Help! Timing Belt Replacement Out 180 Degrees

[Matt_2003 TDI]

2003 MK4 ALH, 160k miles, second owner, car was otherwise running fine when we got it in for its 2nd timing belt replacement but first one done by yours truly.

In setting the cam, injection pump, and crank time when removing the old belt... well, what looked like the TDC mark on the flywheel turned out to be a mirage. However, to the best of my knowledge the rest of the procedure went perfectly - no gears moved independently, and overall it seemed to be a pretty straightforward job.

Fast forward to having the new timing belt on and tensioned, when i went to rotate the engine by hand you can definitely feel a valve or some type of interference at about 10 degrees past my TDC lockout point (which, turns out, may actually Bottom Dead Center... anyways).

Where do we go from here? I'm in no urgent rush where i'd need to have a mechanic come bail me out, but my thought was to take off the timing belt and advance / retard the crank shaft to get the valve out of the way. Or, do we just jump straight ahead to re-timing the full engine from here to TDC? What do we need to consider about the injection pump, as it "locked" perfectly as well but would we need to advance it 1 revolution as well?

 

[dink]

start from scratch, injection pump should be good, might have to unbolt and remove cam to get crank to top dead center. when the crank is aligned at top dead center , put the cam back in lock it in place , install timing belt

 

[Matt_2003 TDI]

Thanks for your reply!

Why would the injection pump be good if all else is 180 degrees out?

Researching through - others have advised to turn the crank 90 degrees or adjust so all pistons at mid-height, then move cam to TDC (180 from current position) and then flywheel / crank to TDC - would that work as well? Would prefer to leave the Cam in if at all possible...

 

[dink]

injection pump will not be out, it will be timed for top dead center. you could try do the came that way , i took the cam out , i think it was 10 nuts and i put the new cam seal on

 

[Matt_2003 TDI]

Where I'm at now (to the best of my estimation:

• Cam Shaft: #1 lobes are in "Up" position, but not sure if they're right or 180 degrees off
• IP: pinned correctly at TDC (confirmed im in the hole, cross referenced photos on this site) Does the IP only have one position that would be TDC? Just worried about getting it out of sync with the cam shaft
• Crank: 180 degrees off

Would the following work to reset to factor timing from where I'm at now?

1. Lock IP to TDC (currently is)
2. Lock Cam (to 180 degrees off of TDC) <-- not sure if this step is necessary, but its easy enough
3. Remove TB
4. Turn Crank so that all Pistons are middle of chamber
5. Adjust Cam to TDC, insert cam lock
6. Turn Crank to TDC, insert crank lock
7. Re-install and tension TB

Will steps 4 and 5 work that easily or would we hit any interference while making those revolutions or trying to resync both at TDC?

 

[Matt_2003 TDI]

injection pump will not be out, it will be timed for top dead center. you could try do the came that way , i took the cam out , i think it was 10 nuts and i put the new cam seal on

I guess if you take the cam out, how do you put it back in and ensure orientation to TDC?

 

[dink]

a4timingbelt.pdf

 

[Matt_2003 TDI]

That’s the procedure i‘ve been using - just trying to see how / where to re-sync up to that Now that I’m off the “happy path”... especially if removing the cam. Appreciate your help!

 

[scurvy]

The only real area for concern is that the belt can move the crank and cam toward each other in timing when doing up the tensioner. Make sure you're slipping the belt on in the preferred order so they don't move when you tension it the proper way.

Also, there's a fool's hole at 12 o'clock on the IP that isn't actually the pin detent hole, check it with a mirror & flashlight to make sure you're going into the hole in the boss... but that won't lock up the engine, it will make it not start or run (injection timing will be too advanced).

Our old 2000 NB had two (count 'em - TWO) top dead center marks on the flywheel thanks to the stealership, make sure you're using the right one. There's a secondary mark on the harmonic balancer that will help make sure you're in the right neighborhood.

 

[Matt_2003 TDI]

The only real area for concern is that the belt can move the crank and cam toward each other in timing when doing up the tensioner. Make sure you're slipping the belt on in the preferred order so they don't move when you tension it the proper way.

How close do these need to be? I’d imagine that even if i were off by a tooth or two between the cam and crank the engine would still turn without valve interference...?

Secondly (and perhaps a dumb question) - shouldn’t the piston no. 1 be at top when the engine is... TDC? I removed the glow plugs and checked where the pistons are at. number 1 looks like its almost at the bottom, 2 and 3 are nearing the top - in fact it looks like the interference I’m hitting when trying to turn the engine over is the first valve (passenger side closer to TB) on cylinder 2. Does that reinforce that the Cam and IP are at TDC, and just the Crank is 180 off?

 

[KLXD]

Pump is fine pinned. There's only a single slot in the flange where the pin can go through. The "hole" mentioned above is actually the space to the side of the boss that the hole is in.

If it's truly 180 out on the crank with the belt off you probably need to back it off a bit then rotate the cam a bit and GENTLY try the crank again. Repeat until you can rotate the crank past TDC on #2 and #4. Then you're home free. At that point #1 is on the way up and you can rotate the cam to the correct position, move the crank to TDC on #1 and proceed as usual.

If you're uncomfortable doing it this way just remove the cam.

 

[Matt_2003 TDI]

If it's truly 180 out on the crank with the belt off you probably need to back it off a bit then rotate the cam a bit and GENTLY try the crank again. Repeat until you can rotate the crank past TDC on #2 and #4. Then you're home free. At that point #1 is on the way up and you can rotate the cam to the correct position, move the crank to TDC on #1 and proceed as usual.

Worth a shot I think! When you say “proceed as usual”... just to make sure i have this right: i get trying to cheat the setup into turning past TDC on 2. Then the “home free” part - would you rotate the engine back to TDC on the flywheel, and then reset to factory TDC? I’d imagine there would need to be some level of adjustment past the guesstimate that gets the engine to revolve again?

 

[Matt_2003 TDI]

Nevermind i see what you mean. Get past TDC on 2 so that 1 is on the upstroke, and reset from there.

 

[jokila]

Nevermind i see what you mean. Get past TDC on 2 so that 1 is on the upstroke, and reset from there.

Get crank to TDC, rotate crank counterclockwise 90 degrees. All the pistons are halfway in their bores with the crank in that position.

Disconnect cam and rotate it as you need to. No need to loosen it out. Once you have the cam locked/indexed at its TDC position, rotate crank to TDC and go on with the rest of the procedure.

 

[KLXD]

Yeahbut, if I'm understanding where he's got it now if he backs the crank off he'll be bringing #2 back up when he goes forward again rather than #1.

 

[Matt_2003 TDI]

Correct - At this point it sounds like to just loosen the cam and start from scratch, right?

 

[Matt_2003 TDI]

Out of curiosity, why is there an aversion to removing the Cam? in this post and others, folks like Yuri seem to be wary of that procedure.

 

[fatmobile]

Putting the crank at 90 degrees allows the cam to turn without hitting anything.
Turn the cam until both the number 1 cam lobes point up and lock it.

Then the crank can be turned to TDC. Backwards or forward whatever it takes.
I hope you have a good mark. I worked on one where I never could find TDC on the flywheel.
I had to put a tube in the #1 glowplug with the other end in colored water.
Turned the crank and watched to see if it was pulling water into the tube or pushing it out.
I put a good mark on the flywheel when I found it.

Both 1 and 4 should be at TDC but since the valves are up on #1 it's the one that will fire.
And the injection pump locks on #1.
Then you won't be 180 out.

 

[U4ick]

Out of curiosity, why is there an aversion to removing the Cam? in this post and others, folks like Yuri seem to be wary of that procedure.

I think perhaps it's apprehension as to the level of competence of someone they don't know and is doing a timing belt job for the first time.

