1.9l TD AAZ Timing belt tensioner pulley broke off

[vwdriverfoundvw]

Hello,

I took my van for a drive yesterday and the engine suddenly shut down. After being towed home and some troubleshooting, it looks like the timing belt tensioner pulley bolt has sheared right off. Has anyone ever seen this happen?also, I cranked the engine a bunch of times trying to restart with the belt totally loose. Did I damage my valves?

Can anyone point me to part numbers of the belt, tensioner pulley, and cover?

[Gizmoman]

Sorry to hear about your issue. I've never heard of this happening to an AAZ but there may be others with more experience who will chime in.

Sadly there is probably some damage done to either the pistons or the valves or both. As you know, these are zero clearance engines. Let's hope the damage is minimal or somehow you got lucky and all the valves were closed (if that's even possible).

Makes me want to go and check mine.
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82 Vanagon Westy - AAZ 1.9 TD, HE200 Holset, WAIC, 27.75 dia tires, Electric power steering, 5-speed AAP w/.078 5th
Oversize spare carrier - stock location (no longer for sale).

[?Waldo?]

If you cranked it with the tensioner gone undoubtedly there was some piston/valve contact. Remove the head and replace any valves that touched the pistons.

[zuhandenheit]

I'm really sorry to hear this.

Do you have any idea what happened to the stud? Had you ever replaced the tensioner and if so, did you notice anything out of the ordinary?

--

Anyway, if I were you, and supposing I could do the work myself, I would pull the head right away, check that there's no damage to the pistons and then maybe try to get a good used head (can be found for cheap, often), or possibly if I had the money a nice new one (these are around $1000 -- don't consider Prothe), an appropriate headgasket (based on piston protrusion) and other gaskets, and head studs, and then reassemble ASAP.

I say this mainly because it might take me longer to find a good machinist than to find a head, and I wouldn't want to feel rushed. The head studs would make it possible to swap to the old head after a rebuild for little more than the cost of a headgasket, supposing you can do the work yourself. And I like having stuff like a spare head, given that I want to travel and it isn't always easy to get AAZ parts in the US!

--

Anyway, I don't think you need to order a TB and tensioner just yet, but you will have to determine which style of tensioner you need. You'll be able to quickly get all the info you need with a google search -- just look a the pictures of the two styles of tensioners.

[Farfromslow]

When replacing the TB tensioner and idler pulleys the studs and or bolts are one time use and should be replaced as well. Most good kits come with them but if they don’t you should purchase them separate. They also need to be torqued properly, I have seen them fail shortly after install when a mechanic has either not torqued or not replaced, unfortunately in all of the cases I have seen there has been valve damage.

[zuhandenheit]

[Gizmoman]

Here is a link to a new KOLBENSCHMIDT 1.9 head.
https://www.cascadegerman.com/product/028103265d-kol/
I highly recommend joining the IDI forum http://vwdiesel.net/forum/index.php?board=6.0.

There are plenty of folks here that can help but these guys deal specifically with this engine and can help you with the details - and there are plenty. As to the tensioner pulley, I believe there were two different variations depending on year.

It's hard to imagine the engine just died without making some horrible noise - although I suppose it's possible. As you have just learned the hard way, never crank an AAZ engine if it quits abruptly.
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82 Vanagon Westy - AAZ 1.9 TD, HE200 Holset, WAIC, 27.75 dia tires, Electric power steering, 5-speed AAP w/.078 5th
Oversize spare carrier - stock location (no longer for sale).

[?Waldo?]

[chrissev2]

Usually when pulleys fail on these motors it is the crank shaft pulley keyway that fails. The older ones have a keyway that becomes loose and eventually the crank pulley just works its way off. The fix is to machine the crank to a "D" shape and install the later TDI pulley.

I am running the Kolbenschmidt head on my 1.9 AAZ without issue. It is a good, cheap replacement for the OEM head when this sort of thing happens.

Likely your cylinder head will be destroyed as the pistons will have smashed the valves into the head and bent and broken them.

You can usually re-use the block when this happens, though you should check for cracked pistons and damage to the connecting rods (they may be bent or the bearings may be damaged from the impact).

The event you have experienced is what is known as a "catastrophic engine malfunction" and results in major engine damage.

Hopefully you are able to save your block. The head probably isn't worth the effort.
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1986 westfalia auto 1.9TD
2023 VW Atlas 3.6 VR6 Highline
2019 Golf Wagon 4 motion
1978 Volkswagen super beetle convertible
1992 Eurovan 2.5 5spd westfalia

[HBB]

As others have noted, this situation normally calls for replacing/rebuilding the head.

