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Engine Specific Info and Questions => IDI Engine => Topic started by: haybayian on May 23, 2008, 08:51:49 am
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I am a bit puzzled about my camshaft sproket. The camshaft has a slot, presumably for a woodruff key. However the reman shop where I bought this engine delivered this AAZ (long block) to me without a camshaft sproket key. Haynes is rather uncommited and not much help. Now what should I do? I have already set my engine on TDC to time the IP and I think that the camshaft is sliding in its sproket.
Your advice will be appreciated.
Haybayian
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No key, friction fit on mine as it has to be to time the crank to the cam.
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thats right! make sure u loosen the sprocket when you time your motor other wise it won't be dead on.
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i think ETKA only shows the need for a woodruff key on the injection pump sprocket.
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Theres no wooddruff key in the 1.6 as well.... i dont knw abt the 1.9... i havn;t opened up mine yet!
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funny thing is my brother has been acumalting 1.6 turbo engines for his samurai ... one of them has a keyed camshaft and sprocket , it came out of a 1986 jetta .........
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that is weird. I don't see how you could time it perfectly like that. I know you could get it close, but the whole deal with having no key is so it slides on the nose for perfect timing. Let me/us know what happens with that one. I am very interested in it for some reason. Or if someone put it in there as "upgrade" thinking it needed it.
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All vw diesel do not have a key. They are all wedgemated.Sometimes people will mix the pump and cam gears then wonder why it's so hard to get the belt to line up or it'll run until the pump gear gets loose. That is also why once you get used to or understand the trick it's so easy to get the belt lined up right the first time.
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that is weird. I don't see how you could time it perfectly like that. I know you could get it close, but the whole deal with having no key is so it slides on the nose for perfect timing. Let me/us know what happens with that one. I am very interested in it for some reason. Or if someone put it in there as "upgrade" thinking it needed it.
My engine (1993 AAZ from a Jetta)came out as a long block from a reputable remanufacturing shop in Toronto. The camshaft sprocket was bolted on the tapered end of the camshaft with no woodruf key. However, I noticed in the inside of the sprocket mating part that traces of a forced in key were present. I consulted my Haynes manual that implies that some VW diesel engines have a key, some don't and that in any case one should make sure that the bolt (lug) is of the right length so that the sprocket will be forced in . Bentley describes the AAZ as having no woodruf key at this place.
What I think and what I have done:
I think that both should work fine, hence the Germans' soul searching. My camshaft end is tapered with a keyway. I have called my VW dealer explaining my dilema and they sold me a woodruf key. I have set my crank /cam/IP on TDC slid the timing belt without forcing the camshaft sprocket too much over the key (in other words leaving the sprocket in a wobbly position). Then I have tightened the camshaft sprocket bolt to torque and checked the IP timing. The engine has not been fired yet but I expect that everything is in order. A final word. the woodruf key IMHO does not prevent proper TDC positioning on the camshaft.
Hope this is useful.
Haybayian.
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Does your camshaft have a groove for a key? If not, you should not put a key in the cam. Personally I trust myself far more than some dealer grease monkey as at least around here, they know little to nothing about the older engines. With a keyed camshaft there is no way to adjust cam timing relative to engine timing. Maybe they designed the keyway to have the cam in the general vicinity of correct timing, but there is no way it can be right on.
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yeah, i feel a woodruff key would definitely would effect cam timing since then u are timing it by the tooth of the belt as opposed to the cam being locked exactly at tdc and the sprocket being bolted down to exactly that.
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Does your camshaft have a groove for a key? If not, you should not put a key in the cam. Personally I trust myself far more than some dealer grease monkey as at least around here, they know little to nothing about the older engines. With a keyed camshaft there is no way to adjust cam timing relative to engine timing. Maybe they designed the keyway to have the cam in the general vicinity of correct timing, but there is no way it can be right on.
Thanks for your input.
As I have indicated my AAZ's camshaft came with a keyway or a groove . As there is no keyway in the sprocket the woodruf key is probably meant as a "locking device", as in to prevent the camshaft to slide in the sprocket.
The sprocket is to be pushed first with little pressure over the end of the camshaft which allow for a fair bit of play and then once the three TDC positions are acertained the sprocket is driven in to 33 f-lbs with the bolt.
I am not being judgemental of VW engineering all I am interested is to make sense of what I have. It seems to me that both (key or no key)approaches are workable. I chose to use a woodruf key because this is what my camshaft called for and as far as I can tell it worked for me.
Hope this is of some use to anyone.
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i think ETKA only shows the need for a woodruff key on the injection pump sprocket.
My alternator has a slot for the key.
