First Post - Broken Timing Belt Fiasco

[pvc4life]

First, this web site is great, I have been able to solve a lot of my questions by searching through the forums here.

So on to my timing belt. I bought a used 1986 TD Jetta about two months ago with 100k on it for $2,00 and the timing belt failed within 175 miles. I'm pretty confident that it was just a freak accident. It ran like a champ for the short time I had it running.  The guy I bought it from owns a shop and offered to rebuild the head because he felt terrible.

I took it all apart (first time ever working on a diesel) and he replaced the bent valve and a lifter or two while he was in there and gave it back with a new timing belt and head gasket.  I got it back together and it wasn't running right. After trying to diagnose it we determined it probably had a leaky intake valve. I tore it apart again and it definitely had no combustion on the second cylinder.

My dad took the head to his work and had some one clean up all the seats and I have ordered all new valves (only two of them were 100% true upon closer inspection), stem seals, lifters etc.

I hope to get the car back up and running next week. Then I get to figure out where the leak is coming from on the injector pump....

[745 turbogreasel]

Fill the IP, and pressurize it, the leak should be obvious.  Especially if you use ATF for color.
It is good you replaced the valves, they love to drop a head awhile after getting bent.
You might want to personally recheck each lifter cup for cracks.
Also closely check the piston protrusion to be sure you didn't get a bent rod as well.

[bajacalal]

Just, FYI, timing belts are not an item that causes the engine to run poorly, or run differently when they're too old. They will still keep the engine in perfect timing until the second they snap. Unlike chains which stretch and fatigue, the timing belt doesn't stretch too much but becomes brittle and prone to cracks and failure.

[pvc4life]

754 - I determined the leak on the IP is at the fuel load adjusting screw actually. I just ordered a Bosch rebuild kit for it so hopefully replacing the o-ring does the trick. Also, thanks for the suggestion on checking the protrusion, we made sure to double check it when we first got it apart.

Bajacalal - The timing belt was supposedly replaced recently so it really shouldn't have failed (it was one of the first questions I asked when I bought the car). I think that is why the guy I got it from felt so bad when I called him to tell him it failed.

[745 turbogreasel]

You can change just that oring, but the others are equally old.

Did the belt fall off, lose teeth, shred from the side, or snap?  Or if it was missing the cover, it could have choked on debris.

[pvc4life]

I fixed the leak by just replacing the o-ring. I bought a full bosch kit so eventually i plan to rebuild the pump, just not this weekend. Also, the alternator belt shredded, we believe it tore because of a foriegn object because there was an impact looking mark on the injection pump pulley. Never found the actual part. We cleaned up the pulley before putting it back together so it wouldn't wear on the belt. It had the timing belt cover on so it wasn't exposed. Really no idea what got loose but it's not there anymore.

I got it back together yesterday. Starts right away and runs pretty good. A little more smoke under load and a little less power than before (I think, I only had it for 5 days before it failed so I'm not positive). I think I just need to play with timing a little bit. We used a dial indicator to measure the pump timing but it was in thousands of inches instead of mm. I also need to  check the cam timing and make sure it's perfect, we don't have the cam lock tool and were using a make shift part that might have allowed for 2 or 3 degrees or so of play.

[damac]

I fixed the leak by just replacing the o-ring. I bought a full bosch kit so eventually i plan to rebuild the pump, just not this weekend. Also, the alternator belt shredded, we believe it tore because of a foriegn object because there was an impact looking mark on the injection pump pulley. Never found the actual part. We cleaned up the pulley before putting it back together so it wouldn't wear on the belt. It had the timing belt cover on so it wasn't exposed. Really no idea what got loose but it's not there anymore.

I got it back together yesterday. Starts right away and runs pretty good. A little more smoke under load and a little less power than before (I think, I only had it for 5 days before it failed so I'm not positive). I think I just need to play with timing a little bit. We used a dial indicator to measure the pump timing but it was in thousands of inches instead of mm. I also need to  check the cam timing and make sure it's perfect, we don't have the cam lock tool and were using a make shift part that might have allowed for 2 or 3 degrees or so of play.

first off sounds real odd about the belt so soon after the guy did the install.  what brand was the timing belt, how did it fail and was the tensioner still tight to the block after this happened?  sounds fishy

also on the timing, did the guy put it all back together or just replace parts and dump it on you?  thats a crappy deal, it wouldn't take long to time the engine for you.  i have a feeling i wouldn't be giving this person my business.

you should probably get a bently manual for your car.  if you timed the engine properly the cam and tdc should have been set so everything lines up and belt tensioned.  then you rotate the pump around with the dial gage to get the desired advance on the pump, which there are specs for.  there is no cam timing to adjust unless you messed it up the first time and are flirting with disaster and your engine guts smacking into each other again.

