Crack that injector and intank filter - PeachParts Mercedes-Benz Forum

treetops · #1 09-10-2014, 03:25 PM

Jeeze I really hate to ask this-kinda feel like if have to ask I shouldnt be doing it, BUT where do I crack the injector and wheres the intank filter/stainer? Long story short I've got the common knock at idle and cracking that injector and/or changing that filter seems to be the common 1st steps.

Do I crack it at the top were the fuel line connects or in the middle? I've read both as well as at the IP.

Now, I've change both filters in the engine bay, prefilter shows green diesel, but the bubble is quite large and I think I can see some exiting towards the pump letting air in. Also looks like the flow from the tank is a bit off or weak, thinking intank filter or strainer. The fuel lines connect to nipples on the tank by the differential. Only thing I can clearly see a hexagonal fitting bottom center of the tank with no hoses, is that it?

Thanks

Treetops
w124 OM603.96

leathermang · #2 09-10-2014, 03:35 PM

That is certainly an attitude which can pay off in the long run... I have ruined many a nice thing being just one step farther than the information I should have had.

DO NOT TOUCH the injector pump..

You open the hard fuel line AT THE INJECTOR.... just a little...
just enough for fuel to escape....and where you can re tighten it fast when you want to....

Don't worry about the bubble... I do not think there is any way to get rid of it...
if you have fuel with no air at the injector you are fine.

Diesel green ? Are you saying you think you need to treat your system with Biobar or something to kill that ' green ' stuff ?

Have you pumped your hand pump.....? and made sure it is tightened back down afterwards... if it is leaking... it will leak air...and you will have to do something to fix that situation...

On your car I do not know where the in tank filter is... I only have 123 manuals..

junqueyardjim · #3 09-10-2014, 03:53 PM

Treetops - maybe you should change that to "Out there, lost in the weeds". Hey, whatever you are reading (or smoking) put it away. Sounds like your car is running. They mostly all knock a little at idle. Oh, I am not understanding your line and it is not starting and you feel you probably have air in the system. OK, then loosen the nuts a little bit where the end of the injector lines, (steel) threads to the end of the injectors. Then crank the engine with the starter until fuel begins to "weep" out. Tighten the nuts and engine should start.

treetops · #4 09-10-2014, 04:21 PM

Oh leather, I now know that feeling and no I did not touch the IP. Thanks for the where to info. No green as in the color of diesel around here.

Yeah Jim the car runs well and perhaps there is no problem and no I dont smoke, that crap is too strong these days. Still think the knock is louder than typical and was following things I could do anyway thanks.

Diesel911 · #5 09-10-2014, 08:33 PM

Diesel Fuel For Cars and Trucks that are on the Road is supposed to be dyed Green.

Diesel Fuel for off road use like Farm Equipment is dyed Red.

In the past Disel Fuel was some shade of yellow. In fact the first time I encountered Off Road Diesel I though the Fuel had Rust in it as I had previously seen when the Steel Fuel Tank the Diesel Fuel was in was rusting inside. However, the Fuel Tank was Aluminum.

Later I learned the truth.

Quahog · #6 09-10-2014, 10:02 PM

despite the snark, junque has good proceedural advice, if you have an injector that is out of spec and 'nailing', with the car running, cracking the line @ the injector will disable it -smooth out the sound-until you tighten up again.

The car may idle rougher for it, but you are listening for change/reduction in the clatter. Do each one in turn to isolate a bad injector(s). If the relative change is the same across all 6, then that is 'normal' or all are out of spec. Testing the pop pressure is the only real way to know for sure.
It could be that what you are hearing is normal and the key is to note any change over time.

treetops · #7 09-10-2014, 11:06 PM

Thanks was a simple question which I was not clear on what to 'crack'. I've had good luck with getting to this and that done on the car and didnt want to go all wrenches at the fuel system...only to find out I buggered something.

Anyway, the fuel thermostat started leaking. I just hooked the prefilter directly to the fuel pump line and took out the thermo. (either I broke the plastic nipple bit loose by moving the prefilter or it gave out) Engine 'sounds' better like after a diesel purge, which is what I was after. Possibly the thermo was leaking for some time as I ve notice a drop in mpg to 23 around town and letting in air causing the louder to me knock. Time will tell.

Treetops

Maxbumpo · #8 09-11-2014, 10:22 AM

Intake screen clogged? Maybe, maybe not. Easy to test: Make sure your fuel tank is more than half full, and temporarily reverse the fuel lines in the engine bay. Mark them somehow so you know which was supply and which was return, so you can put them back when done.

If the car runs better with the lines reversed, then POSSIBLY you have a clogged intake screen. Another possibility would be a leak in the supply line allowing air to be sucked in. A good test for air leaks is to install a clear fuel line on the return line side in the engine bay, and if you can see bubbles returning to the fuel tank, you know you've got an air leak to find and fix.

Please remember to put the lines back into original configuration when done, otherwise you will "run out of fuel" while there is still about 1/4 of a tank back there.

treetops · #9 09-11-2014, 02:30 PM

Thanks Max, great ideas to follow. I've been meaning to renew the injector return lines and the old faded/cant see thru lines from the main filter to the IP. Thats about all Im touching on the IP...lol