Hello Group!

I have a 2011, RAM 1500, 5.7 Hemi. I love this truck but I have a ticking sound between 10 and 20 miles per hour, ONLY when MDS is active. The thing I'm trying to understand is what is turned off when the MDS system is inactive. If I override the MDS, by placing my truck in manual mode, the noise immediately goes away. So, whatever the MDS just turned off (or on, depending on how you look at it) is directly linked to the problem. Can anyone offer me some guidance on the MDS controls so I can help figure out this obnoxious tapping sound at low speeds. (No, overriding the MDS isn't an option as I want to fix the problem, not mask it.) 3 different dealers and no one has a clue...I find that baffling! Help!

Michael

 

lots of threads regarding this issue. Do a search on this site and read them if you have the time. Here is the latest one.

https://dodgeforum.com/forum/4th-gen...-coasting.html

 

Hello RAM Tread!

I think I figured it out finally, NO THANKS to any RAM dealer in my area, BTW.

The MDS system, controls fuel AND 4 solenoids that fire oil pressure to shut off the valves during MDS ECO operation. If one of the solenoids fails, the values will stay in operation even though that cylinder isn't firing at that time. Essentially the increased oil pressure releases a spring the separates the valve from the cam shaft.(Overriding the MDS by shifting into manual mode or tow/haul mode and the noise goes away. Therefore, the MDS system is DIRECTLY related to the problem/tapping noise!) On Thursday, I'm having all four solenoids replaced under the intake manifold and I'm banking high bucks that this will cure the tapping noise (valves running when they're not supposed to be) in my engine. Hence, a tapping sound!

Thanks for the support and I hope this helps other people if they're hearing this as well.

Michael

P.S. The pictures were found on the web to help reference the oil path to one of the MDS solenoids and the spring release.

 

I would think if you had a bad solenoid, you would get a CEL with a code.

My understanding of the MDS is that oil pressure is cut off to the solenoid when MDS is active. The cam still pushes on the push-rod but the lifter is disabled so the valve stays shut. So unless the MDS solenoid failed so that the lifter is always getting oil pressure, then I don't think your theory is correct. Good luck and let us know how it works out.

 

Pedro Dog,

Thank you.

Here's the quote from a link about the MDS system and why I mentioned it the way I did:

"The MDS solenoid valves control the flow. When activated, pressurized oil pushes a latching pin on each MDS lifter which becomes a lost motion link. The base of the MDS lifter follows the camshaft while the top remains stationary. The MDS lifter is held in place against the pushrod by light spring pressure but unable to move because of the much higher force of the valve spring."

Regardless of pressure, the outcome is the same...the solenoid controls the movement of the value on the deactivated cylinder. Hence, if the solenoid fails, the value would remain operational (again, I only hear the tapping when the MDS is supposed to be working) and therefore, could be causing a tapping sound.

I'll have my answer tomorrow and for all our sakes, I hope I'm right.

 

Update: The noise is quieter but still there. Once again, I'm stumped as to what part of the MDS system is causing this low speed, engine idle coasting tapping sound.

I'm shocked that no one out here has had this problem yet or heard of anything like it.

Thoughts?

 

I have the same issue, no update ? I Slap it over into 5th and avoid the mds but would love to solve before I sell it. I noticed that I had an exhaust leak, that projected the noise and that lead to me noticing the sound. Since I've heard it, I cant stand it. 2009 Ram 5.7 sport crew