Tinwan

Did the first top end rebuild in 1999 including valve guides on a 1990-C4 at 50,000 klms. I’ve always used it infrequently so when imported from Asia to Australia, I at first used it as my daily drive with many extended motorway drives. The engine has always run perfectly except now has developed annoying oil leaks mostly from the o-ring seals at the base of 2 cylinder barrels, Power steering o-ring seal and valve covers although now Porsche offers alloy OEM replacement versions. My question- If I rebuild again at 74000 klms, will the engine leak oil eventually with infrequent use as I’m not sure if the new improved seal kits were installed back in 1999. It’s a great car and a shame to throw more money at it so is there another way ?

elbeee964

for those as conversion-challenged as me:
31k miles = 50k km
46k miles =74k km

guards red

Might be worth looking at the oil your putting in it before making any serious decisons. If you're using anything less than a 10/40 10/50, it might be worth shifting to one with a thicker weight. Give it a while to settle down and the old oil to work out of the system and it might dry up.

Worth a shot.

Tinwan

The Oil question- Now that I think of it, at one stage years after the rebuild the Porsche dealer in Hong Kong used the wrong Mobil 1 (OW 40) normally used in the latest 997's just before the car was exported. When the car arrived in Sydney my local Porsche mechanic replaced it with Mobil 1 (15W 50) which it runs now. Its quite strange that if I do trips more than 3 hours the engine will not leak a drop for sometimes days later. If I drive for less than 30 minutes it will leak enough to annoy my mates clean driveway

LouZ

There are also a lot of threads regarding Mobil1's new formulation which has lowered the level of ZDDP, which reports state that the air-cooled cars need.
I had a cam gasket leak that completly stopped once I switched to an oil with high levels of ZDDP (Brad Penn 20-50).

Tinwan

http://www.mobiloil.com/USA-English/..._Products.aspx

Other makers like Brad Penn and Penrite actually state the Zinc content in their oils, at Mobil you need to ask . I cant buy Brad Penn in Australia although I can get Penrite SIN 10 which has plenty of zinc content as per the spec sheet @ 1200 ppm

Andy Roe

Yep, I'd initially try using a thicker oil. How much oil is it leaking/using? If you think the engine runs fine and has plenty of power, I'd weigh up the cost of a rebuild versus a few litres of oil every now and then! I assume you have the engine undertray removed, as this would catch any oil before it dripped onto your mates driveway!

springer3

Stop changing brands of oil. Each additive package "conditions" the rubber seals. Changing brands causes additional conditioning (damage). My C2 has run the same oil since new, and has never leaked nor has the engine been opened for anything except valve adjustments. 64,000 miles.

Tinwan

I needed the rebuild as the cam lobes were wearing prematurely so valve adjustment became impossible. The painted surface falls off the inside of original magnesium valve covers and it grinds away at the cams quite rare I believe. I replaced the valve covers with alloy ones made in the USA and they still leak although they modified them recently to the same spec as the alloy OEM type now offered

Had the car from near new so 1999 was when it needed to be dropped out. I don’t think the 2 barrels leak that much, I have decided to replace the Power steering seal and adjust the valves while replacing the valve covers with the latest US made alloy models which have just arrived. I will do an engine oil flush and replace with Penrite SIN 10 fully synthetic oil 10w70 as its Zinc (ZDDP) content is high and good for conditioning oil seals similar to any members comments and trial of Brad Penn 20W50 (cant buy that here) and see how it goes. The engine tray is removed and leakage it not dramatic for example if I drive more than 3 hours the engine will not leak a drop for sometimes days later. Drive for less than 30 minutes it will leak enough to annoy my mate’s nice clean driveway nearly immediately. Thank you all for your comments, as I don’t drive it very often, I cant really justify pulling it down again, I was told recently that even the latest models leak oil, that made me feel a lot better..