Where's the coolant going?
 

My coolant level keeps slowly going down and I smell a little coolant outside the car when I park but there is no fluid anywhere. The car is going into the shop on Wednesday for this but is there any experience from other '94 - '95 W124 owners on this?

Haven't had my hands on a 94-95 W124, but on other cars this usually means a slow leak somewhere. Can be water pump leaking out the weep holes (and the coolant drops on the ground off the front of the pan) or any other hose in there.

Best way to find it is a pressure tester.

The worst possibility is a cracked head, not usually a problem on the M104.

Peter

Very possibly it's head gasket time.
Could also be the water pump or the o-ring on the heater hose nipple on the left rear corner of the head.
Lot's of other possiblities too; radiator, loose hose clamp, etc.

Gilly

Mine has a slow leak on the radiator side seam. Very hard to find.

Head gasket was done at 66,000 miles, the water pump at 115,000 miles, the oil is clean and clear and the cap to the tank is 1 year old.
I did hear a hissing sound near the tank on Satruday (now that I remember) and the smell began on the passenger side forward area. I know the expansion tank is there, but how active is that system in terms of fluid transfer to the upper tank and back during driving?

Could also be a bad coolant tank or tank hose, only leaks under pressure. The seat in the tank for the cap could also have some crud under it or be cracked or scratched.

I'd have said coolant tank cap but yours is new -- it is an MB cap, right, not an aftermarket?

Peter

Update. The reason the coolant level was going down and the smell was noticed was because the hose from the tank to the bottom of the radiator had a pinhole leak. The service advisor basically said 'how did you notice that small of a leak?' I've owned almost 40 cars in my life - about 50% shouldn't have been on the road. '78 Dodge aspen wagons, '70 Fords with no brakes, plenty of rusty Subarus, VW beetles. I check ALL FLUIDS almost everyday. I am scared of breaking down with the kids in the car. I had the spark plugs replaced too. Total was $275.00. Just turned 201,000 miles.

Ya' know...I really like my dealer, very good customer service and they run on time usually and I always have access to a loaner car. But sometimes I think the techs in the back miss the obvious solutions.
I had the hose from the upper tank to the radiator replaced but the level was still going down and the smell was still there. I thought to replace the fairly new radiator cap myself since it costs me about $5. I think the problem is now solved. Yesterday there was no smell at shutdown and the coolant level stayed the same.
I'm thinking about giving the service advisor a call as constrcutive feedback. This has happened once before and it involved the radiator cap again.

Glad to hear that the problem is solved, but in case it happens again, I worked out a way to find small leakes.

I had this problem with my fuel tank where it would leak, but no one could guess where from, so what I did to see if it is the cap or something else, is tie a paper towler around the pope going from the cap to the tank. Sure enough after the next fill up and a small drive, there was marks on it even though it was dry since fuel evaporates quite quick in small quantities.

You could have dome something similar on the radiator hoses, but you won't have to now ;)

xp

dtf

You should definitely discuss this with the service advisor, the tech(s) and the service manager.

You are taking your car to them because you trust them. Let them know how it went. The feedback is invaluable.

This also lets them know what your expectations are. If you handle it well and diplomatically you will all benefit.


Haasman