #3
Hello, and welcome to the forum though I'm a quite new myself. I checked out your youtube on this machine. Will be watching here for updates especially when you get to installing your 4BT. I will be interested in where you source it. The mechanical engines seem to be getting harder to find or perhaps I don't know where to look.
My little salesman has plenty of them. The shipping is what kills the deal on most of them though.
 

·
Registered
Joined
·
10,817 Posts
Welcome to the forum. You are seeking reliability and the 4bt can fit that ticket. Main thing is to make sure the engine is in good shape. The term "Good Used Engine" can often come back and bite you. Have seen minor rebuilds end up costing many thousands of dollars. Where you live snow appears to be readily available. LOL. You mention the Allison AT545. It is probably an OK transmission so long as you don't plan on high speed highway driving. It has no lockup torque converter and no OD gear. Typically found in vehicles that didn't go over 50-55 MPH. In the used Cummins world they are hard to even give away. You mentioned a source that had plenty of them. Haven't seen many such sources lately. Those engines haven't been built in the USA for about 15 years and most companies have scrapped the vans they were in. A lot of what we are seeing these days are the ISBe engines which are electronic, not the standard mechanical 4bt.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #5
Welcome to the forum. You are seeking reliability and the 4bt can fit that ticket. Main thing is to make sure the engine is in good shape. The term "Good Used Engine" can often come back and bite you. Have seen minor rebuilds end up costing many thousands of dollars. Where you live snow appears to be readily available. LOL. You mention the Allison AT545. It is probably an OK transmission so long as you don't plan on high speed highway driving. It has no lockup torque converter and no OD gear. Typically found in vehicles that didn't go over 50-55 MPH. In the used Cummins world they are hard to even give away. You mentioned a source that had plenty of them. Haven't seen many such sources lately. Those engines haven't been built in the USA for about 15 years and most companies have scrapped the vans they were in. A lot of what we are seeing these days are the ISBe engines which are electronic, not the standard mechanical 4bt.
I see lots of them for sale, rebuilt mostly. Time is on my side. My snowcat might go 12mph tops when it is complete (which is normal in the snowcat world).

I am not after speed. I am after reliability and this fits the ticket. Should be fun even if I have to build one myself LOL.
 

·
Registered
Joined
·
1,461 Posts
What kind of final drive would you be replacing? What engine would you be replacing? Would your final drive hold up to diesel torque? What are the ratios for 12 mph?

Ed
 

·
Super Moderator
Joined
·
8,682 Posts

·
Registered
Joined
·
13 Posts
Discussion Starter #8
What kind of final drive would you be replacing? What engine would you be replacing? Would your final drive hold up to diesel torque? What are the ratios for 12 mph?

Ed
These normally have a ford 300 industrial inline six and a 3 speed c6 behind them.

I will be using a 4bt allison at545 combo. The OC12 rear diff is more than capable of handling that type of torque since some of them are connected to 6bt engines.

Speed is not important to me. Others with this same combo run about 12 mph top speed. If I eliminate the drop boxes on the rear diff I might get 18 mph top speed. These machines were built for torque obviously.
 

·
Registered
Joined
·
10,817 Posts
Just remember the Cummins likes to operate in the 1600-2000 RPM range. Peak torque is in the 1700-1800 RPM area.The old 300 I6 was a great engine but it turns much higher RPM. Might need an OD transmission just to get to 12 MPH.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #10
Just remember the Cummins likes to operate in the 1600-2000 RPM range. Peak torque is in the 1700-1800 RPM area.The old 300 I6 was a great engine but it turns much higher RPM. Might need an OD transmission just to get to 12 MPH.
The 4bt and allison at545 is a proven combo with this differential for 12mph. 18mph if you eliminate the rear differential drop boxes. I will be happy with 10mph crawling through snow though...
 

·
Premium Member
Joined
·
1,783 Posts
I love Snocats !!!!!!!!!!!!!!!! I know where there is a Thiokol named "Eddie" which has been sitting in a Lemon Grove for about 10 years now after it came back from Antartica. I live near Port Hueneme Naval Base where everything that comes back from Antarctica comes thru. Alas it is in Socal so there isn't alot of snow available , so I have just left Eddie sit. I could probably get it for <$500, and it has a Ford Industrial 4 cyl Pinto motor in it.

