Allison Transmission Fluid Check Protocol

[4rickyg]

Checked my trans fluid through the dipstick today looks like I am a couple quarts low. The fluid is clear not red. Does this mean it is synthetic? Not Dexron 3? Which I think is usually red.

  Do I add the fluid through the dick stick tube? Allison 4000 series, temp was 160 when I checked. I could not get an accurate reading from the keypad it said l o 0 6. Wasn't sure what that meant so I went to the dipstick. Thanks for any info.

[timaz996]

The key pad needs the temp to be operating temp...I think 180. Read the manual and it should say. I don't the know the answer for color of fluid.

[Brian J]

Recommended trans fluid is Transynd 668. The color us red.

[David Pratt]

Allison recommends that the fluid be checked using the key pad for the best accuracy.

Instructions;

1 Park the coach on a level surface, engine must be running, shift to N (neutral) and apply parking brake.

2. Let the engine idle for at a minimum of 2 minutes if engine is already at operating temperature or until the transmission fluid temperature is at 140 deg F or above.

3. Push simultaneously to enter diagnostic mode and fluid level check.

4. If you get a "-" in the display window of the shift pad it will be followed by a countdown that starts at 8 and is normal.

5. "o L" will be displayed, ("o L" represents "Fluid (Oil) Level Check Mode"), followed by a "o K". The "o K display indicates the fluid is within the correct fluid level zone. If a "L o" is displayed instead of "o K", ("L o" represents "Low Oil Level"and will be followed by the number of quarts the transmission fluid is low. EXAMPLE: o L Lo 02. Where 2 indicates that you are two quarts low. Adding two quarts of fluid will bring the fluid level within the middle of the "o K" zone. If the fluid level is hi, "Hi" will be displayed followed by the number of quarts it is high.

The maximum quarts low that will be displayed is 5. In this case You should add one quart of fluid at a time until the fluid level gets within the "o K" Zone.

When your check is completed just press N (neutral) to exit the diagnostic mode.

The above procedure is covered in your Allison Transmission Owners Manual and there are You Tube videos describing the procedure.

[MPfeif]

Transynd is (one of) the recommended fluid, definitely not dexron. I haven't seen it in less than gallon quantities, and I paid $50 for it a couple years ago.

Last time mine was in the shop, they used Mobil 1 DELVAC, another synthetic approved for Allison transmissions.

Here's the link to all the approved fluids https://www.allisontransmission.com/parts-service/approved-fluids/on-highway-fluids

It is red, though it is a less intense red than you may be used to seeing. wipe the stick with a white towel, and you'll see some red/pink.

My experience was the key pad check was not very accurate for a reading of 2 qts high ... I pulled 0.5 qts out and the key pad check was happy. It was reading high on the dipstick before pulling 0.5 qts out, and in range after.

Per the Allison Transmission Owners manual, I'm trusting the key pad check more than the dipstick.

Yes, I know why it was high, the shop overfilled it a bit after a service.

You add through the dipstick, if you're using the vertical dipstick tube. Some have two dipsticks, one running horizontal quite a ways to be accessible from the back of the engine, and another (vertical, or mostly) reachable though the floor hatches.

[jacwjames]

5 hours ago, 4rickyg said:

Checked my trans fluid through the dipstick today looks like I am a couple quarts low. The fluid is clear not red. Does this mean it is synthetic? Not Dexron 3? Which I think is usually red.

  Do I add the fluid through the dick stick tube? Allison 4000 series, temp was 160 when I checked. I could not get an accurate reading from the keypad it said l o 0 6. Wasn't sure what that meant so I went to the dipstick. Thanks for any info.

The coach has to be parked and stationary for several minutes for it to read correctly.  If you try and check to early it will show a count down. 

Before I'd add any oil I'd drive it to get the temp up and then park and wait while the engine is idling, after ~5 minutes check the level using the shift pad.   If it says add 2 I'd add 1, drive and check again. 

Edited 22 hours ago by jacwjames

[georgecederholm]

16 hours ago, 4rickyg said:

Do I add the fluid through the dick stick tube? Allison 4000 series, temp was 160 when I checked. I could not get an accurate reading from the keypad it said l o 0 6. Wasn't sure what that meant so I went to the dipstick. Thanks for any info.