A number of folks on TDI Club swear by this guy for rebuilding:

https://www.facebook.com/FranksVWTDIS/


I would imagine that piston damage is unlikely with a loose belt, but you won't really know what's going on until you pull the head.

[vwdriverfoundvw]

Thanks for all the replies. Lots of good info. I'm also on vwdiesel.net forum and love all the support of this comunity.

This is my first real experience with this engine. Coming from an aircooled bay window, I bought this AAZ converted Vanagon just over a year ago and have had no problems to date. I have no idea what happened at the last belt change so no clue as to why this stud failed.

I'll be sure to update this thread as I progress through teardown and rebuild.

[Gizmoman]

Once you become familiar with the engine, you'll find it to be quite bulletproof when built properly. I took my time with my rebuild (my first diesel as well) and it's really paying off - knock on wood.

If you have a turbo, make sure to get an EGT probe and gauge. keep the EGTs under 1200 and it will last a very long time.
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82 Vanagon Westy - AAZ 1.9 TD, HE200 Holset, WAIC, 27.75 dia tires, Electric power steering, 5-speed AAP w/.078 5th
Oversize spare carrier - stock location (no longer for sale).

[chrissev2]

[briansc]

This man in No. Carolina, not Prothe or related, has one rebuilt 1;9TD head with believe new parts for about $300. I am buying complete 1.9TD engine from him at great price as he's moving. out of state and selling all extra vw parts. Email is [email protected] and his ebay id believe is tomaryberry, his name is Tom Berry...Brian

[zuhandenheit]

I thought about mentioning a spare rebuilt head I'm holding, too, but it has some known issues. Probably as often as not, there will be a used head on vwdiesel.net. But I checked when I last posted here and didn't find anything.

As others have said, there's a real chance of piston damage, so the first step is to pull the head.

I was somewhat baffled by the claim that tensioner pulley studs come with timing belt kits and am relieved to get an explanation! It's a strange failure and like Andrew, I wondered if the motor was run without a tb cover -- if an large enough object found its way between the belt and pulleys, maybe the tension on the belt was responsible for the broken stud.

Anyway I find it hard to see why it would suddenly fail, otherwise. The forces on the stud should be steady . . . and consider how much force it would take to snap a stud/bolt of that size, in even remotely good condition.

Have you looked closely for damage to the belt? I'm sure satisfying our (just my?) curiosity isn't a priority, but it would be nice to have some further clues that might indicate a cause of the failure.

[Gizmoman]

^^^ I agree - finding out why it broke should be part of the fix.
The geometry of the belt as it's forces are translated to the idler should be quite minimal - it is probably the weakest link though assuming the belt is in good condition.
If something like a rock got in there it would probably be the first to go.
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82 Vanagon Westy - AAZ 1.9 TD, HE200 Holset, WAIC, 27.75 dia tires, Electric power steering, 5-speed AAP w/.078 5th
Oversize spare carrier - stock location (no longer for sale).

[vwdriverfoundvw]

Update. I have disassembled to the point of having the head off and removing the valves.

There are witness marks on pistons but none look horrible to me.

The exhaust valve of piston 4 was stuck slighty open after removing the spring. When trying to remove, it gets jammed into its guide. Its lifter actually has a shattered face where the valve contacts it. This one definitely took a good hit.


Photos of piston tops, smashed lifter, and sheared pulley bolt can be seen in this album: https://photos.app.goo.gl/tgCZeDmuUy12eabf7

[Gizmoman]

Looks like you may have gotten off easy. Probably hard to tell but does the tensioner stud look like a clean break or is it like a taffy pull?

Not sure I'd trust that piston - certainly your call though. Let us know how your progressing.
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82 Vanagon Westy - AAZ 1.9 TD, HE200 Holset, WAIC, 27.75 dia tires, Electric power steering, 5-speed AAP w/.078 5th
Oversize spare carrier - stock location (no longer for sale).

[Farfromslow]

I apologize for any misinformation about the belt kits coming with studs, I was indeed thinking of the ALH kits. I do believe however that replacing that stud is good practice and why my shop replaces them, there is no way to know how many times that fastener has been reused or if the previous person in there actually torqued it properly, to me it is cheap insurance.

[?Waldo?]

Idparts sells it individually. Here's a link: https://www.idparts.com/tensioner-stud-a3-ahub4-1z-p-2589.html