Bent rocker arm retainers

[John1]

I am a bit stumped. The attached picture is the rocker arm retainers. As you can see, they are bent. I am finishing rebuilding my engine and just noticed these.
I am wondering why this can happen. They were all tight. The only item in question I can guess is the engine was seriously over revved.

I am open to opinions about the cause of this. Can't find anything on the forum.

Cheers, 

 

[Gilaguy23]

Ive heard of this before and what was mentioned was over torquing the bolts which causes it to bend like they are. There are also some posts mentioning this on this forum. I think their cheap to replace and fairly easy to get. In a pinch Id think you could stick the one end in a vise and use a cresent and tweek the bent end back to norm.

 

[Intimnasc]

Yeah they are easy to install. Link below replaces all of them and the rockers for 100 bucks. Look it up but I believe torque is 19 ft lbs.

https://thejeephut.com/products/omi...MI2OONwYvHkQMVkThECB0UkggnEAQYAiABEgJcFfD_BwE

 

[Intimnasc]

Ive heard of this before and what was mentioned was over torquing the bolts which causes it to bend like they are. There are also some posts mentioning this on this forum. I think their cheap to replace and fairly easy to get. In a pinch Id think you could stick the one end in a vise and use a cresent and tweek the bent end back to norm.

BTW I loved the duck made me take a picture of the gnome on my desk at work.

 

[John1]

BTW I loved the duck made me take a picture of the gnome on my desk at work.

I am a newer owner and the engine had 150K on it when I tore it down for a rebuild. Cracked piston skirt. They came off bent. I straightened them already and put them back on at 19# but am now thinking of something more substantial. They are really flimsy. Oil grooves were all clocked correctly when they came off. No one had been in the engine since it was new except to fix a manifold leak and silicone a few gasket leaks. I would be curious on someones input on valve float being the cause.

 

[GoldenGorilla]

I'm not sure what terrible thing happened to these. The 2.5L shares the rocker stands, rockers and retainers with the 4.0L and there are plenty around to get some fresh ones. Personally I would not put those or the rockers they retained back in. I also suspect it was over-revved. I would also take a close look at the valves. If there was that much twisting at the rocker, it may have all been happening on the pushrod, but if the valve guides got tweaked, I'd address that now also.

 

[John1]

I'm not sure what terrible thing happened to these. The 2.5L shares the rocker stands, rockers and retainers with the 4.0L and there are plenty around to get some fresh ones. Personally I would not put those or the rockers they retained back in. I also suspect it was over-revved. I would also take a close look at the valves. If there was that much twisting at the rocker, it may have all been happening on the pushrod, but if the valve guides got tweaked, I'd address that now also.

I was just putting it back together when I noticed these. We have new pushrods, lifters, guides and valves I was just going to reuse the rockers and retainers. I don't agree with the over torque thoughts, but I do certain think over-revved can be a culprit. Looking at the geometry of the thing I can see how it would happen if they floated enough. I have ordered new ones to replace these. It was more of a question as an exercise in what might have happened. The engine was running fine until the piston skirt pooped the bed and then it was only the dreaded tic tic tic that started getting louder. Thanks

 

[JeepDrivesBest]

I'd definitely go with new retainers since you're already that deep into the rebuild - those look pretty tweaked and for the small cost it's not worth the risk of them failing later.

 

[sab]

If over-revving caused them to bend, I'd expect to see witness marks where the top edge of the rocker hit it. Do you see any marks?

 

[lBasket]

How do you overrev it in the first place? Is your rev limiter removed somehow

 

[Intimnasc]

I took mine a little further and ARP studded the heads with a new timing chain and gears. Of course mine had a flat cam lobe and a ground up lifter. I went ahead and lapped in the valves while I was in there.

 

[GoldenGorilla]

How do you overrev it in the first place? Is your rev limiter removed somehow

The PCM has a fuel cutoff programmed at some rpm, but it wouldn't necessarily mean THIS engine was OK at that RPM. There's enough variance in TJs that I could see some not being OK at 5200rpm or whatever the 2.5L limit is.

You can also forcibly over rev an engine in a manual with a bad 5-2 or 4-1 downshift.

 

[lBasket]

The PCM has a fuel cutoff programmed at some rpm, but it wouldn't necessarily mean THIS engine was OK at that RPM. There's enough variance in TJs that I could see some not being OK at 5200rpm or whatever the 2.5L limit is.

You can also forcibly over rev an engine in a manual with a bad downshift.

Oh yeah I wasn't thinking about money shift whoops. I know mine doesn't care about hitting the rev limiter figured that was the norm

 

[sab]

The PCM has a fuel cutoff programmed at some rpm, but it wouldn't necessarily mean THIS engine was OK at that RPM. There's enough variance in TJs that I could see some not being OK at 5200rpm or whatever the 2.5L limit is.

You can also forcibly over rev an engine in a manual with a bad 5-2 or 4-1 downshift.

Obviously, I can't speak to the design of the valve train on the 2.5L or even the similar 4.0L valve train because I wasn't there, but the factor of safety built into valve spring designs (regarding its resonant frequency, which is what causes valves to float) would usually account for subtle production variations between engines. In modern vehicles with a rev limiter, inertial over-revving is the most likely cause, meaning that the wheels drive the engine into an over-rev situation. That can happen with a badly-placed downshift, but it can also happen if you're accelerating down a step hill and touch the rev limiter.

Edited to add another situation where you can get inertial over-revving, and it could definitely happen with an off-road vehicle - catching a bit of air as you hit the rev limiter.

In the "old days", we also had to worry about staying on the throttle too long because there were no rev limiters.

 

[Moglocker]

I am a bit stumped. The attached picture is the rocker arm retainers. As you can see, they are bent. I am finishing rebuilding my engine and just noticed these.
I am wondering why this can happen. They were all tight. The only item in question I can guess is the engine was seriously over revved.

I am open to opinions about the cause of this. Can't find anything on the forum.

Cheers, View attachment 661266

They bend from the removal process,(probably wouldn’t if you used a small impact.I would just replace them,and if the the rocker balls have eaten into the rockers I would replace everything,not expensive at all.

 

[John1]

Thanks for all your comments. As I mentioned they are being replaced. I am going to vote for a missed downshift rpm spike by the previous owner. As I said still ran fine. When I bought this thing I liked the paint, no rust on the frame, good u-joints, tranny shifted well, steering tight. Little did I know somebody must have really flogged the engine. Oh well. Its fixed now. Going to stab it back in tomorrow and fire it up.