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Mystery · 12-21-2013, 08:14 AM

Ok on my previous thread I reported that my tranny was shuddering while ascending 6% and more grades in NC mountains. Took it to Allison service and they said fluid was low and dirty so we did full service. On my return trip to NC mountains it shuddered but not as bad as before. Tranny oil temp never exceeded 142. Feels like a shudder and hesitation. Could it be torque converter or even an engine issue, Seems to run great on flats and rolling interstate hills. Even climbed a long grade near my home in Ga with no probs and did it faster than before service. Could it be a sticking valve body issue? Any input is appreciated! Thanking all in advance and Merry Christmas!

Mystery · 12-21-2013, 08:17 AM

Quote:

Originally Posted by Mystery

Ok on my previous thread I reported that my tranny was shuddering while ascending 6% and more grades in NC mountains. Took it to Allison service and they said fluid was low and dirty so we did full service. On my return trip to NC mountains it shuddered but not as bad as before. Tranny oil temp never exceeded 142. Feels like a shudder and hesitation. Could it be torque converter or even an engine issue, Seems to run great on flats and rolling interstate hills. Even climbed a long grade near my home in Ga with no probs and did it faster than before service. Could it be a sticking valve body issue? Any input is appreciated! Thanking all in advance and Merry Christmas!

Also, when it went for service there were no diagnostic code thrown. They told me they did extensive road testing too.

palehorse89 · 12-21-2013, 08:33 AM

Quote:

Originally Posted by Mystery

Also, when it went for service there were no diagnostic code thrown. They told me they did extensive road testing too.

My Allison use to run cool due to my Hydraulic fan speed running to fast, after adjusting the "priority valve" on my system and talking to Spartan techs, my tranny temp. is up around the temp. of the coolant (180 deg.) I never had a problem with the Allison running around 140 deg. but my fan was roaring at a idle. Did they say anything about the temp. of the tranny oil?
Reading here: http://www.irv2.com/forums/search.php?searchid=5454861

From the Allison Manual:

Typical continuous sump operating temperature: 200 deg. F

Steve Ownby · 12-21-2013, 09:14 AM

Quote:

Originally Posted by Mystery

Also, when it went for service there were no diagnostic code thrown. They told me they did extensive road testing too.

Did they make any comment about how it performed during their road test? You might try unhooking the battery ground cable for an hour or so and let the TCM reset. The electronics use adaptive technology and will reset to OEM parameters and then relearn your driving style. Long shot but cheap. It actually could be the engine your are feeling. Since the torque converter is locked mostly it makes it more likely you would feel a miss or hesitation. When fuel filters start to plug up you will get issues when on a hard pull first. Let us know how it shakes out.

Mystery · 12-21-2013, 10:51 AM

The techs said it ran well on the road test. Had computer hooked to tranny for diagnostics. I was beginning to think engine issue too. I do trust these techs but will be two weeks bf I can take it back. Tranny always seems to run cool. Fuel filters were changed last spring and driven 5k since then. The silver leaf never showed lock up releasing. I have a 9% 1.5 mile climb to my home in NC mountains and it got down to 25 in 2 when I usually pull it in 3rd at 35 to 38.

slickest1 · 12-21-2013, 11:36 AM

I would check your motor mounts. Especially on the passenger side. Had that happen on large trucks.

Mystery · 12-22-2013, 10:45 AM

Would problem motor mounts cause shuddering and deceleration? Motor seems to be running well. Shuddering makes sense but loss of speed on a grade?

1ciderdog · 12-23-2013, 05:43 PM

I almost hate to mention this but the indication my HEUI pump was failing was the engine periodically felt like it was misfiring. Hope that is not the problem.

Tha_Rooster · 12-23-2013, 07:01 PM

If you give it more acceleration does it down shift and quit shuttering.

Mystery · 12-24-2013, 10:11 AM

In all occasions I had it to the floor bc I was climbing steep grades. No problems w down shift, but at downshift it lost speed (2 to 3 mph). Motor had no problem turning rpm except for shuddering. Problem only appears when climbing steep grades w load on engine. Flats and rolling interstate hills are no problem. Beginning to think motor instead of tranny.

Mystery · 12-24-2013, 10:12 AM

Shuddering did not seem to effect rpm.

Mystery · 12-24-2013, 10:14 AM

Heui pump failure would present symptoms on flats too? Not sure?

palehorse89 · 12-24-2013, 10:20 AM

Now after you posting this, I had my Cummins do it years ago, the same thing you are stating, did it a couple of times one summer then it when away. Still don't know if it was a fuel problem, shot of bad fuel, fuel filters...... not sure. Serviced it come fall before storage and have never had it do it again. Does it seem like it is shuttering from lack of fuel under a hard pull? I would start with new filters and cut open the old ones to see what is inside of them stuck to the paper media, might give you a clue to what is going on.

Mystery · 12-24-2013, 10:56 AM

Palehorse , thank you I will certainly have cat check the filters. I had service about 2000 miles ago and did purchase fuel down in Florida at a station I had never used before. Shuddering did start after this but not until climbing steep grades in NC. So I did not correlate the problem. I certainly hope it is the fuel filters. I had oil analyzed less than 5000 miles ago and it was in very good shape so I hope Heui is in good shape.