Fuel distributor piston spring

[alabbasi]

Does anyone know where I can get a fuel distributor piston spring? I managed to lose mine while trying to clean the fuel distributor (V8)

[Robert Squires]

* "Fuel distributor piston spring"! What are you referring to? There's no spring on a K-Jetronic plunger (what you're calling a piston?). Or are you talking about the spring in the line pressure regulator? That, along with some shims, is probably available in a pressure regulator kit from MB.
* Disassembly of the fuel distributor (splitting the halves), if that's what you're doing, isn't particularly a good idea. The major parts are lapped in and precisely assembled, something you're unlikely to duplicate on the bench. Better to run a strong cleaner through it. Most likely whatever symptom you're trying to cure is caused by something else anyway. The fuel distributor isn't a very common replacement item (yet it gets blamed for a multitude of sins).

[alabbasi]

Hey there, thanks for responding.

I'm talking about this part. I did not split but in an effort to clean it the piston came out and so did the spring. I cannot find the spring.

[Robert Squires]

* I got out a KE-Jetronic Bosch manual and looked for that spring on the central plunger. You're absolutely right! There it is. The Bosch manual says that "In some versions a pressure spring is used to assist this hydraulic force (line and control fuel pressures). It (the spring) prevents the control plunger from being drawn up due to vacuum effects when the system cools down." So the good news is that the spring is an engine-off assist, and that you could probably adjust out the pressure-effect difference, with the engine running, caused by the spring (if you couldn't find another spring).
* I would try to find a core fuel distributor off the same model MB. Tell the dismantler/junk yard/independent that you don't necessarily need a FD that works because you just need that spring. Then again, if your initial problem was fuel distributor related, a good used FD should take care of both problems. Don't forget the o-ring and the fact that you'll need to reset duty cycle (idle mix).

[Benz Mercedes]

I may have one for a 380 , i'm not sure if it will fit your V8 what model do you have , also , I'm curious as to how you could take a picture of a spring that you can't find .

[alabbasi]

Hey there and thanks for your offer. The picture was taken from the web and is not from my distributor. I was fortunately able to find the spring while cleaning up the shop and quickly put it back in the distributor.

Thanks again.

[Benz Mercedes]

glad to here that , i'm sure you went through some frustration until you found it .

Brian

[alabbasi]

I had to step away before i head butted something!

[jhodg5ck]

I know that picture...;-) Pictures detailing the complete tear down are available on my site.

Jonathan

[alabbasi]

Originally Posted by jhodg5ck

I know that picture...;-) Pictures detailing the complete tear down are available on my site.

Jonathan

Yep, credit goes out to Jonathan who provides a detailed description of the tear down. One of the many times that his resourcefulness has helped me in the past.

[GerritDr]

Originally Posted by alabbasi

Hey there, thanks for responding.

I'm talking about this part. I did not split but in an effort to clean it the piston came out and so did the spring. I cannot find the spring.

I know this Thread was quite some time ago but I might have a likewise issue with the Kjet of my Porsche 928S of 1980 :
Car starts hard warm+cold when car is started after 1h or when engine is completely cold.
I can also always here a little squealing sound during the priming of my pump before the actual start...
Once started, and I cut engine after 5 secs and try to start again it always start properly.
Could the spring (or missing spring) on top of the plunger be the root cause ?

I have a FD with Bosch nr 0438 100 027

[Frank Reiner]

GD:

For both hot & cold starts look first to the condition of the fuel accumulator.

[GerritDr]

Hi Frank,

Accumulator is new, I also put 8 new injectors because I thought they were leaking
Same for WUR
Control pressure cold and warm is in range
and my system pressure is also perfect

Gerrit

[Frank Reiner]

Next step:
Leave a pressure gauge connected to read system pressure after shutdown.
The initial drop after shutdown should be to about 40 psi. Thereafter the decline should be on the order of 1-2 psi per hour.
If the pressure drops to zero in a matter of minutes, look to the o-rings in the pressure regulator.

[GerritDr]

Frank,

The system pressure after shutdown is
2,8 bar (40,6 psi)
After 10 minutes : 2,7 bar (39,1 psi)
After 20 minutes : 2,6 bar (37,7 psi)
After 30 minutes : 2,5 bar (36,3 psi)

So it takes about 5 till 6 hours before pressure is completely dropped till 0