Waited Too Long For Timing Belt in Modded Engine (95K miles)...

A5INKY

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I replaced the TB at 155K miles prior to major mods (see sig for the basics) that came a bit after 190K miles. Even though the head got a full rebuild I reused the 35K mile TB, figured I would let it live it's life. Fast forward about a year and I found myself in a very messy divorce from my wife of 17 years, two kids - no fun. Went many months without a reasonable work space, tools in storage - really bad deal. Finally just got set up again with a place to work and dove back into the car and all the maintenance that was allowed to slide. Worked on it all last weekend but ran out of time to inspect the cam (Colt Stage II that went in with the TB at 155K) and decided to wait until this weekend. Once the cam was inspected, I planned to order all needed parts including a TB kit and replace it in the next couple weeks. I am right at 250K miles now, so that 100K mile TB has 5K miles of life left, right? WRONG.

Merging on to the expressway today, I put my foot in it to blow past a D-bag that tried to close the gap I was shooting for once he saw my turn signal. Full boost and pulling hard it just shut down - no bang, no nothing. Didn't initially register it was actually dead and I though it might have gone into limp mode. Tried to restart, nothing. Coasted to the next exit and into the nearest parking lot, no start. No bad sounds, just no start. Called a tow truck and began to wait. Just for giggles tried to start it again and it fired up, sounding fine - hmmm. Canceled the tow truck and headed for my shop and tools, seemed to be running fine, boosting well sounding good. Got on the throttle a little again and it nearly died but stayed running, not sounding so good this time. Was really close so I limped it to my shop and started the diagnostic. VC came off, cam actually looked pretty good. Removed the IC pipe and TB cover and found this:



Sheared 21 teeth off the TB - really not good. I went home to make dinner for the kids, enough of that for tonight.

Before it is asked, yes it was a quality belt kit (Bora Parts) installed with the correct tools (Metalnerd) and procedure (Bentley "Repair" manual). Job went by the book both times with no question of perfection.

I will lock the crank at TDC tomorrow and see where the timing is sitting right now. I have no hope that there was no piston / valve contact, that seems too unlikely. I'm not that lucky.

Why this thread?

- First is to ask what the chances are of not smacking valves with a one tooth TB jump (assuming that is what happened)?

- Second as a caution, this happened on a belt with 95K miles on it. It doesn't make that much sense to me, but I have heard it said that the TB change interval needs shortened with a modded engine. Never heard any evidence or rationale for this before, so I didn't put too much stock in it. However, you can see what waiting did for me.:(
 
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mlemorie

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No good man, thats rough. Unfortunately you are pretty much guaranteed to have collided pistons and valves at this point, and it will be a head off job to get it back into winning shape. All TDI's from 04 and up got moved to an 80k timing belt interval.
 

JFettig

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Wow, I would find it hard to believe that you only skipped 1 tooth.

Hope it turns out ok!
 

slamhouse

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I'm finding it hard to believe that the age of the belt dictated the removal of several teeth in rapid succession.

I'm sensing something bigger going on that caused a rapid stop of either the camshaft or the crankshaft resulting in the shearing of the teeth.

Your timing has likely jump to extreme retardation(-30 degrees) during the major stress event and during cranking, it pulled it back to a runnable time(-10 degrees) with driveability issues.
 

JFettig

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This happens. That's how it happens. Much higher angular acceleration due to much higher power adds stress.

I'm definitely sticking with 80k for PD belts - I believe the new recommendation was check at 80k, 90k, and 100k?
 

slamhouse

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Replace at 80k miles now.

There shouldn't be any increase of torsional stress due to angular acceleration on a modified vehicle especially if larger nozzles are install lowering injection pressure and less stress on the belt. A larger valve profile might yield higher stresses though.

Edit: going to have to think about this one as the combustion event is more violent resulting in a more rapid acceleration of the crankshaft in relation to the camshaft.
 
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A5INKY

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My life has been so upside-down for this past year and a half, not too surprised I missed the 80K TB interval memo.

Been thinking about this more and I have to agree, the tooth skip is not plausible. The gap in the belt is not enough to allow a skip on the upper cog, but then there is the fact that the cog on the crank is half the size. I can't believe I drove it home and the cam doesn't appear damaged. That had to cause some serious stress on the followers.

Best case now is that the pistons survived somehow. You can bet I will be measuring protrusion very carefully. Been thinking about taking my porting up a notch anyway. Off comes the head...
 

dieselpower04

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Wow that sucks man. I had heard about the 80k mile change from Kook, and was going to wait till 90k...maybe I won't now...
 
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slamhouse

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A5INKY,

What kind of power are you putting to the wheels? been thinking of doing your exact mods :)
 

nathan_b

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At 95k, you knew better, I wish you no valve damage.

