'75 w115 300D without Primer Pump! - PeachParts Mercedes-Benz Forum

warmblood58 · #1 04-29-2011, 09:49 PM

So apparently my primer pump was removed and I need to replace all filters on this neglected beast - a good prime procedure in lieu of a primer pump? This car has not run in awhile so it needs a full service, valve adjustment, etc. - best way to prime minus a prime pump? Thanks!

Diesel911 · #2 04-29-2011, 10:24 PM

On some of the older models the Fuel Filter was not a Spin-on type Fuel Filter.

I have seen pictures where bolted onto that type of Filter Housing was a Hand Primer; sort of a large Button that you pushed.

The only think I can think without a Hand Primer that would help is if you filled the Filter Housing with clean Diesel Fuel.

Also, while I do not know if your Fuel Injection Pump has one but the older Bosch Fuel Injection pumps used to have one or 2 Air Bleed Screws on the Fuel Injection Pump Housing so that when you cranked the Engine the Air Quickly bled out of the Screw.

vstech · #3 04-30-2011, 12:13 AM

what I do is unhook the return line, cap off the line going to the tank, and leave open the line leaving the filter... then hook a shop vac blowing into the fuel filler neck.
a few seconds later, fuel flows through the filters, and out the return hose... then hook it back to the return line, and voila! primed.

warmblood58 · #4 04-30-2011, 03:58 AM

Quote:

Originally Posted by vstech

what I do is unhook the return line, cap off the line going to the tank, and leave open the line leaving the filter... then hook a shop vac blowing into the fuel filler neck.
a few seconds later, fuel flows through the filters, and out the return hose... then hook it back to the return line, and voila! primed.

I like it! I will give it a shot -thanks vstech!

Stretch · #5 04-30-2011, 05:16 AM

Quote:

Originally Posted by vstech

what I do is unhook the return line, cap off the line going to the tank, and leave open the line leaving the filter... then hook a shop vac blowing into the fuel filler neck.
a few seconds later, fuel flows through the filters, and out the return hose... then hook it back to the return line, and voila! primed.

That is nice - have you tried blocking off the tank vent to get an even quicker response or isn't that necessary?

1980sd · #6 04-30-2011, 05:17 AM

Quote:

Originally Posted by vstech

what I do is unhook the return line, cap off the line going to the tank, and leave open the line leaving the filter... then hook a shop vac blowing into the fuel filler neck.
a few seconds later, fuel flows through the filters, and out the return hose... then hook it back to the return line, and voila! primed.

I'd probably just fill my tank with sawdust...

Stretch · #7 04-30-2011, 05:29 AM

Quote:

Originally Posted by 1980sd

I'd probably just fill my tank with sawdust...

Ha! In the cold it might even work as an anti gelling agent I think you're on to something there...

Palangi · #8 04-30-2011, 08:50 PM

See that round disk lookin' thingy next to the fuel filter??

That's your primer pump. The 115 300D had a different style than all the others.

Diesel911 · #9 05-01-2011, 12:50 AM

Some one posted some pics of the Hand Primer in the other thread he started.

kerry · #10 05-01-2011, 12:58 AM

You could also put a Mity Vac on the cigar hose return line and suck fuel thru the system.

warmblood58 · #11 05-01-2011, 01:17 AM

Quote:

Originally Posted by kerry

You could also put a Mity Vac on the cigar hose return line and suck fuel thru the system.

As always Kerry, you are a man of impeccable reasoning! Easy, fast solution, thanks!

funola · #12 05-01-2011, 08:53 AM

Quote:

Originally Posted by vstech

what I do is unhook the return line, cap off the line going to the tank, and leave open the line leaving the filter... then hook a shop vac blowing into the fuel filler neck.
a few seconds later, fuel flows through the filters, and out the return hose... then hook it back to the return line, and voila! primed.

The problem I see with this practice is that the air coming out of the shop vac may not be clean air. Safer to use an air compressor on low pressure or a bicycle pump.

vstech · #13 05-01-2011, 12:13 PM

Quote:

Originally Posted by funola

The problem I see with this practice is that the air coming out of the shop vac may not be clean air. Safer to use an air compressor on low pressure or a bicycle pump.

this is a good point. if your shop vac has dust etc in it, you'd have to clean it first. but the filter in the shop vac should catch any large particles...
most shop vacs have a decent filter on the output air joint... Mine is HEPA rated... I'm good with that for my fuel tank.

warmblood58 · #14 05-01-2011, 01:49 PM

Quote:

Originally Posted by Palangi

See that round disk lookin' thingy next to the fuel filter??

That's your primer pump. The 115 300D had a different style than all the others.

yea, which is why I posted here - no pump, it was removed apparently =