I have a 95 E300D and am losing coolant but there doesn't seem to be any signs of a leak. I replaced the cap today. It's going somewhere as I've put in about a gallon over the last week.

Any ideas?

Thanx.

Dave

Try pressure testing the cooling system with the engine cold at about 20 psi. If it doesn't show any signs of leak in the first hour you may have to leave it on all day.

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DRIVE HARD-DRIVE FAST-DRIVE TO GET THE HELL OUT OF MY WAY.

1986 190E 2.3-16 Pearl Black!!
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1994 E320 Cabrio Red with black top!!
1985 500 SEL Anthracite Grey !!
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Also check the oil for any signs of coolant and make sure the cap is functioning properly.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record

Did you bleed the system?

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1998 SL500 Sport Model

Actually I just got the car less than a month ago. I have a few days on the warranty - I think it expires this week. Erol's Autobahn couldn't find any leak . . . but the mechanic was saying something about maybe air in the system, but I'm not a mechanic and didn't know what he was suggesting. Erol seemed to think it was running too well for it to be a serious problem, but this does concern me . . . head gasket or cracked head.

They put on a new radiator cap.

Thanx for all the replies.

MB coolant will leave a white residue where it leaks and dries up. Check the radiator neck area and all your hoses.

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dtf
1994 E320 Wagon (Died @ 308,669 miles)
1995 E300 Diesel (228,000)
1999 E300 Turbodiesel ( died @ 255,000)
2006 Toyota Tundra SR5 AC 4X4 (115,000 miles) rusted frame - sold to chop shop
2011 Audi A4 Avant (165,000 miles) Seized engine - donated to Salvation Army
BMW 330 xi 6 speed manual (175,034 miles)
2014 E350 4Matic Wagon 128,000 miles
2018 Dodge Ram 21,000 miles

Recently I changed both upper and lower hoses on my '91 300SE. I just so happen to live on a hill and had the nose up when refilling the system. What's this about bleeding the cooling system? After also changing the coolant level sensor there does not appear to be any leaks but the last couple of days I have noticed the faint odor of antifreeze after it's warmed up. Hoses, tank, pump, radiator checked out and nothing seems to be leaking.

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1991 300SE (my ride, 279,000 miles, looks almost new
1954 Cadillac (21 yo son's car, he bought when age 15)
1972 SeaBird 19 ft runabout (old but solid, slant six, Volvo sterndrive perfect condition, undergoing complete overhaul and refit)
1998 Toyota Rav4 (my sons daily driver when he is in the Continental US, PROUDLY serving in US Navy)

My 94 E3OOTD needs topping up once a month 1/2"[12mm] in the header tank no sign of a leak, oil clean any ideas??

Peter

Check the auxiliary water pump for leakage. The one in our 1991 300CE was leaking around 110,000 miles. It's a simple DIY job to replace it.

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Fred Hoelzle

I don't see any signs of coolant leaking. I drove some yesterday and revervoir tank dropped about 3-4 inches. I brought it home and parked it! I'm afraid to drive. I think tomorrow I'll take it to the shop and leave it until they get it fixed whatever it is!

What's the going rate on a cracked head - which is worse case scenario. Somebody in another thread mentioned that they had seen 3 cracked heads in this model and they all were losing coolant with no explantion.

I'll try to look around the auxillary water pump today.

Thanx again for comments.

Dave

I had a couple of diesel come thru the shop last year that had a very slight leak coming from the thermostat gasket. It was very hard to detect but they where leaking.

__________________
DRIVE HARD-DRIVE FAST-DRIVE TO GET THE HELL OUT OF MY WAY.

1986 190E 2.3-16 Pearl Black!!
1987 190E 2.3-16 Smoke Silver!!
1986 190E 2.5-16 Pearl Black!!
2004 CLK 500 Cabrio Designo package!!
1994 E320 Cabrio Red with black top!!
1985 500 SEL Anthracite Grey !!
2011 Subaru Impreza STI 380HP (Yeah Baby)

Well, I got GOOD NEWS today. I went expecting the worse case scenario. Erol did a pressure test today and water started shotting out the Heater Valve (I think I have that right). It's by the battery. Not a cheap part, but a lot better than any engine problems. I forget if he said it was $390 or $490. He thot he had a used one but it was the wrong one.

Thanx again for the various input.

Erol talked like this is not a part that is usaully a problem.

Dave