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3000 RPM & IMS


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So I have heard all these rumors regarding 3000 RPM with the M96 engine that there is some harmonic imbalance/distortion at 3000 RPM and is related to the IMS bearing failures. Is this an urban legend? It just seems like such a natural rpm during initial drive warm-up. It also fits with legal speeds.

Does anyone know if driving at 3000 RPM is a bad thing related to the engine or more specifically the IMS?

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All engines have some RPM zones that create harmonics; on the M96/97 it happens around 3,000 to 3,200 RPM. While there is some limited data that appears to indicate that it is not good for the IMS bearing, the fact that a lot of factory IMS bearing make it beyond 100,000 miles says the day to day risk exposure may not be great.

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Totally up to you. What you need to consider is that your road speed in that range is going to be around 70 MPH (+/- depending upon wheel/tire combo) and that a large number of owners are blissfully unaware of the harmonic zones and cruise for long periods at those speeds everyday without a problem. Track usage cars buzz past this range dozens of times every hour, again without issue.

The reality of the IMS issue is that, yes, they are somewhat prone to catastrophic failures, but currently at an unknown rate. What is known is that more frequent oil changes and usage of heavier weight oils seem to help. However, if the level of concern is high enough to cause you to alter how you use the car, or loss of sleep, there is also a known and proven fix for the problem…………….

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Understood. Thus everything being said, it seems logical that one would be better off while warming up or cruising to maintain RPM under or above the 3000-3250 RPM mark. Would you consider that a fair statement? Thank you for your help!!

Totally up to you. What you need to consider is that your road speed in that range is going to be around 70 MPH (+/- depending upon wheel/tire combo) and that a large number of owners are blissfully unaware of the harmonic zones and cruise for long periods at those speeds everyday without a problem. Track usage cars buzz past this range dozens of times every hour, again without issue.

The reality of the IMS issue is that, yes, they are somewhat prone to catastrophic failures, but currently at an unknown rate. What is known is that more frequent oil changes and usage of heavier weight oils seem to help. However, if the level of concern is high enough to cause you to alter how you use the car, or loss of sleep, there is also a known and proven fix for the problem…………….

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I think what Jeff in PA is trying to say is don't obsess over it as there is no proven data to support IMS failures caused by that particular RPM.

Understood. Thus everything being said, it seems logical that one would be better off while warming up or cruising to maintain RPM under or above the 3000-3250 RPM mark. Would you consider that a fair statement? Thank you for your help!!

Totally up to you. What you need to consider is that your road speed in that range is going to be around 70 MPH (+/- depending upon wheel/tire combo) and that a large number of owners are blissfully unaware of the harmonic zones and cruise for long periods at those speeds everyday without a problem. Track usage cars buzz past this range dozens of times every hour, again without issue.

The reality of the IMS issue is that, yes, they are somewhat prone to catastrophic failures, but currently at an unknown rate. What is known is that more frequent oil changes and usage of heavier weight oils seem to help. However, if the level of concern is high enough to cause you to alter how you use the car, or loss of sleep, there is also a known and proven fix for the problem…………….

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