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Old 02-11-2018, 02:12 PM   #1
Mini-Skoolie
 
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Need advice on 6.5 Detroit Diesel Maintenance

I've tried looking for answers in this forum but could not find any that was close to what I was looking for so I apologize in advance if it has already been answered in a different post.

I finally have time this week to work on my 1995 Chevy Van 30 Collins Super Bantam automatic that I purchased last month and have ordered a Manual for a Chevy G30 but wanted to get advice from someone who has experience. I've change car and motorcycle oil before but never a diesel and know that sometimes things don't go exactly as planned. Here are the following things I am curios about:

1. What type of oil to use, capacity, viscosity etc (I live in California and the bus has 348k miles).
2. What type of automatic transmission fluid to use.
3. Coolant flush
4. What else should I look out for or replace given the fact that I don't have any service history of the bus and want to start from scratch?

Thank you in advance. Cheers!
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Old 02-11-2018, 02:33 PM   #2
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With no known starting point, you need to create one.

Engine:

Drain and re-fill oil. It will depend on the engine, but most run 15W40, and Rotella T4 is the most popular. Get it at Sams for about $60 per 5 gallons.

New oil filter goes without saying, and pre-fill it before attaching. Fuel filter(s), water separator filter. When the oil is draining, get a mid-flow sample to send to Blackstone Labs for analysis. They will tell you quite a lot about your engine, although you won't be able to tell them the milage on the oil.

Changing the coolant would be a safe, but it can be expensive. If the coolant looks good you can test the additive level with test strips. If you change it, determine what additives you need and whether or not to use separate additives or a filter with them in it. Don't do both.

Change the belts, and keep the old ones as spares. One day you will thank me for this.

Transmission .... Drain and refill, changing the filter(s). One external and one in the sump. Most Allisons are okay with Dexron III or better. Allison recommends Transynd, and if you use that you can extend the service interval, but they are very proud of that stuff. There are equivalents, none of them are cheap.

Air system ... Make sure there is no water in it by draining the tanks from the drain valves. Location varies. If there is an air-dryer you can get that off and replace, or rejuvenate, the dessicant. If there isn't an air-dryer and you live in a humid climate, get a second hand one and fit it.

Brakes .... For air-brakes check the lining thickness and movement of the actuating arm. For hydraulic brakes check the linings and change the fluid. There may be a special routine for fluid change if you have ABS.

Chassis ... Grease all lube points.

Rear axle ... Change oil ... It's likely to be 80W140 or similar, and there should be a lot of it.

Write mileage and date on all new filters with a Sharpie.
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Old 02-11-2018, 10:40 PM   #3
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Quote:
Originally Posted by jnymdnyt View Post
I've tried looking for answers in this forum but could not find any that was close to what I was looking for so I apologize in advance if it has already been answered in a different post.

I finally have time this week to work on my 1995 Chevy Van 30 Collins Super Bantam automatic that I purchased last month and have ordered a Manual for a Chevy G30 but wanted to get advice from someone who has experience. I've change car and motorcycle oil before but never a diesel and know that sometimes things don't go exactly as planned. Here are the following things I am curios about:

1. What type of oil to use, capacity, viscosity etc (I live in California and the bus has 348k miles).
2. What type of automatic transmission fluid to use.
3. Coolant flush
4. What else should I look out for or replace given the fact that I don't have any service history of the bus and want to start from scratch?

Thank you in advance. Cheers!
1:Oil 15W40 (7 quarts)
2EXRON VI
3: Regular ol' green stuff. Your Detroit doesn't need any special additives.
4a: Check if your PMD has been relocated, if not, move it!
4b: A good harmonic balancer (previously mentioned)
4c: Previously mentioned check/replacement of brakes/belts/hoses (you don't have an air system or air brakes to worry about) along with check battery, charging system, wiring connections (especially GROUND connections)

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Old 02-11-2018, 11:50 PM   #4
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Do NOT use the LE rated oil that is commonly found on the shelf at Wal-Mart, Costco, O'Reillys, NAPA, etc. Your old engine will die if you put the new emissions spe'c oil into it. Your old engine really does need the ZDDP (zinc and other stuff) that is still found in the old formula oils.

