4g61t.org

So... my colt melted the groundstrap on cyl 3 spark plug. The car still ran but obviously stumbled when i got into it anymore than about 25 percent throttle, but otherwise idled fine and sounded perfectly normal...

Im pretty sure it detonated under high boost however. With that being said however i had 30 psi on cylinder 3 and i pulled the cylinder head after a compression test.

I Still have stock headbolts and a stock composite ORIGINAL headgasket on the motor and was getting some rust looking coolant which i hadnt had before... I didnt have overheating problems though.

Upon removing the cylinder head i found no obvious signs that the gasket was blown but i guess it could have been something i didnt see. Cyl 3 had no scoring on the walls so im not 100 percent sure if the ringlands didnt break though... Should i see atleast some scoring with broken ringlands or would i obviously see at the edges of the piston? Has anyone see the ringlands break but the top of the piston turn out fine?

Ive also flipped the cyl head upside down and filled each combusion chamber with alcohol and released pressure on the cams (close valves) and none of the alcohol leaked through from the valve seat area out into the intake/exhaust ports. The seats appear fine without removing the valves and the alcohol test indiciates they are ok

Am i lucky possibly? New hg and bolts and be done? Im expecting to see something majorly damaged here causing the low compression and im not...

it's too bad the head wasn't still attached at this point.

Makes it easier to confirm a leak down. and compression test.

If the head is fine for sealing, and the gasket for sure wasn't blown out to the side - not affecting the adjacent cylinders in either direction, then the bottom end is seriously suspect.

Seeing as how you will be doing an oil change after any and all work that is performed, you can fill that cylinder with water and see how fast it leaks down compared to cylinder 2. Then try 1 and 4. Leave the piston part way down the bore and fill it up. If side by side pistons show leakage quite quickly down only one hole, I would be looking for ring lands, and piston chunks.

You could do it with oil too, but I figure water will make it go quicker.

Should i see atleast some scoring with broken ringlands or would i obviously see at the edges of the piston? Has anyone see the ringlands break but the top of the piston turn out fine?

http://www.4g61t.org/forum/viewtopic.php?f=64&t=38157 see bottom of page 3 pic....

car ran good.. not as much power as I thought it should have. and it smoked..it would go thru a quart of oil about every 50-70 miles....(since fixed I havent added any oil in over 500 miles) I did a comp test and had 140 in 3 cyl's..and 80 or something like that in 1 cyl.. which ended up being the bad one.. I didnt see anything wrong when I pulled the head.. it wasnt untill I pulled the piston to put new rings on it when I seen the damaged piston... and there was 0 marks or damage to the cyl wall..


Steve

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Steve 89 colt 2.3 stroker stock top end. evo3@20 psi 13.489@99.30mph 3/10 2012
On drag radials.auto trans.launching @ 5 psi and no traction thru 2nd.

I've taken apart a 4g63t after a blown headgasket and the cylinder walls were perfectly fine. However, when i removed the pistons, the ring lands basically fell apart in my hand. I believe they were only being held together by the rings, for what its worth.

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go fast- break stuff- repair- repeat

Thanks for the replies, ill have to check it out when i get some time. SUPER busy at the moment but ill post my findings and hopefully some pics...