reoccuring fuel leak!!!!

[greythunder]

i have replaced all the fuel hoses a while back with the kit from **************. there is one junction, at the bottom of the lift pump, that I cannot get to stop leaking.

after the ************** hoses it was leaking so I replaced it with 5/16" fuel hose from orielly's. I asked the guy behind the counter if diesels needed special fuel hoses, he said he doesn't think so.

then I noticed it was leaking again, so I looked closer, the hose clamp broke and wouldn't go tight enough. I replaced the clamp with one left over from the ms kit, the type that doesn't cut into the hose, and it's leaking AGAIN!!!

am I missing something? wrong type of hose or clamp?

and what is the procedure for depressurizing the system? im getting tired of mopping up diesel for the hose replacement

[dieselbenz1]

Are you certain it is not the fuel heater that is leaking. You could try to bypass it to see since it is in that area.

[vstech]

yes.
diesel needs special diesel rated fuel hose. green stripe at o'riellys.

as for depressurizing the lines... park facing up hill, and take the fuel cap off to bleed pressure out first (put it back on once the burp is done) but if your fuel tank is full, you will still have fuel spill out of the open fuel lines. the tank is above the floorpan of the vehicle, so the lines are under pressure of gravity.

be sure to check the fuel heater. there is an o-ring in the body of the fuel section that fails.

most stuff from MS is junk, and over priced to boot (it's why our site blocks their web address, or name) it's too bad, because, his video's are fairly decent, if they weren't blatant ads for his junk we'd likely allow links to them.

[greythunder]

thanks for the replies! pretty sure its the lift pump. it has a clear line out the top of it going to the main filter and the problem hose out the bottom. when I do an image search for lift pump om602 it is what comes up.

the hose has the green stripe down it. I guess he gave me the right one. maybe I am putting the clamp on too tight.....

[Onetoomany]

I feel your pain on mopping up.

I've been working around my fuel system for awhile, and use the following method to purge and refill with fuel:

Purge: Take off your supply hose from the metal hose. Its the one closer to the firewall. Dial your compressor to ~30psi and squirt air into the supply for about 15 seconds, sometimes longer. This should clear most of the fuel back through the return line into your tank. You'll get some dribbles, but nothing like the biblical flood. FYI I also replaced my main return line with clear blue polyethylene tubing so I can see progress.

Refill: I have a small airtex fuel pump and some more 3/8" hose, attached to a small piece of lamp cord. Just hook it up from your supply and let it pump until your return line from main filter runs bubble-free. This will prime your IP, lift pump, and all the lines except your injection lines, and allow for quick starts. Saves that expensive starter.

Ditto on diesel hose - gotta have it. and the fuel heater is a pain, I bypassed mine because I live in warm places. Cold weather sucks unless you want it. Don't do that though if you see below freezing temps. A cold night in scottsdale is about 45 degrees....

Amazon and Jegs and Summit also sell good diesel rated hose. I have had the best luck with fuel hose clamps from Summit racing. they usually have free shipping and sell nice stuff for less than the price of MBZ. I don't like fuel hose/hardware from Big Box retail shops. If you shop it around, you can usually have nice braided hoses and AN fittings for the price of dealer hose. And properly installed, those NEVER leak.

[OM617YOTA]

I'll +1 that diesel fuel line needs to be some serious stuff, especially if your area has any kind of biodiesel mandate. I like Gates Barricade, it's held up fine where the generic bulk stuff from Lowes softened and swelled.

[Diesel911]

Originally Posted by greythunder

i have replaced all the fuel hoses a while back with the kit from **************. there is one junction, at the bottom of the lift pump, that I cannot get to stop leaking.

after the ************** hoses it was leaking so I replaced it with 5/16" fuel hose from orielly's. I asked the guy behind the counter if diesels needed special fuel hoses, he said he doesn't think so.

then I noticed it was leaking again, so I looked closer, the hose clamp broke and wouldn't go tight enough. I replaced the clamp with one left over from the ms kit, the type that doesn't cut into the hose, and it's leaking AGAIN!!!

am I missing something? wrong type of hose or clamp?

and what is the procedure for depressurizing the system? im getting tired of mopping up diesel for the hose replacement

SAE 30R7 is the Regular Fuel Hose that GoodYear or Gates makes and is sold in the Auto Part Chain Stores. It is rated for Diesel Fuel so it is sort of a unversal Fuel Hose for low pressures (not for Fuel Injection).
5/16" ID is the correct size for mine but I am not sure it is the correct size for your 1992.

Also the Wrong Hose would not likey leak right away. I used a piece of Vacuum Hose as Injector Return Hose when I first got My Volvo Diesel and it only lasted a week and starte leaking. But, it did work for that week till the Diesel Fuel and heat ate up the Hose.

[greythunder]

that's what's weird. It doesn't leak for a few days after a repair, then it starts. I will try to find the goodyear/gates stuff and try.... AGAIN!!! it's getting really old everywhere I drive to get out of the car and smell diesel.

[Diesel911]

Originally Posted by greythunder

that's what's weird. It doesn't leak for a few days after a repair, then it starts. I will try to find the goodyear/gates stuff and try.... AGAIN!!! it's getting really old everywhere I drive to get out of the car and smell diesel.

Are you sure 5/16" ID is the right sized and is it possible that the Clamp is too wide for the Nipple on the Pump. Keep in mind I don't know what the Fuel Supply/Lift Pump looks like on your 1992.
Or if it the type of Clamps that are stock on the Mercedes they don't have as much ranges as the normal Worm Gear Type clamps do. Maybe try a regular Worm Gear clamp just to see if it works.

If the Hose was cut to short when the Engine rocks it could be pulling on the Hose.