B5 20v non turbo

[southafricaADR]

Hi guys I have a B5 20v engine code ADR
I'm having a problem with camshaft sprocket snapping off the key way. I've been through 5 sprockets and it's just the same story. Why will the camshafts lock up? Cylinder head has been to engineering shop valves have been done, new oil pump rings and bug end and main bearings timing is perfect on the chain side as well as on the cambelt.
Cam caps are for this head and the car was running with this head.
Please Help!!!

[Cybersombosis]

Sounds to me you may have oil starvation issues. What weight and type of oil are you using? Have you checked to see if the pick up tube in the oil pan is clogged?

[southafricaADR]

I have checked...everything looks good
I turned the engine over by hand and it snapped the key way

[Cybersombosis]

Something is jamming the cam then. Maybe something dropped down the spark plug hole during reassembly so a bore scope would be good. Maybe you dropped a valve.

[walky_talky20]

To test ease of rotation of the cylinder head components, you can rotate the crankshaft 90 degrees away from #1 TDC or BDC. You can rotate either forward or backwards, whichever is the closer way to get to 90 degrees This ensures that none of the pistons are at TDC, all pistons will be at mid-stroke. Then you can attempt to rotate both cams freely without the timing belt installed.

If you broke the keyway *by hand* you must be seriously strong. You literally sheared off steel with only 2:1 gear reduction. That's crazy.

Other than dropped valve/foreign object jamming things up, the other possibility is that your engine is simply timed wrong. Perhaps you read the marks incorrectly, there are wrong parts in the engine, or something is modified.
- Cam pulley installed backwards showing an innacurate TDC mark is a super common issue on early 20v 1.8's.
- Crank damper pulley rubber twisted so the TDC mark is innacurate is another issue.
- Crank damper pulley bolted up 90 degrees out is maybe possible if you try hard enough?
- Crankshaft t-belt cog keyway sheared and no longer aligned is also possible.

A quick solve for any and all mechanical timing uncertainty, which I highly recommend:
- Find Crank TDC *manually* using a dowel or something else put down the #1 plug hole (do not use damper markings)
- Find Camshaft TDC using the notches at the rear of the cams (do not use the t-belt sprocket mark).