Need clunk/vibration diagnostic help

FloridaMutt

Veteran Member
Joined
Jan 2, 2006
Location
Central florida
TDI
'04 GL Manual Jetta Wagon
Vehicle- 2004 Wagon (5 speed, BEW engine, 149,000 miles) Only mayor engine work, it had the timing belt done at 90k.

I am used to using engine compression to brake/reduce speed which according to my brother in law (auto mechanic) is not good, so I will stop. He said I am wasting clutch life (expensive replacement) and only gaining brake pad life (inexpensive replacement).

This last week, going to work in the morning, I found myself coming to a stop at a light and dropped into 2nd gear, and as soon as I did that the brake pedal got super hard and I had to do a leg press to get the car to stop on time. Simultaneously, I also heard/felt a "clunk" on the driver side, maybe in front of me/underneath me. I have had since experienced the same thing at least 3-4 times, so I stopped using engine compression to stop. In fact I stopped using the car until I can figure what the issue is and repair it.

When starting to move from a full stop (if too sudden) I can also feel the clunk. Additionally when starting up the car, I can feel the engine shaking back and forth more than it used to before on start up (I have owned the car since it had 19K), not while idling though.

At first pass I can't find anything visually wrong/broken under the hood, or from what I can see underneath the car without removing the plastic engine cover. My BIL suggested I depress the clutch pedal while keeping the transmission in neutral for a couple of minutes, then try to get it into gear to test the master cylinder but that made no difference.

Does any of this sound like something obvious to you? Where would you be looking? I am thinking some engine mount is broken (I have only changed the dog-bone when I did a suspension refresh maybe 4-5 years ago).
 

Tdijarhead

Top Post Dawg
Joined
Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Wife’s car, 2005 Golf TDI Mine, all 5 spds
Two things probably going on here. The hard plastic hose leading from the tandem pump to the master brake cylinder that supplies vacuum is probably cracked, split or the nipple on the tandem pump where the hose attaches is loose allowing vacuum loss. Hence the hard brake pedal.



The clunk could be motor mounts, I'm going to replace all three on my 05 BEW this weekend, but I have 337K miles. Yours must sit around a lot?



More likely the DMF (dual mass flywheel ) is giving up the ghost. They often go out at 140-200K miles.


I always downshift, using that compression is part of the beauty of driving a manual.
 

FloridaMutt

Veteran Member
Joined
Jan 2, 2006
Location
Central florida
TDI
'04 GL Manual Jetta Wagon
Two things probably going on here. The hard plastic hose leading from the tandem pump to the master brake cylinder that supplies vacuum is probably cracked, split or the nipple on the tandem pump where the hose attaches is loose allowing vacuum loss. Hence the hard brake pedal.
So it makes sense that if there's a motor mount broken allowing the motor to twist beyond the normal, then this twisting allows the crack to open.

The clunk could be motor mounts, I'm going to replace all three on my 05 BEW this weekend, but I have 337K miles. Yours must sit around a lot?
Yeah, I drive it between 12-15K a year. It is now just a commuting car, my wife's van is used for anything we need to be together.


More likely the DMF (dual mass flywheel ) is giving up the ghost. They often go out at 140-200K miles.
What would indicate this, other than the rattle that I have read here in discussions? I do not think it is rattling.

I always downshift, using that compression is part of the beauty of driving a manual.
yup, I also grew up and learned to drive in hilly terrain where old crappy brake pads could overheat and not work, so engine compression was safer. Now I live in flat Florida, but I kept the habit.
 

csstevej

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north nj
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2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
Check out your lower control arm large aft bushing, I’m willing to bet the rubber bushing in there is cracked out on both sides of the rubber bushing.
It’s not a solid bushing.
Easy way to check it out is run it up on ramps, crawl under neath car and grab the arm and rock it for and aft....... any movement and it’s no good.
 

FloridaMutt

Veteran Member
Joined
Jan 2, 2006
Location
Central florida
TDI
'04 GL Manual Jetta Wagon
Check out your lower control arm large aft bushing, I’m willing to bet the rubber bushing in there is cracked out on both sides of the rubber bushing.
It’s not a solid bushing.
Easy way to check it out is run it up on ramps, crawl under neath car and grab the arm and rock it for and aft....... any movement and it’s no good.
Thanks, I’ll be checking that ASAP. On one side It would be a bit of a disappointment, that was one of the things I changed when I did the suspension and front end refresh a few years ago. On the other side, it is an easy fix and not as complicated as a transmission issue.


well, checked and it wasn't that, it turns out it was the dogbone having come loose from the engine/transmission side.
 
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FloridaMutt

Veteran Member
Joined
Jan 2, 2006
Location
Central florida
TDI
'04 GL Manual Jetta Wagon
Two things probably going on here. The hard plastic hose leading from the tandem pump to the master brake cylinder that supplies vacuum is probably cracked, split or the nipple on the tandem pump where the hose attaches is loose allowing vacuum loss. Hence the hard brake pedal.



The clunk could be motor mounts, I'm going to replace all three on my 05 BEW this weekend, but I have 337K miles. Yours must sit around a lot?



More likely the DMF (dual mass flywheel ) is giving up the ghost. They often go out at 140-200K miles.


I always downshift, using that compression is part of the beauty of driving a manual.

You were right about the plastic hose being cracked and losing vaccum when the engine twisted. Replaced that as well as I got enough vac hose to replace anything that is easily accessible.


The clunk turned to be a lose dogbone, so I replaced that as well. The engine mounts look to be intact, but there's rubber "powder" around them, so they may need changing as well. How easy are they to change? I will need an engine support bar right?
 

Nero Morg

Top Post Dawg
Joined
Oct 19, 2017
Location
OR
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2014 A6 TDI, 2001 Jetta TDI, 2014 Passat TDI
Block of wood and a jack under the trans/oil pan should be OK. Wide block of wood to distribute the weight, don't go crazy with lifting it. That's how I change dmine not long ago.
 

Tdijarhead

Top Post Dawg
Joined
Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Wife’s car, 2005 Golf TDI Mine, all 5 spds
You were right about the plastic hose being cracked and losing vaccum when the engine twisted. Replaced that as well as I got enough vac hose to replace anything that is easily accessible.


The clunk turned to be a lose dogbone, so I replaced that as well. The engine mounts look to be intact, but there's rubber "powder" around them, so they may need changing as well. How easy are they to change? I will need an engine support bar right?



I bought an engine support bar a couple of years ago, it makes doing a timing belt or engine mounts so much easier, but a block of wood and a jack will work. Its important to get the weight of the engine off the mounts before you take them loose.


If you don't relieve the weight from the mount before you unscrew the big bolts the steel of those mounting bolts will strip the aluminum threads.



I did mine this last weekend and I am now clunkless, (is that a word?).
 

FloridaMutt

Veteran Member
Joined
Jan 2, 2006
Location
Central florida
TDI
'04 GL Manual Jetta Wagon
thanks, my only concern with the jack/block of wood is that I have read on teh forum that it is important not to mess the alignment of the mounts. I guess it will be something I'll learn/notice once I do it.
 

Nero Morg

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Joined
Oct 19, 2017
Location
OR
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2014 A6 TDI, 2001 Jetta TDI, 2014 Passat TDI
It shouldn't be a problem. When the mount is loose and the engine on yhr wood, you can grab the top of the engine and pull/push it where it needs to go easily enough.
 

Rob Mayercik

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Dec 19, 2001
Location
NJ, U.S.A.
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2002 Jetta GLS, Baltic Green/Beige
Also, if the 2004s used one-time stretch bolts for the mounts like the ALHs do, make sure you replace them all.
 
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