Spark plugs closed or hammered shut

[TurboD1987]

Hi guys car has a real problem and would like any input. The motor made a low bang noise and then started running so rough I just made it home. Later I found the head of 1 of the screws for the throttle plate was gone. I removed the plugs and 3 were closed up tight, how is this possible?
Thanks for any and all help

 

[counterman]

Could be broken piston crown parts. It is possible that a piston was damaged, and that pieces migrated through the intake valve, back into the intake, and into other cylinders. Just how hard were you turning it when it let go? Could have been caused by the screw head, but, over the years, I have seen engines ingest air cleaner wingnuts, etc. with little to no apparent damage. It seems unlikely to me that a single tiny screw head would have caused that much carnage in half of the holes in the motor. Thanks, Rudy.

 

[Hacksaw]

Uh-oh!

I've heard of the wrong plugs hitting the pistons if they were too long, but that's only if they're newly installed plugs.

If it's 3 plugs with smashed closed electrodes, then likely something in the turbo or upstream of the throttle came apart! And I seriously doubt that broken off pieces of anything will come back out the intake valve & into another cylinder. More likely it went out the exhaust valve.

It's a pain, but I would pull the heads & look at the damage. If any debris came from before the turbo, then the turbo will also be trashed as well. Debris coming out of the engine through the exhaust will also trash the turbo.

 

[counterman]

Any updates? I am curious to see what the problem is. Other than something breaking in the combustion chamber area, like a piston or valves, the turbo is also a strong suspect. Failure of the compressor side of the turbo can scatter debris into the inlet stream. It would have to pass through the intercooler and throttle body, but it could easily cause trash to end up in the cylinders and the resulting plug damage. Rudy.

 

[bmackinnon]

let me guess.... accufab throttle body??

 

[TurboD1987]

very good guess !

 

[Boost231]

let me guess.... accufab throttle body??

That would be my guess as well. i made a post warning people to fix them if they had them. what happend to the one we had do it was the throttle body bolt mashed into the piston and it would tap everytime it would come to the top of the cylinder. anyways pull the heads and see what the damage is.

 

[TurboD1987]

pics show the screw head gone and turbo looks fine on the exhaust side?

 

[Boost231]

looks just like what happend to my buddy. top of the head stuck to the piston and once the piston came to the top it would tap. pull the heads. we didn't notice that bolt head missing till we where about to pull the motor. pulled all the main caps etc, etc and couldnt figure it out. pulled the motor then the heads and bam.

 

[Phoneguy]

How old is the timing chain?

Bryan

 

[bmackinnon]

very good guess !

Obviously, you aren't the first poor guy whose motor got thrashed thanks to that P.O.S. screw on the accufab tb .... easy guess... I feel for ya'... If you search here on the site, you'll find several others' same pain, and info of what screws to use as a replacement for the defective ones that come with that tb... :frown:

edit: here - http://www.turbobuick.com/forums/general-turbo-buick-tech/265059-add-me-list.html

and here: http://www.turbobuick.com/forums/engine-tech/221882-found-cause-eng-noise.html

and here: http://www.turbobuick.com/forums/general-turbo-buick-tech/63065-motor-update.html

and here: http://www.turbobuick.com/forums/general-turbo-buick-tech/165003-accufab-70mm-tb.html

 

[TurboD1987]

Great info guys thanks , I did not want to tear the engine apart since it is still original and was thinking of rounding up a borescope first to look inside the cyl through the spark plug hole. Engine has about 40,0000 miles.

 

[Way2QWK]

I tried using the bore scope in mine, but we were not able to see the screw head. Even if we were, I dont know how we would have got it out unless the head was pulled.

 

[L8TRH8R]

Are there new units still having this issue? Mine is still on the box should I replace the screws now before we put the top end back on?

 

[WSLN 6]

My vote goes to yes......get soome new stainless ones and locktite them in.

 

[L8TRH8R]

Will do. Better safe then sorry!

 

[Boost231]

yes replace them now. look at this link Pictures by Way2QWK - Photobucket . you can see pictures of what we found when we pulled the heads. Note- wish we would have pulled the heads before every main cap, also like posted above i brought the bore scope over to way2qwk and we could see anything.

 

[bmackinnon]

My vote goes to yes......get soome new stainless ones and locktite them in.

Don't use stainless... it's too brittle, which is why the heads have been snapping off. Just use steel button head screws, don't over-torque them, and yes, locktite them...

 

[L8TRH8R]

Will do. Thanks all.