Headgasket replacement

[trancend]

Hello, I hope the day finds you well.

I'm about to order some parts and tools for replacing the headgasket in my '12 Sonic LS 1.8.

The car has 130K on it and has been driven lightly its entire life.

The combustion test turned from blue to yellow, so I don't have a choice. The car runs great otherwise.

Should I bother with a compression test before hand? I'm not sure how well the bottom ends hold up, and would rather not replace the headgasket if the piston rings are likely to fail in this motor.

I think the head is good, but needs to be decked, so I'm not sure if there is anything else that needs to be done to compensate for the difference in clearance. Should I just buy a new/rebuilt head? Again, if the pistons are due to fail soon, then this would be even more of a waste.

I was also going to replace the timing belt, water pump, and oil cooler seals as well.

I don't want to pay what the dealership is charging for labor, and especially for parts (like double, far too expensive).

Are there any other glaring issues that should be addressed while I'm in there?

I'll be perusing existing threads in the meantime, just wanted to get this out there before I spend a boat load on parts and tools.

Thank you and good day.

 

[trancend]

I found a used engine from a scrap yard from the same year and with the same transmission as the one already in my car (2012 1.8 5 Speed, non VVT). However, it has 95K on it, so is definitely approaching or within head gasket failure range.

Also, I don't know how this engine was driven or cared for. I know that the one in my car was driven extremely lightly, since I was always trying to increase the MPG number, and didn't feel like wearing out a new set of $900 tires or the $550 RS suspension upgrade.

So now I'm stuck deciding between replacing the head gasket on a high-mileage (130K) lightly driven motor, or swapping in a not-as-high-mileage motor (95K) with an unknown history.

The scrap motor is being sold for a reasonable price, though I would have to return my existing motor as a core trade-in.

I do know that my engine currently runs strong, with a smooth idle and buttery smooth shifts, even when short/granny shifting below 1K (I know it's bad practice, but had to try it a few times after replacing plugs - think I'm more of a V8 person, prefer smooth low-end torque). It also shuts off immediately without any hesitation whatsoever.