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Tech Area => General Buick Tech => Topic started by: Scoobum on November 02 2015, 05:40:08 PM

Title: Clean Piston and Frost Plug Question
Post by: Scoobum on November 02 2015, 05:40:08 PM: First off...we have the PS rear piston absolutely clean. Head gaskets are intact. Secondly...we have a frost plug in the water jacket behind the PS rear cylinder. Why would the top of the piston be clean...and will the frost plug sitting in the water jacket behind the cylinder affect anything? I doubt we can get it out. This is how the engine was handed to us...how it got there...is a mystery. The short block is mint. Pistons and bearings are mint...and the cylinders still have crosshatch marks on them. Crank end play is within tolerance.
Title: Clean Piston and Frost Plug Question
Post by: larrym on November 02 2015, 05:54:25 PM: Any cracks? Head or cylinder wall? When I did my first head gasket in the head lifted and the fire ring was intact when I pulled it apart.
Title: Re: Clean Piston and Frost Plug Question
Post by: Scoobum on November 02 2015, 06:02:31 PM: Removed the piston/rod...both are fine...and the cylinder is fine as well. I'll have Dan check the head for a noticeable crack or cracks.
Title: Re: Clean Piston and Frost Plug Question
Post by: Steve Wood on November 02 2015, 07:34:02 PM: that is typically the leanest cylinder. The power plate was designed to rearrange air flow to bring it in line with the others.
Title: Re: Clean Piston and Frost Plug Question
Post by: Scoobum on November 03 2015, 02:52:39 AM: Quote from: Steve Wood on November 02 2015, 07:34:02 PM
that is typically the leanest cylinder. The power plate was designed to rearrange air flow to bring it in line with the others.

Engine was handed to us with no Power Plate.
Title: Re: Clean Piston and Frost Plug Question
Post by: Steve Wood on November 03 2015, 09:09:49 AM: so it was definitely lean on that cylinder compared to the others...don't know if that was the full reason, or not
Title: Re: Clean Piston and Frost Plug Question
Post by: Scoobum on November 03 2015, 07:31:32 PM: Quote from: Steve Wood on November 03 2015, 09:09:49 AM
so it was definitely lean on that cylinder compared to the others...don't know if that was the full reason, or not

The head gaskets appeared to be intact upon disassembly. Steve...any other reason or reasons that piston would be clean? Injector stuck open...spark plug not firing? Open to suggestions.
Title: Clean Piston and Frost Plug Question
Post by: larrym on November 03 2015, 08:49:31 PM: Intake manifold gasket sucking water in, there is a port right there?
Title: Re: Clean Piston and Frost Plug Question
Post by: Scoobum on November 04 2015, 01:58:05 AM: Quote from: larrym on November 03 2015, 08:49:31 PM
Intake manifold gasket sucking water in, there is a port right there?

I usually put a dab of silicone around the cooling passages when I install an intake. There wasn't any on this one.
Title: Clean Piston and Frost Plug Question
Post by: Steve Wood on November 04 2015, 08:25:04 AM: You can usually see where it was leaking by but that sounds most plausible to me

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