Porsche 996 rear main seal (RMS) replacement

I’ve just got a Porsche 996 in stock and it rear main seal (RMS to its friends) is leaking. This is not at all uncommon – most 996 and Gen1 997 Carreras will suffer from it at some stage in their lives. Normally is it anything to worry about; if you can cope with a little bit of oil dripping onto your garage floor, the usual advice is to live with it until the clutch needs replacing. The gearbox and clutch have to be removed to get at the seal, you see.

Good advice until you want to sell the car. Quite understandably, anyone buying a 911 will be concerned to see oil coming out of the engine, even if they realise it’s an RMS leak. Indeed, it’s a great way to negotiate a discount!

Now,I never knowingly sell a car that’s got something wrong with it (and if I do, I make sure the buyer is aware of it), as I’m an honest chap. So, this RMS leak had to be fixed. I entrusted the job to Andy Windsor of AW Motorsport and went along to help. I’m not going to document the steps involved in the job, but suffice it to say, it’s not that hard. Dropping the gearbox is a bit fiddly as the top bolts are hard to access (some people prefer to drop the engine and gearbox together), but once that’s done it’s straightforward.

Porsche has changed the design of the seal a number of times during the life of the 996 and 997, and this was very apparent when we compared the old and the new ones (see photo above). The original was rubber with a spring ring, while the new one had a solid metal insert within the rubber, making much stiffer.

The key is to ensure the new seal is properly fitted. And this means using the correct Porsche tool to press it in (below). Some people tap it in with a hammer but there’s a risk of damage and not getting it straight. Also, there’s nothing to stop the seal disappearing into the engine if you push it too far – the tool avoids this.

So, all in all, a simple solution for a much-exaggerated problem. Still, at least this 996 shouldn’t suffer another RMS for quite some time.

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