Issues following timing belt change
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Scooby Newbie
Joined: Apr 2026
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Issues following timing belt change
Hello everyone,
I am seeking advice and guidance following a timing belt change on my VW T25 EJ25D conversion.
The engine runs briefly on 2 cylinders and then dies. Any attempt to throttle it kills it off. The obvious thing is of course that the belt wasn't installed correctly and the engine isn't timed. However all the marks line up. So I'm a bit stumped
Other things to note:
Compression is 140 across all cylinders.
The ECU is a Speeduino unit that has been working great.
There is spark on all 4 cylinders.
Can anyone offer any pointers? It feels like a timing issue but I can't find fault in the belt installation.
I am seeking advice and guidance following a timing belt change on my VW T25 EJ25D conversion.
The engine runs briefly on 2 cylinders and then dies. Any attempt to throttle it kills it off. The obvious thing is of course that the belt wasn't installed correctly and the engine isn't timed. However all the marks line up. So I'm a bit stumped
Other things to note:
Compression is 140 across all cylinders.
The ECU is a Speeduino unit that has been working great.
There is spark on all 4 cylinders.
Can anyone offer any pointers? It feels like a timing issue but I can't find fault in the belt installation.
Scooby Regular
Joined: Mar 2002
Posts: 6,837
Likes: 427
From: north east
if it has occurred directly after then it pretty much has to be an issue with installation........
presume 4cam engine?? have the teeth on the central belt pulley been damaged?? are the "single" marks on the outer pulleys correctly aligned with the outer casing and hence the inner "double" marks should be aligned
on the centre timing pulley have you incorrectly used the TDC mark instead??
https://www.alldrivesubaroo.com.au/s...t-replacement/
presume 4cam engine?? have the teeth on the central belt pulley been damaged?? are the "single" marks on the outer pulleys correctly aligned with the outer casing and hence the inner "double" marks should be aligned
on the centre timing pulley have you incorrectly used the TDC mark instead??
https://www.alldrivesubaroo.com.au/s...t-replacement/
Last edited by stockcar; Apr 10, 2026 at 09:19 AM.
Thread Starter
Scooby Newbie
Joined: Apr 2026
Posts: 3
Likes: 0
if it has occurred directly after then it pretty much has to be an issue with installation........
presume 4cam engine?? have the teeth on the central belt pulley been damaged?? are the "single" marks on the outer pulleys correctly aligned with the outer casing and hence the inner "double" marks should be aligned
on the centre timing pulley have you incorrectly used the TDC mark instead??
https://www.alldrivesubaroo.com.au/s...t-replacement/
presume 4cam engine?? have the teeth on the central belt pulley been damaged?? are the "single" marks on the outer pulleys correctly aligned with the outer casing and hence the inner "double" marks should be aligned
on the centre timing pulley have you incorrectly used the TDC mark instead??
https://www.alldrivesubaroo.com.au/s...t-replacement/
Scooby Regular
Joined: Mar 2002
Posts: 6,837
Likes: 427
From: north east
there are 2x specific marks on the central timing pulley
firstly, there is small triangular "arrow / pyramid" indent that often gets mistaken for the timing mark !! this is TDC only and is effectively 90deg out and vehicle will not run...........when correct this should point horizontally to the right
what you need to use is the 'straight line' which is mirrored on the front face and also on one of the teeth at the back of the pulley - THIS is the timing mark and should point vertically
firstly, there is small triangular "arrow / pyramid" indent that often gets mistaken for the timing mark !! this is TDC only and is effectively 90deg out and vehicle will not run...........when correct this should point horizontally to the right
what you need to use is the 'straight line' which is mirrored on the front face and also on one of the teeth at the back of the pulley - THIS is the timing mark and should point vertically
Thread Starter
Scooby Newbie
Joined: Apr 2026
Posts: 3
Likes: 0
there are 2x specific marks on the central timing pulley
firstly, there is small triangular "arrow / pyramid" indent that often gets mistaken for the timing mark !! this is TDC only and is effectively 90deg out and vehicle will not run...........when correct this should point horizontally to the right
what you need to use is the 'straight line' which is mirrored on the front face and also on one of the teeth at the back of the pulley - THIS is the timing mark and should point vertically
firstly, there is small triangular "arrow / pyramid" indent that often gets mistaken for the timing mark !! this is TDC only and is effectively 90deg out and vehicle will not run...........when correct this should point horizontally to the right
what you need to use is the 'straight line' which is mirrored on the front face and also on one of the teeth at the back of the pulley - THIS is the timing mark and should point vertically
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