Do you see any repercussions to permanently turning off the mds?

[Kayakbiker]

Hi guys,

I read all about cam failure and the theory’s behind them. I got a tuner and shut off the mds because I purchased a v8, I didn't want and don’t care for the 4 cylinder mode. Anyhow I got to thinking I haven’t heard of any repercussions to permanently turning off the mds and leaving everything stock (lifters). I think... it will be fine I just plan on not idling too much and changing the oil a little before it needs it. Your thoughts?

 

[Brandon-w]

I Think it'***** and miss. Run Good oil and don't worry about it. That's my opinion. There will Likely be a flurry of opinions but it comes down to what you want to do seeing as there's no 100% solid facts.

Sent from my SM-G981W using Tapatalk

 

[2012RAM1500RT]

I turned my MDS off manually before I got a tuner and turned it off permanently after I got a Diablo Tuner. I change my oil religiously at 5000 miles, always have and always will don't care what any test results say, oil is cheaper than engine components. I've seen nothing on mine it has hurt (fuel mileage and all) so it will stay off. To be fair I've only had it turned off with a tuner for 6000 miles so far. 136000 miles and still going strong so far.

 

[Justin Stafford]

I've always manually disabled my mds in my '12 1500, 255000km and still tows my holiday trailer every summer.
I get the same fuel mileage
There's no issues, just don't run your hemi like an idiot an you'll be fine.

 

[ram1500rsm]

Disabled mds almost 3 years ago. 97k miles currently and I change my oil when the dash tells me so. Zero issues.

 

[chrisbh17]

I dont think the act of turning off (or leaving enabled) MDS is what causes the cam/lifter failures. I think its the extra moving parts involved, a lack of oil flow at lower RPMs, and inferior materials like needle bearings that go kaput and lock up the roller.

It happens to mostly MDS engines, but I dont think its the actual MDS system that is at fault.

I do disable MDS most of the time in my truck, using the Gear +/- buttons. I have a MaxCare Lifetime warranty, so a tune is mostly out of the question so I will never really disable MDS permanently. And if the parts are whats a part of the issue, just turning it off is not the cure.....you would need to remove the MDS parts and replace with standard (or Hellcat since they seem to hold up better)

 

[hunterdan]

I saw a video recently that said that a possible reason for the cam and lifter failure could be the result of never going into mds. When idling, you obviously never go into 4cyl mode, so the theory does have some weight to it. So, all that said, I believe the issue is far less common than it's made out to be, and that proper oil changes can help.

 

[chrisbh17]

I saw a video recently that said that a possible reason for the cam and lifter failure could be the result of never going into mds. When idling, you obviously never go into 4cyl mode, so the theory does have some weight to it. So, all that said, I believe the issue is far less common than it's made out to be, and that proper oil changes can help.

Yeah the idea there was, when not in MDS mode, its blocking the oil from getting to the MDS lifters.

A lot of the wiped cams/lifters are from vehicles that idle a lot....so it could be that, or it could be low oil flow at idle RPMs. Or a combination of both.

Looking at my oil pressure at idle vs idle+just a little more RPM, I tend to think its low oil flow in general. If we could just bump our idles up 100RPM or so, it would be much better IMHO.

 

[2012RAM1500RT]

If I ever have the lifter failure I will absolutely replace and remove anything to do with the MDS. Until then I don't miss it and can't see anything it has hurt by not having it.

 

[Wild one]

The idle rpm on my truck is bumped up to where it idles right around 750 rpm,and my hot idling oil pressure runs at a pretty stable 51 psi when hot with dual remote filters and Redline 5W-30.In contrast my wifes untuned 6.4 Challenger with 0W-40 PUP idles right around 650 rpm,and it's hot idling oil pressure scares the **** out of me,as it's hot idling oil pressure is in the 30 /32 psi range when it's hot,that's with a 180 thermostat to.It's gonna to get tuned very soon,and the first thing on the agenda will be to bump it's idle rpm up to roughly the same as my truck right around 750 rpm

 

[chrisbh17]

The idle rpm on my truck is bumped up to where it idles right around 750 rpm,and my hot idling oil pressure runs at a pretty stable 51 psi when hot with dual remote filters and Redline 5W-30.In contrast my wifes untuned 6.4 Challenger with 0W-40 PUP idles right around 650 rpm,and it's hot idling oil pressure scares the **** out of me,as it's hot idling oil pressure is in the 30 /32 psi range when it's hot,that's with a 180 thermostat to.It's gonna to get tuned very soon,and the first thing on the agenda will be to bump it's idle rpm up to roughly the same as my truck right around 750 rpm

Exactly.

