MK6 TDI Sportwagen 6MT, On/ Off Throttle Thump

2011 TDI Sportwagen, 6MT, 115K miles

Hoping someone can shed some light on this issues. Ive searched, but haven't found any solid leads.

When going on/ off the throttle a thump can be felt. Equivalent to a small pothole. No sounds accompany the thump feeling. It feel like a front/ back movement, felt in the seat.

The thump is more pronounced in 4,5,6 gears around 2k RPMS.

I replaced the 3 main mounts with OEM parts (motor, trans, dogbone).

The car has a Valeo single mass flywheel conversion.

I removed the subframe brace and inspected the mounts they both seem solid, but I have replacements on hand.

Am I missing something?

Thanks in advance.

Possibly exhaust system is loose from the clutch installation? I had that happen on my old JSW.


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calimustang said:

Possibly exhaust system is loose from the clutch installation? I had that happen on my old JSW.


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Possible, but I would think that would make a noise.

Also to add, in a higher gear at a low RPM, when the throttle is barely engaged, the car bucks lightly.

I just had the P2015 code come up. Ive read about this and know about the dieselgeek part to fix it. I am also waiting on a call back from the dealer to see if I am eligible for the extended warranty that covers this.

Could the thumping be related to this?

From reading online, it seems like the only real symptom of the intake runner flap issue are hard starts and misfires.

I also have a "thump." My car is also a '11 JSW 6MT with 77k. Same- also checked dogbone and mounts and suspension is tight.

When I am cruising down the road in 3rd or 4th and then let off the pedal, the car lets off with a thud just like the driveline was loose or something. If I drop the accelerator it does it. I can soften it by just remembering to let off slow on the pedal. If I keep the rpm's the same and push the clutch down there is no thump. It is worse when the car is warm.

While it seemed to be felt in the driveline/ suspension, I always felt it was related to boost or some sort of engine management thing. My car was in an accident and there was a crack in the intercooler, and as a result I would get this pulsing in torque on the driveline - this feels kinda like that but more oomph.

I also have a Valeo SMF clutch in my car. How long has it lasted for you? The clutch engagement is pretty good but the car is not as smooth and quiet and certainly on the highway. Lots of people are telling me that my synchros are going to go and after 1000k miles so far nothing.

That sounds exactly like my issue. I put about 1k miles on the SMF kit without an issue and it getting progressively worse.

I’m going to check all the mounts and re-tourqe everything. It definitely feels like something large is moving (engine).

I put the car on ramps to check the torque on the subframe bolts. Ive read about the subframe clunk and movement, so I checked and noticed that I can see "scoring" around the bolts - indicating there is movement.

I just ordered the ECS subframe locking collar kit.

It should be here in the next couple days. Ill report back after install and some driving.

I think this is just a feature of these cars... Mine does the clunk on/off throttle under 2k rpms. I have to be very careful about the way I apply throttle to reduce it. I'll be curious to see if you have any luck with the subframe locking kit. I installed the 034 dogbone insert to try to reduce engine movement with some luck, and my car definitely needs the subframe locking kit at some point as I do get the clunk on turn-in during aggressive driving and track days. These cars just have a lot of engine movement from the factory, I'm also guessing the SMF just exacerbated this symptom.

Look forward to your research. Thank you! The ECS instructions are so well written - gives you much confidence and gave me an education about bolts, torque, etc.

My guess is that the smf has beat up the gearbox and it's about to go south. When it does, go back to a dmf arrangement. The dampeners and fluid cocktails will only buy a minimal amount of time.

turbobrick240 said:

My guess is that the smf has beat up the gearbox and it's about to go south. When it does, go back to a dmf arrangement. The dampeners and fluid cocktails will only buy a minimal amount of time.

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I hope not, but on a side notes...I'm also a volvo guy. Here's my 98 v70r..
Untitled by britt edward, on Flickr

icrashcars said:

I hope not, but on a side notes...I'm also a volvo guy. Here's my 98 v70r..
Untitled by britt edward, on Flickr

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That's a bad looking brick- in a good way!

Update

I installed the ECS locking collar kit and replaced the upper and lower dogbone bushings.

There is a noticeable improvement. There is still some movement/ thump, but it is minor compared to before.

Nice. Best of luck with the smf. Keep us updated every 10k or so on how the gearbox holds up.

my 2014 manual does this..............stock DMF...


i ASSUMED it was due to mounts, but my car just broke 60k and shouldn't have any mount issues yet....but, there have been some bad wheel hop episodes with my car, so there might be

icrashcars said:

Update

I installed the ECS locking collar kit and replaced the upper and lower dogbone bushings.

There is a noticeable improvement. There is still some movement/ thump, but it is minor compared to before.

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I like to ask how easy, or shall I say how hard, was it to press out/press in the two round mounts (the two round rubbers mounted inside the subframe cradle).

I don't have a hydraulic press but was thinking of using some wood blocks, regular car jack and a round steel object slightly small then the rubber, then press the rubbers out against a truck frame.

fastalan said:

I like to ask how easy, or shall I say how hard, was it to press out/press in the two round mounts (the two round rubbers mounted inside the subframe cradle).

I don't have a hydraulic press but was thinking of using some wood blocks, regular car jack and a round steel object slightly small then the rubber, then press the rubbers out against a truck frame.

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It took me about 60 minutes.
Removed Subframe
Cut out old mounts with as jig saw
I used a bench grinder to take a little of the material off the edge (lip) of the mounts so they were more tapered.
Froze the mounts in the freezer overnight.
I used a manual wheel bearing press I have. I bought a thinner/ longer bolt that would fit through the centers of the mounts. I really only used the metal press plates, so could prob fab something.This

I was able to press them in about 75% of the way. I then whacked it with a hammer and it popped right in.

The key is the grinding of material to make tapered edge. Remove as little as possible. Also taper the edge of the opening where the dogbone fits in.

icrashcars said:

It took me about 60 minutes.
Removed Subframe
Cut out old mounts with as jig saw
I used a bench grinder to take a little of the material off the edge (lip) of the mounts so they were more tapered.
Froze the mounts in the freezer overnight.
I used a manual wheel bearing press I have. I bought a thinner/ longer bolt that would fit through the centers of the mounts. I really only used the metal press plates, so could prob fab something.This
I was able to press them in about 75% of the way. I then whacked it with a hammer and it popped right in.
The key is the grinding of material to make tapered edge. Remove as little as possible. Also taper the edge of the opening where the dogbone fits in.

Click to expand...

Nice to know it could be done with a wheel bearing press. If I can't rent one from the auto part store then I definitely has to improvise a bit. I think it could be a bit of a challenge.

Previously my dealer quoted me on the job for about 4-5 hours of labour along. The funny thing is that VW does sell a ready to go cradle for about $700. If I can't get it done myself I might just take the cradle and the mounts to a car shop and pay them to swap the rubber out.