The bleeding procedure kind of differs depending on which model you're working on. On some models such as the V8s you can fill the coolant through the upper hose (disconnected at radiator) and hold it as high as possible to take advantage of gravity which will make all the air go to the top. But hold the hose as high as possible when filling. This method can take a while, but is the best way to clear the system of air pockets. In diesels, you can just fill the coolant through the expansion tank until it hits the full mark and run the car (I like to drive it to force out the air pocket) with the heat on so you know the t-stat has opened. If you go driving after filling up the system, be sure to take extra coolant along with you and stop periodically to check the level. Don't worry if the temp gauge on a diesel goes above normal, those engines can certainly handle the heat. On gasoline powered cars, once you have filled the coolant to the specified mark, just idle it (rev it periodically) until you feel heat coming through the vents (turn the defroster on full blast) and top up the level afterwards. Some of the V8s such as the 4.5 were notrious for air pockets and when running them to bleed them, it' normal (on any model) for the auxiliary fan(s) to kick in and run for a while. Hope this helps!
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Rgds,
Aaron Greenberg
MB technician
Precision Motorcars, Cincinnati, Ohio
'67 250SE Cabriolet
'77 450SL
'80 300SD
'85 380SE
'86 420SEL
'89 420SEL
'93 300E 2.8
'74 Jensen Interceptor Mk.III
'81 DeLorean DMC12
'84 BMW 745i Turbo
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