Transmission Maintenance

[John Hennessey]

Just had the coach serviced at Boyer Trucks in Savage MN  Asked about the transmission cooler leaking problem and was told by the mechanic that even if the cooler leaks if you are checking your tranny fluid often and notice a dilution of color or foam or milkiness that if you get it soon enough you can get a new cooler, and have the transmission flush and you may be able to save yourself a $15000.00 repair bill. He recommends replacing, flushing and then drive to see how it works rather than just replacing the transmission.  He said the Allison 4000 are a really tough transmission.  Anybody have any ideas about this?   LInda Hennessey

[Bill Sprague]

I've been doing some reading on oil analysis.  Blackstone Laboratories will do a "standard" oil analysis that include checking for coolant.  The test is $25.  

http://www.blackstone-labs.com/

I'm considering putting it on a regular schedule.  

[Gerald Farris]

Linda,
Your mechanic was right, but the vast majority of Beaver owners never check the color or condition of their transmission fluid. At best, they just periodically check the fluid level with the shift pad. The biggest problem with coolant contamination in the transmission fluid is that the clutch facing material and the adhesive that is used with it is not waterproof, and therefore the coolant will destroy the transmission clutch plates fairly quickly.

Gerald

[Edward Buker]

Linda,

If you could catch it before the damage was done it would be a good stroke of luck. The type failure that our coolers get is a cracked tube or attachment joint due to the fixed bundle design. Better designs float the bundle of tubes to eliminate the expansion and contraction stress cycles.The pressure difference between the cooler and the antifreeze system on shut down would drive the antifreeze into the oil cooler side as the transmission pressure and flow stop. The fluid is probably exchanging in the other direction during driving with the transmission pump moving fluid under pressure through the cooler. The long and short of this is that it does not take a lot of antifreeze in the mix to create the problem and with the pressure differences involved the fluids will mix pretty rapidly once the crack is formed. You may get lucky and certainly there is a lot of information to be gained about the fluid quality and pending problems with the analysis anyway, it just may not be a big help with preventing the damage due to this issue.

Later Ed

[John Hennessey]

I looked up the specs on analysis and found that 0.2 percentage of water is within specs.  It seems the glycol is the agent that damages the clutch plate and gasket adhesive.  That explains the necessity of getting glycol flushed out as soon as possible to prevent massive damage.  Some solvents only do massive damage with prolonged contact although I'm not sure about glycol since it is technically not a solvent. The mechanic was probably right in saying that if you catch it soon enough there would be limited damage.  I'm still waiting for my tranny fluid analysis although I have not had any tranny issues and the mechanic told me the fluid looked good.    Linda Hennessey

[Bill Sprague]

....... I'm still waiting for my tranny fluid analysis although I have not had any tranny issues and the mechanic told me the fluid looked good.    Linda Hennessey

Linda,

Would you please post some details?  Who is doing the fluid analysis?  Where are they?  How do you get a sample to them?  How much does it cost?

Thanks.

[John Hennessey]

I had Boyer draw the sample and they send it to Ziegler Cat in Bloomington MN. they have a lab on site for all types of testing.  Drawing the sample and the cost of the test was $26.

[George Harwell]

I purchase a fluid sample kit from my local Allison shop, draw the sample and send it off to Allison in Indianapolis via the post office. The label is pre printed with the address. The results are posted on the web via TRACKMYSAMPLE.com. I pull the sample each October and will continue as long as the fluid test good. The cost for the kit was around $50 this year. Last fluid change was July 08. The 03 Monterey turned 102,000 this past summer, hope to add another 100,000.

[Joel Weiss]

I've been using http://www.jglubricantservices.com/ for my oil and transmission fluid analyses for several years.  One of the owners is a former senior Allison technical guy who was largely responsible for the development of Transynd.  Their prices are lower than Blackwell the last time I checked (they include some things Blackwell charged extra for). They have an inexpensive pump for withdrawing samples.  My last transmission analysis was a year ago and the fluid had <0.1% water and a Total Acid Number of 0.62

[Tim Bentley Co-Admin]

Having been through a transmission failure I'll add my comments.  You cannot see if there is water in the fluid by looking at it. When my transmission was over heating, I stopped by an Allison dealer to have the fluid level checked.  The fluid was so clear that the tech had trouble seeing it on the dip stick.  Maybe if he had drawn out a cup full he could have seen the water content.  You would be really lucky to catch the water problem with a fluid analysis.  It only took a few hundreds miles to destroy my transmission, so you would need to analyze your fluid every few days on a long trip to catch the problem.

The best way to tell if you have a water problem is to be aware of your transmissions temperature.  I first noticed that I had a problem when my transmission  temperature went to 205 and stayed there for a couple hundred miles.  I knew that was high, it always ran at 195, except for long down hill braking.  Sometime after, the temperature went to 135 and stayed there.  Even thought a tech said my fluid was clear, I should have stopped at the 205 and not proceeded until I had the fluid analysis, at that point I believe we could have saved the transmission.

My advice:
Monitor your transmission temperature at all times, know what normal is for your coach, stop and have a fluid analysis if the temperature is even a little over normal for an extended period. Do not move until you get the results.

[John Hennessey]

Great info Tim.  Thanks

[Steve Huber Co-Admin]

Tim,
Good info! Now I've got to get to OR (next summer?) to get my Silverleaf reprogrammed so I can monitor tranny temp on the Drive display.
Steve

[John Hennessey]

I should mention one more thing the mechanic told me and that is that if the fluid is a pale pink it has been diluted. That tech should have been suspicious since the fluid was so clear. It should be red

[Stan Simpson]

Is it okay to mix OEM transmission fluid with synthetic?

Stan

[Edward Buker]

Stan it is O.K. to do so. The procedure for change to synthetic is to drain with a filter change which leaves a significant amount of the original fluid in the system as a mix. The second change with filters allows you to go to the full synthetic change schedule even though about 5% of Dexron in the fluid make up remains. The fluids are compatible.

Later Ed