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2001 1.8t Jetta cam timing question
10-27-2016, 08:23 PM
Post: #1
2001 1.8t Jetta cam timing question
Hi, So i replaced the timing belt at 79K miles on my 2001 1.8T in July. All was well until last week when on of the motor mount bolts broke which caused the new timing belt to get shredded and jammed, although it did not completely break off, behind the the idler.

I have since read that the motor mount bolts as well as the bolts for the bracket etc are all "stretch bolts" and should never be reused, so i am assuming that has something to do with why mine motor mount broke.
I was driving very slow when the motor mount broke and i did not hear anything so i am hoping that none of the valves got bent, but here is what is happening.....

The timing belt got damaged and was jammed behind the idler so I did not bother to mark it, I just cut it off. Then I turned the crank with the belt off to line up the timing mark on the flywheel, then put new belt on and turned crank to line up the cam mark. I had the number 1 spark plug out and a long screwdriver in cylinder so i could see when it was up and down. I could see that the screwdriver was moving but then I suddenly got to a spot where the crank did not want to move anymore. I did not force it, and i went ahead and removed all the spark plugs, but it still did not want to move past a certain point. I then tried turning it counter clockwise and it turned about 3/4 of a turn and the same thing happened, it got to a spot where it did not want to turn any further. I again did not force it, so that is where i am at now, crank will turn about 3/4 of a turn in either direction then hits a spot and can't turn further.

I know this is a classic symptom of bent valves, but looking back I think that I should have put the new belt on and turned the crank till the cam lined up, then took belt off and turned crank to line up flywheel. is there a chance that my cam is just out of time now and I'm hitting it? If so, how can i turn the cam without turning the crank? Also, how can i determine if the valves are bent? I can't do a compression test cause i can't start it. Do i have to pull the head off and look? Can i bend the valves by turning the engine by hand?
Also, if there is damage, what will i need to do?? have head resurfaced at machine shop right? would it be worth it to do on this car? car runs great aside from this, and only has 80K miles. Thanks to anyone who can help or offer some advise....
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10-27-2016, 10:44 PM
Post: #2
RE: 2001 1.8t Jetta cam timing question
At this point we don't know if anything is damaged yet. (that's a BIG yet) Here's what I would do...

Turn the crank by hand till you feel all of the pistons are below TDC. (look with a light or measure with something soft like a plastic straw) While the pistons are away from the head you can now turn the cam till it's at the alignment mark without fear of doing further damage. At this point you can turn the crank by hand till it's at TDC on it's timing mark, although you may have to fiddle with both the crank and cam if you come to a hard spot. IOW, don't force anything. Once you get things lined up you can install the cam belt and then you can check compression.

Hint: if the valves have hit the pistons you will see marks on the pistons looking closely through the spark plug holes with a flashlight. You will also have lots of clearance to the rockers, which will be obvious if the valve cover is off.

BTW, while the cam belt is off you may want to do the water pump.

Last tip: If the valves are bent (no compression in one or more cyls) the head probably will not need machining but will have to come off to replace the bad valves. OTOH, you may get lucky and after you replace the belt it may be ok. Time will tell.
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11-01-2016, 04:03 PM
Post: #3
RE: 2001 1.8t Jetta cam timing question
(10-27-2016 10:44 PM)Rupe Wrote:  At this point we don't know if anything is damaged yet. (that's a BIG yet) Here's what I would do...

Turn the crank by hand till you feel all of the pistons are below TDC. (look with a light or measure with something soft like a plastic straw) While the pistons are away from the head you can now turn the cam till it's at the alignment mark without fear of doing further damage. At this point you can turn the crank by hand till it's at TDC on it's timing mark, although you may have to fiddle with both the crank and cam if you come to a hard spot. IOW, don't force anything. Once you get things lined up you can install the cam belt and then you can check compression.

Hint: if the valves have hit the pistons you will see marks on the pistons looking closely through the spark plug holes with a flashlight. You will also have lots of clearance to the rockers, which will be obvious if the valve cover is off.

BTW, while the cam belt is off you may want to do the water pump.

Last tip: If the valves are bent (no compression in one or more cyls) the head probably will not need machining but will have to come off to replace the bad valves. OTOH, you may get lucky and after you replace the belt it may be ok. Time will tell.


Thanks for the advise, I did replace the water pump in July when I originally did the timing belt.
I guess what I want to ask is. Can I, or how do I turn the Cam without turning the crank?
Or is it possible that the reason I can't turn the crank more then 3/4 a turn in each direction, could it be because the cam is out of time and unable to move?
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11-01-2016, 06:10 PM (This post was last modified: 11-01-2016 06:12 PM by Rupe.)
Post: #4
RE: 2001 1.8t Jetta cam timing question
I had presumed the timing belt was still off so that's the way I worded my response. If it's back on and in the right place (big I*IF*) then of course there's a problem... BUT... now it sounds like you put another new one on without going through the bother to align the marks first, which means you should start from scratch. IOW, take the belt off and get things in the right place BEFORE installing the belt. At that point rotate the engine by hand BEFORE using the starter motor.... and go at least 2 full turns of the crankshaft with the spark plugs out so you can feel for any tight spots. You may want to check compression before you do final assembly. If compression is ok then put it together and see how it runs.

BTW, if the belt tension is not correct that may be the cause of the failure. With the proper tension you should be able to twist the belt 90 degrees with 2 fingers on the longest run between pulleys. If it's too tight it will "sing" and fail early. If it's not tight enough it may skip time.

Hint: to find the proper tension on most vehicles, install the belt and lightly tighten the belt adjuster, then slightly rotate the engine crank (the cam should move slightly) to take up the slack on the side of the belt that DOES NOT have the adjustment. At that point loosen then retighten the tensioner pulley lock nut with the slack removed from the idler side. Rotate the engine again (2 turns) to center the belt then recheck your adjustments. NOW is when you double check the longer side of the belt to see if it's just right. (90 degree twist)
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