Weeping cloth braided fuel hose? - PeachParts Mercedes-Benz Forum

JHZR2 · #1 06-03-2018, 11:03 PM

This is on my 1982 300CD. Kind of sticky, not really leaking or smelling of diesel.

The car has been sitting for a few years, not sure if that makes a difference.

Strangely, only one section is doing this.

Is there any reason other than aesthetic, to use the cloth braided fuel hose?

In the same spirit, does anyone have the official MB part numbers for the OE fuel hose? I was trying to search for numbers but couldnt easily find them.

Anyone have a good source of OE fuel hose from a dealer or parts house? Pelican doesnt seem to offer OE MB 7.5mm hose.

Thanks!

BillGrissom · #2 06-03-2018, 11:28 PM

My 1984 & 85 300D had rubber hose at that Lift Pump suction location. Don't know if original. I have since replaced w/ Goodyear Barricade brand since rated for bio-diesel. You can buy at NAPA or ebay. Not cheap, but should last much longer since has an inner viton liner. Re the cloth-covered injector return hoses, I replaced w/ 1/8" viton hose advertised for M-B on ebay. Has held up for several years so far.

rocky raccoon · #3 06-04-2018, 05:26 AM

That hose is readily available from many sources. See ebay. On a more important note, I have never seen a worse looking fuel filter.

JHZR2 · #4 06-04-2018, 07:35 AM

Quote:

Originally Posted by rocky raccoon

That hose is readily available from many sources. See ebay. On a more important note, I have never seen a worse looking fuel filter.

OE MB hose? The same hose you would get from a dealership, not a Corteco or other variant?

Yes, sure, one can get 30R9 and 30R14 barrier hose from all over.

The filter really isn't bad at all. Bosch filters are unpainted, and the aluminum gets a bit oxidized from time and exposure to humidity. But I did buy Mann filters to replace since they're painted and should do better in that regard.

JHZR2 · #5 06-04-2018, 07:43 AM

I am aware but that's not what I asked for

kuene · #6 06-04-2018, 09:20 AM

I think he meant the plastic pre-filter

tjts1 · #7 06-04-2018, 09:34 AM

I gave up on the cloth braded hoses a long time ago. All of them harden and leak sooner or later.

97 SL320 · #8 06-04-2018, 10:43 AM

Failed cloth braided hose is one of the reasons air cooled VW / Porsche 914 would catch fire and burn, replace the hose with smooth covered hose.

HarvAMG · #9 06-04-2018, 04:28 PM

Quote:

Originally Posted by 97 SL320

Failed cloth braided hose is one of the reasons air cooled VW / Porsche 914 would catch fire and burn, replace the hose with smooth covered hose.

Well, leaking gas will ignite and burn. Leaking diesel won't.

tjts1 · #10 06-04-2018, 04:31 PM

Quote:

Originally Posted by HarvAMG

Well, leaking gas will ignite and burn. Leaking diesel won't.

I've got a hot exhaust manifold that would beg to differ.

97 SL320 · #11 06-04-2018, 05:19 PM

And mix in a fine spray for good measure. . .

rocky raccoon · #12 06-04-2018, 05:28 PM

Yes of course, the prefilter. Looks clogged with junk, probably bio particles. May want to treat your tank with biocide.

Of course you can expect to replace your return hoses from time to time.

No, your exhaust manifold will not get hot enough to ignite Diesel fuel.

97 SL320 · #13 06-04-2018, 07:24 PM

Quote:

Originally Posted by rocky raccoon

No, your exhaust manifold will not get hot enough to ignite Diesel fuel.

OK try this:

Rig up a garden sprayer so the nozzle points at the exhaust manifold.

Pull a long hill to get things hot.

Spray the exhaust manifold with diesel fuel.

Post pics here.

I've dribbled brake fluid ( from taking the cap off ) on a hot exhaust manifold and have had a flash fire.

Flash point is the temp where a liquid makes sufficient amount of vapor that a strong ignition source will result in a flame.

Auto ignition is the temp where a liquid will burn without an outside ignition source.

Note that , compared to diesel fuel, gasoline has a very low flash point but a high auto ignition point. This makes gasoline explosive since it generates lots of easy to ignite vapors.

Diesel fuel has a higher flash point but a lower auto ignition point compared to gasoline.

View attached chart and see source here. https://en.wikipedia.org/wiki/Flash_point

vwnate1 · #14 06-04-2018, 08:05 PM

VW & Porsche's caught fire because old leaky hose that should have been replaced, wasn't ~ not because of any defect in the cloth braided hose .

It's always fun to see lazy/incompetent folks try to shift the blame .

The O.P. here said the hose is over two years old, it should have been changed or replaced with the Viton lined stuff .

BillGrissom · #15 06-04-2018, 10:35 PM

Re fuel leaks, the worse I saw was a ~1970's Volvo station wagon my sister was considering buying (didn't). It had MPFI with a short rubber hose to each injector and each hose was dripping. Those hoses hold high-pressure (~50 psig), so leak = fine spray of gasoline. Current MPFI cars have metal (or nylon) rails to the injectors, with Viton O-rings. Yes, Viton is best for gasoline, ethanol, and bio-diesel.