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Topic: My Allison transmission is acting up  (Read 3810 times) previous topic - next topic

Re: My Allison transmission is acting up

Reply #20 –
Roland,
An accumulator and an intercooler are two different  things.
I don 't think I have ever seen an accumulator in a transmission oil cooling circuit.
Do you see two transmission oil lines going to the bottom of the radiator?
If you do that's where the intercooler is located in the radiator.
If so then the radiator needs to come out and be repaired or replaced.
Decisions $ decisions $!!!

Re: My Allison transmission is acting up

Reply #21 –
John guess I am not using the proper terminology. The accumulator is attached to the engine radiator and that is used to cool the transmission fluid. This part is not available. My thought was to reroute the transmission coolant lines to a separately mounted "radiator" with a separate fan to cool the transmission fluid. The folks here are not keen on modifying hence my question on wether it is feasible to run a bit bypassing the accumulator so I can do it myself.

Roland

Re: My Allison transmission is acting up

Reply #22 –
I don't think you could go very far without over heating the transmission.
A call to Allison might help.

Re: My Allison transmission is acting up

Reply #23 –
Roland,

Nothing wrong with your idea. Race cars cool conventional transaxles with external oil coolers all the time. Would have to be a rugged unit with well engineered mounts, etc. Heat is the biggest enemy of automatic transmissions with their lifespan dropping dramatically once the temp gets too warm. In other words, the little transmission coolers you see at Autozone won't do the trick.

Here is something to look at but would want to contact B&M to see how one of their products matches up to the liter per minute flow rate required by the Allison. New B M Hi Tek Automatic Transmission Oil Cooling System Cooler Free Shipping HN

B&M has been a leader in racing and HD automatic transmissions modifications for as long as I can remember. Here is their website: B&M HOME ยป B&M

Pierce

Re: My Allison transmission is acting up

Reply #24 –
Roland,

Sounds like what you're wanting to know is if it would be possible to disconnect the lines from the transmission to the cooling coil inside the radiator, tie them together, and drive the coach without a trans cooler. Since your radiator is also full of tranny oil, it would need to be dealt with and a line installed across the abandoned couplings for trans oil.  Maybe others more knowledgeable will know the answer to that, but you for sure won't want to drive it any further with contaminated ATF in the tranny. One can always hope that a flush and new fluid will show the trans is ok.  Hopefully all you need is some cleanup and a new radiator. 

How about it....is it feasible to drive the coach without a transmission cooler?  Anyone know? 

I hope I'm not violating a forum policy here, but there has been, in the past, an Allison fluid engineer on the IRV2 forum.  I believe he has shown up on this forum also, a very knowledgeable guy.  Might give a shout out to him....Tom I believe. 

Re: My Allison transmission is acting up

Reply #25 –
Chuck, the dealer here said that they had to remove the tranny, they are certain the the solinoids will need attentions as well sat the plates. The engine coolant will also have to be flushed etc. However they won't start the process unless they have all the parts. Kinda don't blame them as the coach will then be occupying a bay and they are a busy outfit. That is the reason for my driving sans accumulator until I can install a transmission cooler. Would not let the temps go over two hundred, but I wonder if it feasible.

Roland

Re: My Allison transmission is acting up

Reply #26 –
Chuck,

Again, heat is the enemy here and torque converter slippage at idle and first gear will create a lot of heat. Roland has lockup half of second and all of third and fourth so the heat generated will be much less but still there. I watch my trans temp like a hawk.

No, you can't drive without a tranny cooler and expect the Allison to live.

Pierce

Re: My Allison transmission is acting up

Reply #27 –
Roland,

Trying to read between the lines here. Are you thinking of putting the lines together and perhaps driving to another shop? Or, do you want to get it fixed leaving the radiator alone with the AT lines directly connected to get somewhere to then install a separate cooler? With ATF in the coolant and probably vice versa, both issues should be addressed before any drive. Then you could drive the vehicle to another shop for cooler installation but not to another city in summer heat.

Pierce

Re: My Allison transmission is acting up

Reply #28 –
Was thinking of getting it fixed, bypassing the accumulator, and driving it to where I or someone can install a transmission cooler. Not sure there is a shop in the immediate area that would install a cooler.

Roland

Re: My Allison transmission is acting up

Reply #29 –
OK, then contact someone like B&M to see how feasible a separate cooler would be. They have the experience to tell you how far and under what conditions you can drive the coach without a cooler installed.

