For the guys who think deactivating the mds via a tune is a good idea

[Wild one]

Modern Muscle Xtreme​

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We have added a new section to the website for Hemi Tech articles! Below is our latest addition regarding Lifter failure in the G3 HEMI engine.
Gen 3 Hemi Lifter Failure, Hemi Tick, and P0300.
First, I would like to start off by saying, there is a large quantity of misinformation and BS on the internet regarding the Gen 3 Hemi’ s lifter issues. I have seen all sorts of theories, and “install this part to CURE your hemi engine” posts in forums and all over YouTube. Let’s first look at how the Hemi engine oils to better understand this failure. The main hydraulic lifter feed in the G3 Hemi oils backwards from most every other conventional pushrod V8 engine on the market. The oil travels up through a passage at the deck of the engine block, through a restrictor in the head gasket, up around the head bolts, up through a passage in the head, into the rocker shaft, from the rocker shaft through the rocker body to the pushrod, down the pushrod and finally into the lifter. In terms of how the MDS system operates, when the 4 solenoids located on top of the block open, this sends oil flow and pressure around the body of the MDS lifters to compress the plunger/check ball located on the side of the MDS lifter. When this is compressed, the hydraulic portion of the MDS lifter collapses, and the engine runs in 4-cylinder mode. Unlike GM DOD engines, the typical failure is not the actual hydraulic portion, it’s the lifter axle bearings that fail. When this occurs, the roller wheel starts to skid on the lobe of the camshaft and grind through it sending metal all through the engine. The early signs of lifter failure are a slight tick that can be audibly heard when the engine is running at idle. Later signs of failure include a P0300 code indicating a misfire. Further engine damage can be prevented by CEASING TO RUN THE ENGINE AFTER THE P0300 CODE POPS UP. Many shops and customers will unfortunately waste time/money by trying to replace a coil pack or injector for the cylinder that is misfiring, but 95% of the time P0300 code is present, a lifter axle bearing has already failed and is griding away into the camshaft. This leads us to the question, why does this system fail?
In my opinion the root cause of failure is a two-part problem. Issue #1 is the design of the needle bearings of the lifter. The very early HEMI engines had large roller bearings (and a smaller axle) on their lifters. For some unknown reason, Chrysler went away from this design, and made the needle bearings much smaller, and the axle larger. These small bearings do not seem to take the load of being constantly activated and deactivated as well as the early design lifters. The second issue is lubrication. As I mentioned earlier, the only way the actual lifter bore in these engines receives any oil is when the MDS solenoid opens to deactivate the 4 cylinders worth of lifters. This means that during idle, and when the MDS is not active, the body of the G3 Hemi lifter receives NO OIL! (Mild caveat here, the lifter does receive some splash lube up from the crankshaft, but it is VERY minimal as the main oil galley blocks a very large portion of the potential splash lube. Combine this with the very high cam/crank centerline (7.464 Inches-compare that to a small block chevy at 4.521”) and the potential for the lifter to get any splash lube is near zero.
The next logical question is, how to we fix it? We address the two issues I mentioned earlier (Needle bearing Size, and Lubrication). The Latest design 8784AD NON MDS lifters (Hellcat Lifters) have larger roller bearings, so this takes care of problem number one. To remedy problem number two, we simply need to install MDS plugs into the block. Installing the MDS plug allows for full flow of pressurized oil to go around the body of the lifter, and drip down on to the roller wheel to properly lubricate the bearings.
In summary, the fix is an MMX MDS Delete Kit. Our kits include the NON MDS Camshaft, NON MDS Hellcat Lifters, MDS Plugs, and other supporting hardware. This fully takes care of the needle bearing issue, and the lubrication issue. Buying quality oil and having a frequent oil change interval also helps tremendously with keeping the factory MDS system functioning for as long as possible.
-Byron Walker

 

[HEMIMANN]

This is why I leave MDS on, except when towing (when I'm not stopping much so crank is running @ highway speed and splashing cam).

I think it was @Hemi395 that noted his ticking was less with MDS on?

And to think all this b.s. was all due to marketing, the EPA, and bean counters - marketing because the only benefit to a Hemi valve train is for racing rpm, EPA because of imposed CAFE mileage regulations causing engine makers to do dumb stuff like this, and finally the engine makers for going ahead with throwback Hemi anyway, getting a bunch of people to buy, and pretending "Hemi tick" is normal and hiding engine failures.

What an absolute cluster fuch of a product introduction.

