I went wheeling about a week ago with some friends and heading back down on our last trail my XJ sounded and ran a little rough. We got down to the trail head and started airing up our rigs with my OBA system when I heard a nasty mechanical POP. The engine died and I was about 2 hours west of home. I called a friend and he drove 2 hours to get me, my busted junk and my family. It took a couple of days before I could remove the valve cover and start poking around and this is what I found.



The red arrow is pointing to the #6 intake valve, or to be more exact, where the valve should be.

I pulled the cylinder head hoping to find minimal damge, but ended up with a little more than that.

Here's a shot of the #6 combustion chamber.


Heres' what the intake valve looks like.


The area indicated by the red arrow is the damage to the guide. You can also see the damage to the edge of the intake port.


The piston took a beating as well.


The good news is that there wasn't any coolant in the crankcase, the #6 sparkplug wasn't damaged, and the block appears to be fine.

Today I took the head, #6 piston, #6 intake valve, and 3 pieces of valve spring to the shop that did my machining for me. I was prepared to hear "You need a new cylineder head." Instead I was told that the damage was actually fairly minor and it would cost about $50 to repair the damage!

The root cause of the failure was single break in the valve spring. The spring broke a second time while we were airing up and that allowed the rocker arm to pound the valve enough that the retainers finally popped out and allowed the valve to drop into the cylinder.

The new parts are on order and I should be back on the road in a week to 10 days.

Moral of the story...even new-ish parts can fail.

 

That sucks man, but glad to hear that's it's not too much of a biggie.

 

While slowly scrolling to see the pics and looking for damage etc. I scrolled down to where you showed the Valve, AND SPIT COFFEE ALL OVER THE KEYBOARD !!

Holy Cow Dude !!...LOL

SOunds like she is gonna live again !!

Sorry about the bad luck, !!

 

That is the nastiest valve i have ever seen! Good to hear the block is still good.

 

What are they gonna do about the piston? Is it salvageable or is replacement their recommendation?
At least it didn't go through into the crankcase.

 

No the piston can't be used...it collapsed and the divot in it very deep. A new Keith Black/Silvolite piston is on it's way.

 

Sorry about your luck, but that valve is a sweet paper weight. I noticed your fuel rail is red? is that just painted or is it something special?

 

Red paint generates increased horsepower and economy.

It's a stock fuel tail.

 

.........And bent valves

 

thats a pretty valve you got there. at least the dameage isnt nearly as bad as some of us have seen.