Houston, we have a problem - Mike, I need your analysis!

[MaxPF]

I mentioned in another thread that I got what was supposed to be a 2007 Allison with 21K miles on it. Well, I still think it has only 21k miles on it, but when I pulled the output shaft I found the P3 planetary was junk. So, I began tearing into the trans and found a lot more issues. Now, this is the first broken Allison I have been into, but I have seen similar damage to other transmissions that I am familiar with. My thoughts are a loss of lube and ultimately a complete loss of pressure, but I want to see what Mike and the rest of you think.

Here's the C5 clutches. I cannot stress how new these looked (as did the other undamaged clutches), which makes me think this was a 21k mile trans:

Here's the bushing (whats left of it) in the output shaft:

Here's the intermediate shaft:

Here's P3. It looks a lot blacker in person than it does in the pics. One pinion is very crunchy when it turns :

Interestingly, only 2 of the 4 pinions showed signs of damage. Here you can see a "good" one on the left and a fried one on the right:

P2 looked and felt fine. I'm guessing there was no power flowing through it when whatever failed, failed:

The bushing in P2's hub looked hashed though:

P1 has seen better days

C3 got a bit crispy:

Thrust washer showed signs of lube starvation:

C2 was wasted:

Here's the intermediate shaft bushing in the input shaft:

so, what do you think? Lube failure, or something else? I'm thinking it lost a cooler line at speed, and eventually lost enough fluid that holding pressure to the clutches was lost, but I'm not an Allison guru. All I know is that if the seller doesn't make good on it I'm out some money :angry4:

 

[BLKLMM]

no pics??

 

[Kat]

no pics??

Working for me

 

[BLKLMM]

hmm... mine sucks and Ive refreshed page several times

 

[MaxPF]

The pics are slowish loading. Give em a minute. Server upgrade coming soon

 

[THEFERMANATOR]

I was gonna say it looks like a cooler line blew and somebody drove it until it ran out of oil, OR they towed it with the trans in neutral and the engine not running. That would cause all of that damage as well since the lube flow comes from the excess fluid pressure that is run through the cooler and then the trans according to my diagrams.

And since you have it apart, could you PLEASE take the C2 apply piston out and snap a couple of pics of it for me? And also what type of sealing rings did it have for the C1/C2 drum?

 

[MaxPF]

I was gonna say it looks like a cooler line blew and somebody drove it until it ran out of oil, OR they towed it with the trans in neutral and the engine not running. That would cause all of that damage as well since the lube flow comes from the excess fluid pressure that is run through the cooler and then the trans according to my diagrams.

Hmm, I hadn't considered that. Would towing have caused damage all the way up to the C2 clutches though

And since you have it apart, could you PLEASE take the C2 apply piston out and snap a couple of pics of it for me? And also what type of sealing rings did it have for the C1/C2 drum?

I actually don't have the C2 piston removed yet. I need to dig out my clutch spring press to get the C2 assembly apart. I CAN tell you from what I have seen that it is very different from the 05-earlier assemblies. I will try to get the pics for you, but if these guys want this trans back to exchange for another I may not get the chance.

I assume you are talking about the rings on the pump extension that seal to the input drum? They are a split ring with an overlapping seam. Not scarf cut, but a complete half-and-half overlap.

 

[Mike L.]

Stuck lube valve in the pump? Dex 6 fluid in sub zero temps has been known to solidify in the cooler lines and cooler. Towing with rear wheels on the ground. Plugged radiator heat exchanger.

 

[MaxPF]

Thanks for the input Mike :thumb:

Of course, the seller wouldn't make good on the unit, so I'm going to have to file a small claims suit

One more question Mike, would you trust the sun and ring gears on the sets that were burnt, or junk them all? If I have to junk the entire P1 and P3 gear sets I might as well toss the whole trans in the scrap barrel

 

[Mike L.]

Thanks for the input Mike :thumb:

Of course, the seller wouldn't make good on the unit, so I'm going to have to file a small claims suit

One more question Mike, would you trust the sun and ring gears on the sets that were burnt, or junk them all? If I have to junk the entire P1 and P3 gear sets I might as well toss the whole trans in the scrap barrel

If the ring gears are blackend from the heat, I would not use them.

 

[MaxPF]

If the ring gears are blackend from the heat, I would not use them.

There is no discoloration on them. I will have to use a magnifier to examine the teeth surface, but I assume if there is no pitting or spalling on the surfaces that the case hardening is probably intact.

Let me rephrase the question one more time: If they looked undamaged to you, would YOU use them in a build?

Thanks again :thumb:

 

[Mike L.]

There is no discoloration on them. I will have to use a magnifier to examine the teeth surface, but I assume if there is no pitting or spalling on the surfaces that the case hardening is probably intact.

Let me rephrase the question one more time: If they looked undamaged to you, would YOU use them in a build?

Thanks again :thumb:

Not in a customers truck.

 

[THEFERMANATOR]

If you were closer I would set you up with the guts out of this other ALLISON I have as it only had 87K miles and looks PERFECT. That tyranny was most likely flat towed with the trans in neutral to cause that kind of damage I would think. That would be the only explanation I can come up with as to why only a couple of the planetary gears got toasted and some others are fine. If it was flat towed only a small portion of the powertrain through it would have had oil to them from the pan level, and you would get very little splash oiling. If it had been from a broken cooler line it would have lost hydraulic pressure to the point the clutches wouldn't have held before it burned up the guts. And if it had been a plugged cooler I would have expected to see uniform damage to all of the gears.

 

[MaxPF]

If you were closer I would set you up with the guts out of this other ALLISON I have as it only had 87K miles and looks PERFECT. That tyranny was most likely flat towed with the trans in neutral to cause that kind of damage I would think. That would be the only explanation I can come up with as to why only a couple of the planetary gears got toasted and some others are fine. If it was flat towed only a small portion of the powertrain through it would have had oil to them from the pan level, and you would get very little splash oiling. If it had been from a broken cooler line it would have lost hydraulic pressure to the point the clutches wouldn't have held before it burned up the guts. And if it had been a plugged cooler I would have expected to see uniform damage to all of the gears.

Im guessing the other tranny you have is a 5 speed? According to Mike, the planetaries in the 6 speeds are different

 

[MaxPF]

I just thought of something!!!!

MIKE?!?!?! I know you said you cant mix and match gearset parts between the 5 speeds and 6 speeds, but is there any reason why I couldn't swap the entire gear train from a 5 speed into the 6 speed? I'm talking sun, planetary carrier, and ring gears for P1, P2, and P3. The whole deal. If it IS possible, is there any reason not to? Im guessing the angle change on the later gears was to reduce noise, but are the 5 and 6 speed gears comparable strength and durability wise? If so, I might have to con Ferm out of his spare parts

Oh, and in case I haven't mentioned it, THANK YOU ALL for your help and advice. Especially you Mike