Only PD motor tb fail I've had to deal with was at 156k, all factory tb!
Poor luck, they are MONSTER timing belts, dont know what they are missing...
 

A5INKY

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A5INKY,

What kind of power are you putting to the wheels? been thinking of doing your exact mods :)
Been awhile since it was on a dyno, but 203 WHP at the last one. Cleaned up a few details and tune is better now.
 

slamhouse

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How is the driveability now compared to stock in regards to spool up when just crusing at 60 and during acceleration from a stop?
 

A5INKY

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How is the driveability now compared to stock in regards to spool up when just crusing at 60 and during acceleration from a stop?
Right now, not so good....

Really though, the drivability is excellent. Pulls as hard or harder right from the bottom. I have pretty good TDI driving habits so I don't get too heavy footed below 2K RPM but I have never had any lack of power nor turbo surge. It is a beast once up to speed. Punch it at 60 and it pulls you back in the seat.

You would not know it is built making more than 2X OEM HP when at idle or taking off from a stop if it were not for the rattle from the stage III SB clutch/lightweight flywheel and vibration of the urethane engine mounts. People notice something is up, but not because of any lack of power.

With enough load it will spool all the way to 2 bar by ~2200 RPM, but is building plenty of boost to match reasonable fueling even w/o a big load.
 

Drivbiwire

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Remove the cam, remove each lifter, under the lifter depress and check each adjuster for spring return. This may require several depressions to get the oil out. As long as the plunger returns under it's own internal spring force you should be fine.

This will add 30-40 minutes to a timing belt BUT it will tell you if you pranged a lifter or valve.

IF you are lucky (and this may very well be the case) you may only require a new set of lifters if you find that any of the lifters took a hit...highly likely.

I have found in a few circumstances where the lifter took the blow but the engine remained sufficiently in time that there was no other damage aside from replacing the lifters.

Fingers crossed for you, but you may be lucky and only need 8 lifters out of this ordeal.
 

A5INKY

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Whoa, talk to me Pete.

You are saying it is possible to qualify that the valves were not weakened w/o yanking the head? I was assuming that any piston contact would be enough the compromise the strength of the valve head to stem. I had it in my mind to replace every valve that smacked.

Would be so nice to get away with only followers.
 

storx

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wow, bro.. I feel you on the divorce thing.. I just finished my 4 year long divorce this past april. I also know how you feel on the luck of the draw with the teeth sheered off the belt. I had an 2001 Audi TTQ for a while and I installed an GT3076r and AEB head, Then 53k miles later I went to drag strip and on my last run that night I launched and everything was going well tell I got to the 1/8 mile mark and the engine stalled.. I was expecting blown engine coasted off the track then popped the hood and didn't see anything wrong so I tried cranking it and it cranked but acted not normal so I limped it to my trailer and towed it home and when I pulled stuff apart I sheered 13 teeth off the timing belt. So I pulled the head and when I did it didn't look like I bent a valve at first but when I pulled the valves, 4 of them had just barely a slight bend in them. So good luck.. I had no damage besides the slight bend in the valves.. I think the tension of the belt kept the timing from slipping to far off even with he missing teeth.
 

IndigoBlueWagon

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You may get lucky: My son did. Water pump seized at 70 MPH and pulled all the teeth off the belt.

Engine did not lose time. No damage to lifters or valves. New belt and it ran fine. This was 5 months ago, still running great.
 

deejaaa

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You may get lucky: My son did. Water pump seized at 70 MPH and pulled all the teeth off the belt.

Engine did not lose time. No damage to lifters or valves. New belt and it ran fine. This was 5 months ago, still running great.
this is just what happened to me. WP seized. i took it apart and it looked like it had a bad bearing for a long time. the diff was i sheared just one side of the belt and no teeth jumped. i was lucky.
 

nathan_b

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1999.5 alh jetta/ 2002 alh jetta
Remove the cam, remove each lifter, under the lifter depress and check each adjuster for spring return. This may require several depressions to get the oil out. As long as the plunger returns under it's own internal spring force you should be fine.

This will add 30-40 minutes to a timing belt BUT it will tell you if you pranged a lifter or valve.

IF you are lucky (and this may very well be the case) you may only require a new set of lifters if you find that any of the lifters took a hit...highly likely.

I have found in a few circumstances where the lifter took the blow but the engine remained sufficiently in time that there was no other damage aside from replacing the lifters.

Fingers crossed for you, but you may be lucky and only need 8 lifters out of this ordeal.
How can a lifter take a "hit" when the only way it can be impeded is by the valve hitting a piston and causing resistance between the cam and valve, the lifter taking the hit.

