8 to 12 miles per gallon . cause i own one "D
when overheating occurs at highway speeds the cause is usually. a radiator or coolant circulation problem, Check for a restricted or clogged radiator.
The DeVille could have low transmission. Or the internal transmission bands or valves could have failed. The transmission will most likely need a rebuild.
uotside temp sensor in front of the radiator has gone bad
There are several things that can cause your Cadillac Deville to have transmission problems. The most common transmission problems are worn transmission gears.
O2 sensor, and catalytic converter can be ruined. You can also cause internal damage to the engine, depending on what the problem is. Have it repaired.
check radiator for small leaks or cooling lines which would most definitely cause it 2 steam when running after awhile
1 of a 100 but the 1st to check . BAD THERMOSTAT
Heater core has failed.
dirt in the speed snsor bad speedo head in the dash
One reason a 1998 Cadillac Deville would cut off while driving could be the fuel pump or the car is out of fuel. Another reason could be the spark plugs.
A bad resistor or a bad switch.
If the pedal is stuck down, no vacuum to the release diaphragm on the pedal
1 or more out of balance tires
Well... mines doing the same thing. 88 sedan deville, 4.5 ltr v8. It turns over but I watch and nothing is coming through the injectors... no fuel. It happens off and on, sometimes it works and sometimes it doesn't. I think it might be the fuel filter but i can't find that thing.
The blower control module is defective.
door button stuck --bulbs? fuse.
7.5 with filter! Previous answer is incorrect, if you put in 8 with filter change you will be half quart over and cause problems!
My first diagnosis would be a blown freeze plug, check that and you may find your problem.
Possibly a clogged fuel filter. or faulty fuel pump, amongst other things
Blown head gasket or bad radiator cap
cracked head, or leaking head gasket, or cracked block
put a new motor in. it'll cost about the same as fixing the rear main that is more than likely the cause of the problem.