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Transmission Trouble in Omaha

June 05, 2011, 02:28:36 pm

 This may be of interest to members that have a Vsmpc. While en route from Lower Mich. to Nebr.,I started to notice a higher than normal trans temp on the pc after traveling for several hours.This reading is the trans sump temp and should only increase AFTER using the retarder on long grades. As a few of you know, I monitor just about everything and ALL the other digital temps were normal. All the analog gauges on the dash were also normal,including the trans temp gauge which takes it's reading from the out flow of the retarder. You will always see an instant jump in temp on that one when using the retarder.On the first day, I called  the shop I trust in Lakeland Fl.  I got responses like "that's a new one"." Well that's strange ".Do not think bad of this shop.I still respect them.As the temp rose higher the next day,west of Des Moines, I decided to stop at Inland truck repair ,in Omaha.Their response was "that's a weird one","never seen that before". After many checks and eliminating the easy fix,and several calls to Allison, it was decided to drop the control module out of the bottom of the tranny and send it to surgery.They never had an  AAH HAA moment,,,,, .There were several probable causes and they covered all of them. The test drive was a success . The Inland truck people were super. They arranged for us to overnight in the competitors camp ground.( Cummings motors coach care ). The tech told me this was the cleanest ,best looking transmission, (inside and outside), that he had ever worked on. That kind of made me feel good. He said continued use would have  caused some major internal damage,which would have required a complete overhaul. I firmly believe my Vmspc is paid for now. I never would have known I had a problem until the smoke started .Please do not start to stress out .This obviously was a rare problem and may or may not be specific to the HD 4000 transmission. It was possibly an internal leakage from "O" rings ,possible blockage in an internal filter, or  too much oil in the wrong place. One very important fact,,,The oil level sensor will tell you how low you are BUT it will NOT tell you when it is over full. In this case ,the levels were OK  on both the sensor and the dip stick when we left FL.,but in Omaha, the sensor read OK but the oil was 2 gal over full on the stick. They can not explain how this happened as I have put over 2K miles on the coach before the temp rise started.Now, In two short trips ,every thing is OK. The real test will be after an all day drive.That will be July 5th. If anyone else has had a similar problem, I would like to learn more.
Gary O

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Re: Transmission Trouble in Omaha

Reply #1 – June 05, 2011, 02:49:07 pm

Thanks for the info Gary. From what I read of your post the only thing they found wrong was the transmission was overfull. Is that correct? I sure am glad you are in good shape now. Have a safe trip. Tell Sandy we said hello. Mark

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Reply #2 – June 05, 2011, 03:27:52 pm

Very informative and helpful topic.  Thanks for posting.  This has to be one of the few things that Gary O could not fix himself.

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Reply #3 – June 05, 2011, 05:15:07 pm

Gary, I for one, thank you for that meaningful report, yes I use the VMSpc too, but I also have turned the ISM from 450/1450 to the newer 500/1550 settings. Just returned home after a 750 mile round trip, the transmission never got above 194 deg. but noticed it would also go up slightly just from the throttle/power.  Am surprised as I thought it was locked up, not making heat.
Am hoping the additional 100 ft lb torque does not hurt it and yes it will get both filters and the 34 qt. TranSand change this week.
Please keep us informed as to the happenings, OK?
Many Thanks
Dave M

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Reply #4 – June 05, 2011, 08:29:49 pm

Gary,

How about some history? Did you or a shop change trans. fluid before the trip? Amount? Did you stick it in FL and Omaha with a level rig and at the same operating temperature? Ideas on where the extra two gallons came from?

I bought a car last month that had the transmission serviced at a big shop in Sacramento mid January. The car smoked on the way home and covered my wife's windshield behind me. When I stopped at Target, I thought it was going to catch fire from the trans fluid on the catalysts. Put it up in the air at home and found both ends of the trans were dry but it had pushed the extra fluid out the vent. TWO extra gallons. I did notice that there was an inch and a half difference in the dip stick level between a cold check and a hot check. The previous owner had just driven it to work in town and never got it hot. The shop looked at the wrong car specs when they filled it.