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In all the diesel VW engines I have ever taken apart the cam is slotted for a key but the pulley is not. It`s my opinion that if you used a key in this situation you would be reducing the surface area of the cam and cam pulley and thereby increasing the chances of it slipping. I think this would be especialy true after adjusting the timing several times and causing many indents in the cam pulley.
Plus, I`d expect the cam gear to be off center and would cause timing belt tracking issues.
On a different note, the tapers/shaft size are completely different on the cam/pump and could not be mixed up
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On a different note, the tapers/shaft size are completely different on the cam/pump and could not be mixed up
yea the camshaft sprocket hole is huge while the pump sprocket hole is small. idiot proof :lol:
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In all the diesel VW engines I have ever taken apart the cam is slotted for a key but the pulley is not. It`s my opinion that if you used a key in this situation you would be reducing the surface area of the cam and cam pulley and thereby increasing the chances of it slipping. I think this would be especialy true after adjusting the timing several times and causing many indents in the cam pulley.
Plus, I`d expect the cam gear to be off center and would cause timing belt tracking issues.
Thanks for your point which makes sense, in theory. I guess the only way to find out why VW designers thought of a woodruff key at this place would be to ask them. On my own specific cam sprocket there was a slight indentation on the inside edge of the taper but no damage to the extent you are suggesting. The bore was intact and no ovalization could be detected. Considering that this cam dated back (presumably) to 1993, I doubt that forcing the sprocket over such a small woodruff key could possibly lead to an off centered sprocket and belt tracking problem. But not being an engineer I can only speculate and if my timing belt starts acting up I will certainly look back into this key issue. I will try to test this question on some European forums and try to catch a German or French VW engineer who may give us an answer.
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It's possible the camshaft has a key because they grind the diesel cams from the same blanks as the gas cams during manufacturing? Maybe? Would certainly be in keeping with the rest of VWs "use as many pieces for multiple purposes as possible" build philosophy of the Seventies and Eighties.
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It's possible the camshaft has a key because they grind the diesel cams from the same blanks as the gas cams during manufacturing? Maybe? Would certainly be in keeping with the rest of VWs "use as many pieces for multiple purposes as possible" build philosophy of the Seventies and Eighties.
Perhaps, except that (to be the devil's advocate) the other VW 4 cyl users of this cam blank would be gasers and these seem to have a cylindrical sprocket mating assembly (not cones) perhaps of a smaller size. It would make no sense for VW to go into the trouble of cuting a keyway on a tapered end (destined to AAZs and AHUs) if it is not going to be used. IMO in the process of fabricating the shaft it seems to be a useless operation. So thanks guys :lol: I don't think that I have my answer yet.
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hi,
cam-wheels on gassers are mounted like the intermediate-shaft-wheels,
so the blanks are not the same.
the key is -my guess- for fixing the cam in the right position for machining,
no further funktion.: fix it at the cam-end and loosen the wheel when adjusting timing when changing the TB.
remember: the conical surface has to be clean an degreased.. else the
pulley can slip, only the clamping force tranfers the power.
greets, Michael
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hi,
cam-wheels on gassers are mounted like the intermediate-shaft-wheels,
so the blanks are not the same.
the key is -my guess- for fixing the cam in the right position for machining,
no further funktion.: fix it at the cam-end and loosen the wheel when adjusting timing when changing the TB.
remember: the conical surface has to be clean an degreased.. else the
pulley can slip, only the clamping force tranfers the power.
greets, Michael
Danke,
The keyway cut in the cone shape camshaft end seems logical indeed from a machining stand point :) .... hummmm! except for one thing: the other end of the camshaft has already a more functional slot (TDC No 1) that would be plenty for machining cams. I guess only VW could explain all this!
I enjoyed visiting your webpage.
Haybayian
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VW diesel (TD and TDI, also ALH) valve are close to the piston, that need a perfect timing on the cam, there are no other possible reason.
PD motor have an adjustable cam pulley like ALH pump pulley with 3 bolts to set the cam timing, It's not for esthetics.
The first VW cylinder head motor that I have repaired in my life.... 10 years ago, 1.6TD with head gasket failure, I planed the head, I install a 1 notch thinner head gasket, and I reinstall the cam pulley exactly at the same place as when I remove it, I reuse the old timing belt, result = 1 week later all the valves had to touch the piston, not much, but enough to rebuilt the head....... however I used the same method as if there had been a key.
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No key, friction fit on mine as it has to be to time the crank to the cam.
Thank you very much to all of you. The response was unanimous: no woodruff key. I still don't know why Haynes did not bother to expand on the existence of a keyway on this engine, and I will probably never know why AAZs have been built with such a confusing camshaft. I have pulled out my camshaft sprocket, removed the woodruff key and tomorrow I will go through the timing routine for the fourth time .
Thanks again.
Haybayian