Strange coolant leak M52 engine

[taurusalmighty]

My 328i M52 engine has a strange coolant leak. If I leave the car overnight in the garage there is a puddle of green coolant on the garage floor the next morning. If I drive it during the day and park it somewhere, there is no drops on the floor/ground or any visible leak on the engine if I put my head under the car to investigate, even after a couple of hours of the car parked. I asked my mechanic to investigate, and he had the car standing for most of the day, and there was no detectable leak. Leave it overnight, and the coolant gnomes are back. Has anybody had this experience before?

 

[ChrisBrand]

Crack in Expansion bottle?

 

[VeNoM_Ct]

My 328i M52 engine has a strange coolant leak. If I leave the car overnight in the garage there is a puddle of green coolant on the garage floor the next morning. If I drive it during the day and park it somewhere, there is no drops on the floor/ground or any visible leak on the engine if I put my head under the car to investigate, even after a couple of hours of the car parked. I asked my mechanic to investigate, and he had the car standing for most of the day, and there was no detectable leak. Leave it overnight, and the coolant gnomes are back. Has anybody had this experience before?

Check your coolant pipes for cracks... check them all, most likely brittle

 

[taurusalmighty]

Crack in Expansion bottle?

Hi Chris, no. If i lie on my back looking under the engine with the rest of my body pointing forwards, I can see that the coolant has dripped from between the viscous fan and the front of the engine to the right of the water pump. I have found a picture of a M52 and marked with a red arrow where it appears to be leaking from. I am wondering why this would only happen when the engine is cold cold. I wonder also if it could be from behind that aluminium piece that fits onto the front of the engine that connects two coolant hoses?

 

[ChrisBrand]

Must be crack in the pipes. Or the Water Pump (but you did say to the right of it).

Maybe inspect the pipes as they expand once warm and could therefore stop the leak but shrink when cold and open the crack again

 

[Inactive]

Thermostat cover or pipe is cracked.
In your picture at the tip of the red arrow, there is no water behind that cover. Only in the pipe above it and the silver cover above and slightly to the right of your arrow. The wheel to the right of that arrow is the water pump.

Is your thermostat cover plastic or metal like in the picture?

 

[danieljames]

Have you tried a pressure test on the system?

 

[taurusalmighty]

Thermostat cover or pipe is cracked.
In your picture at the tip of the red arrow, there is no water behind that cover. Only in the pipe above it and the silver cover above and slightly to the right of your arrow. The wheel to the right of that arrow is the water pump.

Is your thermostat cover plastic or metal like in the picture?

Thanks for the response. The cover is metal - it used to be plastic, but I had it replaced with the water pump maybe 3 or so years back, as the plastic one cracked.

I also suspected the water pump, but as far as I can gauge, it looks like the coolant may be coming from either the cover or the coolant hose that connects to the cover, as the leak seems to be above the water pump. I have tightened the clamp on the hose already, and have thought that maybe there is a crack in the hose, but then surely I would hear it hiss under temp. I do not know what is behind the cover, ie between the cover and the engine, could it leak there?

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Have you tried a pressure test on the system?

Thanks for the response.... not yet.

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Must be crack in the pipes. Or the Water Pump (but you did say to the right of it).

Maybe inspect the pipes as they expand once warm and could therefore stop the leak but shrink when cold and open the crack again

Thank you, I will have a closer look at the pipe directly above the arrow again.

 

[sclass]

Thermostat housing (if it's the plastic one)...

 

[VeNoM_Ct]

Like i said I had a similar issue would leak when the car was driven... all my pipes were brittle and the leak crack was by/just before the clamp... look for a bulge or pipes that feel very soft.

 

[taurusalmighty]

Like i said I had a similar issue would leak when the car was driven... all my pipes were brittle and the leak crack was by/just before the clamp... look for a bulge or pipes that feel very soft.

Thanks very much, I will have a look

 

[Zound]

Just remember that coolant will tend to evaporate quickly, so it is not good practice to identify leaks by looking for residual puddles after driving the car. You'll need to monitor your coolant level in order to identify which scenarios induce the leak, if not all driving scenarios as would be expected.

 

[VeNoM_Ct]

Just remember that coolant will tend to evaporate quickly, so it is not good practice to identify leaks by looking for residual puddles after driving the car. You'll need to monitor your coolant level in order to identify which scenarios induce the leak, if not all driving scenarios as would be expected.

Yes there also tends to be residue or white (and/or colour of coolant) dry marks water marks close by on the pipes or other parts

 

[taurusalmighty]

Just remember that coolant will tend to evaporate quickly, so it is not good practice to identify leaks by looking for residual puddles after driving the car. You'll need to monitor your coolant level in order to identify which scenarios induce the leak, if not all driving scenarios as would be expected.

Yes there also tends to be residue or white (and/or colour of coolant) dry marks water marks close by on the pipes or other parts

Thanks, I think I have all the info needed to chase this one down.

 

[KPM3_30]

Will be watching this closely. I have a similar issue but I only lose 150ml or less in a week. The loss only happens when the car is left standing overnight. I've tried the pressure test and cylinder head test, both are perfect. Did a cooling system overhaul in Jan with agents parts but still find this is an issue.

 

[danieljames]

On my e36 I was loosing coolant but didn't find any puddles anywhere. Had to top up every 2nd to 3rd day. I couldn't spot the leak.
One day I was under the car and saw some limescale among the bottom of the box. Eventually traced the leak to the heater control valve. how often do Welsh plugs fail on these motors?