Woodenewe

My 1999 996 C4 was car was run with the system tester and diagnosed with a worn cam chain actuator guide, as determined by reading out "9 degree timing error". The recommended repair is to replace timing chain guides which involve "removing frame bracket, heat shield, and cam cover, replace timing chain tensioner blades, refit cams and set timing". They also recommended replacing O-rings on the spark plug tube or tubes that are leaking, O-rings scavenge oil pump and seals. This is expected to take 16 hours of mechanics time and $200+ in parts. They suggested not waiting too long to do the work.

My questions are; does this diagnosis and recommended repair seem reasonable, is the engine at risk of a major failure, and is this repair anything for a DIY’er to tackle?

HHPorscheTech

Unless your local dealer is willing to give you the cam tools, I would let them do it. Also, How did they come to the conclusionthat thetensioner guides are worn? 9 degrees of timing difference is a lot. Has anything happened latley to your engine? Is it running rough, misfiring, stumbling.?? How many miles does the car have on it? Did they get you a log print out that you can email me?

HHPorscheTech

Yes, the it is a good idea while in there to reseal the tubes, oil pump and other assorted seals. because you are already apart, but there should be no additional labor for that. Ask them which bank they think is failing. 9 years and I have replaced maybe on of the early versions and it was an electrical fault..

Tippy

Wow, 9 degrees. I thought the system would default to zero if there was a problem.

Woodenewe

The diagnosis was done in an independant shop using a Porsche system tester. The engine runs fine, and I've only had the car since late May and put on less than 3K miles. The total mileage is 84K. I did not get a printout, and I believe they said right side and 9 degrees out; the printed out bill just said "out of specification". I checked with the Durametric people and was assured their system could verify the condition. Know if anyone on Whidbey Island, Washington has one? I'm considering buying one since access to a P-shop is a ways away. The shop I went to is well known and highly thought of. At $105 an hour shop rate, or $1680 to do the work, is enought to look around a bit.

HHPorscheTech

The cost is right around an average that I agree with. With 84k it is a good possiblity, however with 9 degrees variation you should be feeling rough running (maybe slight). I can tell you that @7 degrees variation there will be a stumble at idle. Why did you take the car in a check engine light? Without being able to see the print out, and if a race team recommends the shop then I would be inclined to agree with the diagnosis. What could wear out is the plastic guides that the chains run on and that would cause the camshaft (when trying to adjust) be unable to reach the specified value....Can't help with washington I am in South Carolina. The tester (Piwis) will cost between 8-10 thousand and there is the licensing fee that Porsche charges to consider. If you can find a older Porsche System Tester two, since the age of your car it should work fine..

Woodenewe

I purchased the Durametric software and read out the faults: none. The "Camshaft position 1 deviation" was -8.89 degrees and "Camshaft position 2 deviation" was -4.68. Both values did not change with variation in enginer RPM. At idle of 700 RPM the "ignition angle" varied from 6.00 to 8.25, "loss adaptation idle" was -2.14 to -2.23, "ignition timing" was 2.5 to 2.6, and "actual angle for camshaft" was 0.06 to 0.34.

Hopefully someone can look at these numbers and tell me if I have a problem. The car runs well, no faults found. I plan to run the car a bit and in a few days, see if there are any changes. Funny thing, the gas gage is now not working correctly; on a full tank it reads 1/4 full. I'll look into the s/w and see if it has a parameter for the fuel gage.

If anyone would like more data, I can download it into a PDF file and email it upon request.
Thanks for any help...

joes c4 cab

Sounds like the flux capicitor to me . . .

Seriously though, that does not sound outrageous for all of that work.

Paul 996

sounds much better than a new engine. What code is yours showing? Mine had a P1531 for bank 1 and then was driven and something inside broke.

99firehawk

those numbers arent abnormal, I would worry about it, if you get a check engine light then worry.

Why was the car taken in the shop where they noticed that

Woodenewe

Brad,
I had the car in to fix a loud squeek from the front suspension. Originally thought to be the left suspension arm; ended up being incorrect (C2 instead of C4) strut mounts installed when the original owner lowered the suspension. I had an air-bag light (had drivers seat out to repair the leather) and asked them to check and clear the memory. They cleared to light and came back with several items needing attention, including the worn cam chain guide being the most serious.

Thanks you for your reassurance (I read your comment as "I would not worry" - right?).

99firehawk

I wouldnt worry about it,

disclaimer: I didnt see the car or diagnose it in person, i can only go by my own experiences and the info that is supplied. If the engine fails tomorrow im not responsibile for it.

it will throw a light before it is out of spec enough to hurt anything unless there is a catastrofic failure. I have never changed guides for being worn, I have changed acuators on a few high milage cars............all had check engine lites on

Woodenewe

Brad,
Thanks for the clarification, and I accept the reasonable disclaimers. I'll just drive it reasonably and hope to get a lot of miles on it.

Woodenewe

Well, it has been a year and I had the TC Guides replaced. The old ones were well worn and it was good to have them out of the engine. While it was in the shop, I had the spark plug tubes seals, scavenge pump O-ring and several seals replaced, the oil separator and hoses plus seals, secondary air check valves, oil pressure switch, serpentine belt, clutch, flywheel, clutch release arm, RMS, intermediate shaft housing, air injection valves, engine case bolts, transmission and front differential lube oil, flush and fill brake fluid, an engine oil change, timing adjust, spark plug check, and the 90K mile check-up (now at 87,500 miles). Runs like a new car! The shop reported the TC deviation at -3 degrees for both banks. My Durametric software reported position 1 at -3.31, but position 2 at +6.0? I need to have them check it again next time I can get into the shop, and I’ll keep an eye on it too. All in all the car runs very well, likely justifies the cost of the repairs (($6500). Just hope I can get a lot of miles on it from here without major problems.

joes c4 cab

Wow that is a lot of work you had done. Glad it worked out for you, but did you consider throwing a new/rebuilt in for a few thousand more?? Then you would have a 2 year warranty too. Just curious.