Does disabling MDS mitigate the mechanical failures associated with it?

[Falcon1772]

Like the title says, if you disable MDS with a tuner or whatever does that save your engine from the lifter/ cam issues that MDS is known to cause?

 

[gofishn]

supposed to help but, IMO, no, not really.

Redline seems to best thing you can do to try and prevent failed lifters

 

[RobertusvT]

I used a tuner to disable mine and it feels better to drive and less laggy. I would guess it that it does help because it completely shuts it off. I am looking to sell my inTune i3 if youre interested.

 

[pacofortacos]

I didn't know MDS was "known" to cause failures???

Some speculate, but there is no concrete proof that lifter/cam failure has anything to do with MDS.

 

[kurek]

this topic always seems to produce more opinions than provable facts.

 

[bran101010]

You are right, it does. Everything I have read points to the VVT, and the smaller oil passage ways. I have seen people have lifter trouble with normal MDS lifters and lifters without MDS.

 

[kurek]

You are right, it does. Everything I have read points to the VVT, and the smaller oil passage ways. I have seen people have lifter trouble with normal MDS lifters and lifters without MDS.

When I see photos of failed Hemi lifters it looks like it's always the roller stops rolling and just grinds on the cam like this



I'm not a mechanical engineer but if you think about it, the inside of the roller has an axle that's in almost full contact with the inner bore of the roller surface while the outside of the roller is only in contact with the cam at one specific spot. Oil is lubricating both sides of it but you have to admit that's a bit of a balancing act for which surface is going to slip first, right? If the contact area between the axle and the roller is 0.05 square inches and the contact area between the cam and the outside of the roller is 0.025 square inches, wouldn't it just want to slip on the cam instead? And over time if it gets a flat spot it's going to just stay there on the flat spot then before much longer you got game over for that one.

Doesn't seem like anything to do with MDS, remember the non-MDS ones fail too.

 

[pacofortacos]

I agree, I think it is lifter caused also.
The roller is not directly oiled though, so could it be just intermittent roller failure?

I am assuming the roller doesn't just roll on a shaft but rather on needle bearings between the roller and shaft - or am I assuming incorrectly????

 

[kurek]

I am assuming the roller doesn't just roll on a shaft but rather on needle bearings between the roller and shaft - or am I assuming incorrectly????

Gotta admit I've never had one apart. The engines I've done valve work on were OHC with their own set of problems unrelated to rollers

 

[chrisbh17]

Afaik the rollers do have needle bearings. My uneducated guess is that the needle bearings eventually fail, possibly due to oil starvation, or maybe just because of cheap needle bearings.

Once that happens there is no more rolling and it starts to eat away the cam. Some people have even reported the lifters spinning in the lifter bore and then the cam is rolling against the side of the litter instead of the actual roller. That REALLY wipes out can lobes.

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[Fast69Mopar]

MDS does not have anything to do with the mechanical failure of the roller lifter. The failures occur on both MDS and non-MDS lifters. The bearings on the roller tips seize and flatten the cam lobes.

I have had lifter failure occur on 5.7's and 6.4's even after MDS has been deleted.

 

[Quyonmob]

In GM trucks, disabling the tuning didn’t solve oiling issues associated with the lifters. Lifters needed to be swapped back to pre AFM (GM’s acronym for MDS) lifters to attain the reliability of pre AFM LS 5.3L (Gen III-IV).

 

[Falcon1772]

Ok, well I learned some stuff here then. I was under the impression that it was the MDS system that caused the failures based on what I read. I've had mine disabled for a couple years now mostly to avoid those failures.

 

[burner71]

Yeah I have a 2500 without MDS and my cam wiped at around 160k or so

 

[anchorsaweigh]

 

[boblonben]

Like the title says, if you disable MDS with a tuner or whatever does that save your engine from the lifter/ cam issues that MDS is known to cause?

easy answser - - - NO.

 

[Tadpole]

I bought my 2009 Laramie 5.7L with 82k miles. Someone had already turned off MDS. A lifter failed at 114k miles.

 

[dhay13]

Afaik the rollers do have needle bearings. My uneducated guess is that the needle bearings eventually fail, possibly due to oil starvation, or maybe just because of cheap needle bearings.

Once that happens there is no more rolling and it starts to eat away the cam. Some people have even reported the lifters spinning in the lifter bore and then the cam is rolling against the side of the litter instead of the actual roller. That REALLY wipes out can lobes.

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Yep. Had a 1969 Chevelle with a 650HP 454. Spun it to about 7500 RPM regularly and a link bar connecting 2 lifters broke and the lifters spun and wiped 2 lobes off the cam. Had a .685/.692 Lunati roller. Well 2 of the lobes didn't have quite that much lift...lol

 

[chrisbh17]

Yep. Had a 1969 Chevelle with a 650HP 454. Spun it to about 7500 RPM regularly and a link bar connecting 2 lifters broke and the lifters spun and wiped 2 lobes off the cam. Had a .685/.692 Lunati roller. Well 2 of the lobes didn't have quite that much lift...lol

You replied to my comment, but I have to reply to yours too...68 and 69 were my 2 favorite years of Chevelles. I had a 1968 but it was a 4 door and only had the 307. Really really wanted an SS but was never in the cards (I was only 17 lol)

Love those cars!

 

[jack67]

I didn't know MDS was "known" to cause failures???

Some speculate, but there is no concrete proof that lifter/cam failure has anything to do with MDS.

Use common sense folks. It's a "No Brainer" when your using 4 cylinders more that the other four when you use all 8 cylinders. It's called balance and it's not balance wear & tear wise when you use 4 cylinders more than the other four. I get around mine using the Tow-Haul Mode at startup, then it will stay running 8 cylinders.
It takes all of two seconds.

If you want to save gas for crying out loud, get a four banger smaller car!!!