emergency engine shutdown Detroit diesel

[tombuchanan]

Thanks for info, but will a temperature around there trip the engine shut down procedure?  That was my main inquiry as I'm reluctant to take it out again without knowing why it shut down the first time.

[plyonsMC9]

Good evening Tom,

I've had my MC9 engine shut down due to "temps" many times and reasons.  You mentioned you just purchased the bus and then it shut down on the way home.  Once right after I had my first coolant change after purchasing the bus.  It turns out my MC9 was finicky and took some effort to burp after refilling w/ coolant.  So driving back from the shop the engine circulated some kind of air bubble, and  * alarm * shut down in normal driving conditions.  First time was hair raising - especially trying to get out of traffic.  2 or 3 other times the bus was serviced and same scenario.  I learned to watch coolant level like a hawk.  And have lots of talks about burping the engine w/ whoever worked on it, which didn't seem to help.  And doing lots of coolant top-offs and watching of the radiator site glass.  Later I had a great mechanic, Joe M., who put in a kind of air bleeder and haven't had that issue since.

Also had the situation where temp sensor wires crossed the engine or shorted out against metal - If I remember correctly, the sensor wire wasn't properly insulated at the time.  Put it in a wiring loom until I could get the wire insulated as it should be.  That 'short' also shut it down 2 or 3 times.

Before I replaced the radiators the engine ran hotter, which of course shut it down especially in long slowmountain grades.  For that I worked at downshifting, and driving by the temperature gauge vs the speedometer.  Not going all that fast anyway.   That was a huge help.  And I do the downshifting to this day just to keep temps where I like them.

If you knew the differential between the true temp and the dash gauge that would help also, so you would know what temp you're actually running.  Others have noted the inaccuracy of the dash temp gauge.  Testify!!  Run the engine to temp, grab the heat gun and have someone read the dash gauge to you while you read the heat gun.  Keep the differential in mind if it's off. 

Eventually you will nail it, and know your engine and the temp shutdown will likely be a thing of the past - but you will always keep it in mind as a savvy driver who knows his rig!

Hope this helps, Phil

[luvrbus]

Keep in mind those sensors come in different degrees for shut down,a friend of mind replaced his sensor and paid no attention to the little detail and install a 180 degree sensor and his MCI would not go around the block before shutting down 

[tombuchanan]

thanks for the info phil, I'm guessing this was my case.  I know the coolant was low and temps were somewhere around 200 when it happened.  where are the temp sensor wires on the mc9?  i can see the sensor wire for the gauge back by the engine (which doesn't work) but i don't see where the one from the front is.   

[Tedsoldbus]

I have a 1980 Prevost, so it may not apply, but my 6V92 shut down 2 times on the interstate on the same day. (that was fun)
All fluids fine, all gauges in the "green"at shut down both times. It would start again after 5 minutes, but then guages would go dead and jake would not work. But the bus still ran, so went to a repair place 2 hours away with fingers crossed. It was the engine run relay. Don't know if you have one of those. Hope you get it worked out.