i had to add the blue liquid windshield stuff this evening and i noticed that the uppper radiator hose had squashed itself in the middle. when i loosened the radiator cap, the hose unsquased itself into its normal round self.

i thought this was weird so i checked it again after driving it and it was once again vaccuum squashed. i had to relieve the pressure by loosening the radiator cap again.

any ideas?

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Jennifer
90 350sdl

You may or may not need a new hose, but you definitely need a new radiator cap. Your cap isn't releasing pressure as it should.

i saved the radiator cap from the parts car. however, the bad one has 100 stamped on it, the good one has 140 stamped on it. it fits fine. will that work? what do the numbers mean?

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Jennifer
90 350sdl

The only way I can imagine a vacuum being created in the system is if some pressure is released as the coolant heats up and begins to evaporate; when it cools down again and condenses the pressure in the system would drop to below atmospheric pressure.

The radiator cap must be releasing pressure too soon (the system should be sealed unless the coolant is way overheated) if this is happening all the time. Try the parts car's cap, or get a new one (should be cheap).

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'81 300TD Wagon 355k (Miss Diesel)
'83 300SD 180k
'84 500SEL 190k (Parting it out)

what do the numbers mean?

140 means 1.4 bar
120 " 1.2 bar
and so on and........

MB superceded the previous caps to the 140, so use that one. Check the hoses, though, so that the new higher pressure doesn't find a bad hose for you

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

I believe the 100, 120 and 140 markings are 1 bar, 1.2 bar and 1.4 bar. Or KPa.

You didn't say which car. I believe the SDL requires a 140 cap. With an aluminum head, don't tempt fate. The 240D should be fine with any cap but watch that temp gauge.

Sixto
95 S420
87 300SDL

A new cap for Garth would read 140, for Pete 120. Best to use the right cap.

The important thing is that you understand that the lower hose must not be able to squish.... use your hand to check when cold.... the lower hose is under suction....and should have a wire inside it to keep it open... if that rusts away then your hose can be sucked closed at high engine speed... causing overheating... but you won't see it when you get out and the engine is idling...