Using Durametric to Detect IMS Bearing Weakness

[Jaxonalden]

JFP,

With that philosophy, and I know Jake did his homework on his Guardian, but what if there was software that was constantly monitoring this data which the computer already is. Then have that monitoring trip an Check Engine light when the cam deviation fluctuates or goes beyond a predetermined value (+/- 4 degrees)?

This sounds like more of a tell tale sign of impending failure than a chip detector...even have a safety net and if those values are exceeded, shut the engine down to prevent catastrophic failure.

Sound like a wiener?

P.S. If shutting down the engine sounds dangerous just think if it hand grenades in traffic.

[JFP in PA]

Problem is that when the IMS is wobbling emough for the Durametric (or PIWIS) to see it, there already is metal all over the engine that will need to be cleaned out before putting it back in service. Jake's approach sees something wrong much earlier, before the inside of the sump looks like a trash can under a machine tool..........

[jaykay]

Originally Posted by Jaxonalden

JFP,

With that philosophy, and I know Jake did his homework on his Guardian, but what if there was software that was constantly monitoring this data which the computer already is. Then have that monitoring trip an Check Engine light when the cam deviation fluctuates or goes beyond a predetermined value (+/- 4 degrees)?

This sounds like more of a tell tale sign of impending failure than a chip detector...even have a safety net and if those values are exceeded, shut the engine down to prevent catastrophic failure.

Sound like a wiener?

P.S. If shutting down the engine sounds dangerous just think if it hand grenades in traffic.

Yes I am with you....this was my ims gaurdian guess but I was wrong....just didn't think about a simple chip detector. Chips can come from anywhere so it would go off from things other than just the ims bearing; I was thinking ims bearing failure isolation. I don't believe you would be able to catch chain tensioner wear with the
guardian (plastic is not magnetic). Cam shaft deviation monitoring might be able to give you tensioner wear due to increased chain slop and loss of motion. This what is what I was most interested in as I have changed my bearing. I guess it was just wishful thinking.

If chain tensioner wear can be shown to produce cam shaft deviation we may have our own product! We could perhaps monitor cam shaft deviation via the OBD port and have an alarm go off when deviation goes outside of 5 degrees. I was thinking of just connecting your iPhone to the OBD port to do a check every so often.

Oh well...I suppose Durametric has this covered already!

[Jaxonalden]

I'm with you Jaykay, I believe monitoring the cam deviation in concert with a chip detector is the way to go. Alarm at 5 degrees?, I'd go with .5 degrees. Any fluctuating deviation is not a good thing, slop is slop.

It can't be hard to monitor those two values and then trigger some sort indicator. This can't be that tough to figure out and then we can all sleep a little better at night. I'll get right on it.

[jaykay]

Yes thanks for the decimal point....yes fluctuation with respect to each other

I am glad you are the electronics wizard!

Maybe an engine builder could speak to the exact nature of deviation with respect tensioner wear

[ChairmanRon]

Originally Posted by Paul

No need to remove engine.

My shop is telling me that with a TIP 986 replacing IMS requires dropping the engine too. Is he wrong?

[ChairmanRon]

Originally Posted by Jaxonalden

JFP,

With that philosophy, and I know Jake did his homework on his Guardian, but what if there was software that was constantly monitoring this data which the computer already is. Then have that monitoring trip an Check Engine light when the cam deviation fluctuates or goes beyond a predetermined value (+/- 4 degrees)?

This sounds like more of a tell tale sign of impending failure than a chip detector...even have a safety net and if those values are exceeded, shut the engine down to prevent catastrophic failure.

Sound like a wiener?

P.S. If shutting down the engine sounds dangerous just think if it hand grenades in traffic.

Brilliant idea.

[Jake Raby]

By the time any valve timing deviations occur the engine has already been subject to foreign object debris from the failing bearing that HAS to have degraded enough to allow for the deviations to e measurable. Collateral damage from foreign object debris wear metals from the IMS bearing have always been the primary modes of engine failure with IMSB failure.
There are lots of issues with measuring camshaft deviations and I know these because I have tried it.. Wait till a tensioner gets lazy or you have thick oil on a cold morning, or under heavy deceleration. What's is supposed to happen in theory doesn't happen. False positives would happen daily.

[jaykay]

Originally Posted by JFP in PA

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.

Just hooked up durametric for the first time. "Cam 2" is showing a deviation of 3.39 deg. Is this getting too close to being out of spec. and does this camshaft need to be "timed". Deviation fluctuation is rock solid at idle.

[papasmurf]

as if the values are fluctuating. If the numbers are not changing then I think you are okay.

[The Radium King]

i've seen both +/- 4 and +/- 6 stated as acceptable limits. watching the numbers with your durametric will tell you two things:

- fluctuating values tell you your ims is wobbling.
- values that slowly increase over time (months, years) speak to deteriorating tensioner paddles (bits of green plastic in your oil filter) and need for eventual rebuild (3.6!!!).
- values that start high are probably due to mis-calibrated sensors from the factory.

[jaykay]

okay great.....thanks guys

I guess 4 degrees is nothing when you are dealing with chain lash!

[navyc130fe]

I have a deviation of 2.0 and -6.0. I'm guessing this is bad.....?? Should I flatbead it to my mechanic??? What say you Boxster Gods???

[JFP in PA]

Originally Posted by The Radium King

i've seen both +/- 4 and +/- 6 stated as acceptable limits.

The OEM spec has been both +/- 4 (early M96) and +/- 6 (later M96/97).

[JFP in PA]

Originally Posted by navyc130fe

I have a deviation of 2.0 and -6.0. I'm guessing this is bad.....?? Should I flatbead it to my mechanic??? What say you Boxster Gods???

Don't panic just yet; if the values are steady (not swinging back and forth and idle), it is probably just wear on one of the tensioners, chain paddles, or a VarioCam unit. These are problems that can be addressed when time and funds permit.

If the deviation values are swinging wildly, shut the car off and call the flatbed.....

[jaykay]

There is mode that can plot the deviation in real time as you idle. As far as I recall you call up cam one and cam two. The display seemed accurate enough to show variance in deviation; you should have flat lines for both parameters. There is also a numerical display that can keep your eye on

[navyc130fe]

They were rock steady at idle. No deviation at all, let run for 5 minutes. I am still contemplating the IMS/RMS upgrade as a precaution. I have a mechanic (Provost Motorsports) who runs a $2k special to replace. Any idea on the price of the tensioners, etc.?? Thanks for the replies!

[jb92563]

I checked my deviation today and I get -4.5 and -6.3.

It is rock steady and does not fluctuate.

Sounds like its slightly out of spec.

What does it mean, timing chain is a little loose?

How do I correct that deviation?

Do i need new chain guides or tensioners?

I have a 2001 S with the 3.2l and 60K miles.

[JFP in PA]

Could be either the chain guide wear paddles or the tensioners, you would need to start looking to see which or if it is both (not uncommon). Could also be the VarioCam unit.

[jaykay]

I found that once I switched to a 5w40 I saw much less plastic material in my oil filter. This may be just due to chain run in on the plastic earlier on in the cars life vs later when chain grooves are more established

I do continue to see little flecks of what looks like vario cam pad material....perhaps as a result of my driving style. I am up and down through 4k a lot on the street.

Anyway perhaps a different oil may help you in the future