Fuel line - what diameter for priming pump?
 

Hi all,

I have decided to install a hand priming pump to my engine, they are only a few pounds and my OM606 doesn't have a manual pump like earlier OM603 engines. The system is self bleed but I have had issues recently with air in the lines, once I then try and reseal different lines to chase the leak I need to re-prime the system. This is fine usually as the battery is at full power and can crank for ages. I have also recently had an issue with there is air in the lines as well as the battery draining slightly - the car isn't a daily drive. This means that I am sometimes having to try and run the starter motor for ages to get the air pumped out again (there is still a leak somewhere) but this sometimes means that the battery runs down without the car starting. I want to install one of the manual hand priming bulbs onto the inlet pipe so that I can manually pump some fuel from the tank around the system meaning far less cranking.

Just wanting to know the correct size line I need - I believe its 6mm but just want to check before buying one!

My experience with Hand Primer Bulbs was back in the 1975-1989. The quality is poor and they rubber on the bulb cracks within 1-2 years when they are left on as a permanent part of the Fuel Supply System.
But, maaybe things are different now.

As for the line size the inside diameter sould be similar to the inside diameter of the lines that are on the Car now.

On my 617.952 on the 300D the Fuel Inlet Hose is 7.5mm ID but 5/16" ID hose works fine.

Hmm I think I will just look to fit an electric pump - I think I have found the air leak (again!) but good to know for the future.

An om603 has a manual pump?

None that I am aware of... Maybe the 84 OM601? I think he made a typo and it should be "earlier mb Diesel engines, or earlier OM 61X engines"

My 84 OM601 has no primer, it's just your standard self bleeding lift pump like all other 60x engines.