Community Forums

Tmargarido · 07-22-2021, 08:57 PM

I believe the air pressure just after the air filter should be negative (ie. a vacuum). On my 2003 DSDP the air blows out of the vacuum port for my filter minder. Does anyone know what is causing this problem. Not only does my filter minder no longer work, but I’m suspecting this might be a symptom for a problem with the Turbo or ebrake.

Skip426 · 07-23-2021, 10:10 AM

Quote:

Originally Posted by Tmargarido

Not only does my filter minder no longer work, but I’m suspecting this might be a symptom for a problem with the Turbo or ebrake.

Not really unusual for air filter minders to fail , and the only time they give anything like a proper reading is at WOT under load .

Are you having engine power issues , or exhaust brake not working properly?

wolfe10 · 07-23-2021, 10:13 AM

That IS strange. Verify that the air filter minder is connected to the "clean side" of the air filter. But even there there will be some vacuum-- less than on the clean side, but still some.

Got me stumped.

Tmargarido · 07-23-2021, 11:45 AM

Skip, I’m sure the filter minder is working, I tested it. Right after the air filter is a huge tube that goes to the turbo. That tube also has a 1” hose going to the air compressor, also it has a small fitting for the vacuum hose that goes to the filter minder. I pulled off the hose and found forced air blowing out of the fitting. I called Cummins and they told me the air compressor could have a back flow problem or the the ebrake could be frozen in the closed position. I’m afraid to drive my coach until I resolve this problem. Might really create some damage.

wolfe10 · 07-23-2021, 11:51 AM

Interesting that the air compressor intake is between air filter and turbo.

Most applications have the air compressor intake off the engine intake manifold. An excellent location, as the air is not only clean, but compressed (boost) and then cooled by the CAC.

Can you remove the hose to the air compressor where it connects to the plumbing between air filter and turbo and verify whether or not there is compressed air coming out with the engine running?

Skip426 · 07-23-2021, 11:57 AM

Ok , differences in the way Spartan got a filtered air supply to the air system compressor . My compressor gets air after the turbo .

Questions .
Does the air system build pressure in both tanks to the point where the alarm no longer sounds and the gauges give a normal reading ? Over 100 PSI?

With the engine running , can you accelerate the engine to 1500 + RPM ?
Does the exhaust sound normal ?

Can you see the exhaust brake actuator ?
If the actuator shaft is retracted the exhaust brake is not stuck closed.
Sorry didn't see the yellow arrow before posting the picture .
Picture shows the actuator shaft connection to the exhaust brake shaft ( lever ) and against the off stop .

Tmargarido · 07-23-2021, 12:01 PM

Wolfe, as you can see from my reply to Skip, Cummins thinks it’s the ebrake or the compressor. My guess is that’s it’s the ebrake, because it’s been making hissing sounds lately. I think I’ll look at the ebrake first. All I have to do now is find the location of the ebrake. This is my first diesel motorhome.

Skip426 · 07-23-2021, 12:06 PM

Here's a picture of the actuator , taken from further back , area in the first picture I posted is in shadows .

Skip426 · 07-23-2021, 12:10 PM

Quote:

Originally Posted by Tmargarido

Wolfe, as you can see from my reply to Skip, Cummins thinks it’s the ebrake or the compressor. My guess is that’s it’s the ebrake, because it’s been making hissing sounds lately. I think I’ll look at the ebrake first. All I have to do now is find the location of the ebrake. This is my first diesel motorhome.

Exhaust brake , will be below the turbo , follow the exhaust pipe back from the muffler towards the turbo . You'll find it .

Exhaust brake on , or partially on , engine power is vastly reduced .

Tmargarido · 07-23-2021, 12:11 PM

Where is the location of the ebrake activator shaft with relation to everything else. I assume it’s somewhere close to the turbo. I see your photo, but still confused regarding general location.

Skip426 · 07-23-2021, 12:20 PM

Bolt in top of second photo , is the drivers side motor mount to the frame rail , engine oil pan on left of photo and exhaust pipe just behind , runs under the oil pan to the muffler , that's on the passenger side on my Freightliner chassis .

Picture was taken , from drivers side of the transmission , looking towards the rear of the coach .

It'll all make sense once you're under the coach ( using all necessary safety precautions ) jack stands or blocking to the frame .

Tmargarido · 07-23-2021, 12:23 PM

Excellent test. I’ll pull the 1” hose this evening. That should convict or eliminate the compressor. Thank you for your insight. I have to finish roofing my garage today, so I can’t test until this evening. I’ll get back to you after I test.

Tmargarido · 07-23-2021, 12:24 PM

Thanks Skip. I’ll let you know what I find.

Tmargarido · 07-30-2021, 02:07 PM

Hi Steve
I finally found the time to look at the compressor hose and the ebrake. I pulled the 1” hose to the compressor off the large pipe just after the air filter then started the engine. The 1” hose was sucking air, but air was blowing out of the port that the hose attaches to, so there was a positive pressure in the big pipe. I then reattached the1” hose to the port on the big pipe. I then inspected the ebrake. It was frozen open. I then proceeded to free up the ebrake linkage. But since it was frozen open that would not cause a positive pressure in the big pipe after the the filter. How can I tell if the turbo is working.