You should be able to determine by calling your local GM dealer how many times the brain box has been swapped out on that engine (GM had an extra long, non-publicized extended warranty on those brain boxes due to the fact they usually only lasted about 20K miles before getting cooked--at almost $3K to replace it if you have to pay cash the extended warranty was a nice thing). The 6.5L in a G-series chassis is famous for cooking the brain box and killing it deader than dead. There are kits (mounting bracket and pig tail extension)available to move the brain box from under the turbo in the valley between the heads to out onto the radiator core support.

Make sure you find all of the batteries. Sometimes both are under the hood. Sometimes only one is under the hood with the second one mounted somewhere on the frame rail. We had one bus that the second battery was mounted on the inside of the frame rail under the driver. If you are lucky you might have only one battery, a Group 31 or 8D, mounted in a battery box in the skirt of the body.

In the process of putting in a new serpentine belt you may want to change out the belt tensioner while you have the belt off. They are not very expensive but it can be a real bummer when you go to put the new belt on only to have the belt tensioner break. Or to have the bearing on the shiv freeze in the next 100 miles. Also check the idler pulley on which the serpentine belt rides. I had one that had been worn off so much that it was too narrow and was starting to shave the inside and outside edge of the belt off.

Good luck and keep us posted as to your progress.
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Old 02-11-2018, 11:53 PM   #5
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Quote:
Originally Posted by cowlitzcoach View Post
Do NOT use the LE rated oil that is commonly found on the shelf at Wal-Mart, Costco, O'Reillys, NAPA, etc. Your old engine will die if you put the new emissions spe'c oil into it. Your old engine really does need the ZDDP (zinc and other stuff) that is still found in the old formula oils.

You should be able to determine by calling your local GM dealer how many times the brain box has been swapped out on that engine. The 6.5L in a G-series chassis is famous for cooking the brain box and killing it deader than dead. There are kits (mounting bracket and pig tail extension)available to move the brain box from under the turbo in the valley between the heads to out onto the radiator core support.

Make sure you find all of the batteries. Sometimes both are under the hood. Sometimes only one is under the hood with the second one mounted somewhere on the frame rail. We had one bus that the second battery was mounted on the inside of the frame rail under the driver. If you are lucky you might have only one battery, a Group 31 or 8D, mounted in a battery box in the skirt of the body.

In the process of putting in a new serpentine belt you may want to change out the belt tensioner while you have the belt off. They are not very expensive but it can be a real bummer when you go to put the new belt on only to have the belt tensioner break. Or to have the bearing on the shiv freeze in the next 100 miles. Also check the idler pulley on which the serpentine belt rides. I had one that had been worn off so much that it was too narrow and was starting to shave the inside and outside edge of the belt off.

Good luck and keep us posted as to your progress.
PMD=Brain Box
+1 on moving it!

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Old 02-13-2018, 12:15 PM   #6
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Thank you to all that responded.

The service manual arrived today and it's bright and sunny outside so it's time to get things going. It might be a bit of a challenge looking for a spot to do this because parking in SF is like gold, more so doing maintenance on a bright Yellow school bus w/o pissing off your neighbors. I just have to be creative.

Using the VIN of the bus I was able to decode a lot of information. I have attached a picture below for future reference.

My approach in normally very slow when doing things for the first time as I have broken enough things in my life to learn to stop, take a deep breath and ask before getting the hammer.

Tigg:

"Change the belts, and keep the old ones as spares. One day you will thank me for this."

"Write mileage and date on all new filters with a Sharpie."

I like these ideas and have done this with motorcycle batteries and oil changes. Thanks!

BennysTire:

"1:Oil 15W40 (7 quarts)
2EXRON VI
3: Regular ol' green stuff. Your Detroit doesn't need any special additives.
4a: Check if your PMD has been relocated, if not, move it!
4b: A good harmonic balancer (previously mentioned)
4c: Previously mentioned check/replacement of brakes/belts/hoses (you don't have an air system or air brakes to worry about) along with check battery, charging system, wiring connections (especially GROUND connections)

PMD=Brain Box
+1 on moving it!"

