ALH Head Replacement and Timing Questions

jakej78b

Veteran Member
Joined
Jun 13, 2019
Location
Alamogordo, New Mexico
TDI
2000 Volkswagen Jetta TDI ALH 1.9
I've recently obtained a 2000 Volkswagen Jetta with the ALH engine and 5spd transmission. It has 230k and I've determined in another thread that likely a valve has met a piston sometime in its past. This of course means that the head should come off which will necessitate having to do timing belt work, which I had intended to do anyways since the timing belt history is unknown on this new to me car.

I've got another engine from a car that had about 255k on it and it had a terminally low oil pressure problem, of which the cause was never determined. The car ran great though, it was involved in an accident which is why it has now become my parts car. I got a new turbo, got a new oil pump, oil pressure sensor was replaced. Oil pressure was measured with a mechanical gauge to be around 70PSI at idle while cold, then the pressure dropped as the engine warmed up to around 7-15PSI, depending on engine load and RPM. The best guess was that it needed new crack and/or rod bearings. The real question with this: Is it likely that low oil pressure would be caused by the head, or hard to know? I'd like to swap this head into my car to have to avoid reworking the head completely. If I run under the assumptions that the low oil pressure environment didn't damage the head and that the head was itself not the cause of the low oil pressure then I should have a perfectly good head waiting to be swapped on my car, no? If it helps, I have pictures of some of the cam caps and of the cam on the head in question.
Now, the timing questions:
A lot of the reading I have done suggests to pop the cam sprocket and loosen the injector pump sprocket when performing a timing belt job. I am wondering why one would do this? Couldn't you just lock the cam, crank, and pump then put the new belt on? The procedures also goes on to show timing the pump again as the last step. I could see fine-tuning it maybe but theoretically if you had perfect timing before, you should have perfect timing after assuming nothing moves. I would assume nothing moves since they are locked, therefore locking their sprockets as well (unless you pop them).

What specialty tools do you REALLY need? Near as I can figure I would only need the cam locking tool, the IP can be locked with a perfect fitting drillbit (of which I have many sizes) and I figure the crank doesn't really need to be locked, as long as I frequently verify that it is still in position by visually verifying the flywheel mark... right? If popping the cam sprocket is necessary I've read that this can be done with a gear puller, no? I don't want to save a few dollars and potentially botch the job, but I also don't want to unnecessarily spend if I don't have to. I have a generic adjustable pin wrench that I think would work for counterholding the cam sprocket assuming it needed to be broken lose to begin with and I have many other tools that could perhaps substitute, though no others come to mind for substitute timing tools.

Looking forward to your replies,
Jake
 

Stupendous60

Veteran Member
Joined
May 18, 2019
Location
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TDI
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lock cam, lock injection pump, I have read in manuals- loosen cam bolt and, from behind, with a drift and a steady hit, pop off sprocket. (I have the tool, but I am sure the drift would work) The advantage of popping the cam gear is once disassembled and reassembled (much easier) route t-belt accordingly, with sprocket off cam end, putting belt over cam sprocket last, (which I suspect is why it is tapered) install sprocket, snug cam bolt/not tighten- tension t-belt and torque tensioner, move crank slightly to allow mark on flywheel to be aligned, (meanwhile cam and IP are still locked) then torque cam bolt using sprocket holder. Remove locks, rotate engine twice to verify marks align correctly etc.
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
The reason why you loosen the IP sprocket and remove the cam sprocket is,
1. it will make it easier to get the TB on.
2. with the cam locked and cam sprocket loose and the IP pinned with its sprocket loose but in the middle of the slot with all three bolts you then tighten the tensioner . When you do this you will see both the cam sprocket and the IP sprocket turn slightly. If you didn’t loosen the respective sockets and everything was pinned and locked you will preload the TB on one side and timing will be off. Once you tighten the tensioner at the corretly then you can tighten the IP bolts , and then tighten the Cam bolt ( book says I believe 35 ft lbs.... most here will go to 40-45 ftlbs ) remove pin and cam lock and rotate engine 2 full revolutions at the crank bolt and make sure everything lines up again. You do that then the engine will fire off and you will need Minimal IP adjustment with VCDS....
 

Vince Waldon

Top Post Dawg
Joined
Apr 25, 2009
Location
Edmonton AB Canada
TDI
2001 ALH Jetta, 2003 ALH Wagon, 2005 BEW Wagon
What you're proposing OP is sometimes laughingly sometimes sadly called "Mark and Pray" in these parts; you're praying the timing was good to begin with, praying nothing moves while you install the new belt, and praying it all stays perfect as you tension the belt down.

It won't, because if the sprocket is not free to spin belt tension will have no where to go... everything is locked at TDC.. and your timing will be off as soon as the TDC locks are removed.

Pretty easy to just do it right and know you're good; in my sig is one of the best step-by-steps, with a picture of every step.
 
Last edited:

Stupendous60

Veteran Member
Joined
May 18, 2019
Location
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TDI
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Oops! I did forget to mention loosening IP sprocket bolts...Vince, excellent break down of t-belt procedure!
 

Nero Morg

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Joined
Oct 19, 2017
Location
OR
TDI
2014 A6 TDI, 2001 Jetta TDI, 2014 Passat TDI
Not usually, no. Whenever I set a timing belt, I ensure the cam and crank are 100% at their timing marks after 2 revolutions. If they are, you're golden. Pump timing can be off (as in pin hole is off a little) because you're going to need to set injection timing anyways.
 

Vince Waldon

Top Post Dawg
Joined
Apr 25, 2009
Location
Edmonton AB Canada
TDI
2001 ALH Jetta, 2003 ALH Wagon, 2005 BEW Wagon
Some people buy/make a jig to lock the crank at TDC as well.. I just keep an eye on it to make sure only the cam sprocket moves at the timing belt is being tensioned.
 

Genesis

Top Post Dawg
Joined
Feb 26, 2003
Location
Sevier County TN
TDI
'03 Jetta Wagon
What Nero said -- the crank is locked (jam a screwdriver in the bellhousing or make/buy a crank lock tool) so it cannot move. Everything else floats when setting the tensioner (both cam and IP sprockets.) The cam and IP themselves are physically locked so only the sprockets move.

One fixed reference, the belt takes up the slack with the others moving when you set the tensioner and thus the loads are centered on the nibs of the belt. Then when you torque the IP bolts and cam sprocket the relationship remains. Note that you have to counterhold the cam sprocket while tightening the center bolt; the lock plate in the cam will NOT take torque (you are at very high risk of breaking the tail of the cam if you don't counterhold the sprocket!)

Then remove the locks and do two full rotations of the crank (clockwise) to make certain there is no valve interference and return to TDC. With the crank back at TDC the cam lock plate and IP pin should go back in. If they do and all you felt was compression you're good.

That is the only correct way to do it; if you sideload the nibs on the belt by having either or both of the others locked you are asking for premature wear and potential failure down the road.
 
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