Prior to early March of this year my 97 C4S was burning about 1 qt every 900 miles and had been consuming at about that rate for at least 20k miles. Almost needless to say, my CEL was lit almost all the time and the engine lacked the urge I'd grown accustomed to. It felt like the timing had been retarded by at least 3 degrees.

I took the car into my local Porsche dealer (Johnson Porsche in Annapolis) in late February with a long list of things I wanted done, foremost among which was a top-end rebuild. I specified that the heads and cam carriers be sent to Bob Hirst (Anchor Atlantic Engineering) in Pitman, NJ, for a thorough cleaning and rework (he uses an ultra-sound cleaning machine of his own design).

After a couple of weeks the heads/carriers came back looking practically new with all SAI ports pristinely clean, three new intake valves, new meticulously-honed manganese-bronze valve guides, and all new exhaust valves.

In addition to the heads, I specified that everything else be done that made sense to do with that access be done (too many to list without going off on tangent). I also had Fabspeed 200-cell sport cats installed.

After Greg Wilson (a Master Mechanic's Master) had reassembled everything and added most of my usual oil (Mobil 1 15W50), he turned the key and it fired up first crank like it had only been minutes before it was last run. Of course it sounded much better with those sport cats combined with my motorsound mufflers. However, the best part is no more CEL, AND, I added only 12 oz of oil over the next 6000k miles!

The next oil change I wanted to try Mobil 1 0W40. After researching all the zinc, Phosphorous and viscosity issues, I reasoned that the Euro-blend 0W40 had relatively high levels of ZI and PH (1000/1100), which was not all that much less than the 1200/1300 of the 15W50. The car seems to run much better with the 0W40, revs more freely, and gets a bit more than one more MPG. After 2500 miles with the 0W40 I've yet to add any oil.

In all, it was expensive (nearly $10k). But this car now runs great, is quicker, has more torque, sounds better, and should be good for at least another 150k miles; well worth it I'd say!

 

 

Koolbeanz.

BTW, how many miles (total) on the odometer before you decided you HAD to go this route.

Gerry

P.S. Last October had my oil changed (to co-incide with the NYS inspection) and, yep, just recently, had my car inspected again. The guy at the inspection station mumbled "You drive this car a lot!" as he compared last year's records to this year's. Miles covered in one year? 3,163. Oil 'consumed'? ...approx. 1/4 of a quart. (Total miles on car: 45,000).

 

Sounds great.What was the milage of your car when you droped it off?How long have you owned the car?Is this your first Porsche?I will be doing the same next month.I am questioning whether to have my regular Porsche specialist do the work or bring it to the dealership.Any thoughts?The price is the same.I like the idea of having a Porsche warrantee on this kind of large project.My car has 90k miles but does not use much oil.About 1qt every 2000 miles.I have leaky chain boxes including the metal gasket between the box and the case.I just feel it is time to refresh the engine.

 

If you use the 0w-40 oil, I'd strongly recommend bypassing the clutch pedal interlock switch so you can start the car without holding the pedal down. This prevents premature wear to the engine's thrust bearings.

 

Steve, trying to understand this correctly.

My Canadian '95 993 can be started without pressing the clutch pedal.

However, I habitually press the pedal anyway on all cars because: For cold-start, I think it makes it easier on the starter and, an extra safety in case it's in gear.

By "engine's thrust bearings", do you mean crank and rod bearings and rod bushings?

How can NOT pressing the clutch pedal affect wear in these bearings?
And wouldn't that make the starter work harder on cold-starts having to turn not only the engine but also some of the 75W90 gear oil in the G50?

Thanks.

 

I am the original purchaser of my '96 C4S. At 75000 miles I had numerous leaks and, after deciding to keep the car for the longer run, decided to do a "split case" rebuild of the engine. We checked everything, did valves and guides, replaced lifters and the thrust bearings + meticulously set the valve timing (added new clutch/flywheel and alternator--WTH at this point).
Prior to overhaul car burned about 1 quart per year (5000 to 6000 miles). Since, I haven't had to add oil. Car runs noticeably better with proper valve timing, just turned 100,000).
Replaced A/C evaporator and clutch master cylinder last week.

 

Waldteufel, Glad to hear everything is working well. I can vouch for Greg Wilson assuming he's the same Greg Wilson that used to be the senior mechanic at the Porsche dealer in Newark, DE. Greg is a wonderful guy, provides lots of help to the PCA club and as I understand it is a pretty good 911 race car driver too. Wouldn't hesitate for a second letting him work on my car.

Congrats.

 

I am the original owner of this 97 and ordered it to my specs. Prior to that I had an 89 944, which I'd also bought new (great car).

The C4S had 129,200 when it went into the shop and it now has just shy of 138k.

Greg was previously at the Newark, DE location (agree with Bill 100%)

Some of you guys report rates of oil consumption that wouldn't have prompted me to take the plunge unless my SAE ports were clogged and triggered the CEL.

Steve W. always has great information, and he was especially helpful to me as I was considering various valve choices. I'd like to know more on the thrust bearing issue running the 0W40 oil. Wonder how a 50-50 0W40/15W50 blend would work?

Tom

 

I had a similar experience with my current 97; I had the valve guides replaced with phosphorous bronze in 2007 at 58k miles ... now at 88k miles and I have never had to add a drop of oil.

All the various 993s I had owned prior tended to need a quart every 1000-1500 miles or so ... and they all had the stock valve guides. The exhaust guides on my 97 were very worn at 58k miles. However, all the other 993s ran beautifully, they were just a little thirstier.

 

Yes, it can be somewhat harder on the starter, but one, starters are cheaper than engine rebuilds, and its not that hard to turn over the gears in the tranny.

The thrust bearing basically controls crankshaft endplay, which is how much the crank can move forward and back. When you press the clutch pedal, the release bearing applies some pressure to end of the crankshaft, especially with heavy duty pressure plates. This pressure, combined with the lack of oil pressure at cranking can cause some wear on the thrust bearing.

You do need to be more careful while cranking to make sure the car is not in gear.