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Broken Rocker Arm How long can I drive before causing significant damage to the Cam shaft

75091 Views 28 Replies 6 Participants Last post by  TaxiGirl
This is the second time that this has happened. Last time, i had a mechanic replace #3 and #5 rocker arms ($500). and later when the familiar tick came back I used MMO and no longer had a problem. Now, the tick is back with a vengence. I was trying to hold out until this Thursday. I have a loss of compression as well when accelerating. And I still have a high pitch or medium high pitched gurgling sound when accelerating also.

Btw i changed my oil yesterday, when mechanic opens the head, does he have drain oil out to replace rocker arms?

2011 dodge grand caravan 3.6 Pentastar
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OMG! I had to educate myself since I have not messed with rocker arms since the 89's 3L and my 69 Nova's small block. The rocker arms in the 3.6L look like something out of a Legos box. Unbelievably tiny and frail compared to what I am used to seeing. Being a retired ME, I can understand that engineering has progressed with FEA and other tools for design but these parts look like they should be stamped with "Singer Sewing Machine Company" on them.
I pulled up this youTube of the situation.
View: https://www.youtube.com/watch?v=MPly9YAM_1E

The analysis of the valve assembly operation must be minutely studied when considering the forces and speeds of operation. And QC of the roller and pin holding it in the rocker arm must be high to prevent premature failure.
 

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317K is great for any assembly with high cycles so I take my hat off to the engineers. Maybe I am old school but I sort of remember cam forces and the dynamics of lift on plate cams (of which these are compared to box cams which encapsulate the followers) and that the hot rod cams with big bumps were the ones that bent the push rods and busted the rocker arms and one would have to go with solid lifters and all that stuff. So, the rise on these cams must be pretty mild in comparison. Well, it is true that when they went with double overhead cams, one has a cam profile for intake and one for exhaust so there is probably the goodness. But everything takes up room so more things make for smaller things.
Forget oil additives since the radial forces on the cam follower are probably shearing that little pin of which it rotates on. If one has hydraulic lifters, the only adjustment I remember doing on the small block V-8 is to tighten until the noise of the lifter stops and 1/4 turn more. It was the solid lifters in which one adjusted the lash since there is no compensation. I need to get an assembly in my hands.
 

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I don't want to say it but this is a very interesting thread (like discussing cancer). From what I researched, the followers rotate on tiny needle bearings (good since this type of bearing was designed for radial loads and no axial loads); so they must be tiny. I am hoping that the bearing are uniquely designed with the shaft as it was delivered to mfg. Then the video makes sense since the guy shows that the bearings have failed and the roller is sitting off center (doesn't sound correct/good since the needle bearing material went somewhere and hopefully not into the cylinder). Anyway, here is a good MOPAR article;
CAMSHAFT/FOLLOWER REPLACEMENT | Mopar Magazine (at https://www.moparmagazine.com/2016/06/camshaftfollower-replacement/ ). It even goes through the removal of the cam shafts from the heads.
 
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