Camshaft Position Deviation / Chain tensioner paddle pad replacement DIY vs Cost?

[Los996]

Hello all, New to P-Cars but not to engine rebuilds. Have done my share of SMB 350 rebuilds so not shy about what it takes.

That being said, I just took ownership of a 2000 911 3.4L 996 with 99.5K miles. They had all service records demonstrating responsible care and appropriate service intervals. 

Like all cars, I like to do my due diligence to "reset the clock" (change oils, fluid, etc).

 

I've read across many posts and all very informative, especially JFP!

 

The first thing I did was put this on a Durametric and getting some data.

Let me first say that I put it on the scanner because the car got a CEL after some vigorous driving and stopped at a light. The codes were P1128 and P1130. Thanks to this forum, I've already run some diagnostics and tests and they seem to point to the MAF. Some slight rough idle when codes were cleared and some slight surging. This corresponded with symptoms and readings.

 

Now, as recommended here to check for possible IMS bearing issues I ran a diagnostic for the Camshaft position deviation 1 and 2 (NO Fault codes for this condition).

After a brief 30 min vigorous drive up and down a main street, the readings at idle were:

Camshaft position deviation 1 :  - 10.02

Camshaft 2 : - 2.55

 

Angle for camshaft bank 1: 0.17

Angle for camshaft bank 1: 0.19

 

They held there rock steady throughout the drive with slight variation from cold start.

 

According to this forum, this seems to be an indication of a possible chain tensioner pad replacement due. If this is the case, what else should I consider as "wear and tear" replacements and is this a DIY situation? Would I need adjust timing, special tools (besides camshaft tool), etc? Does anybody have a how to guide or is this available in the Factory Service Manual?

 

If this is too complicated a task, what can I expect a small specialized shop to do this for?

Also figure it might be a good time to do IMS...

 

Many thanks in advance to all of you.

 

Txs.

 

[JFP in PA]

Welcome to RennTech.

 

As yours is a five chain motor. the likely culprit are the small chain tensioner wear pads between the cams:

 

 

 

While not a difficult job, it does require some specific tooling and knowledge of how the cams are times or "allocated" in Porsche speak.  I'm pretty sure there is a DIY with photos over on the Pelican site for this specific project, but if you can get access to either the factory service manual or the Bentley 996 manual, you can find everything needed.

 

Good luck.

[Los996]

Txs for the prompt JFP. Since these have to be replaced, is it advisable to also replace the chains?

Also, previous owner had done various mods to the car, would an aggressive cam swap generate these differences?

Finally, replace the solenoid as well?

 

FYI, no plastic residue or shavings on oil filter on recent oil change.

 

Txs.

Edited August 7, 2016 by Los996
add text

[JFP in PA]

10 hours ago, Los996 said:

Txs for the prompt JFP. Since these have to be replaced, is it advisable to also replace the chains?

Also, previous owner had done various mods to the car, would an aggressive cam swap generate these differences?

Finally, replace the solenoid as well?

 

FYI, no plastic residue or shavings on oil filter on recent oil change.

 

Txs.

 

To change the chains, the engine has to come out and apart.  So  unless you can see a reason to do it, I'd leave them alone.

A cam swap could have accelerated the wear pad issue.

As you are already there, the solenoid would not be a bad idea.

[Los996]

Txs JFP. Truly a great contributor here. Dug around some more on the threads and started to piece together some info and replies from you on other threads.

