Bump, bump, bump on acceleration ('03 TDI 5-speed)

[richmondvatdi]

Good Sunday Morning Everyone!

I am beginning to sense a very, very slight bump, bump, bump on acceleration. More noticeable in 2nd gear, less in 3rd, even less in 4th. It almost sounds like the beginnings of a classic CV joint failure, except it is on straight line acceleration, not while turning. It only happens when under load, and goes away as soon as I back off the accelerator to steady speed.

The speed of the bump increases with the speed of the car (as opposed to speed of the engine), so I suspect it is somewhere btw. the trans and the wheel.

CV joint boots are in good shape. Front wheels/lugs are tight.

2003 Jetta TDI Wagon
5-speed
165,000 miles

Any ideas?

 

[speed185187]

control arm bushings? or strut bearing plates?

 

[Canadian_Grizzly]

Inner CV's do this when under load and going straight, so you first evaluation may be correct.

 

[richmondvatdi]

Inner CV Joints?

Inner CV's do this when under load and going straight, so you first evaluation may be correct.

Is it possible the inner joints are bad even though boots are in perfect condition? Any time I've had a CV joint go bad, it was accompanied by a cracked boot that let dirt in. The dirt is what killed the joint.

I always thought CV joints basically lasted forever as long as the boot held up. Is my assumption not true?

 

[DPM]

wear happens, even with lubrication.

 

[Ski in NC]

All four of the cv joints run at an angle even when going straight ahead. So a turn is not necessary for a worn cv joint to make a thump. The trick is finding out which one is responsible. Sounds like the inner ones have a reputation for this, so maybe a good place to start. -Eric

 

[richmondvatdi]

This must be in the very early stages, because it is barely detectable. I think I will wait until it gets worse. That way I may be able to confirm what it is before pulling the front end apart.

If it is CV joints, is there any harm in letting it go for a while?

 

[richmondvatdi]

Bump...

I'd like some opinions. Is there any reason not to let it go until it becomes more clear what the problem is, or should I just suck it up and pull the front end apart to confirm the inner CV joint.

 

[Ski in NC]

If it is barely detectable, then I can't see any harm in running it. Aside from the failed joint itself, which you will replace anyway once identified.

-Eric

 

[ninobigfish]

Were you able to find what was cousing the bump? I have he same problem. So, please let me know.

 

[ninobigfish]

Bump

I am having the same situation bump bump when on low velocity. does anyone could help me? a drawing could help. Thank you

 

[richmondvatdi]

It has not gotten any worse in the last 2 months (~8,000 miles). I will continue to monitor. If it gets significantly worse, I will dig into it more.

 

[Caledoniatdi]

This sounds like what I experienced at around 140,000 miles, I replaced my clutch and that fixed the problem.

 

[richmondvatdi]

I Would Not Have Suspected the Clutch

This sounds like what I experienced at around 140,000 miles, I replaced my clutch and that fixed the problem.

Wow. Interesting. I would expect the clutch to start to "grab" when it starts to go, not bump on straight-line acceleration...

 

[Dimitri16V]

Clutch it is..inner joints will click if they are dry or worn out

 

[G_Duguid]

hey guys, i'm sort having the same problem but opposite. i get the same bump, bump, except it is unnoticeable at low speeds, you only really notice it during hard acceleration in fifth around 110km/h. could this be a problem with the clutch?
Thanks for your input.

 

[ninobigfish]

G_Duguid,
The bump problem continues on my 2005 TDI. I disconected the MAF and the bump went away. Clutch? My TDI is auto and I am having the same problem. Most likely is a bad MAF sensor, a blocked hose, or disconected hose. I will work on it and keep you posted and please keep me posted.