Looks like the keypad is actually working and told you it’s 6 quarts low. Testing via the dipstick is not recommended, as you’ve found out, because the keypad is more accurate. 

Yes, you add Transynd 668 through the dipstick tube. I use a metal funnel with a flexible neck about 18” long because the tube opening isn’t a straight shot down from the floor opening. In general, it’s recommended to add slightly less than the OL LO number, drive it, and test again before adding more. This helps prevent over-filling.

[David Pratt]

The method I use to check the fluid level with the key pad is, I will check the fluid level after a trip before I shut down the engine  After I park the coach, I will let it idle while I connect the shore power, water and sewer hose. The Transmission is already at operating temperature this method allows time for the fluid to settle down.

[4rickyg]

When you check with the dipstick should the engine be idling or off?

[Tom Cherry]

33 minutes ago, 4rickyg said:

When you check with the dipstick should the engine be idling or off?

OFF

BUT…you have so much info above.

Allison WARNS against trusting the Dip Stick.  That is why the Key Pad method is the PRIMARY or RECOMMEND Method.

VERY IMPORTANT to get up to temp.  Probably need, based on ambient, to drive at least 25 miles.  I have digital gauges and get it up to 195….which is what Engine is running.

NEXT….auto level or manually level…..then follow the for key pad use.

NOW….comments from Allison reps and Allison tech support.  Your tranny had the original Transynd.  There is a NEWER ONE….the 668…I think is correct…..supposedly it is backwards compatible….but read or call Allison.  Most choose OEM Transynd.  The only OTHER trusted fluid…the Mobil Delvac.  Some Allison certified repair shops have a “non branded” or different name fluid….that they SWEAR is supplied yo them from Allison.  MAYBE??  But XOM Mobil submits samples and Allison TESTS theirs.  There is a LIST of ALLISON CERTIFIED Brands & “Names”…..NEVER TRUST the label….even though it say TES 295 or maybe TES 668.  Check the Allison site.

Allison tech support says to ONLY add half quart max….NO MATTER what the Keypad says (in Quarts).  Drive it for 25 more miles…..then check….  The range or working range, internally, is wide and the DIPS are not to be trusted…but you also verify the keypad a few times,

Case in point.  OTR shop let mine drain too long.  Way more than the 19 Quarts ran out,  Allison says….drop Pan….service…..put on pan…refill with 19 QT.  Mine was low,  I THINK it read 3.  Drove it….after adding ONE….Keypad said OK…Allison said OK THAT IS COOL.STOP!  Add NO MORE

Some 10K later….after a cross country trip…..I noticed a more abrupt downshift from the exhaust brake.  Bothered me.  The Keypad said OK.  Added 1/2 quart…..drove maybe 50 miles….slight improvement.  Did that again….keypad still said, as Allison pointed out, OK.

I put in the THIRD “pint” or Half Quart.  BINGO….smooth as silk….and like before.  All I know….it fixed it….and I followed Alison advice…..and keypad said OK.  That would be a out 2 1/2 quarts over the “19” fill….no way of knowing how much drained out.  It runs and shifts smoothly…just like from day one…

Have 70 K on it.  Been serviced TWICE….gonna be awhile before the pan is dropped….

[Benjamin]

https://www.wanderlodgeownersgroup.com/downloads/PT-42 Files/GPS & ENGINE MONITOR/http___www.allisontransmission.com_servlet_DownloadFile_Dir=publications_pubs&FileToGet=OM2157EN.pdf

Pg 38 pdf, pg 33 manual

A check with the engine off is to check that there is enough oil in the trans to safely start the engine.  A cold check with the engine running checks that there's enough oil to run the trans till hot.  The hot check is the best check. 

As the transmission plates wear, the pistons move further to apply the clutches and brakes, so the transmission requires more oil when worn than when new.  Some of that oil drains back to the pan when off, that's why hot running is the best check of fluid level. 

[David Pratt]

This is the proper procedure for checking the fluid level using the Dip Stick. This is copied out of the Operators Manual for the Allison 3000 and 4000 series Transmission Page 49.

