Thursday, April 16, 2015

Fixing oil leaks on British Motorcars

Rolls-Royce and Bentley motorcars are renowned for their ability to leak oil.  They do so from orifices, joints, and sometimes through seemingly solid metal.  Today I’d like to show you how we address crankshaft oil leaks at the front of the engine. 

A Rolls-Royce V8 being assembled after overhaul at Robison Service (c) JE Robison
The early V8 motors used a loop of rope to seal the hole where the crankshaft emerges from the timing cover.  Behind the rope they had a large washer – an oil slinger – whose job it was to “sling away” most of the oil on the end of the crank, so it didn’t reach the seal.

Rope seals had their origins on steam engines, where they could be wrapped round a shaft and held tight by a large covering washer and nut.  “Tightening the seals” was a regular activity on those old engines.

Inboard power boaters know those rope seals as the gland nuts and packing that seals the propeller shaft where it passes through the hull.  Rope works well there, too, as long as you keep it lubed and tight.

The rope seal doesn’t work so well in a car.  When rope is packed into a groove in the timing cover it seals for a while.  The oil behind it ensures it stays lubricated.  But at some point the rope will wear, and with no way to tighten it up, it will begin to leak.  Collector cars are particularly problematic in this way, because they sit a long time, and the seals dry out.  Then when they are started the dry seals wear quickly until they are wetted by fresh oil. That leakage produces the characteristic drip spots under the front of these motors. 

Traditional Englishmen took those drips in stride, but they prove vexing to many Americans, who are accustomed to leak-free vehicles.  Fix it, they say!  But that’s easier said than done.  When it comes to the free expression of lubricants, British cars are most easily treated with acceptance.  Fixing a front seal leak on a V8 Rolls requires extensive disassembly of the front end, to allow removal of the crank pulley.  Only then – after a couple days of hard work – can you see the seal.  But even now it’s not accessible for change.  No.  The front cover must be removed and once it’s off, you can refit the same piece of nineteenth-century sealing technology, and hope it holds a few more years.

We have a better answer here at Robison Service.  100-some years after the rope seal was invented the idea of using rubber seals came along.  Rubber seals backed by springs are much more durable, and more effective.  State of the art seals that use modern synthetic rubber (pioneered by the Germans in WWII) are even better. They are one of the developments that made the modern leak free car possible.  We can install those seals in your vintage car, and together, one by one, we can stop its ugly drips.

Removing parts to access the front seal - engine removed for ease of service
Here’s a series of photos showing the front of a Rolls-Royce V8, the covers removed, and the new metal and rubber seal.  Through hard work and diligence, we have brought the sealing technology of 1965 to this 1972 Rolls – a feat the original carmakers could never quite accomplish.  It took BMW ownership – and a multi-billion dollar investment – for Rolls-Royce Motors to do this on a production scale.  We can do this on your car for a tiny fraction of what BMW paid.

If you have a leaky old engine, and you want the bleeding stopped on a more permanent basis, this is the way to do it.  Just remember though – this article addresses ONE leak spot.  The typical British motor has over 117 points of potential leakage, all of which must be addressed to eliminate drips.   Many mechanics say that’s simply not possible.  We just say it’s difficult.


But we love challenges, and we are British car fixers through and through.



We remove the front cover, and machine the cover to accept a modern seal, which is pressed into place.  Once done, the seal can be serviced without removal of the front cover.  



Here is the new seal, set in place, prior to refitting the cover.


John Elder Robison is the general manager of J E Robison Service Company, celebrating 30 years of independent Rolls-Royce and Bentley restoration and repair specialists in Springfield, Massachusetts.  John is a longtime technical consultant to the RROC and other car clubs, and he’s owned and restored many fine vehicles.  Find him online at www.robisonservice.com or in the real world at 413-785-1665

Reading this article will make you smarter, especially when it comes to car stuff.  So it's good for you.  But don't take that too far - printing and eating it will probably make you sick.

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