Leak in Radiator?
 

My 95 E320 seems to be leaking as I have to put 32 oz of water in the Radiator resevoir every other day. I crawl under the car and can't fnd the leak. Is this typically in the radiator rather than the hoses? Do any of the "stop radiator leak" products work? Is the radiator replacment a DIY or is it nasty with the fan housing in this model. I have replaced a 85 300SD radiator which was very staightforward. Thx, edge.

Have you checked for a blown headgasket?
PS Do not use stop leak as it only clogs.
Radiator replacement is straightforward.
You mite want to check overflow tank which is under right fender.
go to autozone and borrow pressure tester which should help.
Good luck

If the leak is small it will only leak under pressure, that means when the engine is hot. The water will evaporate and/or blown away which makes is nearly impossible to find the leak. The only way is to find a small leak is by using a pressurise tester when the engine is cold, not just cooled down, but really cold.
I would not replace the radiator if the car is not overheating and you are not sure if it is leaking.

A quart of water every two days doesn't sound trivial
 

You should be able to find some residue; there are fluorescent dyes you can add to coolant to help trace the leak under black-light.

Check water pump near pulley, also check the hose connections. I don't know if your radiator has a plastic neck but if so, it can sometimes develop a crack under the hose clamp that leaks and can eventually fail (neck breaks off).

Will a headgasket leak affect the radiator water level? I thought it just leaks oil. I guess I have to stop bt Autozone for the pressure tester when cols, thanks guys.

Cheepest and easiest is the dye. Ask your local repair shop to add a drop or two to the coolant. It may take a day or two, but you'll definitely see where it's coming out because the dye remains even after the coolant evaporates. And you won't need a black light either.

Been there, done that on two different cars.

Bob
94 e320 Wagon

if your head gasket is leaking into the combustion chamber you will see steam out the exhaust in the morning after sitting overnight, or puffing at idle after a good warm up.

if it is leaking into oil passages, you will find it in the crankcase, either as high level, or foamy residue.

it could theoretically leak to the air and run down the side of the engine too, but i think that is rare.

good luck

tom w

Yes headgasket leak will affect water level.

Well I got the Autozone pressure tester and hooked it up when the engine was off but warm. It showed a very slow leak, like 1lb of pressure after 3 minutes with no visable water leak. I then started the engine and warmed it to 85 degrees with the tester on and there was no change in pressure. I checked the oil and tranny dipsticks and there was no foaming or bubbles. Could this pressure and fluid lost be attributed to the water resevoir cap? Will the results differ if I test on a cold engine? I'm perplexed. ''Btw, the head gasket is leaking some oil and I add a half quart every 2K miles.

If the engine is not consuming the fluid and you don't see any external leaks, the odds are that the cap is faulty and is opening way too early. Then, the system discharges a bunch of water onto the pavement. You fill it up the next day after it cools and it does the same thing.

You could verify this, if you're interested, by putting the overflow hose in a small container and see if it fills during vehicle operation.

Brian.
Interesting tip about the overflow. I never thought of that, although I just replace the cap regardless.

Typical engineer with all kinds of tests........LOL.

I agree........just replace the cap and move on........;)

I replaced the cap today. I should have known, the tell tail was that when I removed the cap, there was no vacuum! Thanks, Brian and everyone else. Spending $13 is alot better than spending $200 and being frustrated.

Don't celebrate too soon grasshopper. There should not be a vacuum in the system, because that is one of the jobs of the coolant cap. Can't call it a radiator cap anymore, because these days it is seldom found on the radiator. A coolant cap has many functions. First it keeps twigs and whatever out of the system. Secondly it keeps the proper pressure on the system to prevent boiling. Thirdly it keeps coolant from escaping from the recovery tank during cool down like Brian said. Lastly it keeps the system from going into a vacuum during the cool down process. How coolant escapes during the cool down process is another lesson. Hopefully you solved the problem. Keep us posted.

I get a vacuum effect when I remove the coolant resevoir cap on my BMW. I assume I would get one on the Mercedes. The pressurized system prevents the coolant from boiling even at extremely high temperatures which allows the engine to cool.