Oils.

[Dell Boy]

Please someone enlighten me. What is the significance of the ash content of the oils used in rotary engines?Derek.

[nortonf1]

It is the quality of an oil which brule its scale without leaving (or almost) of scale in the combustion of the engine.As the rotary is a consumer of oil, it is very important that the engine does not get dirty or little!

[kanonkopdrinker]

And Rotella DD+40 has just 0.78% sulphated ash!Too much ash will lead to a heavy carbon build up - with the accompanying problems this brings ...David

[Dell Boy]

What problems does the carbon create & what symptoms show that carbon is building up.Derek.

[graham]

Hello Derek,First symptoms of the 'wrong' oil (Too many additives that turn to carbon?) Are sticky apex seals leading to a lack of compression at low RPM and a strange noise from the airbox that I don't kow how to describe. (Chock chock chock...)Continued use of a high carbon content oil eventually gums up all the seals and reduces cranking speed compression to almost zero.(Spins fast, difficult to start, hot or cold) High quality 'wrong' oils still lubricate the bearings and seals, a strip down and careful cleaning brings the engine back to life.Low quality 'wrong' oils break down and fail to lubricate the engine internals causing premature wear of rotors, seals and bearing cages. My experience suggests you can get away with almost any oil on a water cooled engine without serious damage but air cooled engines need all the help you can give them.My advice; use Shell Rotella DD40 for air cooled engines if at all possible. Graham.

[Malc]

Just to back up what Graham has said, some of the police air cooled bikes that were used mainly for city centre work ended up with sticking side seals that lead to the 'popping' sound in the air box under acceleration.These engines were stripped and rebuilt with just a good clean and spring set and new bearings. ( A few engines were also found to have 'grown' rotor shafts, so the rotors required delapena honing to bring back to tolerance)The problems lie in that the motor oils apart from specific 2 stroke oils are not meant to be burnt. Shell Rotella is a high detergant oil used to hold the sulphated ash produced in older diesel engines until it can be filtered out rather than forming sludge. Diesel fuel of years ago was high ash content and burnt deposits washed past the piston rings so the Rotella was used to collect this excess ash before it formed sludge. As said by 'Kanoncop' the ash content of the oil itself is low.The sulphated ash is soft and flakey but when left in engines that are left standing and so allowing condensation to form inside, sulphuric acid is produced.The sulphated ash is not a problem on the rotary as long as its in the combustion chamber as the rotor seals sweep this out of the exhaust port. The problems occur while the oil is doing its job of lubricating and cooling the rotor bearings. As it passes through the rotors, the high temperatures 'bake' the oil (both on air and water cooled) causing the carbon build up before being taken round to the carbs and mixed with the fuel and burnt. Hence all the crap that collects in the plenum and the gum in the dashpots.Cleaning the rotors involved soaking in concentrated pressure wash fluid for a couple of days as were not allowed caustic at work.Comp 2 is designed to be burnt and contains no sulpher and so gives a cleaner burn and less smoke. Having said that, the high temperatures around the rotor bearings still bake this oil the same.It is for this reason that the new Nortons that were being designed were going to use a similar lubrication system to the Mazda.The Mazda engines also burn cleaner by having a secondary spark plug firing miliseconds after the first one.Also, this is the reason that detergent oils should not be used on older British bikes without oil filters as the carbon or 'soot' particles travel round with the oil to the bearing surfaces instead of being collected in the sludge trap.malc

[Dell Boy]

Thanks for the replies. four times I had engine failures with my first interpol in 1988 to 1990. Only the last two was due to general wear. The first two were due to a broken oil supply pipe. The third & fourth were the, after 29,000 mile I`ve had enough of this wizzing round so will smear my end plates & avoid starting. This one was run on Morris oil as recommended by the factory & then Rotella 40 None of the rebuilds had the benefit of molying. The first Commander did 90,000 miles but was dog rough but still starting & running at that milage. Always run on Rotella 40 & never stripped or moly treated.Commander no. 2. Was run always on Rotella 40 & smeared at 29,000 miles. This engine was not molyed. Rebuilt with moly treated plates. Now done 60,000 miles. Still running pretty well but mechanically noisy. For the 60,000 miles it has been run on COMMA HD30.Commander no. 3 [sold to Dave Green & is his custom bike] Did, I think about 60,000 miles. 20,000 in my hands. Was running ok until the gearbox failed & I laid it up for about ten years. This was run by the police & myself on rotella 40 oil. I believe Richard stripped it & found excessive carbon which he put down to the wrong oil being used but it was run on rotella.Commander no. 4 bought with 2,500 miles from new. Has done 21,000 now so has covered 17,000 miles on Comma HD30 & about a 1,000 on Comp 2 just chucked in the tank with the HD30 when I ran out of oil at the T.T. This bike is running a treat & ticks over at a rock steady 500 revs & starts instantly. This is briefly my experience in 22 years of Norton rotary ownership to add to the oils debate. As to what is best I still have no firm view but feel confidant to carry on using the Comma HD 30 I have been using for 10 to 12 years.Cheers, Derek.

