Question1978 240D located at 5300 feet elevation (ABQ, NM). Car operated fione for the past 8 years but now, at times, the glowplug light does not come on and car will not start. I have to literally stand on the accelerator to force it to start. Days are hot; car sitting in parking lot all day - although this has happened in the garage in cooler temps as well.
Shop replaced the thermostat and it seems OK, but my mother whose car it is) insists something is wrong with the car because it is running at about 175 w/o air and creeps just past 200 with the AC. She insists something is wrong because it used to always run at 175.
It is 100 degrees here now and running the car w/o AC is insane!
Is the engine temp acceptable at 200 and a little over with the AC on? Will that damage the motor in any way?
And what is the cause of the glowplug/not starting?
AnswerHello Ingrid,
I would have the glow plugs checked as you may have on or more burned out. As you probably know the glow plugs preheat the cylinder before you rotate the engine,so you will have high enough temperature for the fuel to explode spontaneously. Because the engine relies on compression to create the flame, it is imperative that the battery be in excellent condition as well as the starter. The starter must rotate the pistons against much higher compression that with a gas engine.
I would also purchase some injection cleaner and make sure that the fuel filter/water separator is very cleaned and serviced . You my have purchased some fuel with water in it. I would locate a truck stop and go to the diesel counter and ask for some fuel treatment made with biodiesel. Or just purchase some biodiesel to ad to the fuel. I would say about two pints in a tank should help.
It has excellent cleaning properties.
The thermostat should allow the engine to operate in the 175 to 200 degree range. Make sure that you have the radiator, and cooling system flushed properly and make sure that you ad back the correct type and proportion of anti-freeze/coolant. The pressure cap on the radiator should be replaced with a new unit as well.
The cooling system operates under pressure to avoid boiling. If the radiator is not removing enough heat/ which is harder in hot weather of course/ it will allow the radiator to boil over.
If this vehicle has a water pump driven fan with fan clutch, I would also check to make sure it is operating properly. The Clutch engages to help move air through the radiator particularly in traffic, Make sure the cooling shroud is in place over the fan is the car has one. Make sure that the coolant recover tanks has proper water as this allows the pressure cap to burp any air out of the cooling system.
The A/C is designed to work at your high temperatures, and if all things are in good condition you should not have boil over.
If you are loosing any coolant or can smell a sweet odor at the exhaust, you may have a blown head gasket that is allow oil into the cylinder. NO good and the vehicle should not be drive until the head gasket has been replaced.
Good Luck and let me know what you discover.
Ropb
