Yes all those gasket should be replaced during a this head gasket replacement. I suspect the machine shop is to inspect and repair the valve stem guides or any other damage (ie broken off valve bouncing inside the combustion chamber).
I would look at cost. Would it cost less to have the head repaired or replaced?
Next, a new cylinder head could be a good thing but also not a good thing. The good is its new the bad is a new head seals the combustion pressures better but puts a greater stress on the 152,000 miles pistons/piston rings potentially causing them to wear out quicker. Note this is a more of a longevity idea than instant damage or wear.
Keep in mind that there still could be more damage inside to the pistons and cylinder bore.
Did the guy who did the timing belt repair do a leak down test? When there is low compression in a cylinder(s) you want to know what side is leaking. A leak down test will introduce compressed air into the combustion chamber through the spark plug hole. The tester will indicate how much (%) pressure is being loss. If the piston is damage you would hear feel compressed air coming out of the oil filler or if it is intake or exhaust valve you would hear compressed air in the intake or out the exhaust pipe respectively.
Wednesday, March 26th, 2014 AT 6:57 PM