[pvc4life]

first off sounds real odd about the belt so soon after the guy did the install.  what brand was the timing belt, how did it fail and was the tensioner still tight to the block after this happened?  sounds fishy

also on the timing, did the guy put it all back together or just replace parts and dump it on you?  thats a crappy deal, it wouldn't take long to time the engine for you.  i have a feeling i wouldn't be giving this person my business.

you should probably get a bently manual for your car.  if you timed the engine properly the cam and tdc should have been set so everything lines up and belt tensioned.  then you rotate the pump around with the dial gage to get the desired advance on the pump, which there are specs for.  there is no cam timing to adjust unless you messed it up the first time and are flirting with disaster and your engine guts smacking into each other again.

I can't really blame the guy for the timing belt. The car was running fine when I bought it. I replaced the alternator belt late one night and a couple days later the alternator belt broke. It could have been something I did although I don't really know what.

On the timing, I put the car back together, twice now. The first time the guy I got it from rebuilt the head for me but he only replaced the one bent exhaust valve and bought me all the parts to put it back together. After putting it back together it had a miss on one cylinder. I took it all apart and it still had one leaky intake valve. I had some one else I know put all new valves in it and clean up the seats(about $240 for all the parts including valve keepers, seals, head gasket, bolts etc).

Like I said it runs good, just a little bit of smoke under a load on the high end of the RPM range. I don't think the cam is off but Ill double check it to make sure.

I actually have two Bently manuals, one I got off eBay after reading the forums here and my dad had one from the last time he owned a diesel VW in the 90s he found in his garage. I also have an older Haynes manual for vw diesels as well.

[pvc4life]

The next task is to fix the vacuum pump. When trying to take the vacuum pump hose off so I could check the injection pump timing the check valve broke off at the base of the fitting. You can see it at the top of this picture.



I have found rebuilt kits for these but nothing about replacing the check valve. For now I just fitted a new hose over the fitting that that check valve is pressed in to.

[ORCoaster]

Check the section on this forum for tools we may use to time our engines.  Many a good substitute, I use a 3 1/2 inch door hinge across the back of the cam to keep it at TDC on #1 cyl.  IP gets a Carriage bolt that is just the right diameter for the two holes.  Very little wobble. 

For the Vac pump I would replace the check valve with a standard hose fitting and just put a generic check valve in line between the pump and the booster.  Same function different setup.

Now that you have rebuilt the head do you have access to a compression gauge to determine if the rings are good?  Smoke at the high end of the RPM range makes me think of blow by under heavy load. 

Good luck and keep us posted.

[libbydiesel]

I've fixed rotary vac pumps by pulling the lid, driving out the remnants of the stock check valve, tapping the lid to 1/8 NPT making sure to chamfer the edges so the vanes don't catch and installing one of these check valves.  Be sure that when you tap the lid you don't tap so far that the check valve will protrude past the lid.  I then used a 1/2" barb fitting (I cut it off a fitting I had on hand), tapped it to 1/8"NPT and attached it to the check valve.  It works perfectly and is an upgrade from the stock piece in being much more robust.



 

[ORCoaster]

Very well Done I might say.

[theman53]

I've fixed rotary vac pumps by pulling the lid, driving out the remnants of the stock check valve, tapping the lid to 1/8 NPT making sure to chamfer the edges so the vanes don't catch and installing one of these check valves.  Be sure that when you tap the lid you don't tap so far that the check valve will protrude past the lid.  I then cut a 1/2" tapped the inside of a 1/2" barb fitting and tapped the inside of it to 1/8"NPT and attached it to the check valve.  It works perfectly and is an upgrade from the stock piece in being much more robust.



 

When I figure out how to I will copy your post and make it an FAQ sticky since it seems all on here have been having vac pump issues all last year.

[8v-of-fury]

When I figure out how to I will copy your post and make it an FAQ sticky since it seems all on here have been having vac pump issues all last year.

Done.

It has its own post in the FAQ, and a link to that FAQ post in the FAQ Quick Guide, under miscellaneous.

[pvc4life]

I've fixed rotary vac pumps by pulling the lid, driving out the remnants of the stock check valve, tapping the lid to 1/8 NPT making sure to chamfer the edges so the vanes don't catch and installing one of these check valves.  Be sure that when you tap the lid you don't tap so far that the check valve will protrude past the lid.  I then used a 1/2" barb fitting (I cut it off a fitting I had on hand), tapped it to 1/8"NPT and attached it to the check valve.  It works perfectly and is an upgrade from the stock piece in being much more robust.

 

Very nice, I will probably do this next weekend. Thanks for the tip.