Out of curiosity, if you are going by the PDF, what on page 22 did you not understand?

 

[wonneber]

How close do these need to be? I’d imagine that even if i were off by a tooth or two between the cam and crank the engine would still turn without valve interference...?

Close only counts in horse shoes, hand grenades, and atom bombs.
If anything in the timing is off if can effect performance, fuel mileage, and cause the interference you are seeing.

The cam being out of time is causing your issue.

The pump being out could be a starting or performance issue.

You'll learn.

 

[KLXD]

Again, if he just sets the crank at 90* but #2 is on its way up valves will be hit trying to get to the timing mark if the #1 valves are placed in the TDC/firing position. Thus my telling him to go slowly and how to get past TDC if they hit. He doesn't seem to know where it's at. We certainly don't.

Removing the cam isn't a big deal if you have a new seal and use a torque wrench to reinstall the caps.

 

[Nevada_TDI]

Why do you suggest he pulls the camshaft out? If he has the camshaft lock that bolts in the vacuum pump location, there is no way to not get it right. So what am I missing here?

 

[BobnOH]

I too am confused. Is it possible what you think is contact is actually compression?

 

[jokila]

I think perhaps it's apprehension as to the level of competence of someone they don't know and is doing a timing belt job for the first time.

That was said nicer than the way I was going to say it.

Again, if he just sets the crank at 90* but #2 is on its way up valves will be hit trying to get to the timing mark if the #1 valves are placed in the TDC/firing position. Thus my telling him to go slowly and how to get past TDC if they hit. He doesn't seem to know where it's at. We certainly don't.

Removing the cam isn't a big deal if you have a new seal and use a torque wrench to reinstall the caps.

The cam doesn't need to be removed in so much it has to be loosened enough to allow all of the valves to close. The caps don't have to come off.

 

[Matt_2003 TDI]

Update: thank you all for your comments.

Ended up fully removing the cam, and took the opportunity while the valves were all closed to clean out the soot / oil debris in the intake. Cam removal and replacement was pretty straightforward - not sure what there was to fear that.

The interesting part: My flywheel has two marks - im not sure who, but a benevont person painted a green "window" at 180 degrees from TDC, and then a yellow "window" a degree or two offset of both sides at TDC just off of where you can see the stamp - haven't seen this so could have been the mechanic who did the first TB Swap? Anyways, with the Cam removed i reset the Crank / Flywheel to TDC, then reinstalled the Cam, then adjusted the cam (with the TB off) to TDC so the locking plate fit (did this part very gingerly, we were only off by a degree or so when the cam was re-installed). Re-tensioned the TB and turned over with no problems!

I continue to be perplexed with how the crank got down to 180 degrees off - i remember seeing the Yellow marking when i originally locked the cam / crank / IP.... for the life of me cant figure out how that got off. Anyways, hard reset was a way to go, and appreciate the support of this forum.

 

[Matt_2003 TDI]

I too am confused. Is it possible what you think is contact is actually compression?

It was certainly a valve... . What the other posters are mentioning with rotating the crank back 90 degrees was correct - cam had to release all the valves to rotate the crank freely 360 degrees and find the mark. the other part is that #2 was on the way up, so evne going back 90 degrees you'd hit the open valve on no. 2 as you head to TDC on 1.

Either way, worked out in the end.

 

[wonneber]

Glad you got it figured out.
You didn't mention if it's running. ??
I wonder if the 1st mechanic did something wrong to cause the 180 degree out problem if it was that far out.

 

[Matt_2003 TDI]

I would love to tell you it’s running... but part of this project has also been the intake manifold cleaning, tapping the exhaust manifold for an egt sensor, and then various replacements of vacuum and oil lines so I’m not at a point to turn the engine over quite yet.

it’s run pretty clean for 90k miles since the last TB - notsure I can blame the last mechanic in good conscious.

I can say it rotates flawlessly, and even if manually, it was good to hear the chug of the engine turning over a handful of times