By David Chaundy
Back in 2004/2005 when I wrote my first articles on Rolls-Royce Silver Cloud II V8 engines for www.KDA132.com I could never have imagined that the article would be so widely read and so appreciated by people from all over the world. I have very much appreciated the kind remarks and votes of thanks from readers over the years. The articles have generated a considerable volume of e-mail correspondence for me and also Ashley James from people asking for detailed advice when working on their own engines. Ashley and I noticed a regular pattern to the questions asked by owners of Silver Clouds, Silver Shadows, and indeed later cars. With this in mind I have decided to write this article to address gaps in the original engine article, but also to warn owners of the possible pit falls one might encounter when considering re-building a Rolls-Royce V8 engine.
I get more questions on this topic than any other. The list of horror stories from distressed owners seems to grow by the month. The root of the problem is the ridiculous price Crewe charge for new original equipment tappets. I’m not entirely certain of the current list price but it was certainly well in excess of £240 per tappet the last time I enquired. This is a great deal of money to many owners of elderly Rolls-Royce’s. Faced with such prices people are forced to look for an alternative product which is more keenly priced. For many years there was a very good alternative to the original tappets produced by General Motors Corperation in Detroit USA. I fitted a set of these excellent tappets to my own engine and described doing so in my engine article.
Since writing that article I’m advised by a number of sources that General Motors moved production of their hydraulic tappets out of Detroit. Since then many owners of Rolls-Royce cars who have fitted GM tappets to their engines have experienced a variety of problems. The list of reported symptoms is as follows;
Personally I do not recommend the use of anything but genuine Crewe tappets in Rolls-Royce V8 engines today. It is possible to acquire reconditioned Rolls-Royce tappets from specialist spares companies such as Flying Spares or Introcar etc. They offer a considerable saving on new Crewe genuine parts but they are not as keenly priced as generic tappets which more often than not are manufactured in Mexico. I would urge owners about to embark on engine work to think carefully before fitting generic tappets to their cars.
This is the second major cause for concern among our correspondents. I feel many people would rather not tackle the job of removing the cylinder liners. This is an understandable position but one which virtually guarantees the owner trouble when the engine is re-installed in the car after a re-build. Let me explain...
The oldest Rolls-Royce V8’s are now 51 years old over that time internal corrosion will have taken place. To imagine that a particular engine will have escaped the phenomena is to delude one’s self. Imagine the internal spaces around the cylinder liners that should have coolant in them, in most cases after the passage of time there will be almost no space left, it will be full of corrosion. This will stop the engine from being able to transfer heat generated in the cylinders to the coolant because there isn’t a flow of coolant around the liners. More worrying still is the pressure this corrosion places on the walls of the liners themselves. The pressure will literally crush the liner until it deforms. This deformation goes on until the clearance between the pistons and the liner bore is taken up. Rolls-Royce V8’s run with a very fine clearance between the piston and the liner so it takes relatively little movement to cause the piston to scrape against its liner causing the failure of the piston rings, horrendous bore damage, and even broken pistons. When this happens the engine develops a rattle when running. By the time the rattle is heard it is nearly always too late to save the pistons and liners. It is therefore the best policy to tackle the job before the engine develops a “death rattle”. Often if caught in time the pistons and liners can be reused when cleaned up.
Never neglect to remove the cylinder liners when rebuilding an engine. Make certain that the coolant passages are carefully cleaned of all corrosion and new liner seals are fitted.
If you choose not to withdraw the liners and clean out the deposits in the coolant spaces the following will happen.
During the process of rebuilding the engine the deposits in the coolant spaces will dry completely and contract as they do so. When the time comes to refit the engine and fill it with coolant they will be ready to float on the surface of the new coolant. When the rebuilt engine is started, the heat generated detaches even more of the loosened deposits. This detritus floats up to the top of the engine and sits beneath the thermostat waiting for it to open when the coolant reaches normal running temperature. As the thermostat opens the dirt and deposits rush through it and up the top hose into the radiator header tank. There they flow along the rows of capillary tubes in the radiator core blocking them one by one until the core of the radiator is virtually useless. It is pointless to clean or rebuild the radiator because the dirt keeps on moving around the system.
Having decided to remove the liners during an engine re-build, don’t try to pull the liners out without heating the crankcase uniformly to around 100 degrees C. This is best done by heating the crankcase in a vat of water until it boils. The heat expands the aluminium crankcase allowing the liners more room to extract easily. The Rolls-Royce workshop manuals will not tell you to heat the crankcase because they were written when the cars were new with un-corroded cooling passages. Now the oldest V8’s are 51 years old they need the greatest care to be applied to the removal of their cylinder liners if catastrophic damage is to be avoided. To use a hot air gun or a flame on the crankcase is a waste of time. The heat cannot reach the internal sections of the crankcase which retain the liners. You will also harden the deposits around the liners making it more difficult to get them to move. If you over heat the crankcase distortion will occur rendering it unserviceable. The only safe and reliable way to heat the crankcase uniformly is by heating it up in a vat of water as I describe.
Time after time I hear of people pulling the lower sections of the crankcase out along with the liners. This can often be avoided if the crankcase is heated in boiling water. The water also softens the deposits and corrosion around the liners allowing the liner to slide past on its way out without damage and binding.
Crankcases for Silver Cloud II’s are no longer available new and good used castings are now in very short supply. I understand Silver Could III crankcases are becoming increasingly scarce because so many have been terminally damaged by technicians unaware of the problems involved in liner extraction.
Never ever be tempted to use a hammer and drift in an attempt to withdraw the liners. Certain damage to the liner and crankcase will be the result. Only use the correct Rolls-Royce service tool which can be hired from The Rolls-Royce Enthusiasts Club for a small charge. Great pressure is needed to pull the liners out of the crankcase hence a very substantial tool was designed for the job. This locates precisely and distributes the pulling force across the casting reducing the possibility of damage to the machined faces to the minimum.
Further advice will be posted if further issues come to light.