So I've been losing coolant on my 1982 240D.
I drive an hour each way to work, and both at home and at work I park in the dirt, so its sometimes hard to detect leaks.

However I know it is leaving at least a small puddle of coolant under the radiator.
There was always a little on the lip of the radiator as well.
I was probably putting in a half gallon every other day.

I plugged in the coolant circulator one night and within 15 seconds coolant was pretty much pouring from the radiator (from the top where the plastic meets the aluminum).

Installed a new radiator and hoped that my problem was solved.

But it is still losing coolant, quite possibly at the same rate.
No longer a puddle under or on the the radiator though.

I parked on some cardboard sheets last night to help detect leaks, and didn't see any signs.

I read (and sort of understand) older posts about an internal coolant leak, which doesn't sound good.

Are there other places I should check for external leaks?
Get my oil analyzed?
Throw in the towel and get someone who actually knows what they are doing?

Start off by inspecting all your hoses thoroughly and give all the clamps and extra turn. Did you replace your rad cap?

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1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

what model???

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1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg

its a 240D. i checked seal on rad cap and seems fine. never any sign of coolant around cap. replace anyways? just went outside and ran the coolant circulator and checked all connections while it ran.

one (major?) thing i forgot to mention is that the car had/has a wvo conversion with hose-in-hose. system isn't up and running but makes for lots of extra connections. just now tried to syphon off a sample of the old veggie oil thats been in the tank since i got it to make sure i'm not losing any coolant through the heating element in there.

is it safe to assume that an external leak to this degree wont' always leave a puddle?

it could be burning off something hot before it hits the ground.

I suggest you plug the cooling system back to stock and get rid of that extra stuff.

__________________
1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg

What you need is a cooling system Pressure Test to verify where the leak is.
Many shops have this tool, and can check the system in a few minutes.

Radiator Pressure Tester Kit
Radiator Pressure Tester Kit

.

__________________
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Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
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Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

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Return the system to stock.
The leak could easily be in the extra plumbing.

.

realized i should probably conclude this thread in case yet another newbie down the line makes the same dumb mistake that i did. didn't have a coolant leak afterall. Just lack of an expansion tank. guess its not stock on the 240D...

^ Correct, no expansion tank on a 240.

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83 SD

84 CD