Using Durametric to Detect IMS Bearing Weakness
 

Hi Folks,

My '03 986 is under warranty for a bit longer, so I thought I would use my new Durametric software/cable to detect any sign(s) of weakness in the IMS bearing. I read someplace about using it to determine if there is a cam variance within the engine. Can someone point of which specific measurements to look at for this?

Thanks,
Ron

Correlate the Camshaft Deviation between position 1 and position 2, they should be close in degrees. Before I replaced my IMS bearing my deviation was .60 degrees different between the two.

Thanks Jager, I'm going to do a quick check with my laptop and see where my deviation is.:cheers: Praying for a 0.0.:dance:

Thanks -- I'm going to run that test when I get back home in a few days. And I'll flip if it's near there. :(

Next time I buy a Boxster I'm bringing my laptop and Durametric cable for the test drive!

Are these cam shaft parameters easily read from all OBD port scanners....can I get it on my iPhone?

I dont know too much about durametric software and the required hardware. What are all the uses and are there any alternatives? What is the cost and where can one buy the equipment?

Diagnostic Tool for Porsche | Durametric

Google is your friend.

I've only had the chance to use my new Durametric cable/software a few times, but as both a tech guy and a Porsche guy I'm thrilled with it. Knowledge is power, and with the Durametric you can see everything the car's multiple computers see. Far more powerful than a mere code reader. Check out their videos, which provide a pretty good explanation of what it is capable of.

For $300, it is the best money you can spend on your Porsche.

What you should be looking at is if the cam deviation values remain steady at idle. The actual values are irrelevant, as long as they do not exceed the OEM specs (+/- 4 degrees on five chain M96’s). If the values are not rock steady at an idle, and swing back and forth, the IMS bearing is most likely on its way out.

As for what tools will give you this data, PST II, PIWIS, or Durametric are your only choices; and no, nothing exists for the iPhone……………

Keep in mind that the bearing/race contact area starts to get rough when the lubrication breaks down and the first particle is shed. The wear then accelerates.

So depending on a check of the oil filter media, a magnetic drain plug, or a deviation check is no sure thing because you aren't going to do any at a frequent enough interval to catch the problem with any probability before it is spraying significant debris into the oil passages and or taking out the sprocket/chain interface leading to valve clash.

Sure you can get lucky and catch it but the probability is against it.

Just to add to my previous post... My old IMS bearing was not falling apart but close inspection there was a little movement between the inner race and outer as shown in the picture. This bearing might have gone another 200k miles... Who knows?

Yes, I replaced mine with a retro-dual row. My bearing(s) were in great condition but there was another guy in that day that was not so lucky.....just on the verge of disintegration. He was faced with a long process of monitoring oil and oil changes to try and catch any debris.

I would like to monitor the health of the new bearing as well as tensioners. I figure that my oil change intervals would be suitable

I am running the diagnostic now, comparing Cam Deviation 1 and 2. They do NOT change while the engine is idling. Cam Deviation 1 stays at 0.64, and deviation 2 stays at 0.66.

See pic below.

Since the deviations are within the norm and do NOT change, does this mean we do not have a problem indicator with this test right now?

Very good numbers Chairman. The thing to look at is the variation at idle and if its rock steady, you are ok.

But the cam deviation is just one diagnostic for IMSB condition. Some say cam variation occurs only in the very late stages of failure, right before detonation. Noises, like a rattle at idle or a sound like a waterpump going are also signs of a bad IMSB. And of course, metal in the oil filter and magnetic oil drain plug are almost always a sure sign of impending failure.

Theres also the question of how much warning you get from the time the bearing begins to go until total failure. If that period is less than your oil change interval, then you are not going to catch it by oil filter inspection.

For a very legnthy discussion on warning signs of impending IMSB failure, see this discussion on Pedro's Board. IMS guardian

I use cam variation, filter and drain plug examination and a stethescope to listen to the area around the IMSB to check the condition of the IMSB, but the only real guarantee against failure is to get it replaced.

What's the typical cost of an IMS bearing replacement on a Tiptronic vehicle (no clutch jobs being done anyway)?

Around $3k for a TIP.

Does a bearing retrofit require the engine to also drop, or just the tranny?

No need to remove engine.

A picture pulling IMS bearing while the engine is still in my car.

JFP,

You say the actual values are irrelevant but they must mean something. I just took my readings and I'm at +.39 position 1 and +1.93 position 2. Those readings are rock steady at idle all the way to 5,500 rpm. I've been on other forums and sites reading what I can and I've seen everything from positive deviations like mine and minus deviations. Are you saying it's all in the delta between the two?

BTW, I have an '04 3.2 so I think I have a three chain. Are those numbers for my engine also?

As long as the values for cam are between +/- 4 degrees (OEM specs for the M96/97), the actual values are irrelevant as they represent tolerances in the VarioCam, chain slop, component wear, etc. Try as you may to get it on the “ideal” deviation value of “0” when assembling one of these engines, you never will and will always end up with some value that should be in +/- 4 degree range.

The critical issue for determining if the IMS is on the way out (and this is a “win the lottery” odds of actually seeing it before the unit blows) is are the values rock steady at an idle; if they are not, and are moving back and forth, something in the cam drive, usually the IMS bearing, is wobbling badly.