Jeep Strokers

Hello Everyone –
I bought a 4.6 about 2 ½ years ago and have only had one real problem that I believe has turned into one real big problem. About 3 months/1000 mi I started to hear a tapping noise coming from the top end of the engine. Pulled the valve cover and to my surprise the pushrod had punched a hole through the rocker arm. Called the manufacturer and he resent some rocker arms and bridges (Sealed Power). This happened again about 1500 miles later. I called the manufacturer again and requested an explanation as to what would cause this to happen. “Probably a bad casting”. I am not a mechanic and new much less than the little I know now. I regretfully crossed my fingers and took him at his word… Well, I am at about 10,000 miles and the tapping is back. I pulled the valve cover and the same rocker arm above cylinder 6 looks great BUT it is loose and wobbly. The other 11 are firmly in place. The pushrod moves up and down as well. I haven’t called the MFG yet but I believe they have some explaining to do. My question for everyone is – What would believe has gone wrong? Lifter has collapsed? Cam lobe is worn out due to too much pressure? What could they have done wrong during the assembly? I am learning as I go hear and I want to have as much knowledge as I can get before calling the manufacturer to ask for a resolution. What would you ask the manufacturer for if you were in my spot? What would you do/check out before you picked up the phone? I’m not calling out the MFG until I see how they take care of me here.

Any advice would be really appreciated.

Are these stock style pushrods, or something else?

Anyhow. The rocker arm now looks good with no wear, but there is still play? The cam lobe could be worn, lifter could have collapsed, push rod bent, rocker arm bent or worn, or a valve issue. How does the valve look? Take the push rod out and roll it on a piece of glass to check for straightness. Check the valve stem height off other ones (could be bent valve). Swap rockers with another cylinder and see if the problem changes with different rockers. If the top end checks out time to pull the head and check the lifter and cam lobe. Check the push rod ball end. Did you replace the push rod when it ate through the rocker?

Was a higher-lift cam installed?
Broken rocker could be the result of insufficient valve retainer-to-guide clearance, or springs that can't take the lift and are becoming solid (coil bind).
Do the checks Silver suggested and that'll give us clues as to what is wrong.

blk85cj7 wrote:I pulled the valve cover and the same rocker arm above cylinder 6 looks great BUT it is loose and wobbly. The other 11 are firmly in place. The pushrod moves up and down as well. I haven’t called the MFG yet but I believe they have some explaining to do. My question for everyone is – What would believe has gone wrong? Lifter has collapsed? Cam lobe is worn out due to too much pressure?

Possibly both. Definitely sounds like the lifter has collapsed. Coincidentally the same thing happened on my stroker after 34k miles and it was also the no.6 cylinder. Unfortunately I also had one cam lobe (Crane cam) wiped out as well as two lifters (also Crane) but on the plus side, I still had my pristine old original stock cam so I threw that in with new lifters plus my original stock valve springs and had the engine running again in no time. Six years and 35k miles later the engine's still a honey and kickin' ass (knock on wood).

Thanks for the info/questions. Here is the build sheet or at least what I have

53020569 Block magnafluxed, Line Honed, Bored .030 and Decked .015
* 258 Crankshaft Machined .010/.010 with oil holes chamfered
* 707 Connecting Rods Shot Peened, Recondioned with vertical oil clearance set at .002
* Silvolite 3241HC Hypereutectic Coated Skirt Pistons in .030
* 5 Angle Valve Job with 1.94 intake 1.624 exhaust valves
* Comp 68-201-4 Cam .447/.447 212/212 @.050
*Single True Roller Timing Set
* Multi Layer Steel Head Gasket .043 Thick
* 3/8 Big Block Pushrods

All I have done so far is remove the valve cover. I have a 3 month old so I pick away at this when I can get the time.

"Anyhow. The rocker arm now looks good with no wear, but there is still play?" - Rockerarm looks good from the top, I haven't removed it yet. Yes it has a lot of play. It is the second one I have replaced.

I only replaced the rocker.

