dropped valve...cyl. 2 destroyed... but why?!

dieseltech87 · **Joined:** Mon Feb 18, 2013 3:09 am **Posts:** 25

This is kind of an extension of my earlier post "injector removal without tool" well looks like that no 2 injector was stuck because it was molded into my mangled cyl head!

I knew I was in trouble when I went to time it and it would come to a dead stop then turning it full rotation the other way it would do the same.. my heart sank.. so I took it all apart and confirmed what I already knew cyl no 2 dropped a valve and did a funky throwing star move into my head but here's my question before I tear her down to rebuild.. its like a vm 2.8 riddle. Rockers are in tact and perfectly fine. Springs are there keepers and all, cams show no sign of stress and unfortunatly motor wasn't able to be turned enough to get in time so that part I'm not sure of... Why would a valve head just decide to detach and want to go play ping pong? Its very important to figure this out before I order parts.. do I trust the rockers? Cams? I've done overhauls in the past on Detroit's Mercedes but they are predictable in finding out the cause. Without the cause I don't know if I'm fixing the problem and I will not be taking a gamble. So ill answer all questions honestly. I really need to figure this out to move forward. Ill upload a video to YouTube and post a link. Notice the liner play. I hope my block isn't junk!

dieseltech87 · **Joined:** Mon Feb 18, 2013 3:09 am **Posts:** 25

Here it is guys.. viewer discretion is advised... https://www.youtube.com/watch?v=dBmV07g ... ata_player

naturist · **Posted:** Mon Aug 19, 2013 5:03 pm

Ouch! That would surely ruin a guy's day. Hope you get it sorted out, good luck.

camo · **Posted:** Mon Aug 19, 2013 5:22 pm

I would think a detached glow plug tip. are the glow plugs still intact in one piece? if the tip of a bad plug brakes it can hit the valve right at its closing causing it to brake like that, and after that all else is history. Off course, that is if the glow plug broke.
:5SHOTS:

geordi · **Posted:** Mon Aug 19, 2013 8:21 pm

Ok - liner evaluation time. You MIGHT NOT need a full liner and everything under it, but if you have the time / guts, pulling the bottom end for a look is probably a good idea.

The liner is supposed to move, the manual even says that small hold-down bolts and knobs are supposed to be installed after removing the head, to prevent the liners from moving.

I never did, and my liners were quite stuck in place. Yours obviously is a touch loose. This might mean something, it might not. You CAN rotate the pistons all you want without messing up the timing, as the ONLY thing that matters is that cylinder #1 is 90 degrees ATDC when you go to set the timing eventually. That position is reached (correctly) twice on every rotation. There are pinholes in the flywheel to match both.

See if you can dummy up some washers and short bolts to act as hold-downs for the liners, and then you can have a go at rotating the engine to see how forked the liner really is. From your video, it didn't look like there was much damage to the edges of the piston head... But WOW that must have been a mess in there when it was happening.

How are the glow plugs? Is the #2 broken off?

dieseltech87 · **Joined:** Mon Feb 18, 2013 3:09 am **Posts:** 25

Glow plug destroyed. Just on no. 2 cylinder. What's the going price for a crd with my particular problem. I bought another vehicle and thinking of just getting out of it instead of building it. I work 50 hrs a week fixin other people's problems. 125k good body limited all options, tan leather. Comes with brush guard

geordi · **Posted:** Mon Aug 19, 2013 9:53 pm

Honestly... You are probably looking at about $4500/$5000 for it as it sits. The damage to the head and the piston will *maybe* not require a new engine... But that is a big maybe, predicated mostly on the skill of whoever decides to do the rebuild.

Heads can be had for less than a grand, The VM Specialist should be able to source up some pistons... Not too bad, but the real question is if anything else is forked up. If I was doing it, I would potentially go for the rebuild on this, but I would pull the whole engine and work on it on a stand. First thing - steam clean everything as much as possible, and pull the bottom end apart. I would probably want to replace the main bearings just as a matter of principle, the #2 had an amazing amount of stress applied to it, no telling how much the bearings suffered. You need to get in there anyway to unbuckle the piston, so you might as well do it up fresh, right?

DOC4444 · **Posted:** Mon Aug 19, 2013 11:24 pm

Did you set a glow plug code? If so, how long did you drive it before it calved?

Again, sorry for your loss.....

DOC

81Willis · **Posted:** Tue Aug 20, 2013 10:09 am

We saw this same problem on #4 cylinder:
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=75932

The glow plug tip is mangled beyond recognition, and we have no way of knowing if the glow plug broke first, causing the valve to break, or if the valve broke first causing damage to the glow plug. As far as I know these were factory ceramic glow plugs. There was no CEL, or any indication whatsoever of a failed glow plug prior to the engine self destruct sequence.

I took the head to a machine shop and he seemed to think that it was repairable, I have no idea how. The aluminum would have to be welded and built up, then re-machined into the correct shape. He quoted me $500 plus parts to do it. The short block seems to be repairable, but with all of the unknowns we decided to go with a complete used engine.

