Low Compression-Jumped Timing Belt-Not the valves?

[DaDeuceIsLoose]

My car jumped the timing belt a few weeks ago. It wouldn't start, and upon doing a compression test, I found cylinder 2 to have low/zero compression. Figuring it was the valves, I went ahead and pulled the head. Now I can't see any visable damage to any of the valves, is it possible for them to be damaged and not appear damaged? Is there anything that could result in low compression besides the valves? The headgasket was fine, and the pistons appear to not be damaged in any way. Could rings do this?

Also what should I replace since I do have it all apart? I know I should get a metal headgasket and ARP headstuds, but what else?

 

[95blackGsTurbo]

First off did you realign the timing belt before you did the compression test? If not then you won't show compression on a few cylinders. The valves will be overlapping so much that any air taken in will be pushed right out the exhaust valves. You will know if they are bent. They will have physically damage to them and you will also be able to see where they hit the piston when you take the head off. Rings could do it but you would have noticed that in a power loss or a terrible misfire if they whole cylinder is dead. As far as headgaskets go I wouldn't mess with a metal one. I have run them before and they are a P.I.T.A to get to seal. You have to machine the block and head to make sure they are perfectly flat and then coppercoat the gasket with a copper spray then make sure it's perfectly flat. I prefer just a regular NitroSeal one. It's help up to everything I have thrown at it so far and I am confident it will take my FP Green I am installing in the near future. ARP's are always a plus though. Definalty go with them. Make sure you retap the holes to clean them out before you install them.

 

[project_tsi]

Yes, it is very possible for valves to be bent, but look good. I was in the same boat before. Heres what you can do to check for bent valves. w/ the head off remove the ex. and intake manifolds. Also remove the cams. Allow all the valves to seat w/out any cam presssure on them. Now, flip the head up on one side so one set of ports are up, and one are down. Now fill each port full w/ water, and wait, If the water pours out, then obviously the valves are bent. If no water leaks out, then they are good. If water leaks only 2-3 drops in a 15min timeframe, then thats good too. most the time the water will escape quickly. Do this to both sets of ports, you might be surprised as to what you find out.

 

[DaDeuceIsLoose]

Yeah, I redid the timing before I checked the compression. I'm planning on getting the head ported and polished while its out, so getting it milled for the metal HG won't be that big of a deal. Is there anyway to test the valves without taking out the cams?