Initially, compression was about 135/140 dry/wet on all 4. Leakdown terrible, 70%. On disassembly found broken top rings in all 4 but 2cnd ring and oil scrapers fine. Very minor wear on pistons and cylinders. So I had line2linecoatings put 0.001" of antifriction on the skirts and got new ring sets.
Prior to firing up compression was ~205, leakdown ~11% on every cylinder. Fired up after just 5 seconds of cranking. No blue smoke, idling poorly due to disconnected O2 and TPS. Very little blowby out the AOS/fill cap. SO happy.
Here's what is left to do: smoke test front to back for vacuum and exhaust leaks, mount exhaust hangars, adjust gear shifter, recheck all fasteners for torque/loctite, new timing and balance belts, urethane fill of transmission mounts, lexan windows, new clutch line, battery cables, reconnect AOS to J Boot (no more catch cans!), reconnect O2 and TPS, new speed and reference sensors, motor mounts.
What am I forgetting?
Supernaut wrote: Mon Mar 17, 2025 3:19 pm Hi Everyone,
Got my first Porsche, a 1987 924S, last year for something fun. The seller thought the car was raced in the 944 Cup series previously so I'll be looking for history on it at some point. It's lightweighted with the interior, windows, inner door skins, and rear seat removed, roll cage, and 5-point harnesses over race bucket seats. To give you an idea of how it was set up, I thought the brake fluid reservoir looked full of disgusting brown fluid. I was not looking forward to flushing the brakes, but was very pleasantly surprised when removing the cap - the fluid was actually a light blue, like modern windshield wiper fluid color. With the yellowed plastic of the reservoir, it combined colors to appear brown. Even tested low moisture on the meter. Possibly ATE Super Blue Racing?
It came with some wide R-series tires which unfortunately were cracked and 16 years old. After getting new ones, I took it to a local autocross a few times and had a blast annihilating some cones. It ran great, but not nearly as fast as the modern cars. I admit nothing, but there is a chance I leaked some oil on the track.
Had an interesting experience with a clicking noise in the back. I assumed it was one of the drive axles, so took them apart for inspection and regrease which had no result. Wheel bearings all seemed good and rotors had no runout. Removing all parking brake hardware did nothing. Removing the pads made the noise go away while spinning the wheel with that corner of the car jacked up, so I was on to something. I noticed there are two holes for hold down screws on the rotor to attach it to the hub. Only one screw was present, so I ordered another to put in the second hole, and FIXED! I assume the rotor shifted on the hub slightly, and the clicking was the (very slightly eccentrically mounted) rotor pulling the pads up and down in the caliper, making the clicking sound.
The motor has terrible blowby and the highest leak down I've ever measured, 60-70%, all past the rings. Crankcase pressure was very high, contributing to many oil leaks. Compression is good which puzzles me. Anyway I pulled the motor and am tearing it down. Glad to join you all here and looking forward to contributing and learning!
