Re: Engine Compartment insulation
Reply #27 –
The "Series 92 Field Service Recommendations" document (see Detroit Diesel Tec Docs Album) shows 210 as the max. operating temperature and "alarm" at 215 for every configuration of road vehicles. I don't know if your DDEC systems will trigger an engine shut down if it gets to 215. I know my '91 doesn't but I heard that they added it "in later years".
As others suggested, verify it is really getting that hot. The dash gauge isn't very accurate and operates on an electrical resistance change. The higher the resistance the higher the temperature. So if some resistance (i.e. contact corrosion) is added it will "fail safe" by showing a higher temperature.
A laser infrared thermometer gun is invaluable to help diagnose overheating conditions as well as for general traveling to check tire temperatures at rest stops. You can easily check the temperature of the output cooling pipes from each head to see if maybe one of the thermostats is acting up - both heads should be within a few degrees. Another source to get a reading on the temperature is a VMS(SilverLeaf Electronics, Inc. | Knowledge is Horsepower - it reads the DDEC computer directly. It's my understanding that the temperature sensor used by the DDEC is very accurate.
If it is getting too hot, I would suspect the radiator. I know you said it was checked out but did they drain the coolant, pull a hose off and look inside with a dental mirror and flashlight?
The radiator needs to be clean on the inside and outside. Also, the fins need to be firmly attached to the tubes and not crumbling away (typical effect of road salt).
Another thing to check to see if the hydraulic fans are turning at their maximum. Since my coach is a rear radiator I don't have this type of system so I'm not very knowledgeable on it but here's a discussion on it: Radiator fan
My experience 10 years ago with taking the coach into a shop (typically DD, not FOT) is that they will take a guess as to what it MIGHT be (radiator, water pump, thermostats, fans, etc. etc.). If it still overheats, you have just wasted money replacing good parts and get to pay them or the next guy more money to guess the next thing. I now do all my own diagnosis and repairs. Finding mechanics that know these older engines is getting harder and harder and it seems like all anyone wants to do is start replacing parts without a clue if it will actually fix the problem. Finding information on the engines was the hardest thing for me but with forums like this that is all changing. These engines are not hard to work on. The cooling systems is an in-between land - yes the engine is DD but the cooling system was designed by Foretravel - but I believe Foretravel will want to send you to Detroit Diesel. I didn't actually try Foretravel because when I was there it was winter and during summer I was too far away.
Topic: Engine Compartment insulation