Right on the money as always. I was about to ask what PMD was. And I'll need to order tires soon. Thanks!

Cowlitzcoach:

"You should be able to determine by calling your local GM dealer how many times the brain box has been swapped out on that engine (GM had an extra long, non-publicized extended warranty on those brain boxes due to the fact they usually only lasted about 20K miles before getting cooked--at almost $3K to replace it if you have to pay cash the extended warranty was a nice thing). The 6.5L in a G-series chassis is famous for cooking the brain box and killing it deader than dead.

Good luck and keep us posted as to your progress."

Great idea on calling GM to find out. I am also going to call the previous company (safetrans) to see if they have records. It might be a long shot but well worth it. I am hoping to get more insight on what has been done to the bus.

Will definitely keep you posted. Thanks!
Attached Images
File Type: jpg IMG_4717.jpg (211.6 KB, 11 views)
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Old 02-13-2018, 02:20 PM   #7
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Definitely see if Safetrans can hook you up. Best bet, visit the GARAGE and find the maintenance records keeper (eliminate middle-men) they usually keep maintenance records in some sort of spreadsheet that they can just email or place on a thumb drive. I was able to do that with one of my busses and when printed, the records looked like a Grainger catalog!🤣🤣

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Old 02-14-2018, 11:32 PM   #8
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I was finally able to find a spot to work on the bus but my attempt to do routine maintenance was cut short when I saw the drain bolt had JB weld around it so I decided to fix the exhaust which was bent, the hood latch, looked underneath and give it a good cleaning, it probably hasn't been washed in ages so I decided to do that too. There's a lot going on here than I'm use too. And as luck would have it, now it doesn't shift to second or third.

I am debating to replace the oil pan, to reJB weld or spot weld (I can do minor welding) but not a good idea I think because of the weird angle and the fact that it is near fuel lines, or leave it the way it is. I thought I'd listen to some suggestions prior to proceeding.

There is also a leak near the oil drain bolt which looks to be water. I have attached a photo if anyone can identify it that would be great.

I believe the transmission that I have is 4L80E Hydra-Matic. Per Service Manuals AT diagnosis, it could be the following:

1. Sun Gear Shaft or splines are broken (I hope it's not this one)
2. A/transmission Output Speed Sensor
3. A/transmission Input Speed Sensor

It runs on reverse, but just doesn't want to shift to 2nd. I read somewhere that if I disconnect the negative terminal and wait 10 seconds it might reset. The PMD was also relocated under the driver seat.

I called safetrans a call but they didn't want to help. I might swing by but they are an hour and half away. The GM dealership was "busy" and requested I call them back.

The light on the dash also went out but I am not sure if it was originally working.

I am curious about the following:

1. Can I use an OBDII scanner to see error codes?
2. How long can I let diesel sit in the tank? CA gas is notorious for messing carbs/throttle bodies because of the level of ethanol it contains.

On a positive note, the thick service manual is great and makes me feel like I am going to school again.
Attached Images
File Type: jpg Drain bolt.jpg (145.1 KB, 6 views)
File Type: jpg hydramatic tag.jpg (223.2 KB, 9 views)
File Type: jpg Speed sensors.jpg (139.6 KB, 7 views)
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Old 02-15-2018, 12:19 AM   #9
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Quote:
Originally Posted by jnymdnyt View Post
I was finally able to find a spot to work on the bus but my attempt to do routine maintenance was cut short when I saw the drain bolt had JB weld around it so I decided to fix the exhaust which was bent, the hood latch, looked underneath and give it a good cleaning, it probably hasn't been washed in ages so I decided to do that too. There's a lot going on here than I'm use too. And as luck would have it, now it doesn't shift to second or third.

I am debating to replace the oil pan, to reJB weld or spot weld (I can do minor welding) but not a good idea I think because of the weird angle and the fact that it is near fuel lines, or leave it the way it is. I thought I'd listen to some suggestions prior to proceeding.

There is also a leak near the oil drain bolt which looks to be water. I have attached a photo if anyone can identify it that would be great.

I believe the transmission that I have is 4L80E Hydra-Matic. Per Service Manuals AT diagnosis, it could be the following:

1. Sun Gear Shaft or splines are broken (I hope it's not this one)
2. A/transmission Output Speed Sensor
3. A/transmission Input Speed Sensor

It runs on reverse, but just doesn't want to shift to 2nd. I read somewhere that if I disconnect the negative terminal and wait 10 seconds it might reset. The PMD was also relocated under the driver seat.

I called safetrans a call but they didn't want to help. I might swing by but they are an hour and half away. The GM dealership was "busy" and requested I call them back.

The light on the dash also went out but I am not sure if it was originally working.

I am curious about the following:

1. Can I use an OBDII scanner to see error codes?
2. How long can I let diesel sit in the tank? CA gas is notorious for messing carbs/throttle bodies because of the level of ethanol it contains.

On a positive note, the thick service manual is great and makes me feel like I am going to school again.
Your shifting issue is likely not broken internals. When you're driving (in first gear...) is the speedometer showing properly? Or not moving?

YES, OBD-2 scanner works on your bus.

There are products you can add to your diesel tank to extend the "shelf life"... But how long are you thinking?

As to the oil pan... The threads on the pan itself are notoriously weak. My 99 Chevy Suburban has a Honda drain plug because the hole had to be drilled larger and tapped because it stripped out one oil change. I'm not a fan of the JB Weld type repair as anything more than a temporary "get me home" fix. I'd say change the pan, they're cheap enough...

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Old 02-15-2018, 07:17 AM   #10
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I’d check the speed sensor connection. Make sure it’s connected and the wires didn’t get pulled out while you were cleaning everything. Once you get the oil pan fixed, don’t ever let anyone but you remove it or put it back in. As BennysTire said they are weak and some folks want to put a million pounds of torque to the plug so it “won’t leak”. Not necessary and rips the threads out of the pan.
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Old 02-15-2018, 08:07 AM   #11
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Figure out what threads your plug has and get a self tapping oil pan drain plug from dorman. https://www.amazon.com/Dorman-65229-.../dp/B000COBBSE

I always use a little rtv on the outside of the first threads. Make sure you use two wrenches when changing the oil, one to remove the second plug, and one to hold the original plug.
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Old 02-21-2018, 11:53 AM   #12
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Quote:
Originally Posted by BennysTire View Post
Your shifting issue is likely not broken internals. When you're driving (in first gear...) is the speedometer showing properly? Or not moving?

YES, OBD-2 scanner works on your bus.

There are products you can add to your diesel tank to extend the "shelf life"... But how long are you thinking?

As to the oil pan... The threads on the pan itself are notoriously weak. My 99 Chevy Suburban has a Honda drain plug because the hole had to be drilled larger and tapped because it stripped out one oil change. I'm not a fan of the JB Weld type repair as anything more than a temporary "get me home" fix. I'd say change the pan, they're cheap enough...

Sent from my E6883 using Tapatalk
The speedometer works when I am driving it. I agree, I does not seem to be like broken internals.

When I got the bus the PO said he didn't use it much and from the way it looked, I would suspect that it's old diesel in there.

I also disconnected/reconnected the speed sensors but it still was not shifting.

Ashamed to say that I have over torqued one or two oil drain bolts in my life and it's not a hard thing to do. I've since bought a torque wrench to eliminate this mistake. I agree with changing the oil pan. Do it once and do it right. The cheap man pays twice.

I am currently in Portland following my sister's emergency surgery and I have to say there are a lot of skoolies here. Currently snowed in but will be working on the bus once I get back weather permitting.

Thank you!
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Old 02-21-2018, 12:10 PM   #13
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sounds more like you are stuck in second gear with no computer input to the transmission. make sure your transmission fuses are good and that you have power going to the proper pins on its harness..

stuck in second gear is Limp mode.. it will feel like first because it goes directly to second when you shuift to (D) or D. (you wont feel it "shift" to second because its never in first...so it "feels" like you have one gear)

it could be an internal solenoid but if there are no codes set then id def check in your service manual and measure for power at the proper terminals on the harness / check the trans fuses..

reverse and second are mechanically engaged so its possible for the transmission to operate in those 2 gears with the electronics defunct..

