Community Forums

Spk64 · 06-19-2020, 11:13 AM

Looks like slobber tube may be the source.
Was oil changed recently?
If yes, slightly overfill will cause some excess out the slobber tube.
Pictures look like a combination of road dirt and could be oil. Hard to tell from pics.
Our toad and MH looks similar after running through rain soaked roads .
Also had same effect when high pressure fuel line leaked and soaked everything in diesel.

slowmachine · 06-19-2020, 12:12 PM

Quote:

Originally Posted by Spk64

Looks like slobber tube may be the source.

That’s what I was thinking, and typed exhaust by mistake. Too much oil.

Brianna · 06-19-2020, 02:53 PM

Oil was recently changed by cummins in may.
Dipstick (cold) shows oil at the top of hashed area.
Why would it be ok for 400 miles and then suddenly start to slobber?

Brianna · 06-19-2020, 02:54 PM

I drove back to storage lot: fuel cap is there and screwed on tight.

Schuby · 06-19-2020, 03:23 PM

Same issue a few years ago going out west. Drove 8 hours the first day nothing second day in Casper Wyoming oil/grime all over the back. Cummins Oak Creek had just done oil change and put 28 or 29 quarts in or whatever their spec is, I now short it 2 quarts. Haven't had it since!

Tom and Patty · 06-19-2020, 10:46 PM

Quote:

Originally Posted by Brianna

I drove back to storage lot: fuel cap is there and screwed on tight.

Dang I thought I was going to get a chicken dinner.

How is the underbelly...under the bays in front of the wheels. Is it dry up front?

Tom and Patty · 06-19-2020, 10:48 PM

Quote:

Originally Posted by Brianna

I crawled underneath today.

The only thing that is wet is the wiring below this tube.

Is that the notorious crankcase breather or "slobber tube"?

First I thought, dang, the cummins guys didn't tighten the filter correctly, but it is dry.

Could be the tube. My filter was always bone dry and clean. Never was messy like that even after a year of driving.

akeagle · 06-19-2020, 11:11 PM

I don't have a DP, but I seem to remember a suggestion on this site several months or maybe a year ago that an incorrect dipstick was used in a particular engine and the full mark was higher than it should have been.

Just something else that could be checked.

Brianna · 06-20-2020, 04:41 AM

Thanks Schubert.
I went to oak Creek cummins as well.
Good to hear that this problem can be intermittent. I could not make sense of that.
I read that your speed and engine load and exhaust brake can all effect the slobber.
I'm going to do the ice tea plastic bottle with zip tie hack.
Pics to follow.

tizzyfit · 06-20-2020, 05:29 AM

2+ years ago the fuel pump on the cummins 5.9 24 valve engine began having issues. One of the first clues something wasn't right was the oily/soot covering the back of the m/h. I checked the oil level and it was at the full mark on the dipstick and no oil spots on the pavement. $6,700 later, cummins crosspoint replaced the fuel pump and a few other minor parts and the "issue" was resolved.

Brianna · 06-21-2020, 04:56 AM

Tizzy,
Great tip. Thanks.
Any other symptoms from the fuel pump scenario that I should be on the lookout for?
My coach was at Cummins last month. I asked them to look at EVERYTHING since it was my first inspection....but you know how that goes.

tizzyfit · 06-21-2020, 08:42 AM

Quote:

Originally Posted by Brianna

Tizzy,
Great tip. Thanks.
Any other symptoms from the fuel pump scenario that I should be on the lookout for?
My coach was at Cummins last month. I asked them to look at EVERYTHING since it was my first inspection....but you know how that goes.

Cummins Crosspoint plugged their computer into the engine compartment, the "plug" is top center of the radiator. The printout they provided was about 15 pages long, most of which made no sense to me BUT it did tell me to the 1/10 of a mile how many miles on the engine, which was helpful because they had ZEROED OUT the mileage on the odometer. Another item, they disconnected my Banks system which included the turbo boost and exhaust temp, claiming they "didn't like aftermarket stuff on THEIR engines". Obviously, it's MY ENGINE, but they refused to hook everything back the way they found it.
If it is your Bosch fuel pump, check the aftermarket for a replacement. Better quality and probably less money. Check with local diesel mechanics to see if they would be willing to replace the fuel pump. Make sure, who ever does the work, they torque the bolts holding the fuel pump in place. Crosspoint Cummins FAILED to do that simple item, within 2,000 miles I'd lost 1 bolt, 2 others were loose and I was leaking diesel fuel. Took less than 1/2 hr to correct this MISTAKE and for an extra fee, they power washed both sides of the radiator, the rear of the M/H and the car and car hauling trailer.
Not to turn this into a flaming session about Cummins dealerships, Crosspoint Cummins specifically, BUT at another of their facilities, had them replace the exhaust manifold due to a crack. I sprayed the header bolts with Buster daily for a week so they didn't break any bolts BUT did manage to bend the flange when the reinstalled the turbo on the new exhaust system causing serious turbo boost loss, so, I had to have most of their "work" redone to fix that problem.
Let's hope your "issue" is NOT the Bosch fuel pump, that's a financial hit no one needs or wants.

Ljwt330 · 06-21-2020, 10:06 AM

Just a point about your fuel pump(s).

You do not have a 5.9 ISB but you do have a two pumps in the fuel circuit, one of which is problematic. The transfer pump, AKA the lift pump, is the weal link in the Cummins CAPS fuel injection system of your vintage. It is located above the starter motor and it is used to draw fuel from the tank and supply the main high pressure CAPS fuel pump. It only operates for about 30 seconds to draw fuel from the tank by suction, push it to the CAPS pump where the fuel is now continually pulled by suction from the tank to the injectors. If there are any leaks in the lift pump, air can enter the fuel circuit due to the suction and reduce the amount of fuel to the CAPS pump and injectors. The fuel is what the CAPS pump needs for lubrication and cooling and a reduced/air diluted fuel supply will ruing the pump. A costly repair.

First signs of a failing lift pump are reduced power under load, intermittent hard starting, and fuel dripping in the area of the starter motor. Many lift pump failures were due to loose bolts, as mentioned, but also failed gaskets between the mounting parts as the early pumps were not designed to use modern Ultra Low Sulfur diesel. If you lift pump is original, I would monitor it closely both for fuel leaks and engine performance changes.

Your current symptom of residue on the rear of the coach is, IMO, most likely the "slobber tube" as others have mentioned. You, or the mechanic, have not noticed any fuel leaks around the lift pump, apparently, and the performance of your engine has not reportedly changed.

tizzyfit · 06-21-2020, 10:30 AM

"You do not have a 5.9 ISB" Not sure who you directed this statement to. If it was to me, I DO have a Cummins 5.9 24 valve engine.
In my case, my slobber tube empties into a vented plastic container and, over the years, has remained almost free of any engine "slobber", thus ruling out that as the source of the oil/soot I experienced prior to my Bosch pump being replaced.