For those landing on this thread, here are some helpful links on how to do this:

 

To change chain pads / ramps and/or Camshaft on 996

 

Parts: reference Number and Exploded View of Camshaft Driving mechanism:

http://www.porscheatlantaperimeterparts.com/showAssembly.aspx?ukey_assembly=471619

 

Testing / Camshaft Position Deviation Specification / Wear:

 

Your cam deviation specs are +/- +6 degrees at idle; if your engine is at 11 & 15 degrees (cam deviation values) you have a more mechanical issue as your cam timing is way out of whack.  As you car is a 2000, it is a five chain motor, meaning that it has an extra set of cam tensioning paddles between the two cams (note the small chain connecting the two cams with the green arrows, about half way between the two green arrows you can see the wear pad of the five chain tensioner):

 

 

The small wear pads can literally fall apart, throwing the cam timing off (these are worn pads next to new ones):

 

 

I would suggest rescanning the car, looking at the cam deviation values at idle

 

When these pad get beat, the cam deviation values go way out of spec, and the car throws the code you are seeing.  You would also find small yellow/brown plastic bits worn off the pads in both your oil filter and sump.  If the sump contains green plastic bits, they would be coming from the VarioCam unit itself, which can also do this, but is much less common than the chain paddles.  While you are rescanning the car, also activate the VarioCam solenoids one at a time at idle; you should hear a pronounced click, followed by a major movement in the cam timing, along with a big change in how the car idles; this will show you if the VarioCam solenoids and the units themselves are functional.

 

You definitely have a timing problem, as your can deviation values are way out of spec at idle, which is before the VarioCam does anything.  This is most likely the tensioner wear pad issue.  Your VarioCam system is not activating on bank 2 (cam angle does not jump to over 20 degrees), so either the solenoid or the VarioCam unit itself is out.  Did you hear the "click" I mentioned when you activated the VarioCam on bank 2?  If not, I would start with that solenoid.

 

In any case, you need to get to the source of the out of spec cam deviation values; your timing is far enough out that you could get into serious trouble if it moves further.  This is going to require pulling cam covers to inspect the wear pads, which will need special cam holding tooling (the cam cover forms one half of the cam bearings, so a holding tool in needed to keep from potentially snapping the cam in half when the covers are removed).

 

Replace with engine installed:

Replace with Engine dropped:

http://rennlist.com/forums/996-forum/615351-996-ims-timing-chain-guide-transmission-pinion-bearing-and-misc-items-diy-project.html

 

http://www.pelicanparts.com/techarticles/Porsche-996-997-Carrera/16-ENGINE-Camshaft_Swap_and_Valve_Train_Repair/16-ENGINE-Camshaft_Swap_and_Valve_Train_Repair.htm

 

Parts and Part Numbers to Consider:

 

Edited August 11, 2016 by Los996
Added more helpful info

[Los996]

Just wanted to post an update and recommendations for doing the chain pad swap with the engine in the car.

Doing this with the engine in the car was filled with curse words, scrapes and cramps in parts of the body I forgot existed but it got done.

If I decide to help on a friend's car I will document the details.

The biggest issues / challenges are:

1. Enough clearance on Bank 4-6 to place the cover on without screwing up the sealant.

2. Instead of using the Porsche tools recommended by the Bentley and Porsche FSM I would use this Porsche timing tool (recommended by Wayne in 101 Projects book)

 

The reason is that there's not enough clearance to use the factory recommended one with the engine installed. Plus, you kill two birds with one stone because you can check the timing while holding down camshafts and vice versa. However, using this tool is a bit different from what the factory specs requires as this tool is "stationery" while the other one allows you to "wiggle" the camshaft into the perfect vertical position. See write more about this here: http://rennlist.com/forums/996-forum/564427-camshaft-timing-durmetric-readings-errors.html @Dharn55

3.  Getting to tensioner for Bank 4-6 is a nightmare. The compressor has to be moved out of the way, the wiring harnessed loosened the compressor line "moved" slightly out of the way and then the correct socket height  to clear the engine block. The real issue becomes on reinstalling the tensioner because the deep socket you used ( because of size 1 1/4") before to remove now is too "deep" to use . So I ended up placing a 25MM in that one and then compressing some cardboard until there was about 1/2" left at the socket end. Then yo have to use an extension and swivel adapter and apply pressure from the top to thread in but ***CAREFUL*** because you need to apply pressure and go in exact or you stand the chance of cutting into the threads on the block.

