Burning Coolant 2Gals every 200-300 miles.

Type of motor?

 

egr cooler I bet

 

I had a sunken liner on a '98 M11 that was caused three blown head gaskets before a mechanic finally decided he would fix the root cause instead of only replacing head gaskets.

Also have replaced several EGR coolers on a 2008 ISX but I didn't realize they were a common problem on Detroits.

If they have the head off it seems like they have the job half done already. Almost seems a waste to put it back on.

 

The liners set a little above the top of the block, if the do not protrude as per specs the head gasket will fail, why do 2 , do all six.

 

Pony up the extra money for the other 4. The tear down is already done. Plus put and rebuilt head on as well, because if a valuve drops that may not be covered under warrenty.
I did that with my motor with a crowned out piston. I paid for the other 5 as the tear down was already done.Plus now you have a newer warrenty...

 

Sounds like the 2 liners were not shimmed properly.

As for the other 4...are they scarred? I don't fully agree to just replace them just because, but with the head off and pan dropped, I would punch out the rest of the pistons and replace the rings and bearings along with anything questionable (other liners, piston skirts, wrist pins, etc)