Shudder going uphill

escalade

#1

I own a 2009 Cadillac Escalade (no I don’t write rap tunes) and for the past 5 years it has been an excellent vehicle to drive. It still is, but under certain conditions I am experiencing a shudder which lowers the confidence that I usually have in my vehicle. Specifically, when I am climbing a hill and the transmission is in a higher gear, say 4th and the RPMs are relatively low, say 1800, I feel a shudder as the car goes up the hill. When I let my foot off the gas the shudder stops. If I manually shift into a lower gear and raise the RPMs, the engine responds with power galore and I climb the hill without any effort and without any shudder (most of the time). The engine is smooth and is not sputtering when this shudder happens. I do not hear any unusual sounds under the car when this happens. I took it to the GM dealer and they did all they could (analyzed the car for codes, monitored fuel flow rates, searched for GM bulletins, etc) but their response was “we experienced the shudder but cannot find the issue - bring it back when it gets worse”. I read that BG44K will do a good job of cleaning the fuel system in the engine so I tried that but nothing changed. I have about 50K miles on the car and did my 50K maintenance just before a cross-country trip; on the way back from this long trip is when this issue started. The 50K maintenance included changing the transmission fluid and cleaning the filter (not replacing it), changing the differential oil, the transfer case oil, engine oil and filter, inspecting the vehicle, etc. I will continue to drive the vehicle and will bring it back to the dealer if it gets worse, but I’m wondering what I’m supposed to do if it never does and I continually experience this shudder. Or what happens if it gets worse all of a sudden and I’m unable to drive the car up a hill at all?


#2

The shudder sounds like a slipping torque converter clutch (TCC). This is commonly known as TCC shudder. There is a mechanical clutch that should “lock up” in higher gears at 45+ mph in order to improve gas mileage. When the clutch slips under load, it produces a shudder-type vibration.

Try adding a product called Dr. Tranny’s Shudderfixx to the transmission fluid. Sometimes that works to fix the shudder. If it doesn’t, then someone will have to take the transmission apart to fix the TCC.

PS…since the problem started just after the tran fluid was replaced, it’s possible the new fluid was contaminated or is the wrong type. I would try changing the fluid again, verifying it’s the correct type, and adding the Shudder Fixx additive.

PPS… There is already a Technical Service Bulletin (TSB) out on this problem, so it is a known issue to GM. The TSB # is 09-07-39-001. Call your dealer back, cite the TSB number, and ask them what GM is doing about it. If they can’t fix it they may owe you a new transmission under the powertrain warranty.

“Vehicle: 2009 Cadillac Escalade
Nature of Defect:
POWER TRAIN:AUTOMATIC TRANSMISSION
Bulletin Number:
09-07-30-001 Bulletin Date:
Mar 2011
Summary:
GM: WHEN DRIVING AT HIGHWAY SPEEDS THERE MAY A SHUDDER OR BUCKING FEEL AT HIGHWAY SPEEDS. ( NHTSA ITEM NUMBER - 10038263 )”

Meanwhile, I would still try the Shudder Fixx additive since it’s inexpensive and has a chance of helping.


#3

Does your car use a lock-up torque converter? If so, it may have something to do with that. It may be going into and out of lock for some reason. Or consider that maybe this is normal and it has always been doing it, you’ve just not noticed until now. Some shutter as the converter goes into and out of lock is normal.

If it were my car and I was certain it wasn’t there before, and a visual inspection didn’t show anything else wrong (like engine or transmission mounts), I’d probably do a proper transmission service and see if that helped. This isn’t the same as a transmission flush. It involves dropping the pan, draining the old transmission fluid out, and replacing the transmission filter. If that helped, but didn’t fix the problem completely, after a few weeks or a month of normal driving, I’d do it again. Make sure the replacement fluid is the exact fluid recommended in the owner’s manual.

If all that doesn’t fix it, then the guidance you’ve received to wait to see if it gets worse makes sense. And use that time to save up some dollars in your bank account, as you may be looking at a transmission re-build in the near future.


#4

I’m not experienced as a mechanic or even as an auto handyman besides changing out simpler parts - my disclaimer. I know you have an automatic. I am experiencing a similar problem with an 06 Honda CR-V manual 5 speed. I get the shudder going uphill and while accelerating in lower RPM range (for a Honda) in 4th and 5th gear. My mechanic suggested a bad axle but the shudder wasn’t pronounced enough to diagnose exactly which axle. Said to wait until it gets worse. I’ll have them check in about 4 months at the next oil change. Perhaps your automatic tranny shifts down to a lower gear providing higher rpms and less torque eliminating the noticeable shudder? The two people that already responded seem very knowledgeable in the responses regarding the clutch, especially since there is a tech bulletin out regarding the powertrain issue. I am only offering my anecdotal experience in case it may offer another possible answer to the problem.