Sorry, this is not the first time this has happened and it looks like it won't be the last.

I wonder if there are any documented cases of this with upgraded steel glow plugs?

tjkj2002 · **Posted:** Tue Aug 20, 2013 10:20 am

dieseltech87 wrote:

Here it is guys.. viewer discretion is advised... https://www.youtube.com/watch?v=dBmV07g ... ata_player

That's not to bad.

When I was still in CA I had a Cummins 240 come in,ran really rough but still ran.Pulled #1 valve cover and all 4 valves were missing for cylinder #1.Pulled the head and all 4 valves were imbedded into the piston,not flopping around but actually melted into the piston.

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

Did you have a CEL for a failed glow plug prior to the engine failure?

Bosch stopped production of the ceramic glow plugs 3+ years ago due to potential for the tips to crack and fall into the chamber leading to dropped valves, etc. The metallic design is not brittle and will not fail catastrophically.

Bosch just came out with a new design of ceramic glow plugs used in the new grand cherokee diesel...hopefully they solved the design flaw this time.

jeepdan · **Posted:** Tue Aug 20, 2013 3:11 pm

GreenDieselEngineering wrote:

Did you have a CEL for a failed glow plug prior to the engine failure?

Bosch stopped production of the ceramic glow plugs 3+ years ago due to potential for the tips to crack and fall into the chamber leading to dropped valves, etc. The metallic design is not brittle and will not fail catastrophically.

Bosch just came out with a new design of ceramic glow plugs used in the new grand cherokee diesel...hopefully they solved the design flaw this time.

So, Are you suggesting that we get rid of our old ceramics as soon as possible?
I have a set of the Mopar metal glow plugs with the module in my tool cabinet, I just dread changing them out and sending the ECM back to get a retune on the Eco-tune.

DOC4444 · **Posted:** Tue Aug 20, 2013 7:25 pm

Keith advises replacing as soon as they fail electrically (i.e. set a code). He still has ceramics in both of his KJ CRDs and plans to replace only when they fail electrically.

DOC

camo · **Posted:** Tue Aug 20, 2013 10:18 pm

I just replaced my plugs for etcno plugs about a 1000 miles ago. I don't care if the cold start gets a lil harder, it is well compensated by the peace of mind I have now.

camo · **Posted:** Tue Aug 20, 2013 10:18 pm

by the way, my old ceramics are all in good shape and up for grabs for the price of shipping.

geordi · **Posted:** Tue Aug 20, 2013 10:54 pm

I had no problems with the etecnos in my CRD, didn't even know they were in there compared to the ceramics - performance was seamless.

dieseltech87 · **Joined:** Mon Feb 18, 2013 3:09 am **Posts:** 25

No glow plug codes or any codes besides open circuit maf (orm) figured of get 4-5 for it hate to see it go but its just not for me. Afraid to put it on eBay ill keep it before I go below four. I owe the bank more than that unfortunately (bought it almost a year ago). I know ill end up paying out of pocket to get out of it. But it was fun while it lasted. I thought for sure I'd make it to the 200k+ mile club ...

dieseltech87 · **Joined:** Mon Feb 18, 2013 3:09 am **Posts:** 25

And head under a grand? Gotta be used right? I can only find them for 1200-1800 bucks. Someone told me importing parts overseas but that sounds like more hastle than its worth...

kd4pbs · **Posted:** Wed Aug 21, 2013 10:34 am

I'd wager the bottom end is in superb shape. The liner is moving like that due to the piston being deformed and pushing up on the ring ridge at the top of the cylinder, turning the whole reciprocating assembly into an excellent liner removal tool.
That sucks, a LARGE one, and I'm sorry you have to deal with that. Get a used head, put it all back together, and enjoy it for another 130,000 miles.
Now I wish I had replaced my glow plugs when I replaced the rocker arms...

geordi · **Posted:** Wed Aug 21, 2013 6:58 pm

The glow plugs can be replaced at any time, like when you are removing the FCV to gut it.

The piston may or may not be deformed, but the bottom end has to be pulled apart to change the piston anyway. As for the cost of the heads - NEW! I was trying to move a head I had (not damaged) when someone else needed one, he ended up getting it new and complete with valves fully assembled from a dealer for like $850 IIRC.

Bringing stuff in from the UK is easy, just like ordering from anywhere else. I made the effort to get up at 5am to call them on the phone, just because George isn't the fastest at email replies... The girl I spoke with was happy to run the credit card and place the order, and I had the stuff about a week or so later. No customs nonsense, no duties... The individual limits (daily limits) are fairly high for stuff coming INTO the USA, so you should be well below them. I didn't do anything special to receive the rockers.

Right now, Idparts has the rockers cheaper than I paid The VM Specialist for them, so I would talk to them about the heads - they might be able to do you a deal. If you are game for a gamble, car-part.com might be able to source you up a used head for a lot less, then you are only looking for a liner and piston from the UK.

dropped valve...cyl. 2 destroyed... but why?!

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