Engine/Generator Bay Operating Temperatures

[Pete Masterson]

Since the EGT gauge often reads 300 to 400 degrees, the exhaust system probably gets well above 212 much of the time.

I note that I have a couple of fire sensors in my engine compartment -- and one, near where the exhaust pipe passes by goes off if the engine is simply warmed up. A previous owner disconnected it. The dealer re-connected it just before I bought the coach --- and it went off during our test drive. When I replaced the radiator core, the shop (unknown to me) reconnected it. It went off while I was on the freeway heading home. (One that's on the other side of the engine causes no headaches, if it's working.) I must say having a light come on up front reading "engine fire" is not very comforting!

Well, lets just say too, I'm not very impressed with temperature sensors and I sure wouldn't trust one to set off a fire extinguisher with all the resultant mess it would make -- at least not without a fair number of tests to ensure that it only went off when it was -really- necessary. So, start out with some temperature sensors or use an IR thermometer to try to get some reasonable vaules for various places in the engine compartment. Then install the sensors (but not the extinguishers) and continue testing. Once you're satisfied that the extinguishers aren't going to discharge unexpectedly, then it might be worthwhile for peace of mind.*

It occurs to me that fires raise the temperature very quickly -- so something above 500 or 600 degrees ought to be more appropriate than something around 200 where the exhaust system can easily exceed that level.

None the less, I note that my operating manual suggest "concern" if the EGT gets up to 1200 degrees -- which suggests that even 800 or more might be "normal" (although I've never seen it above around 550-600 while climbing I-70 over 10,000 ft. in Colorado). How much cooler the exhaust is once it gets past the EGT sensor is something I'm not sure about.

*It's also a question of just how common engine fires are... They do happen on occasion -- and I've seen one or two on the road in the Bay Area -- but there are some 5 million automobile trips per day in the SF area, so one or two engine fires observed over a 30+ year period suggests that it's pretty rare. And I've never seen a bus with an engine fire.

Pete Masterson

'95 Blue Bird Wanderlodge WBDA 42

El Sobrante CA

"aeonix1@mac.com"

On Feb 20, 2008, at 1:05 PM, gulfquest2 wrote:

After reading the fire stories recently posted here, I have become 

much more aware of my fire extinguisher status onboard.  After 

servicing my factory ABC units, I thought about installing automatic 

units in both the engine bay and the generator bay.  

Does anyone have an idea of the temperature ranges in these bays under 

worst case scenarios (short of fire, that is...)?  The automatic units 

I have are preset to go off at 212 degrees Fahrenheit and I am 

concerned that the presets are too low especially when driving in the 

Southwest in summertime.  Doees anybody have any ideas?

Allen & Conny Cranford

'00 43LXi, "Lone Wolf" 

Tampa Bay, FL