[Dell Boy]

P.S. Commander No. 2 has done 90,000 miles, 60,000 on Comma HD30.Derek.

[Malc]

Hi derek,I find your experiance over the big mileages interesting especially with regard to the smearing on some but not others. I also had oil pipes break on a couple of bikes, thats how my red track bike has a later engine, the original had a broken oil pipe in police use so an engine out of a written off bike was fitted. I was sent some replacement green oil pipe by the factory to cure the problem but after replacing on a few bikes, I was sent a message not to recall them as the replacement pipe was found to be worse than the original.When I ran an Interpol on the road I used Rotella because it was cheaper and it is proven to be ok.Derbyshire bikes had to be changed to Silkoline comp2 not because it was thought to be better but simply because Silkoline had won the contract to supply all lubricants to Derbyshire police at the time.When the contract was won, Silkoline who's main depot and testing laboratory was local asked what bikes were being run and didn't know initially what oil to send. A rep then came and recommended Comp2 pre-mix but apart from being expensive, this had not been tested or approved by the factory. I doubt if the factory could have done much more than read the spec sheet before I had to have every bike in and pump out any remaining rotella, fill with comp2 and bleed the system. Silkoline then said that should another company win the contract at a future date and the bikes had to be run back on a mineral oil then they would take no responsibility for any engine problems that may occur.As I have mentioned before, some bikes as your first Commander covered 90,000 miles without mollying and others would smear at very moderate or low mileages so the lubrication system would seem unlikely to be causing it.Derbyshire had no air cooled bikes smear but most water cooled with I think one exception. My friends Commander is used infrequently and is run on a cheap diesel oil and has never smeared and he has owned it from new so is not molyd. My air cooled track bikes are not molyd and the more extreme use again has caused no smearing so far and I have seen molyd engines also smear and the moly coating crack on an air cooled. At the moment, I am of the opinion to leave the engines alone until there is a problem and only then, if 2 or more surfaces need grinding to consider moly coating. I had one plate with some very small marks in it so lapped it on plate glass with griding paste.While on the subject a few people asked why I stayed with the air cooled bikes when I raced as they thought the water cooled bikes would be better. Well the answer was cost. I bought 2 Commanders, one to race and the other for spares but they still had the same poor gearboxes as the air cooled and for the short circuit races there was little advantage and I had been warned that the more power that was gained the less reliable the gearboxes became. So sold the Commanders and then circumstances meant the red bike only had about 600 mile trackday use of revving to 11,000, eating tyres, drinking oil and returning just over 20 mpg but what fun!Malc

[Assen]

Hi Malc,Concerning the oilpipes failing, how do they fail, slowly with a light leak or do they suddenly shear off, or...Do they become brittle due the oil passing through them like some fuelpipes do when passing petrol? Any advice on how to keep them in check/preventing a faillure?Perhaps it is wise to replace them every couple of years, to be safe?Mine look in perfect order, and if you like me don't like to fix things that ain't broke......what's wise??Groet, Jannes

[Dell Boy]

All my bikes after the first early Interpol have been fitted with the thin black plastic pipe & I have had no failures in 20 years. When a pipe breaks the gearbox fills up with engine oil, then the chain gaiter fills & eventually oil leaks out of various final drive joints. The early bike had large clear plastic pipes which heat hardened & snapped off in use.Derek.

[Malc]

As Derek says, the Interpols with the thinner black pipes are ok but many like mine still run the older version of the clear plastic tubing which I just keep an eye on. The trouble now is that apart from hardening with heat, the tubing, with age, will start to tear very easily so I generally pull on the pipes to see if they are ok around the banjo's where thy fit onto the oil pump. All the cases of breaking I have seen have been on one of the two feed pipes to the engine where the pipe bends round to fit onto the pump banjo.On assembly, the fitting and routing of these pipes is critical. When fitting the gearbox outer casing, the oil pipes pass through the rubber seal on their way to the copper pipes of the engine. It is essential to look through the inspection cover and if need be, shine with a torch and also feel that the oil pipes are routed with the widest possible radius. Sometimes the banjo may need to be slackened off and re-tightened to obtain this.The older pipes have small one way valves fitted, if re-fitting which I dont think is essential, just cut them out of the old pipe and push into the new pipe noting the direction they came out. These were one of the items that were essential until the factory ran of of stock. Malc