-Christopher
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Old 02-21-2018, 12:54 PM   #14
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Quote:
Originally Posted by Twigg View Post
With no known starting point, you need to create one.

Engine:

Drain and re-fill oil. It will depend on the engine, but most run 15W40, and Rotella T4 is the most popular. Get it at Sams for about $60 per 5 gallons.

New oil filter goes without saying, and pre-fill it before attaching. Fuel filter(s), water separator filter. When the oil is draining, get a mid-flow sample to send to Blackstone Labs for analysis. They will tell you quite a lot about your engine, although you won't be able to tell them the milage on the oil.

Changing the coolant would be a safe, but it can be expensive. If the coolant looks good you can test the additive level with test strips. If you change it, determine what additives you need and whether or not to use separate additives or a filter with them in it. Don't do both.

Change the belts, and keep the old ones as spares. One day you will thank me for this.

Transmission .... Drain and refill, changing the filter(s). One external and one in the sump. Most Allisons are okay with Dexron III or better. Allison recommends Transynd, and if you use that you can extend the service interval, but they are very proud of that stuff. There are equivalents, none of them are cheap.

Air system ... Make sure there is no water in it by draining the tanks from the drain valves. Location varies. If there is an air-dryer you can get that off and replace, or rejuvenate, the dessicant. If there isn't an air-dryer and you live in a humid climate, get a second hand one and fit it.

Brakes .... For air-brakes check the lining thickness and movement of the actuating arm. For hydraulic brakes check the linings and change the fluid. There may be a special routine for fluid change if you have ABS.

Chassis ... Grease all lube points.

Rear axle ... Change oil ... It's likely to be 80W140 or similar, and there should be a lot of it.

Write mileage and date on all new filters with a Sharpie.
So...I'm not the only person to save used belts

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Old 02-22-2018, 11:31 AM   #15
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Quote:
Originally Posted by Booyah45828 View Post
Figure out what threads your plug has and get a self tapping oil pan drain plug from dorman. https://www.amazon.com/Dorman-65229-.../dp/B000COBBSE

I always use a little rtv on the outside of the first threads. Make sure you use two wrenches when changing the oil, one to remove the second plug, and one to hold the original plug.
This might be worth a shot. Thanks!

"it could be an internal solenoid but if there are no codes set then id def check in your service manual and measure for power at the proper terminals on the harness / check the trans fuses..

reverse and second are mechanically engaged so its possible for the transmission to operate in those 2 gears with the electronics defunct.."

-Christopher

This makes the most sense. I don't have the service manual with me now but I remember reading something about fuses and solenoids if it won't shift from second but can go in reverse . Thanks!
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Old 02-23-2018, 02:18 AM   #16
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IIRC, the 1997 G-4500 cut-way our church had that had the 6.5L diesel had a motor driven vacuum pump. Among other things it operated the HVAC system.

But for some reason there is a niggling thought in the back of my head that reminded me that it also provided vacuum to do something in the transmission. It has been some years ago now so I don't remember for sure what was going on. The immediate concern was lack of HVAC control. We thought we might be having to swap out the GM factory HVAC controller which would have been a royal PITA. But when a good source of vacuum was put to the controller and it worked we knew we had vacuum problem somewhere upstream.

Again, it has been a lot of years but it just seems to me that the lack of vacuum problem also caused a transmission shifting problem. And if IIRC it was stuck in 2nd or reverse.
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Old 02-23-2018, 01:46 PM   #17
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Quote:
Originally Posted by cowlitzcoach View Post
IIRC, the 1997 G-4500 cut-way our church had that had the 6.5L diesel had a motor driven vacuum pump. Among other things it operated the HVAC system.

But for some reason there is a niggling thought in the back of my head that reminded me that it also provided vacuum to do something in the transmission. It has been some years ago now so I don't remember for sure what was going on. The immediate concern was lack of HVAC control. We thought we might be having to swap out the GM factory HVAC controller which would have been a royal PITA. But when a good source of vacuum was put to the controller and it worked we knew we had vacuum problem somewhere upstream.

