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Shuddering of '98 Merc Villager

My '98 Villager started shuddering at about 35-40 MPH…it feels like the road is corrugated and is fairly violent. The problem is intermittent; it has happened twice to me. My mechanic can’t make it happen.

Two weeks ago I drove through a rainstorm, parked the car in the garage for two days, and found the right rear tire frozen. The mechanic said the brake pad was rusted onto the wheel. He cleaned it up, replaced the wheel cylinders and it seemed to be OK. Is this related? maybe?

The rear brake is not at all likely to be related. You need to improve your description of the shudder. Ok, so you’re driving along - accelerating (hard/soft)? decelerating? just maintaining speed? - at around 35-40. The van starts to shudder, and you …? and then the van…continues to shudder? Stops shaking when…?

Is there a check engine light? How many miles are on the van and are all of its basic maintenance items up to date? Include in the basic maintenance info the service history of the transmission. Has the transmission ever been serviced? Has the fluid been checked?

I am just driving along, probably decelerating slightly. I don’t think I touched the brake pedal but I can’t be sure. When the shuddering starts, I slowed down and it stopped. When I accelerated again it started again on one occasion but not the other.

The van has 148K miles, it has been an excellent vehicle (best I’ve ever owned). The transmission has never been serviced – I don’t know whether the mechanic has checked the fluid level, but I’ll find out. There is no engine light showing. The brake pads, etc are in great shape, the mechanic is checking ABS this morning.

Thanks for your interest.

Hmmmm…148K without a transmission service is not so great, though making it to 148K w/out a service is an accomplishment. The reason I asked about the transmission is that one thing this could be is torque converter clutch (TCC) shudder. For many designs 35-40mph is a magic number - if you hit steady cruising at or above there the TCC locks the engine and transmission together to turn at the same speed. If you decelerate or try to accelerate the TCC unlocks. Problems at locking & unlocking often show up as what you describe.

If your mechanic is not a transmission specialist, I would take it to one - at the very least to have things checked over and have the pan dropped & filter changed.

If this shudder has nothing to do with the brakes then there is no point in checking the ABS system - unless it also has traction control.

An addendum to cigroller’s reply. When you are feeling the shudder, lightly touch the brake pedal enough to make the brake lights come ‘on’. If the shudder goes away, you have another clue that it might be TCC shudder. The ECM will cancel torque converter lockup command when the brakes are activated.

Many thanks to cigroller and Researcher for your help. here’s an update…

I went to a transmission shop last week and talked to Guy A, who told me “you don’t just change out a torque converter, you have to overhaul the whole transmission, for around $2K. But a simple transmission service is $120, why don’t you do that first”. So today I brought my car in for service. Guy A wasn’t there so I talked to Guy B. He drove the car, came back and said “it’s definitely a torque converter problem; I can make it happen anytime I want just by stepping on and off the gas at around 50mph”. He didn’t think much of my chances of getting by with a service, but I had it done anyway, including Lube Guard additive. Then he said, “A new torque converter would cost $450-500 for labor and $250-300 for parts. You DON’T have to overhaul the whole transmission”.

So the forces of chaos are hard at work… My question is "can you change the torque converter without overhauling the transmission. If so, is $700-800 a good price range?

Thanks again!

The general answer is that of course you can change the torque converter without overhauling the transmission.

The harder question is what should you do. There are a couple of problems with doing it. One is that the torque converter itself might not be the problem - or might not be the only problem - giving the shudder. There are controls for the TCC lockup inside of the transmission. If those are having the problem your new torque converter will do nothing.

The other thing to think about is what happens next week when some other problem pops up that is internal to the transmission? The approx. $450-500 labor to pull out and reinstall the transmission is probably best spent only once - rather than paying it now, and then paying it again if something else goes wrong. You have 148K miles on a minivan transmission that has never been serviced before. Its something of a small miracle that it works at all anymore, and I suspect this problem might be the beginning of the end.

The wisest long term strategy is probably to just say - hey, as long as you have that thing pulled out of there, why not go ahead & overhaul it.

If you are thinking of the vehicle as something that you don’t want to spend money on, then just keep going with the occasional shudder. If it gets too bad you can maybe look into disabling the TCC altogether. Do you have an “O/D Off” (overdrive off) button?

Yes, I have an O/D Off button, used only a few times during the life of the car. Does it lockup?

The decision is not a casual one. Overhauling the transmission costs 3X as much as changing the TCC. I guess the decision can be made AFTER the transmission is opened up and the mechanics can look at the guts. Does that make sense?

I have some hope – the guy who serviced it noted that it was clean. Very little on the magnets or anywhere else.