Pierce

Re: My Allison transmission is acting up

Reply #30 –
Just got back from the shop. They could not find the original part or a substitute part for the accumulator. They did however search for a separate transmission cooler and have come up with a cooler that will work with the Allison. Got a quote for parts :o :o 5 coach bucks, waiting for the labor quote. Guess when I went to the shop yesterday they were extremely busy and kinda short with me so I got the impression that they did not want to modify. They will not get the parts until the end of next week sometime, don't think I can stay in a Motel 6 that long and maintain my sanity. Going to continue our journey in the toad and come back when the coach is ready.

Roland

Re: My Allison transmission is acting up

Reply #31 –
Have you priced a genuine Allison reman transmission?

Re: My Allison transmission is acting up

Reply #32 –
Brett, haven't priced the reman transmission, but a big part of the parts cost was for the transmission cooler and associated hydraulic hoses. Will ask though when they call as that might make a difference in total cost.

Roland

Re: My Allison transmission is acting up

Reply #33 –
Has the fluid been drained from the transmission and checked for contamination?  I'd sure do this before tearing into it.  It could be that it is not contaminated, or that it's an insignificant amount, could be the filters caught it.  After all, sounds like your ATF has been blowing into the radiator, and level dropping in the trans.  Other than a hard shift, wasn't the trans working?  I'd sure do some checking before committing to a trans tear down or replacement. 

What or where is this accumulator?  Maybe I'm wrong but the only one I'm aware of is on the retarder, a hydraulic unit.

Re: My Allison transmission is acting up

Reply #34 –
Sounds like this is getting out of hand for a transmission cooler leak. I'm thinking more like Chuck. Have you seen any coolant in the transmission fluid?

Pierce

Re: My Allison transmission is acting up

Reply #35 –
Roland, I have been reading your dilemma. Your coach is different than ours, so the terminology is not clear to me.

We have a transmission retarder which has an Allison accumulator that activates the retarder and it is not related to cooling. We also have a transmission cooler that flows transmission fluid from and to transmission, and to remove heat from transmission fluid, the cooler also has engine coolant flowing in and out, but the two fluids are not in contact with each other. I can see that if the cooler insides deteriorate they could allow engine coolant to flow to transmission and vice versa.

Do you have a retarder and if not, is the 'accumulator' your transmission cooler? And is the Cummins shop installing an air cooled transmission cooler.or another type of engine coolant - transmission fluid cooler?

I have heard that our type of accumulator and our transmission cooler may no longer be available, so we all could face similar issues.

Good luck.

Re: My Allison transmission is acting up

Reply #36 –
Chuck makes sense on not having coolant in the transmission, because the transmission fluid pressures are probably much higher than the coolant, which tops out about 15 PSI, limited by radiator cap setting.

Re: My Allison transmission is acting up

Reply #37 –
1. The transmission fluid is contaminated. The shop took fluid out of the tranny and it was colored like my antifreeze. So although a lot of tranny fluid wound up in the antifreeze for the engine there was some "cross contamination". Shop says only way to assess what needs to be done is to look inside. They will only replace what needs to be replaced. They do not feel that merely flushing the tranny is the appropriate approach although they did give me that option.

1a. The tranny was shifting OK but was a real slam shifting down to first gear. I had to add three quarts of fluid before it was visible on the stick without the engine running. With the engine running it "disappeared".

2. I called the parts department In NAC and described my issue. They said it sounded like a bad transmission cooler. The part number they gave me 29506669 is described as an accumulator. The shop here says that us an incorrect part number as it mounts on the side of the radiator whereas my defunct piece is on the bottom. The Allison shop cannot find a new cooler for my tranny, it is no longer manufactured and there is no replacement therefore they will install a separate tranny cooler.

3. I do not have a retarder so perhaps "accumulator" is not an appropriate description of the bad module. The bad module is my tranny cooler.

I hope this clears things up a bit.

Roland

Re: My Allison transmission is acting up

Reply #38 –
Roland..

So what option are you taking..??? pull the transmission for an inspection or flush.??

Hans

Re: My Allison transmission is acting up

Reply #39 –
Actually, a leak between transmission and coolant OFTEN does the following:

When driving, ATF is generally under more pressure so ATF gets into the coolant.

With engine off, ATF pressure drops to zero and the pressure cap on the coolant system gives the cooling system higher pressure, so coolant flows into the transmission.