4. Accessing the muffler mount bolts at the top and the top most front of the engine valve cover bolt are most challenging and then no real way to torque to spec. You need to "feel" and come as close as possible.

5. Bumpers and heat shield on my car did not need to come off .

6. Make sure you have all secondary hardware such as: new header gasket (crush type), new valve cover bolts, spark plug tubes and o rings, tensioner crush washers and o rings, oil plug crush asher

7. You will have to drain all the oil because when the engine is in the car, when the valve cover comes off, the residual oil will stat to come down, pool over the edges of the engine block. That needs to be sparkling clean for the new sealant

8. Header bolt on Bank 1-3 nearest to coolant hose is difficult to remove because the socket head is too big and the header tube doesn't provide ample clearance.

9. Pre-treat all exhaust bolts with penetrant like PB Blast a day or two before. be very liberal.

10. Fabricate the tensioner compressor tool using a M5 x .80 reverse / left handed die (2000 + models. Only before 1999 was right handed thread). Trust me, tie wraps are a PITA because you need to buy the correct ones for the amount of tension and they need to fifth through the top and bottom holes (top holes are larger in diameter than bottom threaded holes). I ended up using a large Dewalt padded 6" vise to compress and carefully hold while removing and replacing but this is not ideal.

 

These are just a few off the top of my head and here's the before and after on the chain pads / brake pads:

 

Many thanks to @JFP in PA

Edited September 27, 2016 by Los996

[JFP in PA]

Unfortunately, doing this repair is a bit like building a ship in a bottle with the engine still in the car, but as you have shown, it can be done.  But as not everyone has the facilities to drop the engine and do the work, your approach is the next best thing.  Good job

[Schnell Gelb]

One ugly detail with this job is the orientation of the 2 pads on the Actuator. The pads are different as shown above. One pad has 2 oil ports in it and a green 'O' ring on the underside of it. The other pad has neither the oil ports ,nor the 'O' ring .

Each  pad will fit on the top or the bottom of the actuator ! So which pad goes where??

Very few Instructions mention this.

AFAIK , the pad with the oil ports always(for Bank 1 or 2) should be fitted adjacent to the solenoid(INCORRECT ! see below) as pictured at the beginning of this thread.

If this is incorrect Please mention it here !

Edited April 12, 2017 by Schnell Gelb

[Porschetech3]

On 4/10/2017 at 0:42 PM, Schnell Gelb said:

One ugly detail with this job is the orientation of the 2 pads on the Actuator. The pads are different as shown above. One pad has 2 oil ports in it and a green 'O' ring on the underside of it. The other pad has neither the oil ports ,nor the 'O' ring .

Each  pad will fit on the top or the bottom of the actuator ! So which pad goes where??

Very few Instructions mention this.

AFAIK , the pad with the oil ports always(for Bank 1 or 2) should be fitted adjacent to the solenoid as pictured at the beginning of this thread.

If this is incorrect Please mention it here !

 

It's incorrect... I know we just corrected this on the 986 forum, but not here.

 

The pads with the oil holes and O-ring on bank 1 go toward the head, On bank 2 it goes toward the cover.

[Schnell Gelb]

Thank you Porschetech3.

The devil is in the details. We'll never know how many M96 engines have their pads upside down.

If you look carefully at the Actuator for Bank 1 it has a single large oil port at one end only .This 'feeds' the pad with the 'O' ring and 2 oil ports.

See Post #6 for photos and details here. Note the photo is of Bank 2, not Bank 1

http://986forum.com/forums/general-discussions/60995-vario-cam-adjuster-plunger-question-re-p1324-code.html

Edited April 12, 2017 by Schnell Gelb

[Porschetech3]

2 hours ago, Schnell Gelb said:

Thank you Porschetech3.

