Cam Gear keyway broke

[teegale]

http://i.imgur.com/CXJ4uHz.jpg

I made a thread a few weeks ago about my CCT breaking. Well I replaced it and the car still wouldn't start. So I found this. Could this break and the cam gear slipping cause bent valves? I ran a compression test and got about 65-90 psi in all 4 cylinders.

[Corrado_Guy]

You bet it can cause bent valves, those numbers are very low but it is a cold motor so I would use a bore scope and see if you can see any obvious damage otherwise you will need to pull the head.

[teegale]

You bet it can cause bent valves, those numbers are very low but it is a cold motor so I would use a bore scope and see if you can see any obvious damage otherwise you will need to pull the head.

When I tried starting it, the timing wasn't correct. I'll use the borescope to see if I can see anything. Then if no obvious damage would it hurt anything to put a new cam gear on and set the correct timing and try and start it?

[MooseWhip]

I'd say you bent some valves with that compression

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[Corrado_Guy]

When I tried starting it, the timing wasn't correct. I'll use the borescope to see if I can see anything. Then if no obvious damage would it hurt anything to put a new cam gear on and set the correct timing and try and start it?

You want to check for marks on the piston crowns from the valves impacting them, if there is nothing obvious then you may still have a problem. Get your cam gear and then set everything correctly and don't start it, do another cold compression test and see what numbers you come up with. I've had to put valves on a lathe and then use a run-out gauge to see if they are bent but if your compression is good after setting everything up you should be fine. If your timing is a little out when you do your compression test you can get lower numbers so hopefully this is it. If the valves are bent even a little you can drop a valve and this will do a lot of damage so proceed with caution.

[teegale]

You want to check for marks on the piston crowns from the valves impacting them, if there is nothing obvious then you may still have a problem. Get your cam gear and then set everything correctly and don't start it, do another cold compression test and see what numbers you come up with. I've had to put valves on a lathe and then use a run-out gauge to see if they are bent but if your compression is good after setting everything up you should be fine. If your timing is a little out when you do your compression test you can get lower numbers so hopefully this is it. If the valves are bent even a little you can drop a valve and this will do a lot of damage so proceed with caution.

What psi would you consider good once I get the cam gear replaced and everything correctly timed? When my car first had any signs of problems it was completely turned off and I came back out of the store and it wouldn't start. There were no sounds or anything beforehand and no misfires.. Pulled the valve cover and the bottom Cam chain tensioner pad was lodged against the top. Replaced that and now I'm at the current point. Could the keyway have broken from manually cranking the belt backwards and forwards to check the marks?

[teegale]

bump

[walky_talky20]

No, you couldn't have broken the keyway by hand. A lot of times those keyways break off because there is lousy oil supply to the cylinder head and the camshaft is actually trying to lock up.

I'd do what Corrado guy says. Get a camera or boroscope down the plug holes. If you don't see any marks, put it back together and make sure you have good compression. Once you get it running, check the oil pressure too. Always a good idea on a 1.8T anyway.

[bw86]

You could have broken it if you put the gear on backwards like my friends machine shop did.

[teegale]

No, you couldn't have broken the keyway by hand. A lot of times those keyways break off because there is lousy oil supply to the cylinder head and the camshaft is actually trying to lock up.

I'd do what Corrado guy says. Get a camera or boroscope down the plug holes. If you don't see any marks, put it back together and make sure you have good compression. Once you get it running, check the oil pressure too. Always a good idea on a 1.8T anyway.

Last year when i purchased the car it had a broken CCT. Well we got that replaced (with a shitty aftermarket one which broke again now). The oil pressure was low so we dropped the pan and cleaned it out and replaced the pickup tube. I didn't drive it with low oil pressure, just started it a few times. Seems that a lot of the pieces from the CCT pads broke off and went into the pan. This time however the pad was still mostly intact (no big chunks missing) and we changed the oil right after we replaced it to drain anything that may have got in there. I'm thinking maybe it was an issue all along but wasn't found until after my 2nd CCT broke. Bought a OEM CCT this time so I'll do what everyone has been suggesting. Replace the gear and get the timing correct and see what the compression is. Thanks for the help.

[walky_talky20]

Sounds good. I'd still throw an oil pressure gauge on it for good measure. Make sure the pressure is all good. But that's just my recommendation. Good luck with the repairs.

[audi-medic]

had the same thing happen to me when i bought my car, was driving it home but the lcd was pixel dead so i didn't see the oil light, drove a couple of miles and my engine shut down, tried to start it several times than just had it towed home, turned out the top end was so dry that the crank pulled the camshaft sprocket and broke it the same way, and i tried starting it several times!, just changed the T-belt, and the sprocket, cleaned and lubricated the top end of engine, and its been 7 months of hard driving at a stage 2 right now and pulling hard. I had a low compression when i checked a while ago but that was on cold start and i never checked after that. i also have a slight tick but that is probably my VVT.