 

[caulk04]

Nobody wants to read or research, just jump on the wagon of who's yelling loudest.

'Technology bad, me want dinosaur'

 

[Wild one]

This is why I leave MDS on, except when towing (when I'm not stopping much so crank is running @ highway speed and splashing cam).

I think it was @Hemi395 that noted his ticking was less with MDS on?

And to think all this b.s. was all due to marketing, the EPA, and bean counters - marketing because the only benefit to a Hemi valve train is for racing rpm, EPA because of imposed CAFE mileage regulations causing engine makers to do dumb stuff like this, and finally the engine makers for going ahead with throwback Hemi anyway, getting a bunch of people to buy, and pretending "Hemi tick" is normal and hiding engine failures.

What an absolute cluster fuch of a product introduction.

The amount of guys promoting turning MDS off everytime they drive their Hemi vehicles just floors me,hopefully a few of them will start to wise up,and give up on the practice,as they're not doing their hemi's any favours

 

[metalchewy]

The amount of guys promoting turning MDS off everytime they drive their Hemi vehicles just floors me,hopefully a few of them will start to wise up,and give up on the practice,as they're not doing their hemi's any favours

Have to wonder how many exacerbated the problem and hastened the tick by doing just that.

Also good to know their theory on the lifters. I'd heard to use the hellcat lifters if the tick happens, but never heard why.

 

[G-Ride990]

The amount of guys promoting turning MDS off everytime they drive their Hemi vehicles just floors me,hopefully a few of them will start to wise up,and give up on the practice,as they're not doing their hemi's any favours

Well this is embarrassing, I always thought it was fine as I see it all over the forum that guys use +/- gear selector to kill MDS. I do it all the time too.

My poor lifters. Thanks for the info!

 

[duckman631]

I turn off mds with the gear up and down as second nature as soon as I put it in drive. I don’t like the sluggish feeling and drone sound. My understanding with mds is that it runs on 4 cylinders until under load then they all open up. Don’t see how not running all 8 all the time to promote even wear is bad.

 

[crackerjack1957]

Hmmm......Greene told me I didn't need MDS plugs on his cam & Hellcat lifters 5 years ago.
I probably have about 12,000 miles on them.
Petty's Garage even installed top end without a hint MDS solenoids needed to be changed out & plugged.

So even the so called most knowledgeable seem to have failed.

 

[Dodge 1500 4X4]

I turn off mds with the gear up and down as second nature as soon as I put it in drive.

I also don't like how the engine performs, kicking in and out of 4-cylinder deactivation, for me get on a good lubrication strategy and keep down the idle hours and I know Rick up the idle RPMs to 750 that increases oil flow to lifters.

 

[Wild one]

Hmmm......Greene told me I didn't need MDS plugs on his cam & Hellcat lifters 5 years ago.
I probably have about 12,000 miles on them.
Petty's Garage even installed top end without a hint MDS solenoids needed to be changed out & plugged.

So even the so called most knowledgeable seem to have failed.

There's times i look sideways at Jay,lol. I knew all about the plugs way back in 13,and when i cammed this truck 9 years ago,i never even bothered asking him about the plugs,as i already had Roger Stanke's billet block off plugs on hand.The early 3/4 tons were MDS delete 5.7's and every manual transmission Challenger are factory mds deletes,and they all use the block off plugs.
I'm a little surprised about Petty's garage though,they should know how to do a mds delete cam properly,everybody else does,lol.
A fair number of MDS delete cams come with the block off plugs,and have for a few years now

 

[Wild one]

Well this is embarrassing, I always thought it was fine as I see it all over the forum that guys use +/- gear selector to kill MDS. I do it all the time too.

My poor lifters. Thanks for the info!

I've been against defeating the mds via the -/+ or a tune for a few years now G,lol. I've been trying to get the idea across for awhile ,if you're going to defeat the mds do it properly, you might say i've had some push back,lol
Reignited also has a video up all about it to.
At about the 14 minute mark he shows the Mopar plugs.

Is MDS Damaging Your HEMI? The Answer May Surprise You!

I feel like MDS has been unfairly made the culprit for the lifter failures we see on Gen 3 Hemi engines. In this video I explain exactly how the system works...

www.youtube.com

 

[Wild one]

Have to wonder how many exacerbated the problem and hastened the tick by doing just that.

Also good to know their theory on the lifters. I'd heard to use the hellcat lifters if the tick happens, but never heard why.

