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Eddie_NYC 04-01-2013 04:39 PM

Rocker Arm Question
Finally got around to removing the valve cover for the driver side head on my new to me WJ. Bought it cheap as it had a misfire. Confirmed this afternoon that the rocker arm in the back for Cylinder 7 fell off.

My concern is what caused it to fall off? I know this issue is common on these motors due to sludge, etc. I never set cylinder 7 to TDC prior to this as I just wanted to take a peek. The cam lobe for that rocker arm was facing the outside of the motor therefore I was able to slide the rocker arm back in place. But I know it's not supposed to go back in that easy.
I obviously didn't leave it in but I'm confused as to what could have failed?

Valve lash adjuster failure ?

Valve spring failure ?

What would be my next steps to confirm what component failed as it seems that there is no tension on the rocker arm from either the valve or lash adjuster. Should i go ahead and change out the valve spring, stem seals, and valve adjuster and pick up special tool 8516?

Is there another method of doing this job without buying that +/- $100 tool?

Thanks in advance!


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Frango100 04-01-2013 06:38 PM

Re: Rocker Arm Question
It can be that the valve lash adjuster is bad. With the rockerarm removed, you can simply take the lash adjuster out by hand, or you just try to push it in by hand. A good adjuster feels hard and not spongy. It could eventualy be that it totally colapsed and bottomed out and feels hard. Best is to compare its dimension with an other one. If its ok, there is a change that the valve seat dropped. This normally causes severe damage to piston/ head/ cylinder. You could check the valve spring if its not broken. Just try to push and pull on the respective valve. There should not be any play. A bend valve stem or carbon fouled stem could also cause the rocker to fall off.
I changed the valve stem.seals on my 4.7 and made a special.tool to compress the valve spring and remove the keepers. I saw on youtube a guy who removed the rockers using a screwdriver, but at least that engine was on a stand.

Eddie_NYC 04-01-2013 08:26 PM

I'm hoping it's a fouled stem valve or broken valve spring. I haven't noticed any signs of internal damage. Car starts up on first crank, no oil/coolant mixing or disappearing. I haven't had time to do a compression test but will be getting done this weekend when im hopefully putting this rocker arm back in correctly.

My local dealer doesn't stock these items and tells me 5-6 days. Wtf?

I need to find a deal on that special tool to do this job. Does anyone know if Conventional style valve spring tool can work?


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Frango100 04-01-2013 08:44 PM

Re: Rocker Arm Question
2 Attachment(s)
If you only want to install the rocker arm, you could simply use any kind of lever to push the valve down, it doesnīt have to go far to be able to install the rocker. At the same time you will feel how the valve is moving and if there is any binding, which could mean a bend stem or carbon fouled stem.
I wanted to buy the attached tool, but they didnīt want to ship it internationally. I made one myself for a few bucks and a hour of work (not the most beautifull tool, but functional:D).
See here the youtube video removing the rockers with a screw driver: chrysler/jeep 3.7 v6 4.7 v8 valve spring tool - YouTube

new spring tool 3.7v6 4.7v8 easy spring/seal/rocker arm replacement - YouTube

Eddie_NYC 04-02-2013 05:36 AM


The thing is, i can fit the rocker arm back into it's respective location without a tool. This is what concerns me. Either the lash adjuster is bad or the valve spring collapsed or maybe stuck valve? Because something is not putting tension on the rocker arm.

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Frango100 04-02-2013 07:29 AM

Re: Rocker Arm Question
Just compare the distance the lash adjuster is sticking out with an other one, to see if its collapsed. A broken valve spring will be obvious and there will be play on the valve. Can you move the valve by hand? If it doesnīt move at all, did you try to use a prybar or alike to see if the valve moves freely and if it returns to the same heights as the others?

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