On the factory fill my idle RPM with hot (210f-ish) oil was around 34. When I went to PUP it actually dropped a bit to 31/32. Both values under about the same conditions (oil temp, ambient temp, weather, runtime, etc)

5W-30 bumps that up to 36-38 ish, RL5-30 even a bit higher. Not great, but better.

Even just adding 50RPM of throttle gets it into the high 40s/low 50s. I really wish there was a way to permanently adjust it without a tune.

 

[hunterdan]

Exactly.

On the factory fill my idle RPM with hot (210f-ish) oil was around 34. When I went to PUP it actually dropped a bit to 31/32. Both values under about the same conditions (oil temp, ambient temp, weather, runtime, etc)

5W-30 bumps that up to 36-38 ish, RL5-30 even a bit higher. Not great, but better.

Even just adding 50RPM of throttle gets it into the high 40s/low 50s. I really wish there was a way to permanently adjust it without a tune.

You have to remember that pressure is resistance to flow. Thinner, lighter oil will obviously have less pressure under the same conditions since it flows easier. Just because a thicker oil gives you higher pressure, doesn't mean it's a good thing.

 

[chrisbh17]

You have to remember that pressure is resistance to flow. Thinner, lighter oil will obviously have less pressure under the same conditions since it flows easier. Just because a thicker oil gives you higher pressure, doesn't mean it's a good thing.

True.

But like when you hold your finger over the garden hose output...less flow but the water "squirts" better.

It sounds crazy but I wonder if more pressure causes the oil to "squirt"-spread and get into places it normally wouldnt.

 

[Wild one]

You have to remember that pressure is resistance to flow. Thinner, lighter oil will obviously have less pressure under the same conditions since it flows easier. Just because a thicker oil gives you higher pressure, doesn't mean it's a good thing.

You're theory is kind of okay when the oil is cold,but if nothings changed in the engine as far as bearing clearances go,which is where the resistance occurs,the pressure increase when the oil is hot is good,as it's going to force more oil across the bearing face,plus feed more oil to the valve train. The only thing that causes oil pressure in an engine as far as resistance to flow goes,is the bearing clearances,and if they haven't gotten any tighter,the extra pressure created by a slightly thicker oil at operating temp,is usually a benefit to longevity,especially as far as keeping the bottem end of the engine happy.Prime example being a race engine with the bearing clearances opened up,will require a straight 50w to keep the motor alive.You'll be a long time finding a good engine builder reconmending going down on the weight of the oil,the only ones reconmending thinner oils,are manufacture'rs who are more interested in meeting their Cafe/EPA requirements,then they are in keeping the engine in your vehicle alive.As long as it makes it past the warrenty period and meets their Cafe standards is all the manufacture is interested in.They aren;t interested in making your truck last to a 100,000 miles,as that also cuts into their vehicle sales and profit margins

 

[ram1500rsm]

Don't be affraid to turn off MDS fellas. I know we like to think and ponder with stuff and there are horror stories all over the place pretty much about everything.. if your lifters are about to fail it doesnt matter if MDS is in or off, it doesn't matter you added mistery fluid and magical snake pee to your oil, it won't matter what color of oil you have. So Try to enjoy your stuff as much as you can and stay away from the horror story threads. You will find a more enjoyable experience with your Hemi, knocking on wood.

Sure some engines were built on Friday evening and the dude working on it wanted to rush things out and go home,but i'm sure a lot more were built on Monday when everybody was fresh and peachy.

As a data point,my idle speed is stock. 560-570rpm rigth now idling hot. ECT 203F, IAT 122F, engine oil pressure 43psi. Goes to 49 if I set my idle at 750rpm. Castrol Synth 5w30 with the Mopar oil filter.

