W124 Fuel Line Changeout, Gotta ? For You

[Oldwolf]

Will fuel drain by gravity when I remove the 7.5mm fuel hose under the hood from the metal supply line and the fuel pump? It looks like it is lower than the fuel tank, so I'm guessing it will flow by gravity when I take the hose off.

My fuel hose is date stamped 1992 so I'm changing it out. Funny thing though, the fuel hose still looks OK, no swelling or brittleness. Still, 16 years is probably a long enough service life.

[diesel friend]

the tank sits quite high and fuel will run out. Would run the tank as low as you
dare, jack the front left, place a place a plastic bag with some rags underneath
the line and change the line quickly. If the line has still some flexibility would leave it alone. Fuel is running without pressure. Cheers

[Jetmugg]

If you can't raise the bridge, lower the river.

Run the tank down low (less than 1/4 full). Do the work on a sloped driveway, jack up the front end, chock the rear wheels. Use a drain pan of some kind, work fast, have a friend put his thumb over the end of the hard line, etc., etc., etc.

My 2 cents

SteveM

[awsrock]

At the very least, undo the fuel cap. This way some pressure from the tank will be somewhat released.

[Oldwolf]

That's what I thought...thanks. You would leave it be, even if the fuel lines were 16 years old?

[diesel friend]

My W124.128 is from 1/91 and I think I still have the original hose in there as hose is secured to the metal tube with the s/s clamp which requires a special tool to press on. The hose is quite solid, may be a bit stiff but no cracks, no diesel swetten through. Pressure is relatively low in this line and I am not going to change it for some time to come. Cheers

[compress ignite]

If you run the Tank down as low as you feel comfortable...
Then allow the "gravity feed" to further empty the Tank,you may still have a
gallon or two in there.(Depending)

[i-osprey]

I say replace it.

If it does start leaking you might be a long way from a replacement.

It's not that hard and you won't spill much.

Take off the downstream end first, pinch the hose, install new line on downstream fitting, remove upstream fitting and repeat.

The worst that will happen is that you will spill a small amount of diesel in your engine compartment and the container you placed beneath it.

I agree that maybe parking the car on a slope or on ramps would make matters a bit easier.

This is easy and I think you should definitely do it.

[Oldwolf]

I already have the material to do the job. Plus I may be trying some B20 if I can find it. B20 may stress the old line if I leave it in there I think.

Next I plan to look over the feed line at the bottom of the tank. Why can you not just clean the screen rather than replacing it like I read a lot of folks do?

Are the fuel pumps rebuildable? Can't be too much in them, probably no seal either to wear out.

Last, are the hoses leading to and from the fuel heater just fuel hose? The one on the outlet side furthest from the heater doesn't even have a clamp. The MB drawing doesn't show a clamp either. Weirdness.

[i-osprey]

You can remove and clean the tank screen.

You can use regular fuel line for anything that carries fuel.

I have replaced the clear/amber looking lines with rubber fuel line before with no problems.

Changing the line coming from the bottom of the tank is probably a good idea, too, if it hasn't ever been changed.

Mine started leaking after I used some B20.

I don't know about the fuel pump issues you requested.

[pawoSD]

Why not just put one of those little quick clamps on the rubber lines in back? Then nothing will flow/leak....

[Oldwolf]

I changed the fuel lines under the hood this weekend.

It went just fine, only spilled a little fuel which cleaned right up with simple green and the garden hose.

Both the fuel supply line and fuel return line will flow fuel when the hose is removed. I didn't expect fuel out of the return line but after looking at the fuel tank drawing I can see the return line feeds somewhere low into the tank.

I went ahead and changed the primary filter but kept the secondary filter in operation for awhile longer.

I filled up with with B20 but calculating the amount of fuel I had left in the tank and the B20 I added, I actually have B08 (8% Bio Diesel) at this point. Next fill up I'll wait till the tank is nearly empty and fill with B20. Hopefully I won't have a sludge bucket and need to change the primary filter again.

I haven't looked at the hose leaving the fuel tank yet. That's probably 1993 vintage too. Has anyone figure out how to rig some fittings to the outlet so that you only need to change the hose and not buy a factory made hose with metal fitting every time? That would make it easier to install Viton hose down there too.

At some point I may install Viton hose all the way around but my understanding is most modern hose is Bio Diesel compatible so I don't think I'll have trouble with B20 (I hope).

[compress ignite]

It's a Diaphragm style pump...rebuild kits are available.

All Hoses to and from the Fuel Thermostat (The Barrel shaped device mounted on the Driver's side Engine Support Arm) are Fuel grade line.
[Below a certain Temperature the Thermostat routes incoming fuel to the
warming device mounted in the head between cylinders 4+5]

As well as Fuel Lines remember: the Fuel tank Screen 0-ring,IP Shutoff lever
O-ring,Hose to the Tank Vent underneath the Tank,O-ring for the Thermostat.

member JA Davis @ fryerpower.com has Viton kits

[Oldwolf]

I did not know that all four lines going to the fuel heater carried fuel. There must be some amount of flow to the head at all times or the furel would stagnate during the hot months. Right?
The Fryerpower fuel line is 1/8” ID and my hose is 7.5mm, about 0.30”.
http://www.fryerpower.com/store/page14.html