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Reply #5 – June 05, 2011, 09:22:29 pm

Just a little history. I did a complete service on transmission with the "gold " filters around 38K. Spring of 09, at around 90K, I did it again before I left FL.and this time I used the newer high capacity filters. This spring during a complete coach service, I found Trans oil leaking out the tail shaft.I knew that this problem was probably more than just a seal. Improper torque on the carrier bearing, large "o"ring, speed sensor seal, etc.so I had Trans Diesel in Lakeland do the repair. The bearing was OK but every thing else was bad. The tech. added 3qts. of oil. We BOTH checked the dip stick AND the level sensor. This was the first time in the life of the coach that oil had to be added between oil changes. But that's normal since there had been a leak. I rechecked everything again when we headed north. Rechecked at Perry, Ga and a month later at Readville, Tn. The next check was in a rest area in Iowa where the dip stick was 2 gal over full. Later, in the shop, after draining 2 gal, the dip stick was right but the level sensor showed 3qts low. While we were watching (approx.) 4 min, the level read OK and a recheck of the stick showed a rise of about 4" over full. Allison trouble shooters have no repair for this problem. It's not supposed to happen. Does this help or cause more confusion??? Gary O

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Reply #6 – June 05, 2011, 09:28:52 pm

Gary, If it keeps making oil, maybe you could sell the excess, a money maker for you ?
Sure makes no sense it keeps making oil.
What else is common to the transmissiohn fluid, coolant/water ?
Also does the engine oil cooler anywhere near the transmission cooler like the Detroit Diesel setup ?
Time to snoop real good.

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Reply #7 – June 05, 2011, 09:56:17 pm

My guess is that there is a transmission cooler inside the radiator tank, but I would think that the transmission fluid would discolor if it were exposed to water or antifreeze. Who knows, maybe not. Like Dave, I just don't see how else fluid levels could rise.

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Reply #8 – June 05, 2011, 11:31:39 pm

Gary;
    Sounds like a problem with the trans retarder???

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Reply #9 – June 06, 2011, 11:45:03 pm

Gary,

When the fluid was last changed was the amount in the torque converter considered when new fluid was added? When you did the manual fluid level check, did you use both the hot and cold check procedures found in http://healinghaitifund.org/SuperSante_Owners_Manual/Miscellaneous_Equipment/Transmission,%20Allison%20automatic%20OM2995EN.pdf  ?  Strange case you have here. Make sure you let everyone know when you get to the bottom of this.

I had a gearbox problem (between the engine and the prop) on a big geared Lycoming engine. Kept feathering while flying, including a couple of times on final. The Lycoming factory sent two guys out but also could not figure it out after a couple of days of testing. They finally referred me to a old retired guy in San Diego. He was 86 years old but lifted the gearbox out of my car trunk like it was a 5 lb sack of sugar (I should be in half his shape at that age). Had it all apart and found the problem in 15 minutes and fixed it in a few days. Goes to show the factory guys at Allison or Lycoming don't always know everything.

Good luck Gary!

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Reply #10 – June 07, 2011, 12:05:51 am

That is as bad  as having three green lights on final in a Bonanza ( first time ), and have the tower tell you the mains aren't down. After a go a round, every thing OK. They never did find a problem.
 Gary O

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Reply #11 – June 07, 2011, 01:00:01 pm

Gary, Always glad when all 3 rollers work good, on the Arrow, had case of left main light not working due to faulty Micro switch in wheel well being erratic. Always needed a visual from ground when that happened X 3 before found the micro switch issue, would work 5 times then miss 4 in row, then good again, pain in neck. 
Keep hoping all going well in the temp department and a happy trip.
Cheers

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Reply #12 – June 07, 2011, 08:04:52 pm

All  right you guys, learning to speak motorhome is tough enough but now you I have to learn pilot as well? You guys are tough but you do keep us on our toes. My U300 does have an aeronautical altimeter the former owner installed. See how fast I learn?

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