My '87 is running great now. Still periodically I get a coolant low warning light.

Related even: I replaced an upper radiator hose some time ago and only topped off the fluid in the expansion tank, nothing else. Maybe I have some air trapped in there... if so, how do I purge it out?

Thx in advance -

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1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

Alla De Safety stuff,Etc.

Cold engine.

Take upper radiator hose loose from the radiator and Fill with 50/50 mix.
BOTH the Radiator and the engine.

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'84 300SD sold
124.128

it's best to fill the coolant with the vehicle parked so the radiator is MUCH higher than the tail lights... vehicle ramps will do nicely.
you can fill the upper hose first, putting coolant directly into the engine until the radiator begins to spill fluid, then put the hose on, and top off the tank.
be certain your small hose fitting on the head is clear, and not plugged with sediment.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Need a little more on that, plz - what's it look like?

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1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

When vstech and I got my wagon running here is what we did:

When we filled the radiator we found it was beneficial to raise the front of the car and fill from the detached upper radiator hose (detach from the radiator, tip the end of the hose up and use a funnel). We detached the heater hose at the intake manifold (left side at the rear) and poured in coolant to the upper radiator hose into the block until coolant ran out the heater hose port then hooked up the hose again. We unplugged the aux pump and jumped 12 V to the connector to help circulate the coolant into the heater core. (Pin 1 is + or the pump runs backwards)

Note that if the car is shut down the mono valve is open (passes coolant) so the coolant will make it back to the water pump past the mono valve. This ensures the heater core is full.

Also buy or rent a pressure tester and ensure you have no small leaks. Heater hose clamps and the aux pump housing are common suspects beyond the obvious.

Once you have it filled keep a close eye on it for several days as any remaining trapped air migrates out of the system.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech