Curing an annoying long term oil-leak

The long-term restoration of my Daimler V8 is progressing nicely but after removing the brakes they were found to be in a shocking state of repair. Both the front and the rear calipers, together with the separate self-adjusting hand brake mechanism were rusted solid. All these components will be sent away for a full restoration but in the meantime I simply doused everything in copious dollops of WD40. Hopefully this will help when the calipers are taken apart by the reconditioners.

The 1988 XJ40 Sovereign is currently off the road awaiting repairs after the nearside rear was shunted by a 2007-reg VW Golf. The 1989 entry level XJ6 was on hand as alternative transport but over the last few months it had developed an elusive oil leak. No matter how many times I got under the car to try and discover where the oil was coming from, I simply could not locate the source of the leak. There was so much oil over the chassis, the bottom of the engine and the underside of the car; it was almost impossible to find the source of the leak.

I knew that the only way to deal with it would be to have the car steam or pressure cleaned. I really don’t like the idea of cleaning the oil film away from the underside of a car. That coating actually protects the chassis against corrosion and rust. In the end though I had to admit defeat, there was just no alternative, so I popped along to Stripping Services Ltd and had them pressure clean the underneath of the XJ40. Now of course the underside of the Jaguar was spotless and there was not a drop of oil anywhere. However, after a couple of days of use, I got under again for another look. It worked, at last I was able to spot where the oil was coming from. Where the two pipes from the oil cooler entered the crankcase next to the oil filter block there was a small trickle of engine oil. After checking the manual I confirmed that where the pipes

enter the engine, there are two rubber ‘O’ ring seals. It was a pretty fair bet that after thirty years in situ, these seals had become hard and brittle and were no longer doing their job.

I called SNG Barratts, and fortunately they had the correct new ‘O’ rings in stock at the huge cost of 59p each plus VAT. Although the car had only covered less than three thousand miles since the last oil change and as the sump would have to be drained, it seemed good sense to change the oil and filter at the same time. So I also ordered a new filter from Barratts and picked up eight litres of Castrol 10/40 Magnatec locally.

After draining the sump, removing the filter and disconnecting the oil pipes, the old ‘O’ rings could be prised away. They were both very hard and brittle and one of them was clearly broken. Once the new rubber ‘O’ rings were fitted, the oil cooler pipes were refitted and the new filter screwed back in place. The area around the filter block was wiped clean with some cloth to allow any new oil leak to show up clearly. After refilling the sump with eight full litres of Magnatec, the engine was started. To my great relief, no oil appeared to be dripping and the pressure also appeared perfect.

Whilst the car was jacked up I noticed some play in the front wheel bearings, so before taking the car out for a road test it made sense to deal with this job too. The bearings were removed, checked, repacked with grease, then tightened correctly and fitted with new split pins. Job done.

I really don’t like the idea of cleaning the oil film away from the underside of a car. That coating actually protects the chassis against corrosion and rust

The brake calipers from the Daimler V8 restoration were in a shocking state and were left to soak in WD40 prior to being reconditioned. Pressure washing the underside of the XJ40 was necessary to reveal the source of an annoying and persistent oil leak.

The two original rubber ‘O’ rings from the oil cooler pipes on the left are over 30 years old and were clearly unserviceable. Once the underside had been cleaned off, the leak was traced to a trickle seeping out the oil cooler pipe unions near the filter block. New split pins were fitted to secure the large castellated nuts as a matter of course. Using the old ones is a false economy and unsafe. After discovering a small amount of play in the front wheel bearings, both hubs were dismantled, cleaned, re-greased and tightened.