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Series 60 Engine ignition off at highway speed
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Really? How so?
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Thanks for the additional suggestions. We drove from Douglas to Denver without issue.
Re: Does it happen outside of cruise control. I haven’t experienced it. I normally run with cc on 65-68.
Re: Exhaust temp. I don’t know how to check that. The coolant is normally 205-210. The oil temp is 220-226.
Re: Reset ECM. I’ll try that tomorrow.
A mechanic suggested it could be a sensor, likely oil. That reminded me I did have the oil changed in Alaska after I discovered one of the oil filters hadn’t been tightened properly at my last level 3 service. I’m wondering if the oil viscosity/type is affecting temp or pressure and throwing it over the limit?i would expect a fault code under that scenario.
Thanks for all the input.
-jeff
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Bill, no matter how I respond you will remain convinced your experience can be what is happening on a multiplexed Series 60 coach.
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I had the same problem, except not just on a hill. The engine would stop and then it might start up right away or take lots of time.
My problem turned out to be the switch in the back for rear start. It would open and kill the engine. Took a while to find, but a new switch fixed the problem.
Did you try running with the switch in the rear start ?
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Re: rear start switch. That was also suggested and would be an easy explanation for no codes and immediate start. The factors it doesn’t explain is why on grades? And time to fail, it doesn’t happen until the motor has been running for a few hours and is under load. Now it could be coincidence we’ve been in hill country so any occurrence has a 50% chance of uphill or downhill :-). I’m going to run it across Kansas and see if it happens again…I don’t know of any big grades there. If it doesn’t repeat or I can’t get codes I’m going with likely suspects and just replace them all. Sensors, switch. Etc.. Even if I do get a repeat, I’ll probably still replace them all:-) 10 years is a long time for those type of parts.
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The rear start selector switch has historically been an issue, but almost always it has been associated with trying to start a coach, and not causing a shut down.
A quick and dirty, but temporary check and fix is to cycle the switch numerous times. That way any corrosion that might be contributing to the problem gets removed or displaced and the contacts mate better.
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09 Multiplexed 60 Series Coach . It has happened to others, same symptoms. Took Prevost updates and maybe some hardware changes.
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Which begs the question as to why the Calgary Prevost folks did not do that.
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JON, What is the normal operating temps for a Series 60 ? My 1998 Series 60 on level ground with outside temps of 100 runs at 180 with dash air on, 195 with dash ac off. Mountain driving on long 6% grades, never over 200 degrees pulling toad. Should this be the norm for a non EGR Series 60?
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Assuming you have driver’s air and not OTR what you describe is normal.
The engine fan is on full time when the dash air is on. When the dash air is off DDEC is controlling the fan, meaning the fan is off until the engine temp hits about 204. At that point the low speed is engaged. If the engine temp reaches 208 the high speed fan is engaged.
The lower temp with the air on means the fan is running at and since it does not shut off until the air conditioning is shut down the engine thermostat is controlling engine temp.
The gauges likely have some inaccuracy plus they are small and hard to read which is likely why my temps listed above might vary from what the gauge shows.
As an aside, if you are pulling a long steep hill on a hot day with the A/C off you can actually see in your gauge how well your fan clutch is working because as temps reach the 208 point and the high speed of the fan kicks in you can watch the temp drop until the high speed fan drops into the low speed range, at which point the temps will cycle up again.
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Jon:
You noted fan speed will be on high with the dash air on NOT OTR air.
I am assuming the fan will not necessary be on high with OTR air on?
Chuck
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With OTR the engine fan cycles on and off as needed with the fan speed controlled by DDEC and the fan clutch.
With dash air the fan is engaged as long as the dash air is on.
Which is kind of ironic. There is an opinion that OTR uses a lot of HP. And it does use some HP because the alternator has to work to provide the power to run the condenser and evaporator fans and the compressor which do require power. But with dash air the system itself is going to require less power, but running the engine fan all the time requires a lot of power. I don’t know how much is required but some have indicated the engine fan can require as much as 30 HP.
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I would expect it’s set up that way because dash air has the a/c condenser in front of the radiator and they want max air flow for the dash air to work. With OTR, a/c airflow is no longer a function of the radiator fan but rather the electric motors in bay.
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Just a quick update.
We spent some quality time at Prevost Jacksonville. It’s amazing what you wear out when you take a rig that is used to 7k a year and do 30k in 18 mos 🙂
We had not experienced the motor off scenario since Wyoming. We ran pretty hard including passes. The Gents in Jacksonville chased wiring diagrams and found the main 12v relay was a common denominator in the behavior we were seeing and noticed it was heat damaged. We had it replaced and haven’t seen the engine off behavior since.
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That is very good news!
Might you have a photo of it and its location? Sure would like to know where it is located in order to inspect / protect it. THANK YOU!
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