After a rough running, CEL flashing, barely making it home motor failure, I did a compression test to find 0 (zero) compression on the number 1 cylinder. All others were normal.

I took the motor apart to investigate. The #1 spark plug had broken apart, and looked like this...


After pulling the head, I immediately took a look to see if it were a problem with the piston and/or sleeve. All appeared just fine. I took off the oilpan and loosened the rod bolts to #1 and pulled the piston. Again, piston/bearings look fine and rings look fine.

Then I started wondering what on earth could cause a complete loss of compression, so I turned my attention to the head. I found the #1 exhaust port and looked at the valve, and noticed this...


Then I turned the head upside down and noticed this...








FML... I haven't heard of too many people blowing apart valves like this.

 

Dam man that sucks. Are u gonna put new valves in it or get another head??

 

Where do you think the piece of that valve went? hopefully right through the exhaust

 

Damn Jordan I would have never guessed that. Kind of impresses me though that that is all that happened for what the motor has been through the past couple months. Do you think this was caused by your running lean up top issue creating too much heat. Or maybe the broken spark plug did the damage to the valve?

 

Wow that sucks bro. No bueno!!

 

u should be happy thats all it was haha as long as the cylinder wall and piston are in good shape. it coulda been much worse

 

Thankfully your not turbo. Would of lost the turbine

 

That's one for the archives!
Going to be hard to find root cause, but since the chamber isn't beat up by the piece of valve, I'd say it exited rather quickly. If you have a cat on the car, it should be laying in there.
2 scenarios:
Detonation caused the plug to fail and the piece of porcelain got between the valve and seat.
Or the valve just broke and the piece rattled around one time and broke the plug.

How's the piston look?

How were the rest of the plugs?

I'm assuming you have some mods on the car.

Ron

 

From what I can tell, I think the ceramic was pulverized to powder in the combustion chamber, as there is still debris on the piston. The big piece of the valve? I have no idea. I have the ZZP longtube and hi-flow cat. Could not find the broken piece anywhere, not even by the cat.

This was on cylinder #1. All the other cylinders/spark plugs look fine. The #1 piston looks fine, in fact I could have probably even left it in there and never took it out.

BTW, the car is modded just a bit

TVS, E85, 79 lb/hr inj, 2.7" pulley, LS4 TB, Diamond forged pistons (9.5:1), ZZP longtube header, hi-flow cat, full 3" exh, heat exchanger, dual-pass/opt B among many others.

 

I know that the car would go lean above 6500 or so on E85, so I left the rev limiter where it was at and would shift around 6400 or so. I didn't take it up there at all after I saw those IDC's in the HPT log. If I had to guess, I would say that the spark plug broke off and got the valve on the way out of the exhaust.

I would not have guessed this. I thought for sure it would have been rings or sleeves that went, not the valve decapitating itself.

 

its not hard to find the root cause look at the pics they tell you what happened

valves dont break like that they melt away look in the pic of the exh port you can see where the missing part went. the engine running lean caused detonation which broke the porcelain of the plug and small and i mean small parts got stuck between the valve and seat and caused the valve to burn away look at the valve seat its black from overheating in a tight space (the small gap between the valve and seat caused by debris from the plug) so now you all have seen your first burnt valve courtesy of jordan

 

that missing peice is in your exhaust somewhere before the cat. get that thing out unless you want a really bad exhaust rattle.

 

I'm a step ahead of you, buddy. I have searched for the missing pieces but they are nowhere to be found. I do have a hi-flow cat, and the ceramic I am pretty sure was pulverized to powder. The missing valve pieces are just gone. I don't know. I spent a good amount of time looking.

 

it looks as if the port ceiling and wall is damaged. Is it? If so I could smooth it back out. It's a perfect time to get a 3 angle valve job while it's off. I'd at least have the valves in that cylinder done

 

Thats weird. And your valves look a bit dirty for running e, normally they look pretty clean and not sooty. Almost makes me think there was either a low combustion temp issue or a high one. Low combustion temp would be from running no thermostat or a low one. High would be likely from not running enough spark advance or too much heat/boost/compression to be able to run enough spark advance.

 

It's hard to really tell with everything all assembled, but I would probably have you take a look at it anyway. I am probably going to get valvesprings while this is being fixed as well. If I can afford it, I will do the 3 angle valve job on all the valves while it's already off.

Running a stock thermostat with no issues, always around 180-190 degrees. The pictured head had been ported/polished exhaust side only, and installed about April last year. It had been run on 93 pump gas only up until about 3 months ago.

I don't think there is an issue with not enough spark advance, I am running a TVS/2.7" with 25* timing at 12.0 afr (converted to gasoline afr's) and the cruise timing is set high to try for some extra mpg.

Motor is forged pistons at stock compression, boost is around 22-23psi with the TVS/2.7/ported head/3" exh.

 

sounds like to much heat to me. If you can't find the peice then its either gone or stuck in your cat or any muffler you have. Ive never seen this happen before... I'm shocked to be honest haha. Good luck with your fix man!

Also, do you think you could of had some valve float?

 

I was equally shocked when I found what happened. I don't remember anyone else ever having this problem before. So now I've hit the members-only club...

I don't think it was valve float, as I did not rev above 6500 rpms at all during the last 4 months due to the IDC's I was seeing on E85. Valve float would probably not happen unless you're well over 7k.

 

well there goes my theory! haha.

 

do you think seeing the IDC's for the past couple months has something to do with it?

 

I don't think so. I knew that the IDC's would go over 100% if I went over 6500 so I just didn't go over 6500. I would usually shift at 6400 or so. IDC's would be right around 90% or so.

 

90 could create inconsistent fueling.