Does anyone know how to test if the vibration damper pulley ( harmonic balancer) on the crank shaft is in good shape?
Mine drives the ribbed serpentine belt for the alternator and water pump and has a pulley for a v belt to drive the power steering pump on the outside.
It looks fine on the engine (no play or anything) but I didn't even know I had one or what one was until a mate pointed it out whilst we were trying to diagnose the noisy engine in the camper. Turns out that the water pump pulley wheel is hanging and the bearings in the pump have a lot of play plus the tensioner pully bearings are also knackered so it might just be those but I dont want to put it all back together without knowing if the damper pulley is shot too.
Any advice much appreciated.
AHU TDI Vibration Damper Pulley testing
Moderators: User administrators, Moderators
- hotpod
- Registered user
- Posts: 224
- Joined: 11 Jan 2010, 10:44
- 80-90 Mem No: 7802
- Location: St Ives, Cornwall
- Contact:
AHU TDI Vibration Damper Pulley testing
1992 T3 LHD Syncro 16" 4 door doka 1.9na diesel
1990 T3 LHD Syncro 16" Westfalia Joker high top 1.9 TDI
1985 T3 LHD Westfalia Joker high top 1.9 Digijet
1980 T3 LHD factory high top 2.0 Aircooled
1990 T3 LHD Syncro 16" Westfalia Joker high top 1.9 TDI
1985 T3 LHD Westfalia Joker high top 1.9 Digijet
1980 T3 LHD factory high top 2.0 Aircooled
-
- Trader
- Posts: 17170
- Joined: 08 Jun 2009, 09:51
- 80-90 Mem No: 6908
- Location: Surrey Syncronaut #156
- Contact:
Re: AHU TDI Vibration Damper Pulley testing
Are they known for failing? Unless the rubber bonding between the hub and pulley is obviously degraded, split or has chunks missing then I wouldn't worry.
Probably just a failed water pump bearing and the tensioner can't cope or has also failed.
Probably just a failed water pump bearing and the tensioner can't cope or has also failed.
Last edited by silverbullet on 01 Apr 2025, 13:46, edited 1 time in total.
1985 Oettinger 3.2 Caravelle RHD syncro twin slider. SA Microbus bumpers, duplex winch system, ARC 7X15 period alloys
- hotpod
- Registered user
- Posts: 224
- Joined: 11 Jan 2010, 10:44
- 80-90 Mem No: 7802
- Location: St Ives, Cornwall
- Contact:
Re: AHU TDI Vibration Damper Pulley testing
I have no idea if they fail but new ones are for sale so I would guess they do.
Nothing obviously degraded but I was wondering if there was a rule of thumb type way to tell.
I will take it off and do an inspection since this is likely the best time to do it
Nothing obviously degraded but I was wondering if there was a rule of thumb type way to tell.
I will take it off and do an inspection since this is likely the best time to do it

1992 T3 LHD Syncro 16" 4 door doka 1.9na diesel
1990 T3 LHD Syncro 16" Westfalia Joker high top 1.9 TDI
1985 T3 LHD Westfalia Joker high top 1.9 Digijet
1980 T3 LHD factory high top 2.0 Aircooled
1990 T3 LHD Syncro 16" Westfalia Joker high top 1.9 TDI
1985 T3 LHD Westfalia Joker high top 1.9 Digijet
1980 T3 LHD factory high top 2.0 Aircooled
-
- Trader
- Posts: 17170
- Joined: 08 Jun 2009, 09:51
- 80-90 Mem No: 6908
- Location: Surrey Syncronaut #156
- Contact:
Re: AHU TDI Vibration Damper Pulley testing
I have seen delaminated crank dampers on other engines but its a rare thing. If it has a TDC mark then check if it lines up, if not then its loose.
1985 Oettinger 3.2 Caravelle RHD syncro twin slider. SA Microbus bumpers, duplex winch system, ARC 7X15 period alloys
-
- Registered user
- Posts: 169
- Joined: 25 Apr 2014, 03:46
- 80-90 Mem No: 13403
- Location: Rotherfield, East Sussex
Re: AHU TDI Vibration Damper Pulley testing
My last engine was an AHU....I had my pulley replaced when I did the cambelt (which should be done every 4 years regardless of milage) as mine was squeeking and rattling due to shot bearings.
Parts are/were quite common.
This was.....2020.
Parts are/were quite common.
This was.....2020.
1983 1.9TDi Westfalia Vanagon, 5 Speed (AAP) - Now Tax & MOT exempt 

- Oren Kipnis
- Registered user
- Posts: 185
- Joined: 07 Sep 2020, 10:45
- 80-90 Mem No: 17352
- Location: Israel / North Wales, Syncronaut #200
Re: AHU TDI Vibration Damper Pulley testing
Which Alternator is mounted on the engine ?
Does it have a clutch pulley ? It is essential on these.
Does it have a clutch pulley ? It is essential on these.
1990 ex. German Army Syncro, 3 knob, AFN, M469 fully converted to 16". Camper conversion by URO CAMPER in Seville.
- hotpod
- Registered user
- Posts: 224
- Joined: 11 Jan 2010, 10:44
- 80-90 Mem No: 7802
- Location: St Ives, Cornwall
- Contact:
Re: AHU TDI Vibration Damper Pulley testing
Which bearings were shot? and are you talking about the pulley which bolts to the end of the crank shaft and drives the auxiliary belt?Burtybassett wrote: ↑04 Apr 2025, 18:01 My last engine was an AHU....I had my pulley replaced when I did the cambelt (which should be done every 4 years regardless of milage) as mine was squeeking and rattling due to shot bearings.
Parts are/were quite common.
This was.....2020.
1992 T3 LHD Syncro 16" 4 door doka 1.9na diesel
1990 T3 LHD Syncro 16" Westfalia Joker high top 1.9 TDI
1985 T3 LHD Westfalia Joker high top 1.9 Digijet
1980 T3 LHD factory high top 2.0 Aircooled
1990 T3 LHD Syncro 16" Westfalia Joker high top 1.9 TDI
1985 T3 LHD Westfalia Joker high top 1.9 Digijet
1980 T3 LHD factory high top 2.0 Aircooled
- hotpod
- Registered user
- Posts: 224
- Joined: 11 Jan 2010, 10:44
- 80-90 Mem No: 7802
- Location: St Ives, Cornwall
- Contact:
Re: AHU TDI Vibration Damper Pulley testing
Oren Kipnis wrote: ↑04 Apr 2025, 18:42 Which Alternator is mounted on the engine ?
Does it have a clutch pulley ? It is essential on these.
Ii have the 90a and it doesn't have the clutch pulley. I shall look into getting one asap.
1992 T3 LHD Syncro 16" 4 door doka 1.9na diesel
1990 T3 LHD Syncro 16" Westfalia Joker high top 1.9 TDI
1985 T3 LHD Westfalia Joker high top 1.9 Digijet
1980 T3 LHD factory high top 2.0 Aircooled
1990 T3 LHD Syncro 16" Westfalia Joker high top 1.9 TDI
1985 T3 LHD Westfalia Joker high top 1.9 Digijet
1980 T3 LHD factory high top 2.0 Aircooled