Smashed Spark Plug

[Shibbershabber]

SO this is not on one of my Chevys, but I know you guys have all the answers so Ill throw this out to yall


Got a project truck for my son... super clean 91 Mazda B2600 4x4... bought it not running, PO doesnt know why never had it looked at.


Pulling the plugs out today, I found one cross threaded ... really who the Fu@& rams home a spark plug after getting resistance? Probably used an impact? ANYHOW... moving on, the 4th cylinder's plug was DESTROYED!

Never seen one like it.



I checked the model info against the others, its the same plug as the rest, so its not longer, etc.
Also checked the # and it appears these are correct for this engine. (Bosch FR8LCX)


What can cause this to happen?

What can be done about it?

Is there something I can do to test anything or just try to get any debris out of the chamber and stick another plug in there?

Does it appear mechanical or could this have been a failure of the plug?


PO stated that the truck died while on the highway and he just had it towed home and posted it for sale.
Not entirely sure about that... oil looks like its been changed and not driven since... its clean, looks like canola oil on the dipstick.

Engine turns over okay without any odd sounds, etc. even tries to chug a bit but obviously wont start with a dead cylinder.

Thoughts?

 

[wjburken]

SO this is not on one of my Chevys, but I know you guys have all the answers so Ill throw this out to yall


Got a project truck for my son... super clean 91 Mazda B2600 4x4... bought it not running, PO doesnt know why never had it looked at.


Pulling the plugs out today, I found one cross threaded ... really who the Fu@& rams home a spark plug after getting resistance? Probably used an impact? ANYHOW... moving on, the 4th cylinder's plug was DESTROYED!

Never seen one like it.

View attachment 272708

I checked the model info against the others, its the same plug as the rest, so its not longer, etc.
Also checked the # and it appears these are correct for this engine. (Bosch FR8LCX)


What can cause this to happen?

What can be done about it?

Is there something I can do to test anything or just try to get any debris out of the chamber and stick another plug in there?

Does it appear mechanical or could this have been a failure of the plug?


PO stated that the truck died while on the highway and he just had it towed home and posted it for sale.
Not entirely sure about that... oil looks like its been changed and not driven since... its clean, looks like canola oil on the dipstick.

Engine turns over okay without any odd sounds, etc. even tries to chug a bit but obviously wont start with a dead cylinder.

Thoughts?
View attachment 272709

I’d pull the heads and see what’s going on.

 

[Shibbershabber]

I’d pull the heads and see what’s going on.

Other than visually inspecting the piston, what am I looking for

 

[wjburken]

Other than visually inspecting the piston, what am I looking for

That’s about it. If you have a endoscope, shove that in the plug port and take a look.

 

[Shibbershabber]

So worst case is the surface of the piston is damaged and needs to be replaced?

If the piston looks acceptable, then I don't need to worry about anything in the bottom end?

Otherwise I can get a new head for a few hundred bucks and be done

 

[Doubeleive]

I would do like wade suggested Grab a scope from harbor freight or ebay (they have usb ones cheap)

 

[wjburken]

I would do like wade suggested Grab a scope from harbor freight or ebay (they have usb ones cheap)

Here is what I own. Works great.
https://www.harborfreight.com/high-resolution-digital-inspection-camera-with-recorder-61838.html

 

[Shibbershabber]

Got one ordered...

Will look and see if its worth tearing open


Thanks

 

[Jimmyy]

Here’s a cheap usb one

https://www.amazon.com/Endoscope-In...&keywords=USB+endoscope&qid=1615090198&sr=8-8

 

[Shibbershabber]

Would those be good enough to examine the cylinder wall?

I wonder how good the resolution really os

 

[Shibbershabber]

Also had someone else tell me it was a lost cause because putting a new head on my old block would cause excessive oil consumption and somehow damage valves....

Sounds like BS to me, but what yall think?

 

[Jimmyy]

Would those be good enough to examine the cylinder wall?

I wonder how good the resolution really os

I picked one up on eBay. It’s fair, I wouldn’t call it HD. But it would work fine for looking at a piston. eBay has a long shipping time as it came from China. About 3 weeks.

 

[wjburken]

Would those be good enough to examine the cylinder wall?

I wonder how good the resolution really os

Here I a picture I posted a while back of my HF camera.

 

[exp500]

Best you can hope for is the ceramic on plug cracked because the idiot dropped it and didn't throw it away. When piston came up it pounded that loose piece into electrode smashing plug and likely marking piston top. Worst is cracked or holed piston or Bent valve. Make sure to look at valves when open also. Compression test necessary too. Let us know what you find.

 

[Jimmyy]

Screen shot from cheap USB Endoscope. Not great but it was only $8

 

[Shibbershabber]

Best you can hope for is the ceramic on plug cracked because the idiot dropped it and didn't throw it away. When piston came up it pounded that loose piece into electrode smashing plug and likely marking piston top. Worst is cracked or holed piston or Bent valve. Make sure to look at valves when open also. Compression test necessary too. Let us know what you find.

No compression on that cylinder.
Cylinder #1 was about 150... Didn't check 2 or 3

 

[Doubeleive]

Best you can hope for is the ceramic on plug cracked because the idiot dropped it and didn't throw it away. When piston came up it pounded that loose piece into electrode smashing plug and likely marking piston top. Worst is cracked or holed piston or Bent valve. Make sure to look at valves when open also. Compression test necessary too. Let us know what you find.

that's what I was thinking lol considering a plug was cross threaded, when I was young and dumb (versus old and dumb now) I had a mazda wagon I stripped a plug thread, so I went and bought a thread adapter (basically a leave in tap) only I used one that was too short all was well installing it, got it in put the plug in, fired it up and as soon as I backed out of the driveway BAM loud ass noise and engine got real loud, shut it off and found the adapter had blown out and the spark plug was dangling on the wire on the other side of the engine lol, so I went back and bought the longer adapter and that fixed that problem, I didn't care at the time I am sure I dropped a bit of aluminum down inside the motor threading the adapter in I just cleaned up what I could, it drove pretty good even though I beat on that thing and did other stuff to it I think I had jammed the vacuum advance on that thing as well always ran great until I was forced to sell it because I got in a accident without insurance and when I went to court I made a deal with the judge if I sold the car would that satisfy the court, judge said yes so off it went, I just turned around and bought another car lol.

 

[exp500]

No compression most likely a holed piston. If cylinder looks good AND its a low mile motor you might get 50k more miles out of it changing piston. May be better to look for a totalled truck as a donor motor. Or add that LS motor on the stand in the garage!

 

[iamdub]

Here I a picture I posted a while back of my HF camera.
View attachment 272737

Ugh. That cylinder wall looks terrible! Look at that horrible worn spot in the center! Or is that a busted piston? It's so bad that it's unidentifiable!

 

[wjburken]

Ugh. That cylinder wall looks terrible! Look at that horrible worn spot in the center! Or is that a busted piston? It's so bad that it's unidentifiable!