 

COLD CHECK
The Cold Check determines if the transmission has enough fluid to be operated
safely until a Hot Check can be made.
NOTE: The correct fluid level can not be determined unless the
transmission is in a level position.
CAUTION: DO NOT start the engine until the presence of sufficient
transmission fluid has been confirmed. Remove the transmission fluid
dipstick and be sure the static fluid level is near the HOT FULL mark.
CAUTION: The fluid level rises as fluid temperature rises. DO NOT fill
the transmission above the “COLD CHECK” band if the transmission
fluid is below normal operating temperatures. During operation, an
overfull transmission can become overheated, leading to transmission
damage.
A cold check may be made after initial start-up and the presence of transmission
fluid has been confirmed (the sump fluid temperature is then typically 16°–49°C
(60°–120°F). To perform a COLD CHECK, do the following:
1. Start the engine and run it at idle (500–800 rpm) in N (Neutral) for about
one minute.
2. Shift to D (Drive) and then to R (Reverse) to clear the hydraulic circuits of
air.
3. Shift to N (Neutral) and leave engine at idle.
4. Move the vehicle to a level surface, put transmission in N (Neutral), and
set the parking brake.
5. With the engine idling (500–800 rpm), shift to D (Drive) and then to
R (Reverse) to clear air from the hydraulic circuits.
6. Shift to N (Neutral) and leave engine at idle.
7. Remove the dipstick and wipe it clean. Insert the dipstick into the fill tube,
pushing down until it stops.
8. Remove the dipstick and observe the fluid level. If the fluid on the dipstick
is within the COLD CHECK band, the level is satisfactory. If the fluid
level is not within this band, add or drain fluid as necessary to bring the
level within the COLD CHECK band.
9. Perform a Hot Check at the first opportunity after normal operating
temperature (71°–93°C; 160°–200°F) is reached.
 

 

[4rickyg]

The reason I am trying to check with the dipstick is. The last time I had it at the Detroit Allison shop they told me they could not get a reading from the keypad and they used  the dip stick to check it. I read on here somewhere That The keypad will only tell you up to five quarts low, And mine said lo 06 Which I would imagine in six quart? When I checked it last night with the dipstick  after everything cooled down it was in the proper cold level range.

So I think at this point I'm just going to leave it alone and after I get on the road when I stop for fuel I will try the keypad again. Thanks everyone for all the great info.

[96 EVO]

I don't bother checking mine with the keypad unless the tranny is right up to operating temp. 190F+

[georgecederholm]

1 hour ago, 4rickyg said:

The reason I am trying to check with the dipstick is. The last time I had it at the Detroit Allison shop they told me they could not get a reading from the keypad and they used  the dip stick to check it. I read on here somewhere That The keypad will only tell you up to five quarts low, And mine said lo 06 Which I would imagine in six quart? When I checked it last night with the dipstick  after everything cooled down it was in the proper cold level range.

So I think at this point I'm just going to leave it alone and after I get on the road when I stop for fuel I will try the keypad again. Thanks everyone for all the great info.

Rick G,

That seems like a good course of action, although I’d be concerned about why the shop couldn’t do the keypad test. It won’t work under 140°F but they should have known that. Was this a big distributor shop of an independent?

The internet is full of good information and suspect information, and earlier posts quoting from Blue Bird and Allison sources seem to contradict the “conventional wisdom” thrown our here on Monacoers in the past: “don’t trust the dipstick because Monaco supplied that, not Allison”. I’m not sure what to believe anymore, but I always follow the procedure for the keypad and have never been let down.

One other factoid I’ve heard over the years is that the Allison 4000 keypad trick will work up to 8 quarts low (against a 10 gallon full level), while the 2500/3000 series would only work up to 4 quarts low (5 gallon sump). I believe you mentioned a 4000 series, so L O 0 6 if at temp and level should be reliable.

[georgecederholm]

2 hours ago, 96 EVO said:

I don't bother checking mine with the keypad unless the tranny is right up to operating temp. 190F+

OK; I’ll bite. Why? Just curious, as my Allison manual says “over 140°F”. Is a higher temperature more accurate? Or is “over 140°” hard to judge on the dash gauge?

And, what transmission do you have? My 4000 series rarely gets over 180°F. On today’s drive west on I-80 through Pennsylvania’s rolling hills, I saw 165° to 178°.