Violent Shudder

[bradleyj]

My '05 CRD has about 250,000 miles on it. I had a Euro torque converter and new front pump installed when I got my GDE Eco tune at 150,000 miles. Even with the Euro TC I would occasionally get some TC shudder when towing heavy loads uphill but it would stop as soon as I backed off on the accelerator. Didn't happen often. Several times over the last week or so when driving at highway speeds (not towing; just driving) the vehicle will shudder pretty violently, kind of like going over really deeply cut rumble strips. I'll pull over and stop and then when I drive away again everything's fine. I'm just holding a more or less constant speed when this happens, not accelerating hard. Does this sound like a bad torque converter? Trans fluid level is good and fluid looks clean, although it's now got 100,000 miles on it. Any other ideas what might be causing this? It's a pretty severe shudder. Very alarming.

 

[rjkj2005]

Did you check your u-joints?

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[bradleyj]

It just happened again this morning and I paid close attention to what was going on so I've got more info. I was on a moderate uphill grade when I started feeling a light shuddering that quickly developed into a full-blown shudder. When I took my foot off the accelerator the shudder stopped and it started again when I got back on it. Once again, I pulled over, came to a complete stop, looked under the vehicle to see if I could see anything obvious and then I drove off with the problem not occurring again.

A bad u-joint is a good guess but there are a few things that are making me think it's not a u-joint. First, I replaced both rear driveshaft u-joints and the front driveshaft last fall when I replaced the transfer case. Could still be a defective u-joint I suppose, but not too likely. What mostly makes me think it's not a u-joint is that the shuddering seems to be related to engine rpms as opposed to wheel rpms. Even when I was down to less than 10 mph it would shudder just as hard when I got on the gas as when I was going 60. It's acting like it's a problem somewhere between the engine and the transmission. The transmission's never had any work done on it so a problem with it certainly wouldn't surprise me, but the symptoms seem to be more indicative of a problem with the torque converter. Maybe the torque converter clutch isn't fully disengaging? It seems to happen when I get on the gas to maintain speed when I start going up a grade and these are conditions when the TCC would be unlocking, right?

 

[TwoBobsKJ]

What happens when you hit the Overdrive button? Does the shudder stop then?

Going 100K miles with no trans fluid change is a long time. If the fluid still looks and smells fine that's a good thing, but I'd take it to a good, reputable ****** shop and have them put it on their scanner and drive it around. They will be able to tell if the input speed from the engine and the output speed of the ****** match up; if there's a mismatch they will look at the torque converter readings, each of the clutch packs (representing each of the gear sets) and determine where the fault is.

Go with the best ****** shop in your area. There are shops that just want to swap in a new or rebuilt unit without really diagnosing the issue.

Bob

 

[bradleyj]

I'll try hitting the OD button next time this happens to see if the shudder stops. I didn't try that. That should disengage the TCC and downshift, right?

I just wish this wasn't an intermittent problem! I can drive it all day and then all of a sudden it'll happen. I've got to see if I can figure out under what conditions it occurs so I can tell the shop how to reproduce it.

 

[turblediesel]

I'll try hitting the OD button next time this happens to see if the shudder stops. I didn't try that. That should disengage the TCC and downshift, right?

I just wish this wasn't an intermittent problem! I can drive it all day and then all of a sudden it'll happen. I've got to see if I can figure out under what conditions it occurs so I can tell the shop how to reproduce it.

Shouldn't be in OD when towing with a CRD. I cheat a little on long downhills.

You might be getting air in fuel. Next time it happens try pumping the pump on the fuel head and bleed the air out. Many places for air to get into a CRDs fuel system. LOST JEEPS has volumes of info on the problem and solutions.

My jeep got the bad shudders one night at 30° below zero halfway to Anchorage one night. I thought the engine mounts broke.