Path of fuel through a 1985 123 wagon - PeachParts Mercedes-Benz Forum

MeinGreaseCar · #1 11-22-2015, 07:00 AM

OK.. I've owned a couple of diesels. 1985 126 and a 1991 124.

I just inherited from a friend the passed.. a 1985 123 wagon. He has the 'grease car' kit on it. He's had troubles over the years (i'm not sure if the install is bad or not)

I'm trying to figure out where he strayed from factory. I think I can address the grease issues later, as I make home brew biodiesel. Running that unwashed and heated is my plan, and it would be MUCH more forgiving that stuffing the fuel lines, filters, and tank screen with sludgy, poor quality grease that he did on MANY occasions.

Anyway. My question is thus.

I'm ASSUMING that the diesel lines to and from the tank are this way (line the tips up at a 45 degree angle is the 'return to tank' line)????

The path of fuel in my other cars was from tank, through pre filter, through lift pump thru filter housing, through injector pump, then injector return line back across top of filter housing with the outlet back to above bent line return to tank.

That is NOT the way this 123 is at the moment. It goes through the filter housing, then lift pump, then injector pump.

I'm having trouble with priming it. I'm sure the small hand pump isn't in that good of shape.. I was thinking of using air to pressurize the return line (and tank) a small amount to get flow going again.

I'll deal with the grease system later. I'm just trying to get back to diesel operation. Car was running fine, but when I got messing with the grease system (trying to figure it out) I lost prime and have been swearing ever since.

Thanks Much.

JP

vstech · #2 11-22-2015, 10:02 AM

Correct. Bent line is return. Path is as you described. If single tank was used, or main tank was for grease, you've got a job ahead of you.

funola · #3 11-22-2015, 11:13 AM

Quote:

Originally Posted by MeinGreaseCar

.. a 1985 123 wagon. He has the 'grease car' kit on it. He's had troubles over the years (i'm not sure if the install is bad or not)
..................

That is NOT the way this 123 is at the moment. It goes through the filter housing, then lift pump, then injector pump.

I'm having trouble with priming it. ..... (trying to figure it out) I lost prime and have been swearing ever since.

Your car has been changed from a pressure to a vacuum fuel system. The orifice in banjo bolt in the secondary filter housing has been plugged and must be unplugged if you want to go back to a stock fuel system. What you have is very difficult to prime once you lose prime. Best advice I can give is use a Mityvac in conjunction with the priming pump.

MeinGreaseCar · #4 11-23-2015, 11:55 AM

Quote:

Originally Posted by funola

Your car has been changed from a pressure to a vacuum fuel system. The orifice in banjo bolt in the secondary filter housing has been plugged and must be unplugged if you want to go back to a stock fuel system. What you have is very difficult to prime once you lose prime. Best advice I can give is use a Mityvac in conjunction with the priming pump.

A ha.. I do have a mighty vac. I'll give that a try.

So it's SUPPOSED to be like that now with the grease kit? It's not a single tank.. but I know my buddy sludged up the main tank at times (not sure if not installed right, or not performing right)

It looks like the greasecar kit runs a single supply line from the tank. so you essentially have one fuel valve that controls supply.. then the other fuel valve decides if it's going to LOOP the return OR return to tank. Mine seems to be sending fuel from the diesel tank TO the grease tank when set to grease mode.

We'll see. For the moment i just wanna prime the sucker!

JP

MeinGreaseCar · #5 11-23-2015, 04:39 PM

Think I've got it! I got it to run several times. I was able to repeat my success of getting it primed after changing configuration.

I've messed around a few times with it. I just put a heck of a vacuum on with the Mighty Vac.. and wait. bubbles keep pulling through.

I need two lengths of hose to get the greasecar kit all set up. There's really no way to 'half' set it up to test it. I was able to pull the hoses, take apart a few valves and learn how the valves work. With the car off, and the valves unplugged.. I went simple and just blew air thru the valves to confirm how they work in diesel, grease, and flush.

Should be up and going tomorrow. My plan is to run biodiesel in the grease tank. will clean out the main tank this summer with some straight B100 in it too.

JP