L jet fuel injector bolt gaskets

Post your E12 technical questions and comments here. Please, no off-topic posts.

Moderators: Mike W., Pierre

Post Reply
LandShark
Posts: 10
Joined: Thu Jan 09, 2014 3:49 am
Location: ABQ NM

L jet fuel injector bolt gaskets

Post by LandShark »

You know those ceramic like gasket/ washers that insulate both sides of the mounting bolt on L-jet injectors...

Does anyone have a theory on what purpose these gaskets serve?
76' 633 CSi
PatinaBeforePolish
Posts: 300
Joined: Sun Jan 18, 2015 1:22 pm
Location: Baltimore, Md.

Post by PatinaBeforePolish »

I just picked up a set and the parts manager and I were wondering the same thing and also how many people bother to replace them. They look like cardboard but are actually tough like a phenolic resin material. The guess is they're there to absorb vibration - it's kind of an unusual set up but must serve a purpose like everything BMW.
79 528i
LandShark
Posts: 10
Joined: Thu Jan 09, 2014 3:49 am
Location: ABQ NM

Post by LandShark »

Thanks, I figured they were vibration dampers. We want those injectors to last as long as possible.
76' 633 CSi
T.Hanson
Posts: 1696
Joined: Wed Jul 26, 2006 7:39 am

Post by T.Hanson »

Wanting the injectors to inject as long as possible, yes ! Bordering on surreal I think at least one set of mine are original, never cleaned or replaced.

I have asked the experts here about adding any injector sauces. Admitting I know nothing about them, suspect most are snake oil,... if that. I have done it anyway. Maybe once a year, eight months.

Assuming discovering a bad injector announces itself as a rough runner, dead cylinder. Start the show, ignition, fuel,... it hasn't happened to learn how to (pull the rail) find the bad injector.

If anyone has read this far, is it a good idea to have old injectors tested,... BEFORE installing them to the hose fittings, rail, UNDER the throttle body manifold,... etc. ? Or...

Is the general opinion a visual inspection and proper assembly will suffice for a same result ? Generally the silly things keep working.
PatinaBeforePolish
Posts: 300
Joined: Sun Jan 18, 2015 1:22 pm
Location: Baltimore, Md.

Post by PatinaBeforePolish »

Re: injector secret sauces- The most miles I ever put on a BMW was 235k on an 02 325i. I treated it to a round of liqui moly fuel injection and valve cleaner every 60k and when I sent out the original injectors at 200k they tested almost like new for flow. Some may disagree but I primarily use Shell and sometimes Sunoco or BP in the hopes of cleaner gas with additives that help keep things clean.

If you have the injectors out, I recommend sending them to Mr. Injector. They flow test before and after ultrasonic cleaning and install new hoses and clamps on the injector end for about $16 each. They also provide new seals incliding the large one on the clamping side. Ultrasonic is the only way to go and if you want to be really clean, have the intake runners, manifolds and plenum done as well- they get pretty gunky over the years and miles.

You may also want to check the injector rail for corrosion - they're available new if you need a replacement.
79 528i
Post Reply