First Engine Drop Questions

[wilson234]

Acquired a 1989 964 with approximately 90K miles. Had been sitting for awhile, xmas lights all over the instrument gauge, but it did run. Worked through all the warning lights, and ran good. Had lots of oil drips, and periodic issue with the clutch where it would only depress 1/2 way down and get stuck, could not push any further, but would retract fine (essentially like hitting a pedal stop half way down). Luckily since the clutch engages/disengages at the end of the pedal release stroke, I was still able to drive the car. My first guess was a clutch fork shaft issue, but when it got stuck it was really stuck, and I could not understand if the needle bearings were sticking, why wouldn't the fork still rotate at the bushing point of contact. Most recently, around 4K and above I got a weird vibration that I could feel through the clutch pedal.

That's when I decided to drop the engine and investigate.



The two bolts holding the guide tube were missing!!! My guess is the tranmission was initially preventing the guide tube from rotating uncontrollably, but as it worked into the transmission case, it eventually carved enough metal away to allow for the guide tube to spin compleletely 360 degrees without impediment. This is when I assume I got the vibration at 4K, which was consistent.

Nonetheless the clutch fork was still worn, but not my cause of issue with the clutch pedal being stuck at half downward push.


Now my questions, first easy one. What is this plunger mechanism, odd thing there's nothing attached to the metal arm, which does move if you pull it and it looks to me like some cable should be attached to it. Its located behind the intake (only noticed because I can now see the backside of the engine).



One of my head studs was broken. It appears I still have the original dilivar head studs, black finish, non-magnetic. I wasn't planning to take the engine apart that far, just a valve adj, and fixing various oil leaks, but I guess I need to do it. I was planning to replacing all of the studs with the Canyon brand metal ones our host sells? Any other suggestions, or options within the same price range?

Notice only one cam was pitted. Cylinder #1, the pitting is on the trailing face when it engages the rocker arm, if this makes any difference. Photo is not entirely clear, but anyone can opine on whether I need to get this fixed. If it does need to be reground, should I be thinking about a more agressive profile?


Lastly, any 1989 model year 964 guys out there, I was expecting to see the rubber hub clutch, but to my surprise there was a Sachs sprung unit. Based on the part numbers, some OEM porsche parts and other Sachs part numbers, I'm guesssing prior owner, installed a rebuild kit, keeping the OEM flywheel only. Pressure plate, flywheel and clutch disc all looked good. I'm planning to install a new clutch disc, machine and reuse flywheel. New seals, hardware, throw out bearing and guide tube. Can the pressure plate be resurfaced? I was trying to figure out whether my pressure plate is OEM or aftermarket, but I wasn't able to figure it out.



Here's the part numbers:

Flywheel 964102239 (OEM for 1989 model year Middle Weight SMF)
Clutch disc 1861568331 (Sach sprung common replacement for 930 late 70-80s)
Pressure Plate (3032107099)(Cross reference possible porsche part # 95011602303)

Any help would be greatly appreciated!!!