Fuel Filter Bleeding Question - PeachParts Mercedes-Benz Forum

rmmagow · #1 07-17-2003, 02:24 PM

OM617, just changed both the clear and canister filters. I beld system via leaving the canister filter a tad loose and pump the primer until no more air. Messy as hell but easy. The clear filter has an air bubble in it as did the old one. Is this a problem? Car started with about a half turn of the crank and runs more or less as before (which was OK). Any concern here or just leave well enough alone? I am thinking this is going to fix an occasional fuel starvation symptom, severe drop in power once in a blue moon. The clear filter had lots of bits of crap, the big filter was in the car for at least the 20K I've put on, who knows how long before. Now about that A/C........... :-)

Stevo · #2 07-17-2003, 04:07 PM

"severe drop in power once"

My filters needed changing while on a road trip this spring, It would lose power while under a load. Pulled over and changed them both and no more problem. The bubble in the prefilter is normal. I found in two of my cars that the small bet of rubber hoses coming out of the fuel tank were weeping. There are 3 and all were leaking in my "85".

When I change the secondery I fill the filter up with diesel, (from a can) saves a little pumping. You might want to put some anti algee additave in the tank if you saw "bits of crap" in the filter.

#3 07-17-2003, 06:33 PM

You don't need to leave anything loose when bleeding after filter replacement. Simply pump the hand pump until you hear a hissing sound at the top of the main filter then start the engine.

If you have had anything apart in the IP in addition to the filters, you can start the engine quickly with the following procedure:

1. Loosen all 17MM nuts about one turn at the injectors.

2. Have someone turn starter as you watch the injectors. When you see fuel come out of an injector, tell them to stop cranking and tighten line at injector(s) where you saw fuel.

3. Repeat step 2. until you have seen fuel at and tightened all injector lines.

4. Start engine.

This works great especially if you have run out of fuel in a remote area because you can start the engine with minimal battery drain.

Good luck,

rmmagow · #4 07-17-2003, 09:00 PM

A Question about the big filter, how tight is that sucker supposed to be? I seemed to be leaking a bit so I really tightened the 22 MM bolt up top. Not gut wrenching tight, but a lot tighter than I would a spin on type oil filter. Is this filter under injection levels of pressure? Leak seems gone now but boy it's tight for a canister filter.

MVK · #5 07-17-2003, 11:26 PM

You have to tighten it much much tighter than the spin on oil filter.
The spin on oil filter is to be hand tightened to moderate level.
On the spin on fuel filter in benz, I usually hand tighten the canister to my max by hand then tighten the top bolt more while holding the fuel filter from bottom. Works for me.

MVK

#6 07-21-2003, 08:10 AM

Yes, I don't turn the filter like you would a spin on oil filter. I simply use a wrench on the bolt as MVK describes.

Good luck,

Ken300D · #7 07-21-2003, 08:22 AM

When recently changing the "spin-on" fuel filter on my 1982 300D, I was pleasantly surprised to have the car start normally without using the manual primer pump. After getting the fuel filter nearly in position to bolt it up, I filled it full of diesel purge (which is mostly diesel anyway) and then moved it fully into position and bolted it up.

The car started as normal with no hesitation.

Ken300D

P.E.Haiges · #8 07-21-2003, 10:11 AM

Ken300D,

That's because it bleeds itself as I explained previously.

P E H

BWatson · #9 07-21-2003, 05:25 PM

All I do is take off the rubber hose near the firewall on the last injector. It is the last of the injector bypass hoses with the metal plug on the end. Then just pump the hand pump until fuel comes out and voila!

P.E.Haiges · #10 07-21-2003, 07:09 PM

BWatson,

But that fuel is not coming from the injectors or the IP. Its just fuel that should have returned to the tank but is taking the shortest route out. Most is probably coming from the bleed hole in the fuel filter top.

P E H

#11 07-21-2003, 07:33 PM

Apologize for barging in on another mans thread but am having the same problem in getting the fuel filter tight enough to stop this annoying leaking around the bolt head and around the gasket. Barely noticeable but am leary of putting too much force as may strip bolt or threads in cannister. Have been tightening 1/4 turn at a time and it seems like it should be tight enough. Any advice?

rmmagow · #12 07-21-2003, 08:46 PM

Joe,

I made it pretty tight, say about 3/4 a tire lug (pretty scientific heh). Get a spare filter in case you do strip it but I did tighten it a lot. Maybe go to 1/2 a turm at a time. Get a can of brake cleaner and squirt clean after tightening so you know if it's still leaking.