injector seal for a 1972 450SL

[erubin]

I want to replace the seals on my fuel injectors. The shop manual shows two different styles for the lower seal. The 116-078-04-73 seal has a step in the seal and 116-078-07-73 has no step so it looks like a small cross section of hose. They don't state how to choose the correct one.

the engine is in a 1972 450SL but the injectors were replaced in 1986 with the double barbed injectors 000-078-34-23 that don't use a hose clamp in 1986. Should the lower seal match the old 1972 intake manifold or should it match the newer 1986 injection valve (1986)?

[erubin]

i ended upo buying a set of 8 of each type since they are cheap. The old seals turned out to be the ones with a step (116-078-04-73) so I used those.

The hardest thing in this job is making sure no grit gets into the intake through the injector holes. Even after cleaning with compressed air--> brake cleaner--> compressed air before removing the injectors there was still grit in the holes upon removing the injectors. I duct tapped a small dia hose to my shop vac to vacuum out the grit that remained with the injectors removed. With a flash light i could see a few pieces of grit in the intake and vacuumed them out as well by sticking the small vacuum hose into the hole.

Soaked the injectors for 24 hours in Techtron injector cleaner and changed the injector hoses with the special kit. Everything is running fine now. the biggest improvement was changing the fuel pressure regulator. Now I have immediate start up hot and cold since the preesure reg keeps the injectors pressurized for hours/days after shutting down the motor.

[Tomguy]

000-078-34-23 = MB P/N = Bosch # 0 280 150 036? I believe these are the stock injectors (all 8 of mine were these numbers, at least). I would assume by "single barb" you are reffering to Bosch # 0 280 150 024? Same color scheme, same flow rates, but these have a screw-clamp instead of a bottom clamp-ring.
The 450SE at the junkyard had 4 024's, and 4 036's. The 024's were used stock on Volvo B30E engines. All of them have been replaced by the p/n with 036 at the end.

Both of these had identical nozzles, the ONLY difference is the single-barb w/screw-clamp VS double-barb and clamp-ring.

You sure the injectors were replaced? They might be 32 years old... not that it's bad per-se, but just check each one for leaks...

[erubin]

I replaced all 8 injectors in 1986 when i completely restored the engine. i don't recal what the original injectors looked like or their part number. the ones i got in '86 have a bosch number on them: 280 150 036. A search on the internet (or was it the shop manual?) showed that these cross to MB P/N 000-078-34-23.

These injectors have a double barb and hose clamps should not be installed on the injector (per MB). Removoing the old hose requires some cutting and tearing and you must not cut in with a razor blade or knife as this can score the aluminum barbs and lead to leaks. MB recomends removing the old hose with the help of a soldering pensil. The REPAIR KITS COME WITH A SECTION OF HOSE, A HOSE CLAMP AND A steel ring. The clamp gets mounted on the fuel ring side of the hose, not the injector itself. For this reason i decided to buy the MB kits since the hoses fit perfectly on the double barb and don't leak even without a clamp.