I think this is going to hurt

[nylyon-(Admin) 7,268]

It was a nice day, so I took my son's A4 convertible out for a drive.  It's a fun little car, and I decided to give it a little gas from a stop sign.  Went to about ¾ throttle and heard a few knocks then the engine died.  Trying to start it sounded like no compression, but the camshafts were moving so the timing belt didn't break.

 

UHaul was open so I rented a car trailer and towed the car home (cheaper than a wrecker). I pulled off the cam sprocket covers and found this:

 

That does not look good to me, so I pulled out plug #4 and put the borescope down in there:

 

Sure looks to me like a valve slapped the piston, so I suspect that the belt, which is only 2 years old, jumped and wacked the exhaust valves.  Thing that sucks is that this is a V6, and that engine is packed in there, so this will be a bear to get the heads off.  I guess the good news is that his college is on-line classes now, he worked at the University and we're on quarantine so we have no where to go anyway.

 

Ugh.

 

[Daddy Don 905]

Hope you have small hands and long fingers. There is no room for a giant. Good Luck.

[ZXT 2,401]

15 minutes ago, nylyon said:

It was a nice day, so I took my son's A4 convertible out for a drive.  It's a fun little car, and I decided to give it a little gas from a stop sign.  Went to about ¾ throttle and heard a few knocks then the engine died.  Trying to start it sounded like no compression, but the camshafts were moving so the timing belt didn't break.

 

UHaul was open so I rented a car trailer and towed the car home (cheaper than a wrecker). I pulled off the cam sprocket covers and found this:

 

 

That does not look good to me, so I pulled out plug #4 and put the borescope down in there:

 

 

Sure looks to me like a valve slapped the piston, so I suspect that the belt, which is only 2 years old, jumped and wacked the exhaust valves.  Thing that sucks is that this is a V6, and that engine is packed in there, so this will be a bear to get the heads off.  I guess the good news is that his college is on-line classes now, he worked at the University and we're on quarantine so we have no where to go anyway.

 

Ugh.

 

Looks like you have some fun ahead of you! Did you pull all of the plugs and check for bent valves or just that one? I would guess you've probably more than two bent valves. 

 

What year is the car? A 2 year old belt shouldn't have done that.. I know they've been making A4's since the early 90s, so maybe the belt had been on the shelf for a loooong time? 

 

I need to put a new timing belt on my dad's Porsche 944. It was last changed in '94. It's on borrowed time. I recently did a TB/WP/idler replacement on my Porsche 928, and it wasn't too bad - but the 944 is a total different animal. Hopefully I make myself do it before it pops. Interference engines bite!

[nylyon-(Admin) 7,268]

It’s a 2006 A4, the timing belt was replaced 2 years ago, by me.  Can’t imagine what I could have messed up to cause this, I’ve changed hundreds of belts before.

[formariz 11,987]

Something was rubbing on that belt? Tensioner failed?

Edited April 6, 2020 by formariz

[nylyon-(Admin) 7,268]

Sure looks like it, there are 2 idler pulleys, water pump and the tensioner which ride on that side of the belt.  I hope I find out what happened when we take it apart, don’t want a repeat of this for sure.

[tom2p 2,394]

timing belt looks more like a 20 year old belt than a 2 year old belt 

 

outside part well worn on one side 

?

 

one of the pulleys / sprockets or bearing fail ?

 

is there a belt / cam tensioner - if so did it fail ?

 

[formariz 11,987]

4 minutes ago, nylyon said:

Sure looks like it, there are 2 idler pulleys, water pump and the tensioner which ride on that side of the belt.  I hope I find out what happened when we take it apart, don’t want a repeat of this for sure.

Did you change tensioner when belt was changed ? Its part of kit.

[nylyon-(Admin) 7,268]

Everything was changed, tensioner, idler pulleys even the water pump and harmonic balancer, the old one was coming apart.  The engine was silent running, like a Tesla no rubbing noises what so ever.

[nylyon-(Admin) 7,268]

4 minutes ago, tom2p said:

timing belt looks more like a 20 year old belt than a 2 year old belt 

 

outside part well worn on one side 

?

 

one of the pulleys / sprockets or bearing fail ?

 

is there a belt / cam tensioner - if so did it fail ?

 

will find out when we tear the car apart.  The tooth side of the belt looks fine

[ZXT 2,401]

Belt looks ancient to me. Doesn't really look like rub damage, more like it just shredded. Personally, I'd go with a Gates belt this time around!

[formariz 11,987]

Perhaps what ever was rubbing on belt did not go as far as teeth but belt overheated from friction expanding and allowing teeth to skip it.

[Tractorhead 9,064]

Whow, that didn‘t look good.

This are one of the Things nobody needs.

Was it a continuous used Car, or was it it just a „ good Day runner“?

 

Be i right, it was the 2,5 Litre V6 Engine?

 

This engine has as i remember right 2 Timing Belts, one for the Fuel system, another one (larger) for Camshafts.

are you sure, both are changed 2 years ago?

 

Just a simple change of the Belt is allready a mess on that Engine, except you removes the whole Front section,

to get enough room for Work on that.

I agreed with the Belt age on the Pics, if you look at the damaged side, the beltcords seems allready rusted,

but maybe this appears just on the Pict.

