Help with noise in engine

[travelers1214]

Looking for suggestions in diagnosing a noise in the left rear - 2004 DSDP - 370 Cummings/Spartan - hear it down the road 2000rmp about 68 mph down the road, sounds like a "chirp" or "chirping whine" - noise comes and goes -nothing at idle, but do hear it under load while accelerating from a stop - wondered if it could be belt tensioner or something to do with fan drive system?

any suggestions?

[travelers1214]

Looking for suggestions in diagnosing a noise in the left rear - 2004 DSDP - 370 Cummings/Spartan - hear it down the road 2000rmp about 68 mph down the road, sounds like a "chirp" or "chirping whine" - noise comes and goes -nothing at idle, but do hear it under load while accelerating from a stop - wondered if it could be belt tensioner or something to do with fan drive system?

any suggestions?

["007"]

You may have your answer fan belt.
I'll short cut your question down to the Spartan forum also for more exposure.

[Lug_Nut]

"Chirping whine", I'm trying to determine what that would actually sound like. Additionally you state that this sound is coming from the left rear at about 68. At 68 how do you determine it is from the left side?

On the left side rear is the rad and fan. The fan has no belts as it is direct drive from a hydraulic motor. This motor is being operated in a two speed fashion, I believe, and is not affected by load or no load on the engine.

Is it possible you are hearing the turbo charger? They will spin hard (200,000 RPM) under heavy engine load.

Peter

[Cruzer]

It could be a few things. The first thing I'd do is look at the radiator fan. See if there are any lose mounting bolts on the hydraulic fan motor or if the fan blade is contacting the shroud at all. however, I doubt if this is it. The next thing I'd do is loosen up the belt tensioner and remove the belt. Then, I'd turn every pulley over by hand, listening for any noise and checking for any looseness. Check the stationary idler pulley, the belt tensioner idle pulley, the alternator, and the water pump. Also, if the belt is stretched it won't give you adequate tension. There are generally minimum/maximum marks cast into the belt tensioner pivot arm to show you if the belt has stretched too much. When in doubt - throw it out. A third possibility is the dash air conditioning compressor clutch. You can't check this by hand but if the noises go away with the dash air off and come back with the dash air on, you have your answer. A fourth possibility is the turbo. You should have a Variable Geometry turbo. VG turbos work by sliding the volute over the impeller to modulate the turbo boost. If it's sticky the volute could scrape on the turbo but this isn't a very frequent thing.

My money is on a stretched belt or bad idler bearing.

[travelers1214]

Thanks for the suggestions - (We determined the location by the passenger going to the back of the coach and listening.) - we've also determined that the noise is now almost a "knock" at idle when the coach is in gear - goes away when it is in neutral.

We're on the road in Colorado, with home dealer in Missouri - just hoping to not get stranded.

[Lug_Nut]

Does not seem to support the chirp/whine sound, but the knock when in gear (under slight load) could be a fouled injector. I would have a Cummins service shop check it out.

Peter

[Bill0828]

Travelers1214..Is the noise a knocking sound from the engine area? I just had the engine air compressor replaced (13K mi.) on my '04 KSDP. It would go away when the air dryer "spit" and then come back as the engine continued to run. Also, the belts made a heck of a whine when the engine brake was engaged at just about any speed but very loud at 40-50 mph. The other suggestions are valid too.

[travelers1214]

According to Cummins Rocky Mountain - the problem is a blown exhaust gasket. They also found an oil leak, both of which are under warranty - not fixed yet, but impressed with this facility.

Thanks to everyone who contributed...

now... we WERE headed for the backcountry of Colorado!

[cwg]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">now... we WERE headed for the backcountry of Colorado! </div></BLOCKQUOTE>

Your trip started out like ours. On the way up to Eisenhower tunnel on I-70, smoke and oil started pouring out of the engine compartment and we had to wait exactly 24 hours for a capable tow truck. Once we were back in Denver, they diagnosed the problem as a overheated dip stick tube about which we have had some discussion on the forum already.

In retrospect I could have driven the coach in, but Coach-Net did not want us to start it in case there was engine damage (phone diagnosis was blown turbo charger).

Once repaired, the trip was great for the next several weeks. When we left to come home this Sunday, it was 37 degrees in the morning and already the mountains had received a light dusting of snow. What a shock to return to 100 degree heat after that. Hope your trip improves too.

[travelers1214]

Did Cummins Rocky Mountain do your work? Or another shop?.. we CAN recommend them -and they have power for overnight in their parking lot...

37 degress? WHERE? ... we left 100 degrees and way more humidity than I care to think of and Denver in the 80s is heaven... we're headed to Ouray - and some Jeeping!

[cwg]

Rocky Mountain Cummins in Denver did the work and we were well pleased with them. They had about four or five ISL Cummins engines in for the campaign on the bad wrist pins. Only one had a blown engine; the rest were in for the sensor to be installed in order to prevent engine damage.

We were in Breckenridge, Colorado and made side trips to Frisco, Vail, and Silverthorne, all relatively close together. What a wonderful place with great temps. Most of the average elevation was around 9,000 feet so the cooler days prevailed. Some of my friends rode the Leadville 100 mountain bike race and the morning temps at 10,200 were very cool at a time when Denver was in the 90's. Nearly two miles of altitude makes a big difference in temperatures as we saw. Now I know why summer season is so popular, barely lagging behind the ski season of winter.