SilverXJ wrote:Thanks for the info/questions. Here is the build sheet or at least what I have
53020569 Block magnafluxed, Line Honed, Bored .030 and Decked .015

* 258 Crankshaft Machined .010/.010 with oil holes chamfered
* 707 Connecting Rods Shot Peened, Recondioned with vertical oil clearance set at .002
* Silvolite 3241HC Hypereutectic Coated Skirt Pistons in .030
* 5 Angle Valve Job with 1.94 intake 1.624 exhaust valves
* Comp 68-201-4 Cam .447/.447 212/212 @.050
*Single True Roller Timing Set
* Multi Layer Steel Head Gasket .043 Thick
* 3/8 Big Block Pushrods

All I have done so far is remove the valve cover. I have a 3 month old so I pick away at this when I can get the time.

"Anyhow. The rocker arm now looks good with no wear, but there is still play?" - Rockerarm looks good from the top, I haven't removed it yet. Yes it has a lot of play. It is the second one I have replaced.

I only replaced the rocker.

I jacked the previos quotes up. Sorry about that. Spoke to the engine manufacturer and explained how I had replaced the rocker arms twice before this recent failure . He doesn't think it is related. I told him all of these happened on the same valve...quite a coincidence . How could this be the case and it NOT be releated. Is there ANY credence to this?? Looks like he isn't going to honor much at this point.

Remove the rocker arm, remove the push rod and inspect those for starters.

One engine I previous purchased the company installed a set of 3/8" BBC pushrods. One promptly ate through a Yella Terra roller rocker and put some significant wear on the others. Its not that the push rods were a bad idea (they aren't needed at all though) but the parts they used were complete crap with poorly finished ends.

SilverXJ wrote:Remove the rocker arm, remove the push rod and inspect those for starters.

One engine I previous purchased the company installed a set of 3/8" BBC pushrods. One promptly ate through a Yella Terra roller rocker and put some significant wear on the others. Its not that the push rods were a bad idea (they aren't needed at all though) but the parts they used were complete crap with poorly finished ends.

Both the pushrod end and the rocker look worn. That hole in the pushrod is telling? I'd really appreciate observations.

Here is another of the pushrod

Pushrod is junk. I can't tell what the rocker arm looks like though. I would replace both. See if there is a length or part number on the push rod to get the length. I would check the rest of the rockers and push rods too.

Appreciated. Sorry about the poor pic's humid its atlanta. Walked out with the camera and everything fogged up. I was told I can use stock pushrods? Is this the way to go? Any suggestions? Manufacturer offered to send the parts.

BTW the part number on the above push rod is MPR-45-A Melling pushrod.

I found the part at Autozone: http://www.autozone.com/autozone/parts/ ... 107254_0_0_

And Summit: http://www.summitracing.com/parts/MEL-MPR-45-A/

Big difference in Price? Summit is typically competitive??

I would check preload and see where it is at. I would also try to find out the length on those rods. Just because someone said they are stock length doesn't mean its right. I wouldn't use those push rods again.

Just took a look at the Melling catalog:
The pushrod page (without applications) is here:
http://www.mellingengine.com/Portals/5/ ... -chart.pdf
Full catalog is here if you want to look up applications:
http://www.mellingengine.com/Catalog.aspx

The MPR-45-A you mentioned is listed as 9.643" long. 3/8" diameter with B&B ends
The 4.0 Jeep uses a MPR-437 that is 9.639" long. 5/16" diameter the H&H ends.

They don't specifically show the dimensions of the ball ends, but that could be an issue.
And while the MPR-45A length is only 0.004" longer, an engine that's been decked and had the head shaved would need shorter pushrods, not longer. So too much lifter preload could be a factor.

Stock Push Rods: SEALED POWER Part # RP3275
9.641" O.A.L. (Size: Standard)
END TYPE - (B-B) Ball & Ball (Looks like the same as the Mellinh H & H)
http://www.fme-cat.com/PartDetailWindow ... ber=RP3275

AutoZone: Melling MPR-437 Length - 9.639" 5/16" Diameter H-H Ends (Different Chart than above)
http://www.mellingengine.com/Portals/5/ ... -chart.pdf

http://www.jeepstrokers.com/forum/viewt ... =34&t=1191