This Is Why Chrysler Pentastar Rocker Arms Fail - Under the Microscope

[@D2O2]

I suspect there is a common link between all the manufacturers that have failure of the roller bearings in their valve trains. Ford, GM, Chrysler,etc...all seem to have issues with this over the past decade+ and we all know what has happened to oil viscosity in the attempt to improve CAFE numbers. These failures seem to have been almost non-existent when 5w30 oils were the standard, now 0w20,0w16, 0w8!

[@carquestions]

I couldn't agree more D2 - Thanks for the comment and Cheers from Canada!

[@fritzmeldrum329]

If center pin retention is by staking into the stamping, then the pin has to demonstrate a degree of ductility which will have a negative effect on the interface of the needle bearing and the surface of the pin. Needle bearings have a very high Rc value required by the environment they are designed to function within. So you end up with conflicting design intent. If the rockwell Rc values of the center pin and needle bearings have a significant differential this may be a valid issue to investigate. After that perhaps a series of high magnification slides of both components could lead us into the metallurgical structure of both components and the choice of metals.

[@carquestions]

Excellent deduction Fritz - one would think point contact with the needle bearing and pin surface has to be irregular as well with that type of assembly process - Cheers from Canada and thanks!

[@182QKFTW]

Pretty sure the inner race was fixed as initially designed. Somewhere in the ~8 revisions of this rocker they made it rotate to try to fix this issue. The last letter in the part number is how many revisions since (A). I just replaced 24 of them, lifters (lash adjusters) and both exhaust cams on a '15 Wrangler with 123,000 miles. One rocker was seized, and another like yours, but bad enough to let the arm chew the lobe off. *Check the (4) Oil Gallery Plugs behind each phaser* I found 1 backed out. The oil was changed religiously by the only owner. Thanks for taking it apart!

[@carquestions]

Excellent info 182QKFTW - my replacement rocker in the video has a part number of "U" for the last letter - thanks for the tip on the oil gallery plugs - Cheers from Canada!

[@182QKFTW]

Interesting. Here are the OEM part numbers that Melling crosses with. OEM / Interchange Numbers: 5184296AE, 5184296AF, 5184296AH, 7B0109441B (for 2015 Wrangler anyway). Howdy from Fort Worth @@carquestions

[@carquestions]

Manufacturer's number etched on new part NA_39X0828U - nothing like a Mopar part number @@182QKFTW

[@hotroddinwillie2364]

Great discussion and video. Love the later Jeeps and learning lots about them thanks to channels like yours. Cheers. Bill

[@carquestions]

Glad you enjoyed it HRW - Cheers from Canada!

[@fritzmeldrum329]

Interesting analysis, may I suggest going a little deeper into the issue. The Rc hardness of the material could perhaps aid in the overall root cause of the failures.

[@carquestions]

Love to Fritz as soon as I find a Rockwell test rig on Facebook Marketplace 😀

[@WhiteKnight-5775]

I don't think the rollers are getting enough oil. The only oil they get is from the hydraulic lifter pumping oil up through the rocker arm. The rocker arm has a hole that lets oil squirt onto the cam lobe. But nothing directing oil to the rollers themselves. A Chevy rocker arm pivot ball sits in a oil bath. How many Chevy rocker arm pivot balls have you heard that failed back in the day??? Only if they changed to really heavy pressure high RPM springs.

[@carquestions]

Saw only one on a 55 year old vette - you're right - poor lubrication - something that small spinning that fast just throws off it's oil anyway - Cheers Whitey!

[@CEng-ge6sw]

Very well done. Very interesting and educational.

[@carquestions]

Thanks CEng - Cheers from Canada!

[@Netstarr88]

Greedy manufacturers with design failures planned in

[@carquestions]

Won't last forever - that's for sure - Cheers from Canada Nets!

[@alben_pr3650]

Thank you very informative video

[@carquestions]

My pleasure - Alben - Cheers!

[@sheerwillsurvival2064]

13 isn’t that bad luck 🤔. Chrysler did a survey on 3.6 owners that didn’t have roller failure. They found that the owners who keep their foot into a lot and drove higher speeds and charged oil at proper intervals. But they don’t really know

[@carquestions]

That's very interesting SWS - any links for the survey? - would be interesting to know if Police cruisers have low or high failure rates given they idle for hours and get driven at high speeds all the time - thanks and Cheers from Canada!

[@sheerwillsurvival2064]

@@carquestions I can’t remember I looked it up a year ago. It was thru Chrysler but other then that can’t say what link . Sorry.

[@DanMcD80]

Pin should be fixed in place. Sounds like engineered to make the dealers money

[@carquestions]

Doesn't hurt their bottom line does it? ya - Cheers from Canada Dan!

[@JamesHill-w9e]

Would have been better if it was all in focus

[@carquestions]

Sorry Mr1

[@six-pack1332]

Fiat technology, junk.

[@carquestions]

Your on to something - Cheers from Canada SP!

[@ebenwaterman5858]

Unquestionably a misapplication of bearing technology. Class action lawsuit anybody?

[@carquestions]

Sounds like an idea Eben - Cheers from Canada!