Hey guys-We have an 06 BB Vision w/Cat C7 that emits noxious fumes when the heaters are running.This has been an on-going issue for the past 3 yrs..seemed to start when someone put universal antifreeze in it.The system was flushed several times and correct coolant was added which helped for a while but the fumes returned.The bus then had to have the injector cups replaced due to fuel in the water.The system was flushed again by Cat Dealer.Upon getting the bus back the fumes were as bad as ever.We then replaced all the coolant/heater hoses and flushed the system once again.That lasted a week before the driver complained about fumes again.Could this be a heater core issue?Any advice or suggestions would be greatly appreciated.
If the cooling system is tight you would'nt be unable to smell the type of coolant in it.
Did somebody get something on one of the heater cores? candy, crayon, plastic? How about a bad blower motor creating an odd smell? I know you said the smell seems to come and go with the type to coolant in the cooling system?
Is there something elese going on when the coolant gets changed or flushed causing one area or group of the heaters to get hotter, creating the smell?
Did you replace all the heater hose through out the the bus? Is there a heater core leaking/seeping? How about a hose clamp? Some of those behind the panels are near impossible to access to check and tighten.
I require silicone type hose clamps for all hoses and I ride my people about tightening all readily accessible hose clamps everytime the vehicle is serviced with a socket and ratchet. Cold soak leaks are a problem in this part of the country.
Hoses and coolant type should have done it - we had this problem with silicone hoses and "John Deere" (green) spec antifreeze on '07 BB A3RE's. Changed to Cummins blue coolant and flushed the systems and it went away. Smelled like dead fish.