Rebuilding the w123 300D injectors WITH PICS
Posted: Sat 08 Sep, 2012 6:21 pm
Hi everyone.
Some of you may be aware that I imported a bunch of Monark nozzles for the w123 diesels. I still have quite a few sets left- check the parts for sale thread for details.
I finally found some time today to dedicate to splitting a set and prepping them for new nozzles. I will post up the progress including pictures for each step of the way and for those folks looking for some more help there is an excellent pictorial here: http://vincewaldon.com/index.php?option ... &Itemid=28 with great high resolution pictures and a good explanation of the process. I am also happy to answer questions if I can so post away and if I can't answer then surely someone else can on these great boards.
The early 300D had injectors set to open/pop at 115bar, and the later more powerful cars' (post 1980 brains trust?) injectors opened at 135bar. If you are looking for a set to match your own car then this information is clearly written on the outside of the injector.
So splitting them: Keeping each injector's components seperate I then soaked the parts in carburettor cleaner to remove as much varnish and gunk as I could.
Some of the injectors had a thick caking of carbon deposits between them and the body of the nozzle that was so thick I had to use significant force to remove the nozzles. This was probably due to leaking/absent/used heat shields on the car these came from. A lesson to use new heat shields.
Here is what the carbon looked like on the nozzle: And again in the body: The surfaces that need to be lapped were scored and pitted, looking much like this for all of them: After a careful pass over the 1500 grit to remove the bulk of the damage I moved to the much finer 3000 grit to polish them to near mirror shine. I used sandpaper on a sheet of glass as my lapping surface, and ATF as the fluid medium. I used the ATF under the paper to keep the paper from moving around and regularly added it to the surface of the paper. All surfaces look more or less like this now: Once I get my 27mm deep socket back from getting machined, and find a little time I will reassemble them and I can start testing them for leaking and opening pressure. Stay tuned...
Some of you may be aware that I imported a bunch of Monark nozzles for the w123 diesels. I still have quite a few sets left- check the parts for sale thread for details.
I finally found some time today to dedicate to splitting a set and prepping them for new nozzles. I will post up the progress including pictures for each step of the way and for those folks looking for some more help there is an excellent pictorial here: http://vincewaldon.com/index.php?option ... &Itemid=28 with great high resolution pictures and a good explanation of the process. I am also happy to answer questions if I can so post away and if I can't answer then surely someone else can on these great boards.
The early 300D had injectors set to open/pop at 115bar, and the later more powerful cars' (post 1980 brains trust?) injectors opened at 135bar. If you are looking for a set to match your own car then this information is clearly written on the outside of the injector.
So splitting them: Keeping each injector's components seperate I then soaked the parts in carburettor cleaner to remove as much varnish and gunk as I could.
Some of the injectors had a thick caking of carbon deposits between them and the body of the nozzle that was so thick I had to use significant force to remove the nozzles. This was probably due to leaking/absent/used heat shields on the car these came from. A lesson to use new heat shields.
Here is what the carbon looked like on the nozzle: And again in the body: The surfaces that need to be lapped were scored and pitted, looking much like this for all of them: After a careful pass over the 1500 grit to remove the bulk of the damage I moved to the much finer 3000 grit to polish them to near mirror shine. I used sandpaper on a sheet of glass as my lapping surface, and ATF as the fluid medium. I used the ATF under the paper to keep the paper from moving around and regularly added it to the surface of the paper. All surfaces look more or less like this now: Once I get my 27mm deep socket back from getting machined, and find a little time I will reassemble them and I can start testing them for leaking and opening pressure. Stay tuned...