Originally Posted by Redliner
I have to ask......How the heck can a "fuel additive" have anything to do with a valvetrain noise? If it were pre-detonation, I would understand but I thought the clicking noise was due to the bleed-down of the valvetrain compnents to serve the MDS system. Has this not been identified as such?
On the chargerforums web site there was a interesting discussion about what causes the "ticking' sound in modern Hemi engines
and how it can be quieted. Here is the post:
Many here know what we do to stop the Hemi
Tick, but we figured that since there are so many new faces here, they may not have heard that you don't have to have it in your engines.
We have discussed previously that there are 3 culprits that cause the "Hemi Ticking" that is heard in idle and just off idle.
1) Intake and exhaust valves do not have any kind of cushioning from the fuel. Fuel usto have higher amounts of sulfur and tetra ethyl or tetra methyl lead to lubricate and cushion intake and exhaust valves in the old days. When EPA decided to go to unleaded fuels, hardened valves and seats were produced trying to deal with the lack of lubricant. This was adequate at best, but did allow engines to live longer than if they had soft valves and seats. However, when they went to ethyl alcohol, that all changed. Alcohol absorbs moisture and strips lubricity. That was bad enough, but when they reduced the sulfur content from 130 parts per million (ppm) to 30 ppm, it really produced a perfect storm. Both the intake and exhaust valves are now hitting against the valve seats with no cushioning at all. This causes wear, and then of course
....noise or TICK.
2) Fuel injectors depend on at least 70 ppm of sulfur to stay alive. When EPA went to the ethyl alcohol and less than 30 ppm, they have no cushioning allowing them to click or tick also while building up gum and varnish. This restricts the flow of fuel and turns the vaporized spray pattern into an atomized spray pattern. Atomized fuel doesn't burn as well, and helps wash down into the cylinders and wipes out the detergents and dispersants much faster. This is the second part of the Hemi Tick.
3) Because the Hemi has a very short skirt and thin rings with virtually no land area, the piston wants to rock in the bores. This is another reason for the moly piston skirt coatings. It is designed to cushion the short skirt. The problem is that as miles rack up, the moly is worn off and a louder engine or tapping noise begins to occur. This is the third part of the Hemi Tick. This part actually contributes to more aluminum in your oil analysis. An oil analysis is always important to do on any engine you want to take care of as a baseline, and then every 3rd oil change, do one just to be sure nothing is leaking or causing problems.