Hi,

Many diesel medium buty trucks and school busses get a cover to reduce the airflow to the radiator. Would this be useful in 20s or below weather in our cars? I would assume that it would allow faster warmup, which in turn would reduce wear when cold.

I drive mostly all highway, over 65, but the problem is that my apartment is about half a mile away from the highway. I dont like to let the car sit and idle, as the unheated parts wear funny, and it causes high iron readings when doing oil analysis. Its better to warm up under light load... But 65mph (or even 55 if I drive slow) isnt exactly light load. I hate going onto the highway and having my engine temp at 40 or so, so anything that could quicken the warmup would be great. I already dont run the heat until the car is up to temp. I think the fact that I run on the highway would make it ok to have something covering the radiator, as the air hitting the oil pan, etc at high speeds whould have a sufficient cooling effect.

Has anyone done or tried this? Any suggestions?

Thanks,

JMH

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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
2008 ML320 CDI (199k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)

IF the thermostat is working properly, covering the radiator shouldn't speed warm-up times. MBZ 616 and 617 diesels use what I call a "closed loop" cooling circuit.

When cold, the thermostat closes off flow to the radiator while still allowing coolant to circulate in the engine. As the thermostat reaches temperature and opens, some of the coolant flow is permitted to pass through the radiator with the remaining flow still circulating in the engine. With the 'tstat fully open, all flow is directed through the radiator.

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Never a dull moment at Berry Hill Farm.

You can always just put a piece of cardboard infront of the radiator thats what i used to do.
-Bob

One caveat is that sometimes people forget to take out the cover. Every once in a while you hear a story of a mechanic diagnosing a problem with overheating in a car, only to find that somebody forgot about the cover and left it in through the summertime.

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95 E320 Cabriolet, 169K

If you have a radiator type oil cooler, it is a good idea to cover it partially in very cold weather, it prevents overcooling the oil. However, if you forget to uncover it later, you will fry the engine, so I recommend leaving it alone.

If you have a good thermostat, covering the radiator isn't going to do anything. The reason big trucks and buses had the cover is that they had partial flow thermostats -- there was a hole in the closing plate -- and the result was serious over-cooling in very cold temps. Bad design, use to prevent serious overheating with a bad thermostat or something.

Moderate load is the best way to warm up the engine. An MB diesel will NEVER reach operating temp at idle in the drive in cold weather -- must be driven.

If you cannot avoid the highway before you get up to temp, at least drive gently until at least 40 C, no full throttle starts, and try to stay out of the turbo as much as possible. Otherwise, keep the oil changed and don't do any more short distance, cold operating temp driving than you must.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Not true. In 22*f, my TD can reach 81*c in just shy of 45 minutes at 850-900rpm idle.