lynndiwagoner
Well-known member
The link provided above is probably the problem. I did my 2005 2500HD twice.
Allison Transmission question
- Thread starter Garypowell
- Start date
Garypowell
Well-known member
No leaks fluid level OK. Finally got under it today after retuning from a non tow trip. I have a two piece shaft and the front shaft passes through a bearing. Pushing up I can move the shaft up about 1/4 inch. Then had a great conversation with Bob (of bob&patty) and think that is probably the root of my problem. Can't tell if any u joints are bad or the slip york.....learning all these new terms.
I have ave appointment next Tuesday at dealership I trust. We'll know for sure.....update then.
I have ave appointment next Tuesday at dealership I trust. We'll know for sure.....update then.
porthole
Retired
GM used some clunky hoses on the the Allison, great trans - poor cooler lines.
The Allison cooler lines are pressurized all the time, so when cold the crimp fitting on the hoses would tend to allow fluid seepage at the connections.
The aftermarket hoses are superior to and easier to install the the OEM parts.
The driveline clunk the Bob brought up has been around at least since the late 70's - on all three brands. Fixes included "nothing - that is normal" to greasing the spines to replacing the slip yoke. In extreme cases we would replace the the trans or transfer case output shaft.
The clunk could also be, low fluid, poor fluid quality, U-joints, center carrier bearings, solenoids inside the trans or, worse case is the trans has an internal issue.
Allison's are great transmissions and for the number out there, have relatively few problems.
BTW, all three have similar transmissions now, and all three can have any of the above issues.
One other issue with the GM is the transfer case. I don't know when the fix was introduced into the lineup, but there is a problem with the internals wearing through the transfer case housing up top. Nothing is evident until the transfer case fails. The wear causes a minor oil leak that typically goes unnoticed. Doesn't take long for 2 quarts to seep out and have a failure.
Lynn1130
Well-known member
Here is the fix for the transfer case "pump rub" issues along with a list of the transfer cases that could be affected. I did this upgrade to mine several years ago. If that is his problem there will be more noise than just a "bump" once it goes.
http://www.merchant-automotive.com/p-4017-transfer-case-pump-upgrade-kit.aspx
http://www.merchant-automotive.com/p-4017-transfer-case-pump-upgrade-kit.aspx
Bob&Patty
Founders of SoCal Chapter
From what Gary discribed ( I hate diagnosing over the phone) to me. It just might a bad center support bearing and maybe a couple of dry slip yokes. I did advise him at 160K miles that he should have the U joints inspected. I had forgot that the 2008 S/B Chevy/GMC trucks had a 2 piece drive shaft. Must be CRS setting in. I never did this, but I always wanted to tell someone that wanted me to diagnose something on the phone, "hold your car up to the phone so I can look at it". Probably would have be fired for it, was always tempted.
GMCaddic
Active Member
I agree with this. Also make sure your U-bolts on the springs are tight and the axle is not moving check your yoke on the back of the driveline make sure there are no rub marks on it or the rear axle.
I had this happen to me and my driveline broke, luckily I made it home before it totally broke.
As for the pump rub thats only for 98 to early 07 gm trucks. His is an 08 like mine.
Garypowell
Well-known member
Re: RESOLVED Allison Transmission question
Just returned home with my fixed truck. Problem turned out to be loose/broken shackles allowing my left side springs to shift around. Not to mention the springs were flattened too. Every time I hit the gas the torque would move the whole rear end wheel assembly and slide the springs around. Initially they thought a spring was actually broken but it was not. I feel very blessed to have caught this early. Granted if I had knows the day it happened I might not have had the damage I'll describe below...but still very blessed we did not come apart on the road somewhere with who knows what happening.
This movement was where the clunk was coming from.
The movement caused the internal seals of the "pumpkin" (I have learned a new term for differential) to get pinched and go bad. This lead to Diff oil going down the shaft and ruining the new brakes (on both sides) I had installed in January.
During the process they also noticed my front left wheel bearing was going bad. When they called about this to authorize the fix he asked if I had heard a grinding sound. I had but failed to mention it to them. The cause they believe was a steering component close was bent and put undo force on the wheel/bearing causing it to fail.....so they changed out the bearing (and I guess it is now a whole assembly not just a simple bearing change) and the intermediate steering shaft.
AND I THINK I REMEMBER THE POT HOLE THAT DID THIS..... coming home from our last trip pulled the rig from AR into Memphis, TN. Lots of construction always at the 55/40 junction and we hit a pot hole that almost cause me to run off the road. Can't directly connect the two but it is as good as any reason.
Well....except I always contend we are very hard on these trucks. My first truck was a 1996 Diesel Ram and we flattened the springs on that one too.
Driving home no more clunking sound....and lost the grinding sound too from the front left wheel.
Total cost of the work was $4,521.00 but they discounted it down to $3,217.00. Don't like spending any money but when it has to be done it has to be done and it is simply the cost of doing business as we do. Since 2008 we have put about $7,000 in repairs (total) into this truck which I don't feel too bad about either.
Thanks to all for initially helping me think through what I was getting myself into.
Just returned home with my fixed truck. Problem turned out to be loose/broken shackles allowing my left side springs to shift around. Not to mention the springs were flattened too. Every time I hit the gas the torque would move the whole rear end wheel assembly and slide the springs around. Initially they thought a spring was actually broken but it was not. I feel very blessed to have caught this early. Granted if I had knows the day it happened I might not have had the damage I'll describe below...but still very blessed we did not come apart on the road somewhere with who knows what happening.
This movement was where the clunk was coming from.
The movement caused the internal seals of the "pumpkin" (I have learned a new term for differential) to get pinched and go bad. This lead to Diff oil going down the shaft and ruining the new brakes (on both sides) I had installed in January.
During the process they also noticed my front left wheel bearing was going bad. When they called about this to authorize the fix he asked if I had heard a grinding sound. I had but failed to mention it to them. The cause they believe was a steering component close was bent and put undo force on the wheel/bearing causing it to fail.....so they changed out the bearing (and I guess it is now a whole assembly not just a simple bearing change) and the intermediate steering shaft.
AND I THINK I REMEMBER THE POT HOLE THAT DID THIS..... coming home from our last trip pulled the rig from AR into Memphis, TN. Lots of construction always at the 55/40 junction and we hit a pot hole that almost cause me to run off the road. Can't directly connect the two but it is as good as any reason.
Well....except I always contend we are very hard on these trucks. My first truck was a 1996 Diesel Ram and we flattened the springs on that one too.
Driving home no more clunking sound....and lost the grinding sound too from the front left wheel.
Total cost of the work was $4,521.00 but they discounted it down to $3,217.00. Don't like spending any money but when it has to be done it has to be done and it is simply the cost of doing business as we do. Since 2008 we have put about $7,000 in repairs (total) into this truck which I don't feel too bad about either.
Thanks to all for initially helping me think through what I was getting myself into.
Bob&Patty
Founders of SoCal Chapter
Re: RESOLVED Allison Transmission question
Great to here that its in good shape now. That was my point, if you could have held it up to the phone, we could have seen the problem. The front hub bearings are not cheap, but if one comes unscrewed/apart, then the wheel comes off and leaves the truck....NOT GOOD.
Great to here that its in good shape now. That was my point, if you could have held it up to the phone, we could have seen the problem. The front hub bearings are not cheap, but if one comes unscrewed/apart, then the wheel comes off and leaves the truck....NOT GOOD.
