Fuel filter question......the round spin on one
 

When you install the round spin on filter are you supposed to put diesel fuel in there prior to installing it ? I just put it on my car without anything and it took me about 10 minutes to start the car. Did I do it wrong or something ? I didn't think that no fuel in that particular filter would affect anything....

thanks...

yes sir, fill her up and it's a great time to fill the filter with Diesel Purge or Redline fuel conditioner.

Kamil,

As you have demonstrated, it is not required, but for the life of the starter, it is recommended. I fill mine with RedLine Diesel Fuel Catalyst, or, if I have no RedLine, I pour the fuel from the old filter into the new filter. On W123's I then pump the hand pump until I think the air is all out. Typically the sound changes to a grindy noise and the air bubbles in the clear line to the filter housing become rare. On the newer cars, no hand pump, so you have to run the starter to purge the system. The less air in the system, the faster the system fills and the sooner the car starts. Jim

I've heard that if you prefill the filter it can allow unfiltered grit into the I.P. if your fuel isn't absolutely clean....

if the filter is old yes this is true. If you remove a filter for inspection do your best to not let the fuel in the filter flow across the top from the holes in the top (dirty fuel) into the center opening. (clean fuel area.) Keep it nice and level or stuff a clean rag or something into the center to plug it. remove the plug if you reinstall the filter.

New filter: If there is no blowing sand around you should be fine. If your picky make sure you fill the filter up thru the small holes and let the fuel flow thru the filter thru into the center clean fuel area.

PS. Dont forget to pump the hand pump and bleed air out that way after installing the filter.

Do I have it backward? Think I got this right. This fuel filter does "recieve" fuel thru the small outer holes and the fuel is then filtered when it travels thru the element into the center ready for sending to the IP.

Coach,

Keep your finger over the center hole while you fill the filter thru the small holes. Just release your finger enough to let the air out.

That will keep any dirt out of the center section that has the filtered fuel in it.

P E H

FUEL FLOW ?
 

Can someone please explain fuel flow from gas tank to the engine ? What components does it hit and which filters does it go trough first ?

Thanks

Kamil,

First, MB Diesels or any other Diesels except some old Gas start Diesels do not have a gas tank. They have a fuel tank. They don't have a gas pedal either.

OK. Now to answer your question: From the fuel tank, the fuel goes first thru the tank strainer then thru the fuel line to the inline filter and into the fuel pump (and also thru the hand pump when it is being used). Next it goes to the canister filter where some is bled off into the return line to remove air. The injection pump is next in the fuel flow where some is pumped to the injectors and the remainder is released by the pressure valve and sent to the return fuel line. At the injectors, most of the fuel is injected into the engine but a small amount escapes past the injectors and is routed to the return line. The return line goes back to the top of the fuel tank and dumps the excess fuel and any air back into the fuel tank.

P E H

Nice.... thank you :)

Thanks.

Both GMC Diesel trucks I have had, a 1983 and an '83, had no hand pump on the fuel system. I found out after ruining 6 batteries, two per truck, that the easiest way to get fuel to the engine after changing filters or running out of fuel is to go to your local fuel injection service co. and buy a small inline hand pump. I don't remember the name of the co. that makes them but they are worth their weight in gold.

I installed them in the tank line just before the primary filter and tapped a bleed hose into the line that goes from the secondary filter into the back of the injection pump. By opening the valve in the bleed hose I could pump fuel into both filters and right down to the back of the injection pump. About 3 seconds of cranking and I was back in business.

with my diesel's, I do like Jim said but, instead of dumping diesel from old filter to new, I keep a 1 gal. gas can of diesel, I fill my new filters from that. I then dump the old fuel into a 1/2 gal. can and use that to clean parts and as a hand cleaner. enjoy

return line terminus
 

I think I remember reading somewhere on the forum that the fuel return line goes into the BOTTOM of the fuel tank, and that some people have switched the two lines there to avoid cleaning a clogged tank screen. One might test this by blowing through the tubes when the fuel level is low and listening for bubbles.

PEH, in the W123, the return line goes to the BOTTOM of the fuel tank, not the top.

Tony,

On my '79 300SD, from underneath the car, I can't see where the return line goes back into the tank because the tank is in the trunk an donly the outlet is visable. I thought the return line went in the top of the tank because I had a leak in the return line and it only leaked after the car was run which would fill the return with fuel. Seems like if the return line went into the bottom of the tank, it would have leaked all the time.

I wonder if the return could go into the bottom of the tank and extend to the top????

P E H