Slant 6 blown head gasket causing low compression?

[nickname]

My Duster's 198cu slant 6 was clearly misfiring and I found that cylinder 6 had no compression at all and cylinder 3 only 40 psi. Hence, I had the pleasure to remove the head and investigate further.

As you can see from the attached photos, a lot is happening. The gasket has a lot of wear but it's not competely "blown".

So, just wanted to ask your opinion on what do you think was causing the low compression?

What are some steps I should take to avoid it happening soon again?

 

[Murray]

Because you have now disassembled the engine most methods of diagnosis are gone. Measure the head for flatness. Disassemble the valves and check for sticking valves and worn guides. Pull the pistons and inspect rings and ring lands. Measure bores and piston fit.

 

[nickname]

Because you have now disassembled the engine most methods of diagnosis are gone. Measure the head for flatness. Disassemble the valves and check for sticking valves and worn guides. Pull the pistons and inspect rings and ring lands. Measure bores and piston fit.

Yeah, there's only so much diagnosis you can do superficially...now I can actually inspect and fix it.

 

[Desoto291hemi]

Judging from your pics,,,,I think the head was not hardly torqued completely down .
Looking at the head,,,,you still have good witness marks from the fire rings .
The gasket was clearly leaking,,,,,but I think it was caught before major damage .

Your exhaust valves still show good color,,,,,a nice tan which means they are still sealing well
and not burned .

I would clean the deck very thoroughly,,,,,,and inspect all the bores and piston crowns .
I would have the head surfaced flat,,,,and a nice valve job,,,nothing major,,,,,just smooth all the seats again .
Valve stem seals,,,and a new gasket set l

Unless,,,you are wanting to rebuild anyway,,,,then go all out and make it new again .

Tommy

 

[RustyRatRod]

Yeah, there's only so much diagnosis you can do superficially...now I can actually inspect and fix it.

There's a ton of diagnostics you can do pre tear down. You just chose not to. I agree with the others. Check the deck and head for straightness. Have the head checked out and go from there.