T444e/Allison 3000 tranny slipping?

rchurchill · 05-09-2017, 08:44 PM

I've bought my first bus and just drove it 600 miles home from Maryland at ~50mph. A long, slow drive. International 3800 school bus with a T444e engine and a Allison 3000 trans.

The transmission was acting kinda odd. The bus would cruise along at 50-52mph according to the GPS speedometer on my phone, but the speedo on the dash read 65. I kept it almost floored on the highway but didn't want to max anything out. The tach said 2100 RPM generally but when I'd stomp on the pedal it would quickly surge to 2500 RPM and the speed would slowly increase.

So I'm guessing the transmission is slipping. From what little I've read, low fluid is the most common reason for slippage.

Pulled the dipstick with the engine cold and idling and the fluid is red with a touch of darker crap in it. The level is below where it should be by about a 1/2 inch, but still on the dipstick. The spec for a 3000 tranny I saw said it holds 25 liters of fluid, so I don't know what a 1/2 inch on the dipstick translates to. Is that just a quart low or a gallon? Is that low enough to be slipping enough for the speedo to be off by 15%?

I need to track down a couple of quarts of TES-295 transmission fluid locally and try topping it off. I assume you just pour it down the dipstick tube, same as on a car.

Any suggestions on other things to check or look out for? Hopefully low fluid is the problem or am I looking at a major transmission repair?

Thanks
Rene

gbstewart · 05-09-2017, 09:36 PM

Quote:

Originally Posted by rchurchill

I've bought my first bus and just drove it 600 miles home from Maryland at ~50mph. A long, slow drive. International 3800 school bus with a T444e engine and a Allison 3000 trans.

The transmission was acting kinda odd. The bus would cruise along at 50-52mph according to the GPS speedometer on my phone, but the speedo on the dash read 65. I kept it almost floored on the highway but didn't want to max anything out. The tach said 2100 RPM generally but when I'd stomp on the pedal it would quickly surge to 2500 RPM and the speed would slowly increase.

So I'm guessing the transmission is slipping. From what little I've read, low fluid is the most common reason for slippage.

Pulled the dipstick with the engine cold and idling and the fluid is red with a touch of darker crap in it. The level is below where it should be by about a 1/2 inch, but still on the dipstick. The spec for a 3000 tranny I saw said it holds 25 liters of fluid, so I don't know what a 1/2 inch on the dipstick translates to. Is that just a quart low or a gallon? Is that low enough to be slipping enough for the speedo to be off by 15%?

I need to track down a couple of quarts of TES-295 transmission fluid locally and try topping it off. I assume you just pour it down the dipstick tube, same as on a car.

Any suggestions on other things to check or look out for? Hopefully low fluid is the problem or am I looking at a major transmission repair?

Thanks
Rene

what year is your bus? are you sure its a 3000, and not a at545? the t444e isn't a power house, it maybe hard to tell if it was really slipping , what I would do is start with is changing the tranny fluid.
gbstewart

rchurchill · 05-09-2017, 09:45 PM

I haven't found a badge on hardware yet, but the sell claimed it was a 3000. I've requested that they send me the maintenance records. I'm hopeful but not holding my breath for them.

Robin97396 · 05-09-2017, 09:54 PM

Shouldn't one of those vin decoders tell what trans is in it? I'd guess it would have a 1000 or 2000 series.

Robin97396 · 05-09-2017, 09:55 PM

There should be a tag on the right hand side of the transmission.

EastCoastCB · 05-09-2017, 10:13 PM

Does it have 4 gears or 5? Push button shift?

Rameses · 05-09-2017, 10:14 PM

Transmission slippage wouldn't result in an errant speedometer reading.

Robin97396 · 05-09-2017, 10:48 PM

Sounds like the 545 in my experience. Step on the throttle and the RPM goes up but it appears nothing is happening. In actuality you are slowly gaining speed.

gbstewart · 05-10-2017, 07:54 AM

Quote:

Originally Posted by Robin97396

Sounds like the 545 in my experience. Step on the throttle and the RPM goes up but it appears nothing is happening. In actuality you are slowly gaining speed.

I fully agree with you
gbstewart

cadillackid · 05-10-2017, 10:17 AM

acts just like my AT545 does.. the VIN doesnt show transmission on a VION decoder.. the shifter should tell you.. if the lever shifter is a R-N-3-2-1 it is likely 545, it is a pushbutton shifter it is likely a 3000 series, if the lever shifter shows R-N-D-4-2-1 it is likely 1000/2000 series..

what kind of bus? shortie? regular conventional? flat nose front engine, rear engine?
-Christopher

rchurchill · 05-10-2017, 05:50 PM

The shifter lever shows R-N-3-2-1 I'll have to crawl around under the bus this weekend and check for sure. Any thoughts on what would be throwing the speedo off if it's not a slipping transmission?

The bus is a dog nose, class C, 30' International 3800, so not short, not long. A nice middle size. I'm hoping to use the wheelchair lift as a motorcycle lift and bring my bike with me.

rchurchill · 05-10-2017, 05:55 PM

Any thoughts on what would cause the speedo to run fast if it's not the transmission slipping? At highway speeds, I'd expect the transmission to lock up pretty tight, so the behavior of it showing 400 rpm worth of slop without a speed change seems fishy to me.

EastCoastCB · 05-10-2017, 06:07 PM

Quote:

Originally Posted by rchurchill

The shifter lever shows R-N-3-2-1 I'll have to crawl around under the bus this weekend and check for sure. Any thoughts on what would be throwing the speedo off if it's not a slipping transmission?

The bus is a dog nose, class C, 30' International 3800, so not short, not long. A nice middle size. I'm hoping to use the wheelchair lift as a motorcycle lift and bring my bike with me.

That's almost certainly a 545.
If the tires aren't original size that could make the speedo read incorrectly.

cadillackid · 05-10-2017, 08:19 PM

or if they replaced the ECM computer and never repgroammed it with the data from the VIN of the bus. that makes the speedo incorrect
-Christopher

Robin97396 · 05-10-2017, 11:17 PM

Or somebody accidentally changing the dip switches.

cadillackid · 05-11-2017, 03:54 AM

That one should be new enough not to have switches, the speed is from the can bus.
Christopher

rchurchill · 05-14-2017, 01:07 PM

After crawling around under the bus for a bit, I found out that it is an AT545 transmission and it looks like there is some kind of maintenance plate missing from the bottom.

Now I'm wondering if this plate is meant to seal and hold in transmission fluid? If so, then I certainly want to replace it before trying to top off the fluid.

I did manage to get the release valve cleaned up on the air tank and drained out a lot of water so the air suspension is working again.

I'm climbing the learning curve but there is a lot left that I don't know about buses.

cadillackid · 05-14-2017, 02:31 PM

thats just the flywheel inspection plate.. often used to loosen / tighten the flexplate bolts... there should be no fluid present there.. if there is a small engine oil or trans front seal leak you may find transmission fluid in there or oil.. most of us dont worry about a couple drops on the ground overnight... these are old busses.. but you should be able to fill your fluid without any issues.. if it runs out there then something is wrong.
-Christopher

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