 

[hunterdan]

You're theory is kind of okay when the oil is cold,but if nothings changed in the engine as far as bearing clearances go,which is where the resistance occurs,the pressure increase when the oil is hot is good,as it's going to force more oil across the bearing face,plus feed more oil to the valve train. The only thing that causes oil pressure in an engine as far as resistance to flow goes,is the bearing clearances,and if they haven't gotten any tighter,the extra pressure created by a slightly thicker oil at operating temp,is usually a benefit to longevity,especially as far as keeping the bottem end of the engine happy.Prime example being a race engine with the bearing clearances opened up,will require a straight 50w to keep the motor alive.You'll be a long time finding a good engine builder reconmending going down on the weight of the oil,the only ones reconmending thinner oils,are manufacture'rs who are more interested in meeting their Cafe/EPA requirements,then they are in keeping the engine in your vehicle alive.As long as it makes it past the warrenty period and meets their Cafe standards is all the manufacture is interested in.They aren;t interested in making your truck last to a 100,000 miles,as that also cuts into their vehicle sales and profit margins

I've never seen oil pressure rise as the engine warms up, it usually drops off a bit as the oil thins out at operating temp. As for bearing clearances, clearances dictate viscosity, even in race and performance engines. The following article is a good read and gives a good argument on why you should stick with synthetic oils.
https://blog.k1technologies.com/bearing-clearance-and-oil-viscosity-explained

 

[Kayakbiker]

I saw a video recently that said that a possible reason for the cam and lifter failure could be the result of never going into mds. When idling, you obviously never go into 4cyl mode, so the theory does have some weight to it. So, all that said, I believe the issue is far less common than it's made out to be, and that proper oil changes can help.

I saw the video too. Lol That’s what made me think to ask the question. I assume it isn’t the mds causing failures but I wonder if the hemi with mds turned on occasionally likes that extra oil going on there as that guy stated?

I figure as soon as I hear a tick it’s cam time and a super cool idling.( I guess I’ll have to learn how to do it myself. I don’t trust the supposed experts.)

 

[Kayakbiker]

Don't be affraid to turn off MDS fellas. I know we like to think and ponder with stuff and there are horror stories all over the place pretty much about everything.. if your lifters are about to fail it doesnt matter if MDS is in or off, it doesn't matter you added mistery fluid and magical snake pee to your oil, it won't matter what color of oil you have. So Try to enjoy your stuff as much as you can and stay away from the horror story threads. You will find a more enjoyable experience with your Hemi, knocking on wood.

Sure some engines were built on Friday evening and the dude working on it wanted to rush things out and go home,but i'm sure a lot more were built on Monday when everybody was fresh and peachy.

As a data point,my idle speed is stock. 560-570rpm rigth now idling hot. ECT 203F, IAT 122F, engine oil pressure 43psi. Goes to 49 if I set my idle at 750rpm. Castrol Synth 5w30 with the Mopar oil filter.

On point with a great point!! Thanks guys!

 

[HEMIMANN]

I saw a video recently that said that a possible reason for the cam and lifter failure could be the result of never going into mds. When idling, you obviously never go into 4cyl mode, so the theory does have some weight to it. So, all that said, I believe the issue is far less common than it's made out to be, and that proper oil changes can help.

Someone posted in another thread their tick started coming back and when he turned the MDS back on the tick stopped. There was some discussion theorizing about it.

I can't remember who and where. I can barely remember where the toilet is. I turned my MDS back on for the halibut (have Diablo Edge Pulsar Tuner). For now anyway. Who the hell knows? FCA won't share anything with us.

 

[Wild one]

I've never seen oil pressure rise as the engine warms up, it usually drops off a bit as the oil thins out at operating temp. As for bearing clearances, clearances dictate viscosity, even in race and performance engines. The following article is a good read and gives a good argument on why you should stick with synthetic oils.
https://blog.k1technologies.com/bearing-clearance-and-oil-viscosity-explained

I think you're reading my post wrong,lol. I said your idea is okay when the oil is cold,but once the oil is at operating temp it's another story.Smiths article basically backs up what i said,bearing clearances dictate oil pressure,and visicosity.I don't think anybody is disputing the fact synthetic oils are generally a better oil to use in comparision to a dino oil