W210and the disappearing water trick

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baxta

Member
Joined
Jun 29, 2006
Messages
54
Location
suffolk
Car
mercedes e200k
I know this has been discussed about, but I really am pulling my hair out.
I keep losing water somewhere but no one seems to know where. The coolant system has been pressure tested and no leaks found. there is no oil in the water or visa versa. The car doesnt overheat even though I ended up putting back about 4 litres to to top it back up again.
My garage say it could be the head gasket, but as nothing is evident they cannot be sure.
HELP PLEASE.
Is there nothing else they can do to check if its the head gasket?
What else could it be? Bear in mind I have replaced in total about ten litres of coolant after about 150 miles...this must be going somewhere..

Thanks as always guys :confused:
 
There are detectors to test for combustion gases in the coolant as an indicator of the head gasket going. Another test is a static compression leakdown test on individual cylinders.
 
Just a few ideas.

Sounds quite a big leak.

Does it leave any on the ground after it's been standing?
Check the radiator, water pump, heater hoses, filler cap.. Also check the thermostat housing, I've known leaks when the O ring compresses.

Just thinking it could be losing it into the gearbox if the radiator/oil cooler has corroded through.
Get a long net curtain hanging spring and dip the gearbox as a check.

If it's been pressure tested and there is no pressure loss then it shouldn't be losing water, but obviously is so it does sound like it could be internal.

Have a garage waft an emissions test probe over the header tank with the cap off. That should detect any combustion gasses in the water.

When filling it are you ensuring the system is well bled with the heater set to hot.
If not it will have an air lock and blow water out, which you then refill again and on the cycle goes.
Re route the the overflow pipe so you can see if it ejects any water.
 
You guys are great and I truly appreciate the advice that you give. These forums are a Godsend bringing together the wise with the not so wise.
Mobile phones and computers....how did we ever get on in the past???????
Many thanks and I will let you know how I get on
 
The water pumps can leak at the front gland, as said above, get some dye additive then you can see any leaks
 
Theres a coolant pipe between the engine and firewall that can rust. Mine did, it left the pipe as steam, barely visible. You'd be surprised how much coolant you can lose as steam.

Its at the back of the engine, very difficult to reach. I had mine sleeved with a rubber pipe, much easier than replacing the whole thing.

Also, the reservoir cap can leak after a bit. I can't remember which one it is but either the oil filler cap or the coolant reservoir cap has a replaceable o-ring seal.

You should also check the bottom of the radiator, theres a red valve that I presume is a drain - perhaps its leaking. You need to remove the plastic undertray at the bumper (the one that covers the foglamps) to get to it.
 
i had a couple of experiences, not on mercs, where i lost water (lots) all at once, one was a head gasket failure other was a faulty thermostat.
 
Has anyone pressure tested your pressure cap, if it's not holding pressure then you could be losing coolant via your overflow as you drive along
 
They have now checked everything and say they still cannot find the problem ...AGGGGGHHHHHHHHHHH!!!!!!!!!!!!!!!!!!!!!!!!!
 
Who is checking it?

Dealer?

Specialist?
 
My brother in law is manager of a general garage so been using him.
 
Take it to someone who knows the cars inside out.
 

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