Actually there are no Hellcat specific lifters,all non-mds lifters are the so called Hellcat lifters,so if you go to your local dealer and order the 8 non-mds lifters for your 5.7,they'll give you the same lifters that are in the Hellcats.

 

[Wild one]

I turn off mds with the gear up and down as second nature as soon as I put it in drive. I don’t like the sluggish feeling and drone sound. My understanding with mds is that it runs on 4 cylinders until under load then they all open up. Don’t see how not running all 8 all the time to promote even wear is bad.

The crank and pistons aren't really an issue in the hemi's,so that idea about crank/piston wear is far fetched at best,but the hemi does have well documented cam and lifter issues. I've yet to hear of a Hemi blowing up a crank or breaking a piston because of uneven cylinder pressures produced by the mds system. Even high milege Hemi's that have ran mds the majority or all of their life,don't show any appreciable wear differances between the mds and non-mds cylinders,usually the cross hatch is still visible in every cylinder

 

[CanRebel]

The crank and pistons aren't really an issue in the hemi's,so that idea about crank/piston wear is far fetched at best,but the hemi does have well documented cam and lifter issues. I've yet to hear of a Hemi blowing up a crank or breaking a piston because of uneven cylinder pressures produced by the mds system. Even high milege Hemi's that have ran mds the majority or all of their life,don't show any appreciable wear differances between the mds and non-mds cylinders,usually the cross hatch is still visible in every cylinder

I believe them more, if they weren't trying to sell stuff like every one else. Not saying they are wrong.

Personally I think it's all crap. In my view it's quality of parts and high idling.

 

[Racer9]

How the heck am I supposed to justify a new cam if my old one isn't bad??????

 

[Wild one]

In my view it's quality of parts and high idling.

I agree,but we aren't changing Ma Mopars quality of parts,so we might as well do everything possible to keep the $h!tty factory parts alive,lol.
I didn't really think Byron came across as trying to sell anything,either did Re-Ignited,both were just more or less pointing out the downfall to running with-out activating the mds fairly often on a stock cam/lifter set-up

 

[crackerjack1957]

There's times i look sideways at Jay,lol. I knew all about the plugs way back in 13,and when i cammed this truck 9 years ago,i never even bothered asking him about the plugs,as i already had Roger Stanke's billet block off plugs on hand.The early 3/4 tons were MDS delete 5.7's and every manual transmission Challenger are factory mds deletes,and they all use the block off plugs.
I'm a little surprised about Petty's garage though,they should know how to do a mds delete cam properly,everybody else does,lol.
A fair number of MDS delete cams come with the block off plugs,and have for a few years now

Is the MDS harness under the intake removed or left in place with plugs?
Thinking it may control phaser & other sensors

 

[Black1500Ram]

oh how do I wish I had gone non MDs but $ didn’t allow at the time. But after studying the oil passageways I definitely don’t defeat it. (we talked about this in my other thread. Pics included)

I agree,but we aren't changing Ma Mopars quality of parts,so we might as well do everything possible to keep the $h!tty factory parts alive,lol.
I didn't really think Byron came across as trying to sell anything,either did Re-Ignited,both were just more or less pointing out the downfall to running with-out activating the mds fairly often on a stock cam/lifter set-up

I part that sounder salesy to me was Saying that the solution is to buy the MMX delete kit.

Also they stated that the smaller bearing lifters didn’t deal well with the activation deactivation.It’s been shown in several people’s repairs that not only the MDS lifters are the ones that develop wear. Some members have had the wear occur on the non MDS lifter. / non mds cam lobes.

Also, it’s been stated on this forum many times that due to the angle of the lifters that even with the block offs, that it’s highly unlikely that oil draining down the lifter bore would reach the roller bearings.


Thinking about this more, have any stock non MDS 5.7s with pre “AD” part # lifters developed issues?

 

[KYPOTLICKER]

So disabling MDS via the gear selector is bad ?
Not looking forward to listening to the drone, but would rather do that than damage my motor.

 

[duckman631]

So disabling MDS via the gear selector is bad ?
Not looking forward to listening to the drone, but would rather do that than damage my motor.

Seems like 2 schools of thought on this. I personally think owning an 8 cylinder and having all 8 cylinders on all the time is the way to go. I believe having 4 off, and would be off a lot if you do a lot of local driving, can’t be good and would promote uneven wear. I have 114k mi on my truck, just had plugs replaced and they all came out looking pretty good with average wear so I’m sticking with turning it off every time I put the truck in drive. And I do notice a difference with it on and off. When I hit the gas, I want it to move not have to first open up the other 4 then get the full power.