Tach reading low
Not sure where the problem lies.
2002 Itasca Horison, Cummins 300 HP 5.9 ISB, Allison 6 speed transd, Freightliner chassis
Normally at 60 MPH the tach reads about 1700-1800 rpm.
Noticed yesterday while cruising (downhill) at about 65 MPH the tach was reading about 1300 rpm. It was like that all day. It would occasionally rise to 1500 going up hill, it had probably shifted down. Also when the exhaust brake came on while going down hill on cruise control the tach rose to about 2000 rpm. In the past, with the exhaust brake engaged, the rpm was higher than that.
Didn't notice when it started reading low. I know that when I started it up in the morning it was at its normal 600 or so and when I pressed the fast idle button it went up to about 1000 while the air charged.
The previous trip, a few days before, when I started up the front air gauge read about 55 lbs, the rear zero and the air alarm was sounding. As it charged, when the rear gauge passed 65 the low air alarm went off. The front gauge read something less than 60. When the rear gauge came up to near 130, the spitter valve activated. Front gauge still read low.
I checked all around, could not hear any air leaks. Air suspension, which fills from the front tank, seemed to have come up normally. When I restarted the rig, both air gauges read near 130 pounds (max) and worked seemingly normally from then on.
I am suspecting an electrical connection problem:
Quite a few years ago we lost the front gauge--it read zero and while waiting for a mechanic to be available I poked about under the dash and found a suspect connection on the gauge. I tightened it up and it was fine for six months when it quit again. In Mexico!
A mechanic eventually diagnosed a faulty gauge, couldn't get one in a reasonable time so we carried on without it working. In Oregon we took it in to a Freightliner shop who doubted it was the gauge--the tech said he had never seen one fail. But it had. New gauge we ended the problem.
A few weeks and several hundred miles before, the air would not come up and finally replacement of both the air dryer and the governor seemed to cure my problems. It did seem to recharge earlier than I have been used to.
If you think this was frustrating and worrying, add the fact that this all started in southern Mexico. We are now in Mazatlan heading north on Tuesday.
Back to the original topic: Ignore the tach problem until we get home in a couple of weeks?
2002 Itasca Horison, Cummins 300 HP 5.9 ISB, Allison 6 speed transd, Freightliner chassis
Normally at 60 MPH the tach reads about 1700-1800 rpm.
Noticed yesterday while cruising (downhill) at about 65 MPH the tach was reading about 1300 rpm. It was like that all day. It would occasionally rise to 1500 going up hill, it had probably shifted down. Also when the exhaust brake came on while going down hill on cruise control the tach rose to about 2000 rpm. In the past, with the exhaust brake engaged, the rpm was higher than that.
Didn't notice when it started reading low. I know that when I started it up in the morning it was at its normal 600 or so and when I pressed the fast idle button it went up to about 1000 while the air charged.
The previous trip, a few days before, when I started up the front air gauge read about 55 lbs, the rear zero and the air alarm was sounding. As it charged, when the rear gauge passed 65 the low air alarm went off. The front gauge read something less than 60. When the rear gauge came up to near 130, the spitter valve activated. Front gauge still read low.
I checked all around, could not hear any air leaks. Air suspension, which fills from the front tank, seemed to have come up normally. When I restarted the rig, both air gauges read near 130 pounds (max) and worked seemingly normally from then on.
I am suspecting an electrical connection problem:
Quite a few years ago we lost the front gauge--it read zero and while waiting for a mechanic to be available I poked about under the dash and found a suspect connection on the gauge. I tightened it up and it was fine for six months when it quit again. In Mexico!
A mechanic eventually diagnosed a faulty gauge, couldn't get one in a reasonable time so we carried on without it working. In Oregon we took it in to a Freightliner shop who doubted it was the gauge--the tech said he had never seen one fail. But it had. New gauge we ended the problem.
A few weeks and several hundred miles before, the air would not come up and finally replacement of both the air dryer and the governor seemed to cure my problems. It did seem to recharge earlier than I have been used to.
If you think this was frustrating and worrying, add the fact that this all started in southern Mexico. We are now in Mazatlan heading north on Tuesday.
Back to the original topic: Ignore the tach problem until we get home in a couple of weeks?
