driving below 2800 RPM = trouble?

[cvhs18472]

Originally Posted by pbanders

FWIW, I feel sorry for any owner who is so concerned about IMS failure that they feel they have to drive at over 3K all the time. If you really believe the motor is that poorly engineered, either spend a wad of cash to get Jake to fix it for you or get rid of it.

I drive the cars I own for my pleasure, if they can't take the way I want to drive them, then I'll get something else.

Here, Here.
Ed

[kls]

I think Perfectlap's suggestion for driving is ideal. No sacrifice at all, and no guilt for pushing it a bit. I do not see it as being overworried about IMS - just doing what you can to avoid an unlikley issue (like taking an aspirin every day for my healthy heart).

I have read on the LNE Engineering site that 5-40 oil is best, but it wasn't clear (at least to me) if that helped even if the seal to the IMS bearing had not been removed. I am going to increase the frequency of oil changes to 5,000 and use Castrol or RP.

I may be one of the people Pbanders feels sorry for, but I drive at the RPM I want, and use some common sense too.

[spyder803]

The last thing I want is to mess my car up but I really can't imagine me ever lugging the engine, it runs too good to shift that soon. I'm going to just drive it the way I am comfortable driving it and let what ever happens happen.

[Jake Raby]

Some of the information we have gathered is related to shockloading the IMS sees as the transmission of loads from the variocam is sent upstream to the IMS through the timing chains.

The IMS bearings do not have very much longitudinal thrust capability and these shock loads place a lot of shock on these bearing, a portion of that is thrust.

Don't quote me on any of this, as lots of questions are still unanswered and I am working hard to prove whats occurring as the engine is running with the variocam engaging/disengaging continually.

Thats all I am willing to state now and I reserve the right to change this based on future findings.

[Perfectlap]

Jake,
Just in your experience to date, which cars have you noticed the highest number of IMS failures 97-99, 00-02 or 03-04?

[Jake Raby]

Originally Posted by Perfectlap

Jake,
Just in your experience to date, which cars have you noticed the highest number of IMS failures 97-99, 00-02 or 03-04?

IMS?? These issues generally occur post 99, the pre- 99 engines are more prone to cylinder failures.

After 99 the IMS syndrome is random through all models, none are more or less prone to it.

[Rick M]

Jake,

At appoximately what RPM does the VarioCam engage and disengage on a 3.2?

Thanks,

Rick

[turbo23dog]

I had much the same question and thought...

Attempting to translate Jake's most recent statement into my own words, variocam action is shockloading the IMS and a primary suspect in causing IMS failure.

I don't know exactly how Variocam works, but I assume it does its magic as RPMs increase and probably not in a linear but probably more of a logarithmic function. Higher RPMs mean more Variocam effect...

If I have all this right, then my logic tells me that for daily, around town, stop n go driving, one would have a better chance of avoiding an IMS failure by following the recommendation of the owners manual to use 3K rpm for an upshift point for every gear. I would also assume that conservative, smooth acceleration between shifts would lessen loads as well. Hmmm....

I'd also think that you'd be asking for engine failure by trying to accelerate hard with the transmission in 4th, 5th or 6th gear at 30 MPH or less. Same goes for a tip in manual mode...

[jmatta]

That would be the day I use 3k rpm as my shift point...might as well just drive my Grand Cherokee instead.