Compression leak! Need Help!
 

Guys, I have been encountering some small backfiring issue with my 996tt (2002 tip) and the chief mechanic of the authorised dealer said it was the sticky hydraulic tappets which caused the backfiring. Accordingly, I have taken my car to them to have the tappets changed. My car has been with them for almost 2 weeks and yesterday I was told that my car is now encountering some engine compression loss (probably something is leaking after the change of the tappets). I mean how could this happen? Is this poor workmanship or not?

Actually I would like to ask you guys (i) is it reasonable to take 2 weeks to change the tappets? (ii) what can cause the engine compression leak in this situation? Thanks in advance.

Is the car still under warranty?

The tappets on the rotator splint?

I am not sure. I've asked them to check whether they have followed all the necessary procedure in replacing the tappets (eg: to pre-load the new tappets before installing, etc.). Do you think this could be a serious problem? The mechanic said that this is just a simple mechanical problem and should not be difficult to resolve. Do you think so?

Not knowing anything about a 996, but hopefully they are addressing the problem and not a symptom. Two weeks seems like a long time for a Dealer...
Good luck and post the outcome.

When hydraulic tappets are first installed in any engine they take time to "bleed down".
I have encountered this prob before.
Run the engine gently (low RPM's) and allow the new tappets to find their running position.
If, after 20 - 30 minutes of running (engine nicely warmed up) you still have a problem, then different tappets will be the answer.
Are the tappets available in different lengths (heights)?
Perhaps all the tolerences in your engine require shorter ones.
Bob

Will the new tappets require any break-in run? for example, engine speed should be kept above certain rpm in the first 500 miles or km, etc.

Hydraulic lifters do require some time to fully charge with oil. Until they do, you will hear that 'clacking' noise like a loose valve, and the valves will not open fully. This should not cause any compression loss; merely a shorter valve duration. Admittedly I know next to nothing about 996tt's, but I cannot reconcile a compression loss with new lifters unless something went wrong during the install and dealer wants you to eat the bill for a mistake.

2 weeks also seems ridiculously long to change lifters. Did they see a problem right away after the job and take the next week trying to fix it but couldn't? Find the # of billable hours for the job and ask why it took so much longer to complete. A busy shop is not an excuse. They book you in when they have time to do the job.

ianc