Non-Vented tranny dipstick

[hogbody]

Took by 2003 to the stealer to find out why there was tranny fluid blowing out the top back of the tranny all over the transfer case and under the truck. They diagnosed it with a non-vented dipstick. They say with this dipstick pressure builds up and blows fluid out the relief hole. The new vented dipstick that they have on order will prevent this by venting the pressure. They said there was a bulletin out on the issue.

Of course I feel like a unvented dipstick after I had them service my tranny and they changed the spin of filter charging $25.41 for the $8 filter and .5 labor to the tune of $37.50. I became a vented dipstick to the service manager after I got my bill.

[Kennedy]

Wonder if they replaced the magnet when they changed the filter.

First I've heard of vented dipsticks. They sure seem to seal on my trucks...

[More Power]

Yes, I've read where GM did introduce a vented dipstick for the Allison, due to ATF exiting the trans vent. This may be an issue if the Allison gets hot, and why most don't have this problem.

hogbody, Under what conditions did the Allison lose ATF with the original dipstick?

Jim

[hogbody]

I have a 2003 D/A CC with 30,000 miles. The leak occured during a trip where I was pulling my 9300 lb. trailer. I was in eastern oregon and pulling some fairly steep grades between Fossil and Antelope. I drive very conservatively. I was using tow haul. The tranny guage never showed any over heating nor did the truck. I don't recall it getting much over 200 degrees. It usually runs lower than that when pulling. There were no indications of tranny problems.

When I got home I noticed that something had sprayed on my trailer. I started looking around and found fairly fresh ATF from the rear of the tranny back and the bundle of wires on the left side was wet.

It was down about 1 qt.

The repair order shows TSB #03-07-30-054

I posted on the board at the time and was told by several that sometimes pressure causes venting when the tranny is full of atf and it gets hot.

Let me know if you thing there is the potential of any problems.....my dealer is not very knowledgeable.

You would think the labor for a transmission filter change would be included when they flush and refill the tranny for it's service...... It was a seperate labor charge....the charged for a trans flush kit and the atf and the bill came to $119. and then they added the time and charge for the spin on filter $64.79.....beats the hell out of me.

Thanks, Larry

[More Power]

Larry, Routine trans service cost at the dealership is likely based on the 4L60/4L80, which includes the ATF and internal filter for those transmissions. The Allison uses more fluid and a spin-on filter, which adds to the standard rate.

I know the dealer coupons I get from our local GMC dealer indicate diesel service and some tansmission/transaxle/transfer case service is higher.

Jim

[hogbody]

The cost of the service is water under the bridge at this point. Next time I will ask more ??? I had a spin on at home and would have done it myself if they had mentioned it.

Is my tranny ok. I'm very careful with how I pull. There was no burnt smell to the ATF when I checked it and added fluid.

Would you suggest trans synd on the next change (55-60,000) and the deep pan?

They called and I get my new dipstick on Friday!!

[madmatt]

FYI, the vented dipsticks also help to combat torque convertor drainback and is mentioned in that bulletin.

[DA BIG ONE]

A little side note here; Make sure your tranny vent line is in place in case of high water because now w/vented dipstick water has an even easier task getting in and causing issues.

Lots of times I find even the dealer forgets to install vent lines after major service.

[letsgo]

Could you PLEASE explain where this vent line is attached, location that is???? (this is new to me, but then what isnt)

thanks

drive safe

[DA BIG ONE]

Originally posted by letsgo:
Could you PLEASE explain where this vent line is attached, location that is???? (this is new to me, but then what isnt)

thanks

drive safe Some trannies have a little stub w/vent cap attached, others have an actual vent line w/hose running up firewall to a remote vent cap. Vents are usually located at top of transmission case, & the following; t-case, front diff, & rear diff, brake master cyl, hydro boost, steering pump.

In military fording configurations the vents go to a central location (manifold) which senses water pressure which in turn switches from open venting to closed vent attached to crankcase vent system.

Water rushing into the vent on your tranny, or any other big bucks component will dent your pocket big time, if you have no warranty, or insurance!

I would find it strange for allison not to have a vent as described above, perhaps it is too small for application, so, the dipstick vent.

[oyazi]

Originally posted by More Power:
Yes, I've read where GM did introduce a vented dipstick for the Allison, due to ATF exiting the trans vent. This may be an issue if the Allison gets hot, and why most don't have this problem.

hogbody, Under what conditions did the Allison lose ATF with the original dipstick?
Jim I had the same experience on a trip 2yrs ago. Didn't have a clue what was going on. Stopped in Lake Huavasu and was a qrt low. The fluid was all over the drivers side of the tranny & transfer case. The tranny vent question did enter my mind but the temp was < 200* and it was wintertime. Was towing a 4K# TT. Upon return home, I did take it in to a dealer who only reflashed it. Said to try it out and if an issue they would dig further. The same trip the following yr (CA ~ TX ~ CA) was uneventful. The tech said he was a factory trained master tech on the Dmax and expressed confidence at the time and subsequent performance seem to back him up. I am certain that heat was NOT an issue. That trip thru the SW was Jan 2003 @ 'near' record cold spell (snowed in Las Vegas)and the TT was a light load for this truck.

This had happened on our return from TX when the cold temps had abated a lil. Going was very chilly 12*F in Wilcox AZ. The return trip was 10 days later. I still monitor the tranny, transfer case etc and seems to be a bygone issue. Still scratching my head over it ~ weird. Would be interested in hearing some reasonable theories.

This is the first I've heard of vented dipstick ~ and no, I've no drain-down issue.

[ 10-01-2005, 05:58 PM: Message edited by: oyazi ]

[Jim Brzozowski]

When they say check your trans fluid Hot, they mean Hot. If your transmission shows full to the top at only 150 degrees on the gauge its too full.ATF as with all liquids expands at it heats up, that expansion takes room, thus a higher level occurs when you are pulling hard and the fluid temp. is up. I've blown fluid out of the old 4L80E several times until I learned not to put too much in. The best time to check fluid is when you are pulling hard and the temp is as high as it will normally get, the problem is there is usually no level spot to do so. I've never blown any fluid out of the Allison. The critical thing about having that happen is that once it starts to blow the fluid out the vent it seems to start a syphoning effect and tends to pull a little more than it should before it becomes static again thereby self leveling itself to the correct amount, but not that much is usually lost. It takes very little fluid blown out under a truck to show up real good once you spot it, especially if you drive through some dust.

[Kennedy]

Originally posted by letsgo:
Could you PLEASE explain where this vent line is attached, location that is???? (this is new to me, but then what isnt)

thanks

drive safe There is none on the Allison. It has a disc vent on it. The transfer case has a vent hose that runs up to the upper bellhousing bolt.

[DA BIG ONE]

Originally posted by kennedy:
</font><blockquote>quote:</font><hr />Originally posted by letsgo:
Could you PLEASE explain where this vent line is attached, location that is???? (this is new to me, but then what isnt)

thanks

drive safe There is none on the Allison. It has a disc vent on it. The transfer case has a vent hose that runs up to the upper bellhousing bolt. </font>[/QUOTE]JK is it designed to keep out water, or?