I really Like Tucker Sno Cats and the old restored Bombardier Snowmobiles and this time of year when it is raining like it is today, I usually sit in front of the computer looking at pics of them. These are really cool machines and I wish you good luck on your builds. I like your Toyota ??? with the Mattracks !!!

The closest I will ever get is a set of Mattracks on the DeScrambler,,, maybe someday.

Randy
126747
126748
.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #12
I love Snocats !!!!!!!!!!!!!!!! I know where there is a Thiokol named "Eddie" which has been sitting in a Lemon Grove for about 10 years now after it came back from Antartica. I live near Port Hueneme Naval Base where everything that comes back from Antarctica comes thru. Alas it is in Socal so there isn't alot of snow available , so I have just left Eddie sit. I could probably get it for <$500, and it has a Ford Industrial 4 cyl Pinto motor in it.

I really Like Tucker Sno Cats and the old restored Bombardier Snowmobiles and this time of year when it is raining like it is today, I usually sit in front of the computer looking at pics of them. These are really cool machines and I wish you good luck on your builds. I like your Toyota ??? with the Mattracks !!!

The closest I will ever get is a set of Mattracks on the DeScrambler,,, maybe someday.

Randy View attachment 126747 View attachment 126748 .
Hi. I have never owned a toyota. I did however grow weary of the high priced 4bt motors I kept looking at. I came across an NPR frame cut for 300 bucks so I am going to be using that to repower this cat. Thanks for reminding me I have this thread up as I am terrible at updating them.

 

·
Premium Member
Joined
·
1,783 Posts
I was just going by the pictures you posted as far as what looked like a Toyota with Mattracks.

In 2003 I was in Moab and a Ford Pickup with Tracks drove by me, so I hunted them down, and it was the Mattracks guys. My Jeep had 3/4 ton axles so they were a direct bolt up to the ones on the Ford so we were good to go. Next day I ran the jeep into a wall and broke the engine mounts loose so I didn't get to mount the tracks on the Jeep.
I have been dreaming of doing it ever since.The pics you put up reminded me of that.

If you look at my build you will see a Built from Scratch Jeep Scrambler with a 4BT in it. It has the same axles that were in my earlier Jeep so they should just bolt right up to the Mattracks..

Nothing but the $15+K for the tracks and no snow standing in my way !
126756
 

·
Registered
Joined
·
13 Posts
Discussion Starter #14
I was just going by the pictures you posted as far as what looked like a Toyota with Mattracks.

In 2003 I was in Moab and a Ford Pickup with Tracks drove by me, so I hunted them down, and it was the Mattracks guys. My Jeep had 3/4 ton axles so they were a direct bolt up to the ones on the Ford so we were good to go. Next day I ran the jeep into a wall and broke the engine mounts loose so I didn't get to mount the tracks on the Jeep.
I have been dreaming of doing it ever since.The pics you put up reminded me of that.

If you look at my build you will see a Built from Scratch Jeep Scrambler with a 4BT in it. It has the same axles that were in my earlier Jeep so they should just bolt right up to the Mattracks..

Nothing but the $15+K for the tracks and no snow standing in my way ! View attachment 126756
Look again, not a Toyota. :D
 

·
Super Moderator
Joined
·
8,682 Posts
Hi. I have never owned a toyota. I did however grow weary of the high priced 4bt motors I kept looking at. I came across an NPR frame cut for 300 bucks so I am going to be using that to repower this cat. Thanks for reminding me I have this thread up as I am terrible at updating them.

The 4BD2 should do you nicely. They are a little less efficient than the 4BD1, a little quieter and generate a bit more heat (probably not a bad thing in a snow-cat). The injection pump has smaller plungers so you can't get as much power from them.

Main thing to check for is a cracked head. These are pretty tough but still IDI and that head can overheat and crack if it hasn't been looked after.

I'm not sure if anyone here has run a Jatco auto in a swap.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #16
The 4BD2 should do you nicely. They are a little less efficient than the 4BD1, a little quieter and generate a bit more heat (probably not a bad thing in a snow-cat). The injection pump has smaller plungers so you can't get as much power from them.

