Diesel Primer Pump Replacement
on the 1985 300SD
by pwogaman
11/29/04
I've gotten loads of free advice from this and other forums. Now it is my turn to share some guidance.
This past May I replaced my original leaking fuel primer pump. It is a simple painless operation that took about 30 minutes - 15 of which was spent taking the attached pictures.
The location of the existing fuel primer pump (next to the injector pump).
![image](http://www.peachparts.com/diy/primerpump/photo_a.jpg)
![image](http://www.peachparts.com/diy/primerpump/photo_b.jpg)
The updated replacement part - I paid about $30.00 from a dealer simply because I was on travel and did not want to wait to find it cheaper.
![image](http://www.peachparts.com/diy/primerpump/photo_c.jpg)
Use a hose clamp (I used vise grips) to close off the fuel line after the first stage filter (the clear one).
![image](http://www.peachparts.com/diy/primerpump/photo_d.jpg)
Using a screwdriver, loosen and remove the fuel hose.
![image](http://www.peachparts.com/diy/primerpump/photo_e.jpg)
Using either a 17mm or 19mm socket with an extension, remove the fuel line fitting.
![image](http://www.peachparts.com/diy/primerpump/photo_f.jpg)
Setting the fuel line fitting aside (on top of air filter)
![image](http://www.peachparts.com/diy/primerpump/photo_g.jpg)
Now you have room to access the old primer pump
![image](http://www.peachparts.com/diy/primerpump/photo_h.jpg)
Remove old fuel primer pump with a 24mm open end wrench (note pinched off fuel line at bottom of photo.
![image](http://www.peachparts.com/diy/primerpump/photo_i.jpg)
The new and the old parts compared. The new part came with an adapter that was not required in my application.
![image](http://www.peachparts.com/diy/primerpump/photo_j.jpg)
Clean up and ensure you have removed the old copper washer.
![image](http://www.peachparts.com/diy/primerpump/photo_k.jpg)
![image](http://www.peachparts.com/diy/primerpump/photo_l.jpg)
Install new fuel primer pump with a 17mm or 19mm open end wrench.
![image](http://www.peachparts.com/diy/primerpump/photo_m.jpg)
Replace the fuel line fitting, tighten, and enjoy the completed project!
![image](http://www.peachparts.com/diy/primerpump/photo_o.jpg)
Next I'll work on posting my project of adding rear headrests. I did this in under an hour with used brackets and leather headrests I got from mercedesdismantlers.com out in L.A. for under $100 - shipped! If done properly it will be no different than if it was factory installed.
- pwogaman
CategoryDiy