Using Durametric to Detect IMS Bearing Weakness

[Jaxonalden]

Originally Posted by JFP in PA

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……………

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?

[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.

[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.

[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 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.

[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).