Chain Tensioner / Timing Adjustment access question

[crwarren11]

Hi all,

2000 Boxster 2.7L Tiptronic, 117k miles.  Geared up for an oil change and chain tensioner(s) replacement in the coming week.  I would like to adjust timing while I'm in there (I have cam deviation readings at cold startup and after 30min drive, and have confirmed proper function of the variocam solenoids).  I have not gotten under/in the car yet to determine if there is enough space to do this with the engine in the car as I am in the part-ordering stage.  Just wanted to get your input on this so I can get all my ducks in row with respect to all parts I need to perform the work.  Timing adjustment appears to be straightforward in itself.  I just don't know if I will be able to see/access the camshaft sprocket bolts once the pump is removed from each bank.  If access is achievable then I will go ahead and order the scavenge pump o-rings and new encapsulated bolts to perform the work.  If this is an engine-out service, then, well, I'll just stick to the tensioners for now.  Any input and guidance is greatly appreciated.

 

On a side note, I have modeled and 3D printed a cam locking tool for the M96.22.  It looked like everything out there for purchase was for the M96.23 and later models.  I will let you know how it performs after I do the work, but if anyone is interested in the solid model or stl file just let me know.  I have printed out a few extras just in case.

 

Thanks for your help!

 

[JFP in PA]

I don't know if we are experiencing a terminology gap here or not, are you planning on replacing the hydraulic chain tensioners, or the chain wear pads between the cams,  which are the more common cause of excess deviation values on five chain engines?

[crwarren11]

Hydraulic chain tensioners only for now.  I understand that the wear pads are a common source for cam deviation, but this is my first step before I go down the path of replacing the pads.  When I get to the point that I replace the wear pads, then I am planning for engine out.

 

I do not yet have any cam deviation codes and my deviation values are less that 6...but creeping close (-5.34 / -5.80).

 

[JFP in PA]

Long before I would even consider retiming the cams, I would try your idea of installing new hydraulic tensioners (all three), and then re-reading the deviation values.  From experience, I would be willing to bet you are still going to see high values at that point, which means the wear pads still need to be replaced.  When the pads are replaced, normally the engines deviation values drop back to much more acceptable ranges, so if you retimed the cams while the pads were still bad, you would be retiming them again after you replaced them.

 

At the milage on your car, those pads are past due to being replaced. 😉

[crwarren11]

As always, your rationale is strong JFP.  Thank you for your wealth of knowledge.

 

I am hopelessly optimistic that the hydraulic tensioners will bring the deviation values back close to normal and that maybe my wear pads are not too bad yet.  Even though I know the likely outcome of the exercise.  This is my daily for a short work commute and I know the engine-out work in my garage will put her out of service for a while.  (Admittedly poor reasoning)

 

My oil change intervals are less than 5k mi, I have owned since new, I have performed 99% of the work after warranty expired, and I do not hear any chain slap.  I have also yet to see the wear pad particles in the oil filters.  These are my likely unfounded optimistic reasons for hoping the wear pads are not yet in need of replacement (I think they call this false hope).  But I have accepted the reality that the wear pads will need to be done at some point likely in the near future.

 

I will replace the hydraulic tensioners only for now and pull the deviation values again periodically for the next few weeks to see if there is any positive effect.

 

You said 4, I thought there were only 3?

[JFP in PA]

You are correct, there are only three in the M96.  A brain-dead typo on my part! 😜

 

You may see some improvement, but it will not be several degrees, which is what you are looking for.

[crwarren11]

Quick update. Replaced all three tensioners and oil/filter over the weekend. Pretty quick and straightforward. Homemade tool worked great for locking camshaft. Just needed to shave down thickness on the tip a bit to fit into the slot. Bank 2 tensioner was much easier than expected. No need to move the a/c to remove or install the new one. Just used a box wrench to loosen. New version has a hex recess which made install easy with the low profile hex ratchet on the torque wrench.  
 

Thoroughly analyzed the oil filter. No signs of chain guide fragments, so 🤞🏼on those. I have noticed much quieter engine on startup and improved performance. Maybe placebo but I’ll take it!

 

[JFP in PA]

I would expect to see quieter startups, loose or worn tensioners are the most common cause of startup chain slap. Bigger question is what are the cam deviation values post tensioner updates?

[crwarren11]

I did not get a chance to read them yet and wanted to drive a bit first. Traveling this week so hopefully this weekend! 

[Silver_TT]

I would monitor the cam deviation periodically, say every 5K at your oil change.  Goes without saying but this means way more than whatever the engine now sounds like.  I would also refresh the timing before it gets to 6 degrees IMHO.  While on a different engine, I have seen the chain stretch or guides wear enough that it caused the chain to skip teeth ... but it never had triggered a CEL.  Just a tooth or two is enough to completely brick a head on an interference engine; there is very little room for error in this regard.  For example on my Audi 2.0T CPMB engine the timing chain was stretched just under 6 degrees on a hot engine at idle.  This is ridiculous and a ticking time bomb without question -- but if you didn't measure or didn't know you should, you couldn't tell a single bit of difference on the car, it drove perfectly.....  It's such an easy/fast thing to do and the consequences of missing it are so punitive.  It won't help your guides much but running a "good" oil can help reduce chain "stretch".

[crwarren11]

Thank you for the information! I checked today and no difference in deviation values, but I haven’t really driven it much. I am not sure if I have the access to adjust timing with the engine in the car but I’ll read up on this more soon. 
 

I’ve been running mobil1 5W-50 for many years now. 

Edited February 13, 2022 by crwarren11

[JFP in PA]

15 hours ago, crwarren11 said:

 I checked today and no difference in deviation values, but I haven’t really driven it much.

 

Not surprising.  Before even thinking about retiming the cams, you need to address the two small chain wear pads between the cams on this five-chain engine, they wear much faster than the rest of the chain pads and typically are the root cause of the deviation issues.

[crwarren11]

Yes, that is the plan!