Documented owner build record · 993 · air-cooled
1996 993 Carrera top-end rebuild
A month-by-month record of a 114,000-mile 993 top end at AMS Porsche, stalled from March to June 2020 by Covid-19 parts supply, and reported back with unusual honesty about how little of the work an owner can actually judge.
Evidence: Complete month-by-month rebuild record · The car's technical data page: chassis, engine and paint codes
- Vehicle
- 1996 Porsche 911 Carrera Tiptronic S (993)
- Engine
- 114,000-mile 3.6-litre M64/22 flat six with worn exhaust valve guides, perished valve stem seals and worn valve springs → Rebuilt 3.6-litre M64/22 top end at standard displacement, with new valve guides, stem seals and valve springs, and the original pistons and liners reused with new rings
- Published at
- Porsche 993 C2 (P619 HKC)
- Author
- The owner of P619 HKC · January 2020
Vehicle and engine evidence: The car's technical data page: chassis, engine and paint codes · Complete month-by-month rebuild record
Why it came apart
Persistent oil drips that stained the driveway badly enough that the owner began parking over a sandstone flag; a puff of smoke on start-up after three or four weeks standing, which they knew could indicate worn valve guides; and oil reaching the heat exchangers and smoking out from under the wheel arch at shows.
What the project aimed to do
Cure the leaks the earlier cam cover job had not reached — the upper cam covers and timing chain covers — and deal with top-end wear while the engine was out, keeping standard displacement. New piston rings were planned as a matter of course whether or not the bores measured well.
Who did what
AMS Porsche Race Engineering, with Angus named throughout, did all of the work. The owner chose them after narrowing a shortlist on reviews and pricing to two firms, one of which was booked until April. They documented the project month by month and did none of the work themselves.
Source: Complete month-by-month rebuild record
Chassis WP0ZZZ99ZTS316190, model type 993-331, engine M6422-63T, engine number 63T52878, in Polar Silver metallic. The owner records 114,000 miles at the time of the rebuild, and had the lower cam cover gaskets changed once before, in 2015.
Vehicle context: The car's technical data page: chassis, engine and paint codes · Complete month-by-month rebuild record
Documented sequence
Decision and choice of builder
The owner set out the case for going further than another gasket change at 114,000 miles: the upper cam covers and timing chain covers still needed doing, the valve guides could be addressed while the engine was out, and although head studs are not usually a 993 problem the barrels could come off so everything could be checked. The car was dropped off at the end of January 2020.
Strip and inspection
The strip began in mid-February. The owner reports no great surprises: broken and disintegrating heat shield clips, wear to the exhaust valve guides which they call quite normal, and melted or perished valve stem seals that suggested the engine had run hot at some point. Of greater concern were clearly worn valve springs. The liners and pistons were removed and both were fine to reuse with new rings.
Parts supply stall
From March the build stopped for want of parts rather than labour. Porsche was in lockdown and other suppliers were limited; AMS had bought most of what they needed beforehand. The fresh-air servo valve was still at Partisan in Germany and the engine fan was at a powder coater that had closed. The owner used the enforced pause to have the chassis legs inspected again and surface rust cleaned up and painted.
Reassembly and refit
By May the engine had been fully reassembled and refitted, waiting only on the fan and the servo. In June the owner accepted a red fan rather than wait out the powder coater's backlog, and agreed to borrow a 964 servo to make the car operational. The car then failed its MOT on items the owner describes as not too bad, which were rectified, and it passed two days later.
Collection and running in
The car was collected in July 2020 after five months, with a 200-mile drive home. The owner reported again at 250 miles, with a 500-mile running-in period still to complete.
Named components and work
Valve train
New inlet and exhaust valve guides — the strip found both were needed, not just the exhausts — with a new set of valve springs and new valve stem seals replacing melted and perished originals.
Pistons and liners
Measured and found fine to reuse. New piston rings were fitted, as the owner had planned from the outset regardless of the measurements.
Sealing and cooling hardware
The upper cam covers and timing chain covers the earlier 2015 job had not reached, a new set of heat shields in place of broken and disintegrating clips, the fresh-air servo valve refurbished by Partisan in Germany, and the engine fan left in its existing red finish after the powder coater's backlog made waiting impractical.
Work billed alongside the rebuild
Two new rear suspension arms, an MOT with rectification, and everything required for a 24,000-mile service including an ATF fluid change with filter and gaskets. The owner names these explicitly as the reason the total exceeded the quote.
Reported outcomes
Leaks and start-up smoke
No leaks and no smoke at start-up
Reported on collection and again at 250 miles, with the cam covers and timing chain covers described as bone dry. One small drip above the anti-roll bar between engine and gearbox was investigated, no source was found, and no further sign appeared once it was dried off.
Owner-reported compression
Up again
The owner states this in passing on collection. No before or after compression figures are published anywhere on the page.
Road impression
Feels more powerful and responsive, with more torque
Given first after the 200-mile drive home and repeated at 250 miles. The owner immediately qualifies the first impression themselves, allowing that after five months without the car they may simply have forgotten what it drove like, and notes they cannot use it hard until 500 miles are covered.
Cost against quote
Higher than quoted
The owner expected this, and attributes it to needing both inlet and exhaust valve guides and a set of valve springs on strip, plus the suspension, MOT and service work billed at the same time. They record that every firm that quoted described its figure as a starting price. No total is published.
Evidence limits
- No dyno run and no compression figures are published; the claim that compression is up is an unquantified statement.
- The road impressions were formed at 200 and 250 miles inside a 500-mile running-in period, and the owner qualifies them himself.
- The owner says directly that it is difficult to assess the workmanship because it is all hidden, and that they had only had the car back a day when they first wrote.
- No total cost is published, and the bill includes suspension, MOT and service work unrelated to the engine.
- This is a top-end rebuild with the barrels off, not a full bottom-end rebuild; the crankcase was not split.
- The page is dated by month rather than by day, so no precise dates are recorded here.
Access note: The build page and the car's technical data page were publicly readable without an account or paywall when reviewed.
Reviewed source trail
- Complete month-by-month rebuild record · reviewed 2026-08-26
- The car's technical data page: chassis, engine and paint codes · reviewed 2026-08-26