Kim (skyking4ar2) Bertram
Moderator Emeritus
When our coach was delivered to us in Salt Lake City last year, it had about 2,000 delivery miles on it. As we rolled on out over the hills to Oregon, we often noticed a burned smell, a little like something electrical but not that acrid, when pulling a hill, wafting through the coach. We could go in the rear bathroom and it was obvious it was coming from the engine bay. Never smoke, just an odor.
We stopped in California at a Cummins service center for a 5,000 mile check for the transmission, and had oil and fuel filters changed out on the 450 hp version of the Cummins 8.9 ISL. I asked the service tech about the smell, and if it had anything to do with the Diesel Exhaust Fluid used in this engine. He said he did not find anything amiss when he was underneath and that it should burn off. He said there was a burn in period on that exhaust system. I thought 5,000 miles should have burned in anything that needed burning.
Well, here we are at 10,000 plus miles and it hasn?t. Shortly thereafter, I bought the SilverLeaf software to track the computer outputs, especially after a check engine light came on climbing a grade in northern California. I also started monitoring the engine temp and trans temp on the Freightliner dash module as I was driving.
I noticed we would run some high (seemed to me) trans temps when climbing (over 180 degrees) but then learned that was well within the operating range.
All of this background leads to an incident recently climbing the San Juan Mountains out of Taos. Most of the way up the last grade, the engine temp light came on, the engine temp showed 212 degrees, and as I was slowing, the stop engine light came on, the engine derated, and then stopped. A low coolant indicator came on, but checking the coolant, it was at the top of the filler reservoir, just where it always is.
We unhooked the toad, the ambient temps were in the 50?s, let the engine rest, then pulled on over the top of the grade, and rehooked at the bottom of the grade. On we went, same song, different verse another couple hundred miles in to Utah.
The temp gauges running around 1400 RPM which is our normal cruising range at 55 mph, will typically run 170-185 on engine temp and roughly ten degrees lower for trans temps. When we hit a decent grade, or long grade, the engine temp will start clicking up to 200 or so, and if we keep hitting the grade, it will climb to 210 or so. What I noticed, was, that once we top the grade and start down, especially when the engine brake comes on and runs the engine up to 2000 RPM, the engine temp will drop 20 to 30 degrees in an instant.
Finally, we go into the bathroom at the end of this adventure, and there are soot streaks on the mirrors, at the door jambs, dusted in to the shower, and craziest of all, inside the dryer on the tub fins!
I believe the soot and the engine temps are roughly related, i.e. when it is pulling hard, it is pushing soot (hopefully out the tail pipe) and that is the source of the smell. I am also wanting to believe that somehow, the water pump or radiator fan is related to a speed sensor, and that is why the engine temps fluctuate wildly.
Now it?s your turn, if you have some Cummins engine owner experience, to weigh in on the two issues ? where is the soot coming from? And why are the engine temps wildly fluctuating?
And, yes, we are headed to Cummins Coach Care Center in Salt Lake City after Moab.
We stopped in California at a Cummins service center for a 5,000 mile check for the transmission, and had oil and fuel filters changed out on the 450 hp version of the Cummins 8.9 ISL. I asked the service tech about the smell, and if it had anything to do with the Diesel Exhaust Fluid used in this engine. He said he did not find anything amiss when he was underneath and that it should burn off. He said there was a burn in period on that exhaust system. I thought 5,000 miles should have burned in anything that needed burning.
Well, here we are at 10,000 plus miles and it hasn?t. Shortly thereafter, I bought the SilverLeaf software to track the computer outputs, especially after a check engine light came on climbing a grade in northern California. I also started monitoring the engine temp and trans temp on the Freightliner dash module as I was driving.
I noticed we would run some high (seemed to me) trans temps when climbing (over 180 degrees) but then learned that was well within the operating range.
All of this background leads to an incident recently climbing the San Juan Mountains out of Taos. Most of the way up the last grade, the engine temp light came on, the engine temp showed 212 degrees, and as I was slowing, the stop engine light came on, the engine derated, and then stopped. A low coolant indicator came on, but checking the coolant, it was at the top of the filler reservoir, just where it always is.
We unhooked the toad, the ambient temps were in the 50?s, let the engine rest, then pulled on over the top of the grade, and rehooked at the bottom of the grade. On we went, same song, different verse another couple hundred miles in to Utah.
The temp gauges running around 1400 RPM which is our normal cruising range at 55 mph, will typically run 170-185 on engine temp and roughly ten degrees lower for trans temps. When we hit a decent grade, or long grade, the engine temp will start clicking up to 200 or so, and if we keep hitting the grade, it will climb to 210 or so. What I noticed, was, that once we top the grade and start down, especially when the engine brake comes on and runs the engine up to 2000 RPM, the engine temp will drop 20 to 30 degrees in an instant.
Finally, we go into the bathroom at the end of this adventure, and there are soot streaks on the mirrors, at the door jambs, dusted in to the shower, and craziest of all, inside the dryer on the tub fins!
I believe the soot and the engine temps are roughly related, i.e. when it is pulling hard, it is pushing soot (hopefully out the tail pipe) and that is the source of the smell. I am also wanting to believe that somehow, the water pump or radiator fan is related to a speed sensor, and that is why the engine temps fluctuate wildly.
Now it?s your turn, if you have some Cummins engine owner experience, to weigh in on the two issues ? where is the soot coming from? And why are the engine temps wildly fluctuating?
And, yes, we are headed to Cummins Coach Care Center in Salt Lake City after Moab.