Again, it has been a lot of years but it just seems to me that the lack of vacuum problem also caused a transmission shifting problem. And if IIRC it was stuck in 2nd or reverse.
interesting that a 97 would have a mechanical transmission but perhaps on a medium duty.. on the pre 'E' transmissions.. some of them used a Vacuum modulator in which lack of vacuum left the transmission in kickdown mode all the time.. it would still shift but only when you hit redline RPM on the engine.. on a Gas engine this was done to monitor the amount of load on the engine. as when the engine was fully loaded there would be no vacuum and it would downshift or upshift later..

not sure how they would use a vacuum modulator on a diesel.. instead a 700R4 based transmission such as (4L60, later 4L60E. and to some extent the 4L80E). used the throttle cable as a modulator. which would work on a diesel also to sense that the driver was pressing hard on the pedal..

as good point here though is if this is not an electronic transmission then it may have a cable going to the transmission as a modulator.. if that cable is broken or stretched, they OP would get similar results.. lack of upshift

-Christopher
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Old 02-23-2018, 02:09 PM   #18
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The 4l80e is entirely electronic. No cables, vacuum, etc. It shifts based on output shaft speed and a signal from the TPS (throttle position sensor).

It is a very robust trans but they do have their weak points.

Check for power at the transmission harness plug. Check all the fuses for the controller and such.

Unhook the plug on the side of the transmission. If it acts/feels the same, more then likely the problem is electronic as suggested above. The transmission is in "limp mode" which is 2nd gear only and reverse. The change in gear lever position from reverse to drive should feel somewhat firm/harsh as in limp mode, the transmission ramps up line pressure.

I'd bank on electrical. I HATE the oem controllers for the 80e and E4OD. If it were me, I'd look into a stand alone controller from US Shift. Also, if you want to extend the lifespan of the 80E a good bit, look into a TransGo HD2 shift kit for it.
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Old 02-23-2018, 05:34 PM   #19
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Quote:
Originally Posted by Mr4btTahoe View Post
The 4l80e is entirely electronic. No cables, vacuum, etc. It shifts based on output shaft speed and a signal from the TPS (throttle position sensor).

It is a very robust trans but they do have their weak points.

Check for power at the transmission harness plug. Check all the fuses for the controller and such.

Unhook the plug on the side of the transmission. If it acts/feels the same, more then likely the problem is electronic as suggested above. The transmission is in "limp mode" which is 2nd gear only and reverse. The change in gear lever position from reverse to drive should feel somewhat firm/harsh as in limp mode, the transmission ramps up line pressure.

I'd bank on electrical. I HATE the oem controllers for the 80e and E4OD. If it were me, I'd look into a stand alone controller from US Shift. Also, if you want to extend the lifespan of the 80E a good bit, look into a TransGo HD2 shift kit for it.
Should be 2 speed sensors, input and output.
I ran into a problem with putting a stick shift transfer case in my Suburban because the output sensor was in the autotrac transfer case. My options were either get a 2wd 4L80E with both sensors in the trans or have a sensor put into my stick shift case...

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Old 02-27-2018, 12:33 AM   #20
Mini-Skoolie
 
Join Date: Jan 2018
Location: San Francisco
Posts: 25
Coachwork: Collins Super Bantam
Engine: 6.5L Diesel
Rated Cap: 20 passenger
According to the Service Manual 4L80E A/T Diagnosis for running on second gear only it could be the following:

- A/transmission Output Speed sensor assembly.
- System Voltage high (no TCC operation)
- System Voltage low
- QDM (?) & 2-3 Solenoid. Code 81 will set if the PCM/TCM detects an
inappropriate voltage on the 2-3 shift solenoid circuit.

I am going to try the OBDII Scanner and see if it comes up with an error code.

The service manual does not mention any vacuums but 2 speed sensors, input and output, 1-2 shift solenoid and 2-3 shift solenoid which I am hoping is the cause of the problem so I can replace it.

Appreciate everyone's feedback.
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