 

I crossing my fingers the damage woudn‘t be that heavy and could be fixed with relatively low cost.

 

A sadly story it is anyway‘s.

 

 

[bc.gold 3,403]

I have no experience with this belt, but found this information on an Audi A4 that might solve the mystery.

 

TIMING BELT
I ordered a timing belt for the above mentioned car. The OEM of the belt (as
stamped on it) is Contitech. I found the following discrepancies with it as
compared to the Audi OEM belt I procured from the Audi dealer:


1 2 3 4
Imparts Supplied Belt 1" 0.080" 0.210" 0.115"
Audi Supplied Belt 0.750" 0.095" 0.195" 0.115"

1- Belt Width
2- Belt Height at Non Toothed Area
3- Belt Height at Non Toothed Area
4- Belt Tooth Height

As you can see, the only dimension that was NOT different from the Audi supplied
belt was the belt tooth height. I did not use this belt because of the width, 1"
is larger than the cam belt area (approximately 7/8"), it would overlap on both
sides. I did not check it, but I imagine it would be pinched due to its width on
the crank shaft pulley.

Additionally, it is 0.015" less thick than the Audi supplied belt. This would
most definitely affect service life unless it is made of a radically
different/stronger material.

Edited April 6, 2020 by bcgold

[nylyon-(Admin) 7,268]

4 hours ago, Tractorhead said:

Whow, that didn‘t look good.

This are one of the Things nobody needs.

Was it a continuous used Car, or was it it just a „ good Day runner“?

 

Be i right, it was the 2,5 Litre V6 Engine?

 

This engine has as i remember right 2 Timing Belts, one for the Fuel system, another one (larger) for Camshafts.

are you sure, both are changed 2 years ago?

 

Just a simple change of the Belt is allready a mess on that Engine, except you removes the whole Front section,

to get enough room for Work on that.

I agreed with the Belt age on the Pics, if you look at the damaged side, the beltcords seems allready rusted,

but maybe this appears just on the Pict.

 

I crossing my fingers the damage woudn‘t be that heavy and could be fixed with relatively low cost.

 

A sadly story it is anyway‘s.

 

 

the engine is a 3.0, there is only one belt.  The car has to be put into service mode, remove the front bumper slide the carrier out. The hard part is going to be getting the exhaust off.

 

[nylyon-(Admin) 7,268]

3 hours ago, bcgold said:

I have no experience with this belt, but found this information on an Audi A4 that might solve the mystery.

 

TIMING BELT
I ordered a timing belt for the above mentioned car. The OEM of the belt (as
stamped on it) is Contitech. I found the following discrepancies with it as
compared to the Audi OEM belt I procured from the Audi dealer:


1 2 3 4
Imparts Supplied Belt 1" 0.080" 0.210" 0.115"
Audi Supplied Belt 0.750" 0.095" 0.195" 0.115"

1- Belt Width
2- Belt Height at Non Toothed Area
3- Belt Height at Non Toothed Area
4- Belt Tooth Height

As you can see, the only dimension that was NOT different from the Audi supplied
belt was the belt tooth height. I did not use this belt because of the width, 1"
is larger than the cam belt area (approximately 7/8"), it would overlap on both
sides. I did not check it, but I imagine it would be pinched due to its width on
the crank shaft pulley.

Additionally, it is 0.015" less thick than the Audi supplied belt. This would
most definitely affect service life unless it is made of a radically
different/stronger material.

 

very interesting find, where did you see this?

[Tractorhead 9,064]

Ah, ok i’m not familar with the 3.0 Engine.

i just know few issues that can happen on the 2,5L with the Timing Belts so i thought i can help you,

but on the 3.0L i have no touch to be honest, sorry.

 

I hope, there was not a big damage and you can Fix it cheap.

 

[tom2p 2,394]

 

1 hour ago, Tractorhead said:

I hope, there was not a big damage and you can Fix it cheap.

 

well at a minimum appears nylyon is looking at a new belt and tensioner - and possibly and probably some new valves (and related) and also possibly some work to the head (hopefully head not destroyed)

 

don't know the cost of Audi parts - but my guess is they are not cheap 

 

valves can be expensive - especially if they are titanium ...

[formariz 11,987]

For what is worth,my youngest son is a mechanic. He works frequently on Audis and VWs including our own Audi and VW. For what is worth he refuses to install many after market parts on them the timing belt kit being one of them. He has said to me in the past that much of the non OEM parts for these cars have enough differences to make it a potential problem not only performance wise but also fitting issues.He has just last week showed me that the rear axle trailing arm bushing set that I bought for the Golf it will just not fit due to a slight diameter difference.

[nylyon-(Admin) 7,268]

I agree, these were OEM parts that I bought.  Debating what I am going to do.  On one hand, too old to dig that deep into the motor, on the other, to cheep to send it out.  I do love the car though.

 

[formariz 11,987]

There are places around here that part out Audi’s and VWs. You can probably find a good head for it at a reasonable price.

 

https://www.autohaasparts.com/

 

[squonk 41,029]

Any hydraulic dampened tensioners on this engine? Phenolic pulleys? I have seen these fail prematurely.