Ok so I have rough idle, knock loudest after start but now I can still hear it after motor warmed up, instant start, decent power, rebuilt injectors, compression of 290 in #4 and 390 in the others. Seems like a bad valve guide as I can hear air leak near #4 at the head when turning it by hand. Valves have been adjusted and checked again for good measure. No oil in water or vice versa.
Does low compression cause knocking? Otherwise I fear lower end badness. Doubt injection pump problem as this is new at about 190k On Oct 4, 2014 10:26 AM, "Peter Frederick via Mercedes" < mercedes@okiebenz.com> wrote: > There are several things that can cause rough idle with instant start -- > most probably are different pop pressures between the injectors, which is > more or less inevietable with age and use, and leaking pressure valve > seals. Very rare for the pressure valves themselves to leak, but I suppose > it could happen. > > A badly balanced IP could do the same thing, but would have done so from > the factory in most cases. It is necessary to adjust the rack for each > plunger set so they deliver exactly the same amount of fuel as the others, > and if that is wrong, or the clamps on the rack slip or the plunger set > comes loose and shifts, you will get both different amounts of fuel > injected at idle for the different cylinders, and the exact timing of > injection can also be different. The result is rough idle. > > The usual cause is worn injectors -- different pop pressures, worn nozzles > giving different or very poor spray patterns, etc. > > SEcond in line is leaking delivery valve seals, but again, this isn't a > problem that occurs with time, usually it's a result of them not sealing > properly when the 0-rings that seal the delivery valves off from the > outside start to leak and have to be replaced. > > Tight valves on a 615 can cause trouble, but it's usually accompanied by > hard starts due to compression loss. Ditto for a leaking head gasket. > > Peter > > _______________________________________ > http://www.okiebenz.com > > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > > All posts are the result of individual contributors and as such, those > individuals are responsible for the content of the post. The list owner > has no control over the content of the messages of each contributor. > _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: https://server.secureplusplusfour.net:2083/cpsess595060604/3rdparty/mailman/listinfo/mercedes_okiebenz.com
