OBD2/1 timing chain - Single/Double top chain mis-conception.

[mightymidget 0]

Hi all,

I just wanted to clarify something that is often mentioned in this forum stating that the newer OBD2 engine doesn't suffer from timing chain issues as much as the older OBD1 engine. This is often quoted because the newer OBD2 engine is often stated as having a single top timing chain with a newer more durable top tensioner and bolt (without the rivets).

However after investigation it seems that a number of the earlier OBD2 engines also have double top chains and will therefore suffer from the same possible top tensioner failures as seen on the older OBD1 engines.

VW switched to single top chains and new tensioners on late 1996 engines, from engine numbers AAA217001. Anything prior to this will have double top chains with the same crappy riveted top tensioner. OBD2 engines were manufactured from mid 1995 so this means loads of OBD2's must be going around with crappy top tensioners that should be checked/replaced at around 100k mark.

Just wanted to mention this because after reading lots of timing chain posts it seems that a lot of owners are under the mis-conception that OBD2 engines are less likely to fail or suffer timing chain problems. This is true for 217001+ engines but unfortunatley not for all OBD2 owners.

Also it's important to note that you should mention your engine number when ordering timing chain kits (and not OBD1/2) as to ensure you get the correct parts.

Hope this helps someone who might be as confused as what I was when trying to identify your engine parts.

If I'm wrong please someone correct me.

Cheers, MM.

[craggsy 91]

Thats good to know.......can never have enough info like that.

Well done that man

[patpong_pete 0]

mines OBD2 1996 Highline

but my engine number is under 17000

so do u work for vw ?

where did u find this out?

do these crappy top tensioners snap or will u get a warning noise

mines 105 k what sort of noise or rattle to look out for at mo it sounds ok

fingers crossed its ok for another year !

if u need to replace the clutch on vrs then at the same time do the chains etc........ but looking at £500 plus

[mike 6]

nice one, leats i know i have the single chain, when are the single chains usualy changed 120k?

[mightyvr6 0]

Good info there but it should be noted that the later solid polymer upper tensioner/bolt can also be fitted to early engines with duplex chains.

[mightymidget 0]

Good info there but it should be noted that the later solid polymer upper tensioner/bolt can also be fitted to early engines with duplex chains.

That's correct, this is what i'll be doing when I re-new the clutch next month. Currently I'm one of the unlucky OBD2 owners with double top chains and a rubbish old style top tensioner (engine no.AAA168xxx manufactured Dec 96). When I do it I'll replace with the newer solid tensioner and T-bolt. This should out last the remaining life of the car which is currently at 113k miles.

I've read in other forums that it's possible to convert double top chains to single but can't really see any benefit in this as the chains themselves aren't suspect. It's only the runners that wear, I would guess that in extreme cases the slack from a wore or failed old style top tensioner could cause the timing to be out or at worse cause that chain to jump which would result in a wrecked engine.

Apparently the chains themselves are suppose to last the life of the car and never need changing, unfortunately the same durability isn't true of the top tensioners and runners. If you have a newer AAA217001+ engine with lots of chain noise you might be able to get away with just changing the top runner and tensioner bolt. This is relatively easy and doesn't require the removal of the gearbox or any chains. Once the top timing cover is off and the top chain exposed you simply remove two securing bolts and slide a new runner in. At the same time you could examine your top tensioner. If this needs doing then you'll need to remove the gearbox to enable replacement, it would make sense to do the chains and clutch when the gearbox is out.

Owners of older pre AAA217000 can also benefit from changing the top runner and Tensioner bolt. However care should be taken as a wore top-tensioner will probably fall apart once the tension is removed from the tensioner bolt. If it does fall apart it will probably fall into the lower half of the timing housing, the only way to get to this or replace the now un-usable tensioner is to remove the gearbox.

I've found out most of this information from my brother who works on a lot of German cars, however it's all available in various VW forums on the net. Not too sure if I can mention any here without breaking the rules.

MM

[craggsy 91]

AAA248*** for me.....well mine's a R plate so last of the line