I have seen PD motors have tb failure, and just slap a new belt on.
It runs great, for 10k, 15k, 20k... until a valve head breaks off and literally destroys everything.
 
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mrchill

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Sometimes one gets lucky...its not often. I have seen them not lose time...or lose very little...those have survived. I have seen others that looked ok...and blew up later and still others that were spectacularly exploded. If you lost time...I would pull the head, measure protrusion and replace the valves. If protrusion was affected...obviously its time for rods and\or pistons...but even when not, often the rod bearings are damaged.
 

Drivbiwire

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If the belt is still holding time the lifter can take enough of a hit that it does not compress the valve or stem. The lifter plunger will be compressed enough that you get a very light upward deformation of the lobe contact area on the top of the lifter. (small circular raised area, some minor distress cracking may also be present).

If the lifter is not destroyed, you MUST check the plunger under the lifter.

In cases where there was mild contact BUT the belt remained sufficiently in time that the valve was not smashed up thru the lifter the lifter will have very mild damage internal to the plunger mechanism. Often this is missed by the owner, the lifter is put back into the car and you get a tapping or pinging sound since the lifter will not properly "fill" and take up the slack.

For the most part, remove the lifter, depress the plunger several times to remove the trapped oil in the adjuster. There is a spring mechanism that causes the plunger to expand (this is what helps to take up the lash). VW in the ALH and older engines use a "Plastic Wedge" test where you could check the compression of the lifter, the lifter is required to rebound when the wedge is removed (total movement is 1.0-1.5mm it's not much)...same concept with the PD, but I prefer to hold the lifter in my hands and physically check the plunger up close and check for un-impeeded return of the mechanism.

Anyway, as long as the lifters are NOT stressed to the point of failure (fragmented in the head) you are more than likely safe in terms of not having compressed valves.

Another thing you can check to make sure the valves are not compressed, is to depress the valves and make sure there is no sticking that would indicate a valve has expanded excessively inside the guide. Generally if you have any expansion of the valve stem, the lifter will be fragmented in the head.

I think you may have a shot at not having to take the head off, BUT make sure you check all the lifters and valves, at the very least if everything looks good ONLY replace the lifters to insure the adjusters are functioning correctly.
 
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Nash_TDI

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Sorry about your luck. We never did meet up. Now that we both have big turbos we definitely need to hang out/wrench some.
 

A5INKY

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Sorry about your luck. We never did meet up. Now that we both have big turbos we definitely need to hang out/wrench some.
Definitely. Been a crazy year for me, starting to settle a bit finally. I'll PM you in the next couple weeks.
 

A5INKY

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Update, did some disassembly and am now certain the head must come off.

First thing I found is that my Colt cam is done for. Cylinder #1 exhaust is starting to degrade pretty noticeably, chamfer is nearly gone. Cylinder #3 intake is starting to go too. Of note is the chamfer on my Colt seems bigger than the OEM cam that came before, meaning that even though the chamfer is just starting to disappear the wear is pretty bad. I don't want to turn this into yet another over-the-top PD cam analysis thread. However, if anyone wants to see more cam failure related stuff, PM me and I will do my best to provide pics and info. The cam failure is not what this thread is about.

Once the cam was out, next came the followers:

Follower#1 (L-R) cyl 1 ex

Follower #2 cyl 1 in

Follower #3 cyl 2 ex

Follower #4 cyl 2 in

Follower #5 cyl 3 in

Follower #6 cyl 3 ex

Follower #7 cyl 4 in

Follower #8 cyl 4 ex

The followers from the trashed lobes are obvious. Also obvious is that, judging by follower scoring, there were a couple other lobes not long for this world too had the cam continued to be run. What concerns me are the micro cracks radiating from the centers of several followers, #7 is a pretty good pic of this. I think we all know what caused that. Just for grins I pumped the oil out of each follower as Pete recommended to check return. All returned well under the force of their springs. Thanks Pete for offering your guidance, but I think you would agree this thing must come apart.

Next, on Frank's recommendation, I measured down from the VC face to the installed valve stems. Since Frank built the head for me, I appreciate that he was willing to offer advice. Installed height of all valves were within 0.002" of each other except two. One of those was ~0.007" shorter and the other ~0.015" shorter. According to Frank, he holds installed heights to a pretty tight tolerance and these two are well outside of it. I believe this to be good evidence that at least two valves smacked hard enough to permanently deform.

So, off with the head for further analysis. Will be inspecting piston crowns and protrusion. Also plan to pull all the valves and do a more thorough inspection of them. Not sure how many will be replaced yet, but don't plan to leave anything to chance.

That will have to wait for next week though. This weekend I am being taken out of town to parts and activities unknown as a birthday surprise by a new friend :D.
 
