Chain Pad Wear and Cam Deviations

[thom4782]

All: I'd appreciate your advice...

I have an 01S with 106K. I am trying to decide whether to replace the IMS bearing with the IMS Solution. If I do so, then my major worry becomes chain pad wear.

My understanding is that there are two groups of pads. One set of pads is associated with the variocams. The other group I've heard people refer to as the chain paddles located in the IMS area.

I checked my cam deviations this morning. They are -6.16 and -5.83 respectively, which is right on the borderline of the M96 spec of +/- 6. The deviation values were absolutely rock steady this morning as they have been in the past. The first deviation reads the same as when I checked it one year ago. IIRC, the second deviation has changed over a year from something like -4.8 to -5.8. Again, values have been rock steady each time I've checked.

So here's my question. Do anyone see anything in what I've described above that would indicated excessive wear in either group of chain pads. And, if the answer is yes, would the change in deviation angle suggest the wear is in the variocam area.

Thanks for considering this question.

Thom

[The Radium King]

here's a good diagram that shows all the pads and tensioners:

http://www.pelicanparts.com/techarticles/Boxster_Tech/16-ENGINE-Camshaft_Swap_and_Chain_Tensioner/Gp1800.pdf

various levels of work to replace the various components; tensioners can be done with engine in the car, variocam pads can be done by pulling cam covers, ims pads require complete disassembly. the actual replacement items are not that expensive (lne make a billet replacement for one of them); all the cost is in the labour, and I would suggest to really vet your shop before you let them too far into your engine.

the variocam pads have been updated by porshe to a harder material, are not *that* much work to get at (well, I was quoted 12 hours) and are probably the cause of your deviation bumping into the +/-6 limits.

tough call.

[jb92563]

I also have an 01S with 62k miles and I have virtually the identical numbers for cam deviation.

Mine have never changed, but I've only had the car for 16 months.

The fact that our numbers are virtually identical for the same model perhaps leads me to believe that they either wear very consistently or that this is the "nornal" reading for all 01S's.

I do not have any engine issues related to this that I can tell and saw no plastic bits in the oil filter paper.

[thstone]

Unfortunately, I am not aware of any way to correlate cam deviation values with wear of the various components, so it is nearly impossible to know if the high cam deviation values are due to excessive tensioner wear or some other cause.

[Jake Raby]

That engine has one or more issues, those values are just a couple of degrees from throwing a CEL.

I'd recommend rectifying the situation and finding the cause for these deviations before equipping the engine with the IMS Solution. Here that engine would not qualify for an IMS Solution retrofit as it stands today, and the same holds true with any of our Certified Installers as they must qualify engines to our standards.

Cold engines can't have the deviations checked as the vario cam arrangement is in a position where deviations are masked.

[thom4782]

Jake:

Thanks for the heads up on hot v. cold issue when measuring camshaft deviations. I remeasured them this afternoon with the engine hot. Here's what I found

Engine temperature: 98.3 C
Oil temperature: 82.5 C
RPMs: 710
Camshaft deviation bank 1: -5.83 degrees (rock steady)
Camshaft deviation bank 2: -5.72 degrees (rock steady)
Camshaft actual angle bank 1: -0.19 degrees
Camshaft actual angle bank 2: -0.19 degrees

At 3980 RPMs, both camshaft deviation numbers remained rock steady with exactly the same values they had at 710 RPMs. The actual camshaft angles changed when the variocams kicked in: bank 1 was at 23.11 and bank 2 was at 22.95.

What would you suggest I look at next.

Thanks

[Jake Raby]

You have worn components.. Can even be worn or stretching timing chains.