From "Stadter, Jim" Date Tuesday, November 13, 2001 4:31 pm To "928" <928@rennlist.org> Subject [928] nickasil (NPC) My brother just bought a '95 M3 last week. We were talking about BMWs in general and I mentioned to him the Nikasil issue that was brought up on this list a little while back. He just sent me this article which delves into the technical details of the problem. -- Jim Stadter '83 928 S 5-speed (U.S. spec) '88 928 S4 5-speed Hill Country Region PCA (Austin) ------------------------------------------------------------------- > BMW released the M60B30 and M60B40 V8's with the 93 model > year 5,7 and 8 > series. These engines ran until the 95 model year. From the 96 > model year, they were replaced by the M62B44. The 3.0L was > dropped in the > US, but the rest of the world got the M62B35, a 3.5 litre V8. > > There are many rumours about the fate of the M60 engine, but > only one is > true. The engines have been known to suffer damage to the cylinder > bores from the excessive amounts of sulphur in the US fuels. > The blocks are made of Nikasil, which is Aluminum > impregnated with Nickel > and Silicone. Apparently , sulphur reacts adversely with the Nickel > , causing very slight blemishes in the top few millimetres of > the cylinder > bore. The cylinder bores are crosshatched, which is the name > given to a > pattern scratched into the surface of the cylinder wall. > These scratches > help seat and seal the piston rings, allowing good compression. > > When the cylinder walls become damaged, the piston rings can > no longer seal > properly. As a result, the engine suffers from "leakdown". This is > the term given for the amount of air that can escape past the > piston as it > attempts to compress the air into the combustion chamber. A near new > engine , in good condition, should have a leakdown rating of > approximately > 5-8%. BMW's maximum allowable leakdown , on any engine, is > 15%. Anything beyond that requires repair to the engine. > > Leakdown can also be caused by poorly seated valves. > > The problem in the V8's manifests itself as an EXCESSIVELY > rough idle. These > engines, due to their performance oriented cam shafts, have a > noticeable "rock" at idle, this is completely normal. > However, excessively > rough idle will cause the entire car to shake, usually unevenly. The > problem can also cause the engine to lose so much compression > that it will > no longer start. > > While BMW was investigating the cause of the problem, several > different > methods of repair were tried. > > First, they decided to raise the operating temperature of the > engine, in an > attempt to get a better burn of the gas, and therefore lessen > the damage. > The benefits of this campaign , which included replacement of > the engine > EPROM and thermostat, were negligible, if existent. However, they > were an attempt to fix a problem that was not yet fully understood. > > Once it was decided the engines needed to be opened and > repairs made, the > first try was installation of new pistons and rings, this was > only tried > on a few engines and was immediately dismissed as not viable. > > Next step was to replace the short block assembly. This is > what is still > being done now, however, until the problem was 100 percent diagnosed > by BMW, the replacement short blocks were of the same material as the > original engines. This was not so much an oversight, but the only > possible way of keeping cars on the road until a permanent > solution could be > found. > > As a measure of good faith, BMW initiated an engine warranty, > covering all > internally lubricated parts, which includes the short block, for > 100,000 miles, or 6 years. Until this, the engines were only > covered under > the standard 4 year 50,000 mile warranty. > > Now, as the short blocks were being replaced with the same exact part, > future problems could be expected without a doubt. The result of this > situation is that some cars have had 2 and even 3 short block > replacements. > > As of early 1997, all replacement short blocks were of the > new material, > called Alusil. This material has been used in the V12 engines > since their > inception. No reason was given for the change to Nikasil, but > I'd like to > bet that guy no longer has a job. Anyway, Alusil does not suffer the > same problem as Nikasil and if the Alusil short block has > been installed, > you no longer need to worry about the situation. > > How do you tell which material is in your > short block ? > > That part is fairly easy. But it requires getting under the > right front of > the car. All M60 and M62 blocks have casting numbers on the > right side, > directly alongside the 3rd cylinder, slightly above the > coolant drain bolt. > > > These are the casting numbers to look for : > > > Nikasil M60B30 1 725 970 or 1 741 212 > Nikasil M60B40 1 725 963 or 1 742 998 > Alusil M60B30 1 745 871 > Alusil M60B40 1 745 872 > Alusil M62B44 1 745 873 NOTE, all M62 engines are Alusil. > > This is the only way to determine which M60 you have, short > of removing a > cylinder head. > > In performing engine repairs or rebuild procedures in the > future, it is > imperative that you correctly identify the cylinder block, as > the pistons > and > rings used in each style are different and not interchangeable. > > What do I do if my engine idles rough ? > > If you feel your M60 is idling roughly, make an appointment > with your dealer > for an idle quality check. This check is free, under the conditions of > the 100,000 mile engine warranty. During this test, the > technician hooks the > car up to the BMW diagnostic computer system, which monitors the > condition of the engine. If, during this test, the computer > finds that there > is a potential problem, it will order the technician to > perform a manual > leakdown test. If the tech finds any ONE cylinder to have > more than 15% > leakdown, you will be advised of the need for a new short block. You > will then be requested to either leave the vehicle, or make > an appointment > to bring the vehicle back. The dealer will require the car for > approximately 5 days, during which , they are to make a > rental or loaner car > available to you. If you have the test performed, but the results do > not show the need for a new engine, do not go running to the > next dealer for > a new test. The dealer gets paid by BMW for his time, however, > repetitive testing will not be covered, so the second dealer > will not get > paid for his time. This is unfair to the dealer. If your car > passes, but > you > feel it should fail, take it in for another test in a few months, not > straight away. > > -------------------------------------------------------------- > -------------- > -------------------- > "For heart that is pitiless counts not the power that pity hath; > nor foresees that of gentle ruth for anguish and for valour > overthrown, > stern anger may be forged, and a lightning kindled before > which mountains > fall." > The Quenta - Brief History of the Noldoli (High Elves), by J. > R. R. Tolkien > >