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storx

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Good luck man... We should meet when I get to Florida in march... I got the gtb2263vk in and went for first test drive.
 

A5INKY

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Time for an update. This failure turned into a complete debacle for a variety of reasons. However, reassembly started today and will be complete tomorrow. So, hopefully all will be well that ends well.

With installed heights of two valves being up to 0.015" shorter I was concerned that the valves were damaged by the impact with the pistons. When I pulled the head off, the exhaust valves clearly smacked on all 4 cylinders. I shipped the head off the Frank Irving for another rebuild. When he got the head cleaned up he found it to be cracked in 6-8 places. He said this is starting to show up with some higher power PDs. Apparently, mine was one of the worse ones he has seen. The severity of the cracking made him hypothesize that heat and pressures in my engine, coupled with the BRM piston design that places the top compression ring closer to the crown than higher rated euro PDs might have annealed the top ring. This thought combined with the obvious smacking of my exhaust valves, combined with my stock rods that have been subjected to well over 200 BHP for many miles made me decide to pull the bottom end apart.

Bores looked good and were still well within spec, so I ball honed them to prepare the bores for the new rings. Turns out the old rings were not obviously annealed. But now I had it apart so I decided to go ahead and install some PD130 (ASZ) pistons. These pistons locate the rings much lower nearer to the wrist pin. I inspected my rods. Even at my power level, all four were arrow straight and the exact same length. Bearings looked perfect too, I reused them. I went ahead and balanced the pistons and rods to within 0.5 grams. Mixing and matching wrist pins allowed my to put together a balanced set to the same spec. When the bottom end went back together piston protrusion was right in the middle of the 2-hole gasket range with only a 0.02mm variance between all 4 pistons. Clearly the stock PD rods are good to go for at least 200 WHP.

I went ahead and had Frank port the head. The exhaust ports were opened up first on the mill then blended by hand into the hand worked bowls. Circumstance had me putting major pressure on Frank to ship it so I finished up a little of the hand work once I got it back. I don't have dimensions but am very happy with the work. I have a feeling the exhaust ports were a major bottleneck in my engine build. Looking forward to getting back on the dyno soon.

I also bought Frank's stage II BRM cam to replace the worn Colt stage II BEW cam that I had been running. Looking forward to see what the increased PD element travel might yield.

Car will be back on the road tomorrow. I think I will shoot for 75K mile timing belt replacement intervals from here on out. Though I will start inspecting the tensioner position at about 50K looking for evidence of belt stretch. That interval may end up getting shorter still. I will also be breaking it in with the same Joe Gibbs BR break in oil I used last time, but am doing a second 500 mile BR oil change before settling in with my normal Schaeffer's S9000.

On the head cracking. The fellow that did the initial vacuum actuator conversion on my 2056 didn't get the stop screw jam nut tight enough and it fell out not long after the build. I found the problem while replacing the turbine to manifold gasket that blew out as a result. My theory is that with no stop the VNT vanes were closing more or less completely causing a major EMP spike on tip-in. This is one possible anomaly that might have stressed my head. The other was my learning curve early on trying to get the turbo and tune right. It was super smokey for the first couple weeks as I was learning how to properly set up the VNT. We had way too much fuel at first for my poorly set up turbo. My hope is that one or both of these issues are what caused the cracks. May not know for sure until it comes apart next time. I hope that is a long way off.
 

A5INKY

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!#*%!, sometimes it is one thing after another! :(

Went to install the TB this morning and found this:



Key in cam pulley is mostly sheared off. I can only guess that this happened as a result of the piston/valve contact. Looks like the I will be finding a new one tomorrow...
 

kooyajerms

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^at least you were smart enough to look in the sprocket first.



Where did your cracks show up on the head? Before getting it dialed, what do you think the major EMP spikes were?

For myself I get 60psi spike and wonder if a 2:1 spike is of any consequence. I know I know, someone will say combustion pressure etc, but like you're saying, what are the real issues with too much EMP (spike or sustained).

PM Me if you like. Sorry again about that big rebuild, I know what it feels like =(
 

ducesrwld

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man just saw this thread don't hop on here as much these days. i'm going on my 3rd round of injector overhauls, had to get the car towed twice this year and for the most part have maybe only put a couple thousand miles on it. money has been tight and the car is currently just taking up space. i'm hoping for a better 2013 myself...
 

Whitbread

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man just saw this thread don't hop on here as much these days. i'm going on my 3rd round of injector overhauls, had to get the car towed twice this year and for the most part have maybe only put a couple thousand miles on it. money has been tight and the car is currently just taking up space. i'm hoping for a better 2013 myself...
Such a monster being held back by dumb BS :(.
 
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