Hello,
I'm chasing an overheating/coolant loss problem on my daughter's 1978 240D. I noticed that the car does not have a coolant expansion tank, which means that once the coolant gets hot, it's pushed out of the radiator down the hose onto the road.
Could that be stock or did ALL W123 come with such a tank? I'm about to go to a boneyard and get one, but I"d like to know from fellow 240D owners about whether or not what I have is right or wrong.
Thank you!

Bernard

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Bernard
www.californiaclassix.com

My personal Diesel fleet:
1995 Mercedes E300D SE (24-valve, DOHC, 6-cylinder EDS Diesel--> 134hp)
1992 Dodge Ram (intercooled Cummins 6-cylinder turbodiesel--> 160hp)
1985 Mercedes 300CD (5-cylinder turbodiesel--> 120hp)
1978 Mercedes 240D (teenage daughter's first car--> 62hp . . . supposedly)

No coolant tank on 240D at least until 1980......

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Current Mercedes
1979 maple yellow 240D 4-speed

Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT

My 78 240 doesn't have a expansion tank. If your's doesn't have one then it probably never did.

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240D's did not come with the expansion tank. The radiators with the expansion tank system were on the 300D turbo models (82 to 85).

Simple overheating means maybe thermostat or water pump. Beyond that it may lead into plugged up radiator or even blown head gasket.

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Palangi

2004 C240 Wagon 203.261 Baby Benz
2008 ML320 CDI Highway Cruiser
2006 Toyota Prius, Saving the Planet @ 48 mpg
2000 F-150, Destroying the Planet @ 20 mpg



TRUMP .......... WHITEHOUSE
HILLARY .........JAILHOUSE
BERNIE .......... NUTHOUSE
0BAMA .......... OUTHOUSE

I have an 81 and an 83 (both 4 speed manuals) and neither one has an expansion tank. I do add a small amount of coolant every so often, but it always seems to level itself out to just above the cooling tubes in the top tank. No overheating problems though, and it gets HOT where I live-100+ often.-Scott

Take the car down to a carwash and blow out the radiator core.

None of the W123 240Ds came with an expansion tank but the system they have works just fine without one.

I would replace the T stat if blowing the crap out of the radiator fins doesn't help but dont waste your $ trying to modify a system that works fine when all the components are good.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Thank you for the reply. I went to the junkyard and realized that modifying the system isn't that easy, as the expansion tanks have a hose on the bottom that gets back to the radiator. However, the 240D radiator has no provision for such a hose.

Regarding my problem . . . car loses about a pint of coolant a day, during which my daughter drives her car about 70 miles on the freeway, commuting to school. While driving up to about 65mph, all is fine. When going faster, car heats up slowly. When hitting a traffic jamb, it's overheating. No water in oil, no oil in water, no visible coolant loss, except, perhaps, for the radiator cap.

I first replaced all belts and hoses. I then bought a new (all metal) radiator. Tonight I will install a new radiator cap and a new thermostat, both easy fixes. My next approach would be the fan.

In any case, thanks, guys!

Bernard

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Bernard
www.californiaclassix.com

My personal Diesel fleet:
1995 Mercedes E300D SE (24-valve, DOHC, 6-cylinder EDS Diesel--> 134hp)
1992 Dodge Ram (intercooled Cummins 6-cylinder turbodiesel--> 160hp)
1985 Mercedes 300CD (5-cylinder turbodiesel--> 120hp)
1978 Mercedes 240D (teenage daughter's first car--> 62hp . . . supposedly)

You might consider replacing the radiator cap, too, if it's old. Replacing mine helped lower my normal operating temp back into the 82 degree territory.

... Looks like you've already thought of that and it's part of your plan!

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05 E320 CDI - 175K miles
82 300D - 200K miles (sold)

If you are replaceing the T-Stat, look at the water pump. It could be leaking from the weep hole. A bad radiator cap can cause all sorts of overheating and coolant loss issues.

I would not bother with the fan until you find the source of the leak.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Ditto. There is nothing to go bad on a 240 fan.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Try a new radiator cap

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

I put a 300d turbo radiator and expansion tank in mine and it made a hell of a difference.

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