The devil is in the details. We'll never know how many M96 engines have their pads upside down.

If you look carefully at the Actuator for Bank 1 it has a single large oil port at one end only .This 'feeds' the pad with the 'O' ring and 2 oil ports.

See Post #6 for photos and details here. Note the photo is of Bank 2, not Bank 1

http://986forum.com/forums/general-discussions/60995-vario-cam-adjuster-plunger-question-re-p1324-code.html

 

Yep..some will wear the chain and pads a bit more without the "extra" oiling from the oil ports, although there is a lot of oil slinging around inside the cover. The details really do make a difference.Back in my early racing days I had a saying "the "best " way to get 100 extra horsepower is to find 1 horsepower in 100 different places"

Edited April 12, 2017 by Porschetech3

[dporto]

I'm in the midst of doing this job now. I haven't gotten to the cam covers yet as I'm still focusing on dropping the engine/transmission. I only get a couple/few hours at a time to work on it so it's pretty slow going (nights/weekends - in between everything else that needs to be done in my "free time"...). I got the AC compressor out last night and the engine bay is just about clear (all wires/connection that need to be removed). Hopefully if all goes well I'll be dropping the engine/transmission by next weekend - this weekend is kind of screwed with the holiday's...

[Schnell Gelb]

We're with you all the way. Take your time,be methodical. You don't want a do over because you missed a little thing - like a small spring !

Edited April 14, 2017 by Schnell Gelb

[dporto]

^Ha^ I know... I'm finding a bunch of little stuff along the way as well - lots of rusted screws, bolts, speed nuts etc...Which of course all need to be fixed. I'm trying to address the things I can as I run into them. If it's too much of a delay/sidetrack, I'll set it aside for a time when I can give it the attention it needs. I got a couple hours in yesterday evening and got the coolant drained, the under-body panels and all the under braces out of the way of the transmission. In romoving the body trim pieces in front of the rear whewels I found some pretty serious rust/rot. It was clear that these pieces had never been removed and the corners were just packed with dirt that had accumulated there over the years. I'll defi nitely have to revisit these areas and do some serious rust removal/remediation. Tonight/tomorrow should be cable/wire connections to the transmission etc...Almost forgot to mention the axles... 

Edited April 17, 2017 by dporto

[dporto]

So, it's still a little early for this question, but I figure I may as well get it out of the way. While I get that the crankshaft should be locked/pinned at TDC, I'm wondering about locking the camsfaft(s). If I do, how would I change the pads and/or chain? 

[Schnell Gelb]

To change the pads both camshafts,the Actuator and cam-to-cam chain are usually removed as an assembly. The pad/chain change is done on the bench.Some good Youtube videos may help. You need to plan how you will compress the actuator - is yours a right hand thread or Left hand ?

Edited April 25, 2017 by Schnell Gelb

[dporto]

Yeah, I don't know about the thread yet, as I haven't gotten to them yet. I was a little confused about locking the cams... 

[mdreef]

Hi dporto,

 

I'm preparing for this job on my 2001 cabriolet as well and would like to know how your project went - especially what you did to lock your cams.  Did you buy the special tool?

Any lessons learned/advice other than what's been mentioned in the previous posts?

 

Thanks!

 

[mdreef]

On 7/15/2017 at 6:38 PM, Ahsai said:

I'll repeat here again in case you missed it. Please refer to the Pelican steps. If you use the cams hold down tools that John mentioned, they will work buy they don't index the cams so you need to make sure you're at the right TDC before opening the cam cover.

 

At the right TDC, the notch at the end of the intake cam of bank 2 above the scavenge pump should point TOWARD the crankshaft (should point away if you were working on bank 1). This is critical because the cams will have the least stress on them (from the valve springs) only in this position.

 

[mdreef]

Great info - thank you!  

[Paul Gavazzzi]

2000 996 C4 -- approx 90k miles. Runs well, IMS Solution (dual row)/clutch/flywheel done at around 60k miles. .5 qt sump installed. 

 

I have the LN IMS toolkit with the cam lock.

 

Durametric reports a -5.5 and -7.78 so, it looks like the Vario Cam wear pads are in need of replacement. From my research this looks doable without dropping the engine... I am assuming I will have to remove the muffler (and header?). LN suggests replacing the cam to cam chains -- is that a good idea?

 

any suggestions before I tear it down would be helpful. Thanks!

Edited May 13, 2020 by Paul Gavazzzi
misspelling

[JFP in PA]

2 minutes ago, Paul Gavazzzi said:

2000 996 C4 -- approx 90k miles. Runs well, IMS Solution (dual row)/clutch/flywheel done at around 60k miles. .5 qt sump installed. 

 

I have the LN IMS toolkit with the cam lock.

 

Duratech reports a -5.5 and -7.78 so, it looks like the Vario Cam wear pads are in need of replacement. From my research this looks doable without dropping the engine... I am assuming I will have to remove the muffler (and header?). LN suggests replacing the cam to cam chains -- is that a good idea?

 

any suggestions before I tear it down would be helpful. Thanks!

 

Welcome to RennTech 

 

You are not very far out of spec, so I need to ask if you drove the car for at least 20 min. to completely warm everything up before taking the readings?  It is very easy to get inaccurate and misleading readings by not properly warming up the engine before doing so.

 

You are going to need the cam retaining tools to hold the cams while removing the cam cover.  I would also suggest you search out the several DIY write ups on this topic, and familiarize yourself thoroughly before starting.  It can be done with the engine in, but is often quicker with it out.

 

Good luck.

[Paul Gavazzzi]

Did drive the car for at least twenty... started at -9 or more. Read this thread and the pelican parts/101 project material. What started me looking was some chain slap on cold start. Replaced all the external tensioners -- Oil change with redline... helped some. but I am thinking damage done... better safe than sorry. Should I try the solenoid first?

[JFP in PA]

Five chain motors have a problem with the small pads between the cams, which is a well known problem:

 

 

 

If you had a solenoid issue, the car would code for it, besides which if you go in to do the pads, you could change out the solenoid then if you wanted.

[hankster66]

Jumping on this related thread for advice on my clutch/IMS project where I discovered cam deviations of -10.44 / -5.64.

 

Background

- 2000 996.1 C2, 90K miles

- Recently purchased, no IMS/RMS ever done

- No faults, leaks, smoke, strange sounds from car, other than clutch issue.

- oil cleared blackstone analysis at purchase (done by owner), current oil/filter/sump check pending

- As preventative, planned LN IMS retrofit with clutch/flywheel repair

 

Current Status

- In running through LN pre-qualification durametric tests, all checked out ok except for cam deviations of -10.44 / -5.64. I ran engine for 30 minutes, of which 5 minutes were driving around the block (can't go far as clutch is "gone").

- Stopped proceeding further (with dropping transmission, etc.) pending further research on cam development

- LN recommending (based on values) variocam pad replacement and preferably chains 4 and 5

 

Tentative Plans

- Rerun durametric tests at cold start and at running temp to see trend for cam variation

- Do oil filter/sump check and scope cylinders before dropping anything to better assess engine / IMS condition

- Determine next steps, including whether I'll proceed with IMS replacement (if I discover dual row and operational) which I could do later after taking care of more imminent concerns.

 

Questions

- Assuming deviations are correct, any opinions on how imminent of a concern this is (i.e., car should not be driven until corrected)?

- Are there other tests I could/should do to get a better sense of what's going on before proceeding?

- Assuming that I'm better off dropping the engine (which seems daunting to me) than working on it in place, what else would be "crazy" for me not to do while in there?

- Any videos/references you have used that might help me assess whether I proceed on this journey as a DIY or pursue indy shop job?

- Did I miss anything I should be thinking about?