Transmission Oil Change

[Edward Buker]

I would like to do my first pass drain and fill conversion to TranSynd on my Allison 4000 this spring. The coach manual (2002 Marquis) indicates a 39Qt fill capacity with a drain and filter change. I was unsure of how close the 39Qt estimate has proven to be from experience. We do not a have a means to easily measure the number of quarts that would have been drained out. Like to avoid the possibility of overfilling and I am unsure of how much to put in before taking a run to warm the fluid up enough to get a reading from the console.

I was considering measuring the existing fluid location on the dipstick cold after sitting. When filling with the new fluid, maybe at 34 quarts, I was considering starting the engine just long enough to fill the passages and filters and then after a short period of "drain" time get a cold fluid dipstick measure. Then fill the Allison to close to the prior measured level before heading out for a warmed up fluid console measurement.

I would welcome any experience on what the fill amount has been or if there is a flaw in the cold fluid dipstick plan for a preliminary measurement. I know the final measurement needs to be done warm with the engine running. It would be nice to skip the whole cold fluid measurement if a similar fill amount has been observed...

thanks Ed

[Bruce Benson]

Ed,

Let me start by saying that I have been forced to learn about Allison fluid and now consider myself to be somewhat of an authority.  

In December of 2008 I had a company in Texas called RV Mobile Lube come out and service my unit, including a transmission fluid change.  The long and the short of the story is that the coach never moved (until the tow truck came) after they drained the transmission.  Later, when I measured it, I found 23 quarts total in it.  That is after they had added more when the first testing proved futile.  I am currently suing them for the damage that I believe they caused to the transmission.

My C-12 has a shallow pan.  I am not sure about yours.  Allison made them both ways.  A shallow pan is 2" deep and a deep one is 4" deep.  You can also call Allison with your transmission serial number and they will tell you which you have.

There is additional oil in the inter-cooler.  It took 44 quarts to refill my entire transmission after it was repaired.  Allison says it should take 40, so 4 quarts are outside of the transmission.  

Allison says that a deep pan needs 39, as you stated, but a shallow pan only needs 31.  On my coach, I would add the 31 to the 4 and come up with about 35 quarts for a refill.  

Yes, it is OK to be a few quarts low on start up.  No, it is far from OK to be real low on start up.  The Allison bulletins tell you not to use the dip stick as a measure when filling.  I can tell you from hard experience that is good counsel.  Until the fluid is circulated in the transmission by the charge pump, the dip stick is useless.  The specific procedure they recommend is to measure the fluid removed.  Throughout the failure, my dipstick showed overfull but when we drained and measured only 23 quarts came out.

If you are low you will burn up the charge pump and you can kiss 10 grand goodbye.  If you over fill, you will not damage the transmission unless you run it hard before you adjust it back down.  You might also make a mess if you overfill as it does have an overflow port.  At the first start up, immediately put the selector in D then R.  If you do not feel it engage, shut it down and rethink!  You will need to idle it in D for a few minutes to warm it up enough to get an electronic reading.    

I think I would go to the full refill number for the transmission(31 or 39), at a minimum, before I started the engine.

[Edward Buker]

Bruce,

Thanks for the insight. I could add a gallon of TranSynd and then refill that gallon jug from the drained reservoir pan until I am very close to having the drain pan empty...just seems like a pain with lots of chances for spilling fluid. Hard to tip a 39Qt reservoir and fill a gallon jug, one at a time.

I did measure from the pan seam where it joins the main casing and that was 4 inches to the bottom so I am pretty sure that I have the 4 inch pan. I was a little surprised that the cooler seemed to drain 4 additional quarts in your case and the manual capacity does seem to account for that at 31 and 39 quarts. Maybe some additional experience on this job is out there....

Wouldn't it be nice to have a funnel arrangement with a calibrated paddlewheel built in it that gave you a readout in quarts of the fluid drained...

Later Ed

[Bruce Benson]

The 31/39 are Allison numbers.  According to the Allison publications they do not include coolers or external hoses.  Check this publication for details:
http://www.allisontransmission.com/servlet/DownloadFile?Dir=publications/pubs&FileToGet=SA5429EN.pdf

It does not surprise me that your coach is different from mine.  Beavers seem to be like that and then you throw in the Monaco factor.  I have heard that cooling was a factor on my model year and that the rear door was changed.  Perhaps that is a reason for going to the 4 inch.  I suspect it was whichever was cheaper on that day though.  If you want to know which you have without crawling under the coach (obviously not for you, Ed), I found this link just now at Allison where all you need is your serial number and it will provide you with the build options for your transmission:
http://www.allisontransmission.com/myallisontransmission/mytransmissioninformation/

My cooling is an external heat exchanger mounted in line with the engine coolant going to the radiator.  

I would be comfortable going with an initial fill of 38 or 39 quarts in your case.  I found that buying it from the parts counter at the Allison distributor was fairly reasonable, considering.  I think I paid around $36 a gallon but that was a couple of years ago.  You will need to buy at least 10 gallons anyway, so you might as well start with 38 or 39.

We measured ours in 5 gallon fuel cans.  With what I know now, I would not measure it next time.  

[Edward Buker]

Bruce,

Thanks for all the helpful advice. I called a local International dealer that stocked the high capacity filter kit and that was priced around $65 and the TranSynd was $36 a gallon so I thought that was fair pricing. I will verify the pan size via Allison and expect to start out with around 38qts. Monaco might have opted for the deeper pan as part of the upping of the C12 to 505HP given they already seemed to have some heat issues.

My rear hatch is completely louvered and vented. Works so much better than my 89 Beaver did with a 3208 which had very limited venting....  really hot bedroom after a days run.

Time to get back to work here. I'm putting up some crown moulding today, just love dealing with all those compound angles.

Later Ed

[Marty and Suzie Schenck]

I have changed the fluid on my 2002 Patriot Thunder C-12 455hp 4000 Allison 2in valve body and it has never taken more than 32qrts. I have done this 3 times and it comes out the same each time. This includes changing both filters, filling with 30qrts. fluid, bringing it up to temp and then checking fluid level with the touch pad. Touch pad reads 2qrts. low so I add the 2qrt. Recheck touch pad and it reads OL OK. I also check the touch pad oil level each time I take the coach out. These figures would be different for a completely empty tramsmission and cooling unit system.
Marty

[Gerald Farris]

The transmission on my 2000 Marquis takes 32 quarts (8 gallons) of transmission fluid for a drain and refill with filter replacement.

Gerald

[Edward Buker]

 Gerald, I assume that you have the 2 inch pan and that capacity would fit with the other folks input. Seems like the estimate in the manual is pretty close for each of these pans. Soon as the weather gets a little warmer I will get to it. Thanks to all for the insight.

Later Ed