600 SEL disappearing coolant

[drewpasmith]

Hi everyone,

In March of this year, my mechanic replaced the radiator, thermostat, water pump and a number of coolant pipes as preventative maintenance on the 600.

Since that time, she's been slowly loosing coolant.

At first, the coolant level light would only come on during/after hard acceleration. It got to the point where it was constantly on, so I topped it off. And now it's coming on again.

The coolant doesn't smell of oil/ATF, nor is their any evidence of coolant in the ATF/oil.

So where the hell is it going? Has anyone had phantom coolant loss like this before?

Any advice before I take her to the mechanic would be much appreciated.

Cheers,

Drew

 

[markjay]

On a general note:

1. Failed head gasket can cause loss of coolant with no other obvious signs. You do not always get oil in coolant. There may be traces of coolant present in the exhaust fumes (place your hand very carefully behind the exhaust tip and then smell it for coolant), or you could use an MOT exhaust gas analyser to check for presence of exhaust gasses in the coolant expansion bottle (inserting it above to fluid line). Additionally, cylinder compression test would help identify head gasket issues.

2. Coolant could be leaking slowly from a hose or the water pump on top of a hot engine part, thus evaporating immediatly with no sign of dripping under the car. There would be dry residue, but it may occur in a place where it is difficult to see when looking at the engine from the top.

3. The expansion bottle cap has a built-in safety pressure relief valve. If it fails, it will open and release coolant vapour.

4. Coolant can leak into any heat exchanger, e.g. transmission radiator. The test for this is by analysing the ATF for presence of Ethylene Glycol. Keeping in mind that the pressure in the cooling system is higher than in the transmission.

5. The best test is to have the cooling system pressurised using a pressure testing device connected instead of the expansion bottle cap. You leave it for a while and check for any pressure drop. This will test the entire system apart from the cap itself. The downside is that it won't tell you where the actual problem is.

6. As a last resort you could try a coolant system sealer additive. These liquid repairs do not always work and can cause other problems, but might be worth considering as a last-ditch attempt before taking the coolant system apart.

Good luck...

 

[markjay]

And how do I know all this? I had an Alfa Romeo in the eighties.......

 

[drewpasmith]

Superb. Thank you.

In anther thread, I've detailed a flaring 2/3 shift. Someone has suggested that coolant in the ATF may be the reason.

Onwards we go.

 

[drewpasmith]

And how do I know all this? I had an Alfa Romeo in the eighties.......

Your credentials, therefore, are unquestioned!

 

[markjay]

Your credentials, therefore, are unquestioned!

I could probably write a PhD about 'Use of Porous Alloy in The Construction of Italian Engines' ...

 

[aghajaved]

If problem starts right after you got pipes etc replaced then it should be a minor problem of leaking pipe or clamps not properly installed. Hopefully it is not going to be head gasket