| Author | Message | ||
     Bill Coburn Grand Master Username: bill_coburn Post Number: 265 Registered: 4-2003 |
Some months ago I was asked to rescue a failing postwar Phantom fitted with a 1970 Shadow engine. There were some amazing things wrong with the car but the most distracting was that the car was difficult to stop and usually crudded up its plugs in 30 miles! This was inconvenient and disconcerting. One approach had been to pour some strange oil down the plug holes to 'free up' the rings otherwise the advice was to replace the engine ($50K for starters)assuming you could get one. It all seemed a bit much for a car that had done 106,000 miles and very very sedate ones at that! Much discussion followed with my conscripted mentor Mr Chapman. The plugs incidentally would cover themselves in soft black carbon and short themselves out very quickly. A Rolls-Royce vee eight engine does not run well on 5 or 6 cylinders! To free up the rings if they were truly stuck Bob recommended chemically decarbonising the engine. This worked so well that the compression pressures all came in at 140 psi to the pound!! We deduced that if oil was getting to the plugs with the rings apparently working well, it could only come down the valve guides. So Bob prescribed an American version of the current factory seals which are effectively metal caps with an annular seal fitted in the top. This involved scrapping the original cord seals and the compressing caps and secondry springs. Noting the diatribe that went on over locating the main springs I opted for spacer washers around the base of the guides and the tops of the latter had to be slightly chamfered to facilitate pressing the seals on. This whole exercise was done in situ using compressed air to hold the valves shut while their springs were off, the pistons at top dead centre and a couple of pine wedges driven into the flywheel ring gear to stop the crankshft rotating under the pressure of the air. If I was called for tea mid-installation I simply put a paper clip around the valve stem to stop it dropping down when I turned off the compressor. The Factory are probably going to allot a special tool number for this innovation. Having got all that together again I ripped the front off the engine to replace the rotten cross seal, replaced the water pump bearing and the idler pulley bearing, had the alternator bearings replaced and discovered some gentleman had severely dented the reservoir on the power steering pump trying to tension the belts. This was repaired. I had also been eyeing the carburetters with some suspicion since a rich mixture is an excellent way to crudd up plugs. These were stripped. One of the needle valves had a periodic stick down, there were the wrong main needles which were very much richer than the correct ones and the choke kickdown link was badly adjusted. New everything was fitted and the engine started. It has now done nearly 200 miles including very slow running, lots of cold running, flat out running and high speed touring running. I finally plucked up courage to pull the plugs yesterday and they are almost as clean as when I put them in! Whew!!! Oh and the brakes. At the front there were none. The servo simply wound itself up and nothing happened. Master cylinders were overhauled with new rubbers and the system re-bled. Silicone fluid was used again as it had been in the system for some 10 years. The problem I believe was air in the system but I have yet to work out how it got there!!! | ||
| whunter Grand Master Username: whunter Post Number: 101 Registered: 10-2003 |
Egad, someone put silicone brake fluid in in the car. That is bad news. Here is a link to another forum with more information than you desire to know on the subject. http://www.mercedesshop.com/shopforum/showthread.php3?t=105339&highlight=silicone |
