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Slight Coolant Drop

The car is a Nissan Almera 2006.

Since I have had it the coolant in the vented expansion bottle drops occasionally every 1-2 months by a few up to 5mm from the maximum line.

I have checked for leaks exhaustively round radiator and water pump and find nothing with no mayo in the rocker cover, all looks fine. I have just done a 300 mile journey and there was no change in level once the car cooled down.

I'm confused as the car is otherwise fine. I thought coolant was meant to never drop its level unless it leaks? I'll be damned if I can find a leak !

What's going on. Any advice is appreciated

Thanks

D
Reply to
Damo
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Leave it a bit longer and see if it continues to drop; the maximum line is only an approximation. It may stabilise at 5 or 10mm below the line.

If it does continue to drop significantly, do a pressure test or get one done. This pressurises the system to twice its normal amount; it's surprising what this shows up!

Finally, If you are still worried, get a sniff test done to see if you have a failing head gasket.

Chris

Reply to
Chris Whelan

even new cars can lose small amounts of coolant. I would not worry about such a small loss. water pumps can let a small amount by for years without getting significantly worse, for instance. as can radiators and filler caps. if the loss increases significantly, then start investigations.

Reply to
Mrcheerful

surely such a small amount could also be explained by local temperature, heater matrix on or off, trapped air bubbles.

Reply to
critcher

Ok thank you very much for all of your advice, I will keep a close eye on the level and if it gets significantly worse I will arrange a pressure test to see what comes up.

Just a thought could coolant also evaporate out of the reservoir that's open to the atmosphere via the breather?

Reply to
Damo

Yes, it could.

Reply to
Mrcheerful

But much slower than that.

Reply to
Peter Hill

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