Cat 3126 any good??

madhat · 01-06-2019, 09:36 AM

About to buy another bus for conversion. It’s a 7 window Thomas with the wheel chair lift. 9 window on the drivers side. It comes with the cat 3126 and Alison 4 speed. Doing some research and getting more negative opinions on this powertrain. We are going to be driving full time. Lots of highway miles.

EastCoastCB · 01-06-2019, 09:46 AM

I love mine. But its nearly new. I got a backup bus with extremely low use.
Its a great engine as far as I can tell. Smooth, powerful. Nice torque curve. With the highway gearing I've got this is one seriously quiet bus.
I'd buy another if it were in great condition and not too many miles/hours.
They're as good as any other school bus engine of their era. Most of the negativity is due to some problems with the 3116 before it and the C7 that came after it. Of all the school bus Cat engine's I'd say the 3126 is the one to get.

Gdog 5651 · 01-06-2019, 02:24 PM

All of the diesels are pretty good up until computerization/emissions. Electric diesels are pretty good up until emissions I have taken care of almost every kind of diesel engine. Every model from the big 4 since 1971+ Deutz Iveco Renault Nissan Yanmar and others. Until Emission Control came along as long as they were used in a proper application they were all pretty long lived and dependable.They all had and still have their little quirks and problems which is why you get people hating on one or another just like some people like Ford over Chevy over Dodge ect..I cared for a mixed fleet of CATS and MBE and preemissions they were both great powerplants 3116&26 were both good for us the MBE's maybe not quite as good as the CATS but very good none the less well maintained and very few problems with either make. Gene

Johnny Mullet · 01-06-2019, 03:23 PM

These are very good engines. Keep up on the maintenance and it will serve you a long time.

madhat · 01-07-2019, 08:51 AM

Quote:

Originally Posted by EastCoastCB

I love mine. But its nearly new. I got a backup bus with extremely low use.
Its a great engine as far as I can tell. Smooth, powerful. Nice torque curve. With the highway gearing I've got this is one seriously quiet bus.
I'd buy another if it were in great condition and not too many miles/hours.
They're as good as any other school bus engine of their era. Most of the negativity is due to some problems with the 3116 before it and the C7 that came after it. Of all the school bus Cat engine's I'd say the 3126 is the one to get.

Thank you guys you for helping. Your input helped us a lot with our 2 previous conversions.
Another question now. The owner said it has a 4 speed Alison. Does that mean the at 454 ? Because I had that one in my amtran pusher and it wasn’t really a highway tranny.

EastCoastCB · 01-07-2019, 09:42 AM

Quote:

Originally Posted by madhat

Thank you guys you for helping. Your input helped us a lot with our 2 previous conversions.
Another question now. The owner said it has a 4 speed Alison. Does that mean the at 454 ? Because I had that one in my amtran pusher and it wasn’t really a highway tranny.

Most likely a 545 but could be a 643.

PNW_Steve · 01-07-2019, 09:47 AM

There are two different 4 speeds that could be in that bus.

The AT-545 or MT-643. The 643 is the desirable one.

There should be a tag on the transmission. Or take a look at the thread here that details how to tell them apart. Hopefully someone here can remember where to find it......

madhat · 01-08-2019, 01:06 PM

Quote:

Originally Posted by PNW_Steve

There are two different 4 speeds that could be in that bus.

The AT-545 or MT-643. The 643 is the desirable one.

There should be a tag on the transmission. Or take a look at the thread here that details how to tell them apart. Hopefully someone here can remember where to find it......

The dealer said it’s an Allison 2000 series. He wasn’t sure if it was 2500 or something similar. My amtran had the not so desirable 454 and it struggled with hills.

madhat · 01-08-2019, 01:08 PM

I shall name thee “Bigsmall”

PNW_Steve · 01-08-2019, 01:30 PM

Quote:

Originally Posted by madhat

The dealer said it’s an Allison 2000 series. He wasn’t sure if it was 2500 or something similar. My amtran had the not so desirable 454 and it struggled with hills.

The 2000 series are 5 or 6 speed. As best I understand earlier years were 5 speed and around 2006 they had a different valve body and were 6 speeds.

Where is Christopher when you need him?

PNW_Steve · 01-08-2019, 01:31 PM

That should be a nice highway rig with the 3126 and 2500.

Keep us updated.

cadillackid · 01-08-2019, 01:41 PM

steve - correct in model year 2006 the allison 1000/2000 series could be 6 speed.. however seems in school busses 6th gear is always turned off..

with extensive mods you could make the earlier 5 speed into a 6 speed.. by replacing the valve body, the TCM and nodding the harness..

-Christopher

PNW_Steve · 01-08-2019, 01:54 PM

Quote:

Originally Posted by cadillackid

steve - correct in model year 2006 the allison 1000/2000 series could be 6 speed.. however seems in school busses 6th gear is always turned off..

with extensive mods you could make the earlier 5 speed into a 6 speed.. by replacing the valve body, the TCM and nodding the harness..

-Christopher

Yeah, same as the MD-3060's. I will be shopping soon for a spare TCM for you to program up for me

cadillackid · 01-08-2019, 02:01 PM

Quote:

Originally Posted by PNW_Steve

Yeah, same as the MD-3060's. I will be shopping soon for a spare TCM for you to program up for me

I dont have a bench harness for those TCMs yet.. i have to find or make one. they use different connectors than the Gen4/Gen5 TCMs found on the 2006+ 1000/2000
-Christopher

EastCoastCB · 01-08-2019, 03:35 PM

Quote:

Originally Posted by madhat

The dealer said it’s an Allison 2000 series. He wasn’t sure if it was 2500 or something similar. My amtran had the not so desirable 454 and it struggled with hills.

Allison 2000 is a 5 speed with OD and lockup t/c. That's a GOOD drivetrain.