Help with cam deviations
 

I have a 2000 S with 66k with recent IMS upgrade. The car runs great and no codes. I recently bought a Durametric and ran the program to see if there was anything to be concerned about. Turns out that after a thorough warmup bank 1 is showing a cam deviation of 7.08. Bank 2 shows 5.33. At idle cam angles are 2.48 and .92 for banks 1 and 2 respectively. Running rpms up over 3000 results in cam angles of 22.16 and 23.67 for 1 and 2 respectively. I ran this by my local independent and he wasn't too concerned and suggested a wait and see approach since I had not found plastic shards in the oil (yet).
Based on all I have seen and read it looks like variocam tensioner pads. But I wonder if it might just be that bank 1 is and has been out of time. Is there any benefit to simply retiming the bank 1 cams, are tensioner pads a better diagnosis and is there any other likely explanation?http://986forum.com/forums/uploads02...1519778910.jpg

Im confused. You got 3 sets of numbers but im not clear what the test parameters are for each

Not sure if I completely understand your concern.
Cam deviation should be measured when the engine is at operating temperature, and running at idle.
Based on your following statement:
“At idle cam angles are 2.48 and .92 for banks 1 and 2 respectively”
You are well within spec (-6 +6).

The top two numbers are cam deviation at idle for banks 1 and 2. The third and fourth numbers are actual cam angles (not the deviations). Both screen shots were taken with the car well warmed up.
The second screen shot was reflecting the "actual" cam angle once the variocam kicked in (rpm over 3000).
I thought that the +/- 6 number we are concerned about is the "cam deviation" not the actual cam angles. (?)

Cam deviations should be between -6/+6. One of yours is outside the range and likely due to a worn variocam pad. At some point, you'll get a check engine light when the deviation becomes higher.

Actual angles look ok, I forget at what RPMs the variocams kick in, but 3000 rpms is in the range.

And I suppose there is really no way to know if it is variocam pads vs something else short of actually pulling them out. I was wondering (maybe hoping) that somehow the bank one cam was just mistimed and could simply be re-timed.

Pretty sure that this is just pad wear. You won't get a cel before about 9 or 10. Pads need to be changed but it's not urgent. Within 6 is spec

Thanks. I'll do it now. No sense waiting.

dlud if you are planning on doing it yourself it's not a job for the faint of heart. It can be done...I did it with the engine in the car. And I did it because I had debris in the filter. But if I had to do it again I might just pay the indy and let them do it.

dsallean: good advice. Still wringing my hands over which way to go. For other reasons I'm pulling the airbox out anyway so that should help on the 4-6 side. Did you pull your exhaust manifolds? Or how about the aluminum support members running to the transmission?

dlud: I pulled the transmission supports and lowered the engine a little at the front, supported from the top with an engine support bar and from the bottom with a floor jack. I didn't remove the exhaust manifolds and was able to do it by just dropping the engine and shifting it slightly while r & r. Replacement would be straightforward with the engine removed. I have removed engines before...but I was told that Indy's don't remove the engine to perform this service so I thought I would give it a go.

Also, the airbox was not in my way.

When I did mine, I dropped the engine. It was on my previous car which was a tip. I left the transmission attached to the motor and dropped them together. I don’t imagine that the manual transmission is any different (correct me if I’m wrong). If I were to do it again, I’d probably do it the same way. Life is so much easier with the engine out of the car!

NewArt: thanks. It looks like the 1-3 side will be a breeze on my car. 4-6 not so much. I may regret it but I'm going to try to complete the job with the motor in the car. It looks to me that the 4-6 side would be a lot easier without the airbox. Since I'm eventually going to put the 987 airbox in and it is sitting in my garage the 986 airbox may be gone in short order.

Well, it’s certainly doable. You might take dsallean’s suggestion and drop it a wee bit. Dropping the engine a few inches is easy as you don’t have to remove or undo a lot of stuff. This would also give you more room to install the larger airbox. That way you could avoid some of the problems that I had when I installed my 987 air intake system (see my airbox install videos in the diy section of this forum).

I did mine with the engine on the car, no big deal

I’ll be doing this job sometime in 2018. After viewing what’s required I’m sure it can be done with the engine in the car, as other posters have noted. But for my own sanity I’ll be pulling the engine and trans, it’s not that hard with a lift and hydraulic table.

To those who have had their variocam pads replaced, how much did the deviation change? On my car the change was less than a degree or so...

Paul: What were the cam deviations before the job?

Position 1 was -6.92, after worn pads were replaced -6.37.

I will have to look for my numbers when I get home but those would be a concern to me having replaced the pads.

It is a concern, my first motor bent its valves due to stretched chains, but 20,000 miles since the pad replacements on the second motor, it still has about the same deviations.

Suggest you accumulate a list of to-do issues, drop the engine+trans like New Art suggests.
Much depends on your plans for keeping the car.
For example, with the engine out, you can easily futire-proof the vacuum system,RMS/IMS etc

+ AOS = piece of cake!
+ that horrible coolant reservoir job = easy peasy! :)

I just had the transmission out a month ago for a bunch of precautionary stuff: clutch, flywheel, pressure plate, AOS, IMS, water pump, low temp thermostat. So, I wasn't real excited to take the engine out for the cam chain/tensioner pad work. I did remove the 986 airbox in order to replace it with the 987. With the airbox out there is a lot of room on the left side of the engine to do the camshaft removal/reinstall. I think I have a easy solution to the 987 airbox install. I'll post on it if it works out (it's still a work in progress but it's very promising).

I took out the engine and trans to do mine. I would do it that way again. It wasn't that hard to pull the engine and once out very easy to work on.

To update: I'm in the process of replacing the vario-cam pads. I started with the 1-3 bank as that was the one with the worst cam deviation. I'm doing it with the engine in the car. So far, not a real big deal. The most excitement was taking the header/cat off. I was sure that I was going to break off one or more bolts that attach the header to the head. 0 for 6 on breakage! Used a healthy dose of PB over the course of 24 hours and then used an impact driver. They all popped out intact. I'll replace with stainless steel and high temp anti-seize paste.
The indie that I originally talked to about the cam deviations wasn't too worried and suggested a wait and see approach. One pad was ok. The other was severely worn and crumbled when I pulled it off the vario-cam.
http://986forum.com/forums/uploads02...1520472585.jpg

Good on you mate! Good luck on your job. Keep us in the loop!

Now working on 4-6 bank. The cam deviation for this side was 5.3. Since it was within spec (6) I expected the variocam pads to be less worn than on the 1-3 side (7+ cam deviation) that I have already reported on (significant wear). Once again had to remove the header/cat. I thought there was enough room on the 4-6 side that I would not have to remove it. I was wrong. Once again, all bolts came out with a good dose of PB and an impact driver. One of the pads was very worn. Makes me glad I acquired a Durametric when I did and checked the cam deviations. I'm also now a believer in Raby's advice to replace the pads and 4th and 5th timing chains at 40k miles. My 2000 S has 66k miles.
http://986forum.com/forums/uploads02...1520652112.jpg