In order to know how extensive the damage was, I needed to test the compression for each cylinder. A compression test is done using a gauge that can be bought at any autoparts store for about $25 (see picture).
After removing all of the spark plugs, you plug the tester into each of the spark plug holes, one at a time. I put on a new timing belt, complete with a new tensioner arm bolt, and lined up the timing on the crank and camshafts. My 6 year old son happily turned the key for a few seconds at a time as I watched the compression tester. I wrote down the results and repeated the process for each cylinder until all 8 were tested.
Three of eight cylinders (one on the passenger side, two on the driver's side) produced no compression whatsoever, meaning that valves in at least 3 cylinders were damaged. The only way to pull the heads off of the engine is to pull the engine out first. It's not possible to pull the heads with the engine still in the car, at least for an '85 928.
Another Rennlist member, Keven ("86.5_Tiburon") kindly offered to help out by rebuilding a set of heads he had on hand. Once I receive them, I'll be able to pull the engine, pull off the old heads, and install the rebuilt ones.
At this point, I'm going to have to do the following:
- Replace head gaskets
- Replace oil pan gasket
- Replace motor mounts
- Powder coat the intake
- Replace valve guides
- Replace valve seals
- Delete the air pump (no longer needed)
- Replace the oil filter
- Replace the air filter
- Replace the tensioner arm bolt
- Replace the timing belt
- Replace the alternator belt
- Replace the power steering belt
- Replace A/C belt
- Replace all under-hood vacuum lines
- Replace all oil lines
- Replace hood liner
- Replace all A/C o-rings
- Replace A/C drier
- Fix A/C leaks
- Replace spark plug wires
- Replace cam gears
- Replace crank gear
- Replace oil pump gear
- Rebuild the tensioner
- ...and CLEAN UP THAT MESS!