Hemi tick?

22304 Views 36 Replies 19 Participants Last post by wallyo, Apr 6, 2015

bigpav7

Discussion Starter · Jun 6, 2011

so I noticed this annoyng racket coming from the engine while I'm driving near a wall, other cars or a divider. It gets louder when MDS is on and becomes faint again when all cylinders fire up. i tried parking and revving the motor up but heard absolutely nothing at all. Is this the infamous Hemi tick?
Thanks.

2010 Commander Sport Hemi

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Mongo

· #2 · Jun 6, 2011

Are you using the recommended oil viscosity, that the O.M. warns other viscosities will cause problems with the MDS?

A lot of miles with conventional oil might cause some varnish build up that can cause valve train trick. There are some additives that can help remove it, don't know if it will change viscosity and cause problems with the MDS. Synthetic Oil won't produce the varnish build up and will actually clean away varnish build up, and no additives that mess with viscosity.

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Mongo

· #21 · Jun 13, 2011 (Edited)

Has anyone considered the "tick" is the Evap Proportional Purg Solenoid?

This device has traditionally been a source of a "tick" noise in the past on other Chrysler vehicle (other manufacturers as well). From my reading on the Evap System, the latest system work differently and operate the purge solenoid far more often and longer durations than past system. The past was more like the occassional operation to clear the vapors all at once, the new systems are longer slower operation to just clear the vapors slowly.

The purge solenoid opens and closes 5-10 times a second, but varies according to the duty cycle needed to produce the proper vacuum in the evap system, according to the FSM.

The Evap system does NOT use the solenoid until you are in closed loop, meaning the cold motor has to warm up, before it operates and starts making a tic noise. Which co-incides with bigpav7 observation he doesn't get the tick while the motor is idling and its cold.

I get a tic on 3.7L as well, like described here, I've contemplated pulling the connector for the evap purge solenoid and seeing if the tic stops. Beware, I'm sure this will light the MIL/CEL if you do and you may have to pull the battery cable to reset PCM's to clear the codes if you try this.

OR am I missing something, and this HEMI tic is different than my 3.7L tic, that is barely audible and that I can barely hear and only then with the windows open, NOT moving with the engine at idle? Close windows, rolling and wind noise while moving, any noise over idle will drown out that tic completely.

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Mongo

· #27 · Jun 13, 2011

Yea, my 3.7L tic is easily drowned out or eleminated by just closing the windows and/or the slightest road noise, you definitely could NOT hear it over WOT noise, and the 3.7L is quieter than the HEMI. So, they are likely NOT the same thing.

Can't tell if my 3.7L tic is rpm related, since its drowned out as soon as I go over idle.

If the HEMI tic is the valvetrain, then the tic frequency should change with engine rpm. I'm sure I'm telling most of your what you already know.

The Drawback on the Hemi, is the valvetrain geometry, those rocker arms and push rods are at a far more extreme angles than the typical OHV configuration. The old HEMI's were notorous for breaking valvetrain parts all the time. The new HEMI has the cam raised much higher in the block to compensate and reduce the sharp angles in the valve train. So, could the tic just be the natural side-effect of the tortured valvetrain in the HEMI?

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