Main thing to check for is a cracked head. These are pretty tough but still IDI and that head can overheat and crack if it hasn't been looked after.

I'm not sure if anyone here has run a Jatco auto in a swap.
Where do they normally crack at? That might be the case with this one since it has massive blowby. The motor rotates nicely and has good compression that I can feel as I rotate it and listen to the air being compressed in the cylinders.

I am hoping it is something simple where i do not have to rebuild the bottom end. That would be the best case scenario. Worst, I have to buy a head and a rebuild kit. No big deal either way since I got this frame cut for an AT545 and 300 bucks. :D

I have not torn it apart yet but am curious what the wiring is for? Looks like sensors to me. These being mechanical with no ecu I am sure I can get rid of a lot of the things including the power steering pump that will be useless to me. This will be interesting for sure.
 

·
Super Moderator
Joined
·
8,682 Posts
Where do they normally crack at? That might be the case with this one since it has massive blowby. The motor rotates nicely and has good compression that I can feel as I rotate it and listen to the air being compressed in the cylinders.

I am hoping it is something simple where i do not have to rebuild the bottom end. That would be the best case scenario. Worst, I have to buy a head and a rebuild kit. No big deal either way since I got this frame cut for an AT545 and 300 bucks. :D

I have not torn it apart yet but am curious what the wiring is for? Looks like sensors to me. These being mechanical with no ecu I am sure I can get rid of a lot of the things including the power steering pump that will be useless to me. This will be interesting for sure.
Normal place for cracks is in the head between the valves. There's a cooling passage there and leaks into that show up as a pressurised cooling system. Blowby on these engines is usually more than you expect (decent ring gaps from the factory) but too much means check the cylinders. Beware cheap rebuild kits, factory Isuzu is best and if you can reuse the pistons and liners then do so as they are graded for size (big difference in noise and blowby).

The IDI also means these engines can rev more. Which may help you out. ECU wise I think they had a glow plug controller and an overheat protection system which reduced fuel through I think an altitude compensator.

Several people here have cut up box trucks for the 4BD engines. Someone may have a Jatco controller kicking around or know where to find one.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #18
Normal place for cracks is in the head between the valves. There's a cooling passage there and leaks into that show up as a pressurised cooling system. Blowby on these engines is usually more than you expect (decent ring gaps from the factory) but too much means check the cylinders. Beware cheap rebuild kits, factory Isuzu is best and if you can reuse the pistons and liners then do so as they are graded for size (big difference in noise and blowby).

The IDI also means these engines can rev more. Which may help you out. ECU wise I think they had a glow plug controller and an overheat protection system which reduced fuel through I think an altitude compensator.

Several people here have cut up box trucks for the 4BD engines. Someone may have a Jatco controller kicking around or know where to find one.
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....
 

·
Registered
Joined
·
13 Posts
Discussion Starter #19
Normal place for cracks is in the head between the valves. There's a cooling passage there and leaks into that show up as a pressurised cooling system. Blowby on these engines is usually more than you expect (decent ring gaps from the factory) but too much means check the cylinders. Beware cheap rebuild kits, factory Isuzu is best and if you can reuse the pistons and liners then do so as they are graded for size (big difference in noise and blowby).

The IDI also means these engines can rev more. Which may help you out. ECU wise I think they had a glow plug controller and an overheat protection system which reduced fuel through I think an altitude compensator.

Several people here have cut up box trucks for the 4BD engines. Someone may have a Jatco controller kicking around or know where to find one.
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.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #20
Normal place for cracks is in the head between the valves. There's a cooling passage there and leaks into that show up as a pressurised cooling system. Blowby on these engines is usually more than you expect (decent ring gaps from the factory) but too much means check the cylinders. Beware cheap rebuild kits, factory Isuzu is best and if you can reuse the pistons and liners then do so as they are graded for size (big difference in noise and blowby).

The IDI also means these engines can rev more. Which may help you out. ECU wise I think they had a glow plug controller and an overheat protection system which reduced fuel through I think an altitude compensator.

Several people here have cut up box trucks for the 4BD engines. Someone may have a Jatco controller kicking around or know where to find one.
Also, when searching I keep seeing grade 1x or 3x liners. I am guessing that designates some sort of tolerance sizing??
 
1 - 20 of 24 Posts
Top