Vanishing coolant

Soriano51 · Sep 11, 2022

I have a Td5 90 which has recently had a new expansion bottle, water pump and hoses. The tank is filled to the correct level when cold but after every journey the coolant level drops. There is no evidence of a leak, the vehicle has been on the ramp at a local garage , engine running, which showed nothing.
There is no contamination of the oil, and the temperature gauge reads normal, just below halfway.
I'm at a loss to understand what's happening.

Litch · Sep 11, 2022

Any suggestion that the coolant is leaking from the heater matrix?
Is there a smell of coolant when you turn the heater on or do the windows mist up?

Turboman · Sep 11, 2022

Soriano51 said:
I have a Td5 90 which has recently had a new expansion bottle, water pump and hoses. The tank is filled to the correct level when cold but after every journey the coolant level drops. There is no evidence of a leak, the vehicle has been on the ramp at a local garage , engine running, which showed nothing.
There is no contamination of the oil, and the temperature gauge reads normal, just below halfway.
I'm at a loss to understand what's happening.

Look at the heater matrix, as above^^^^.
And check very carefully all hoses and hose connections for staining. Small leaks can evaporate from a hot engine before reaching the ground, or being visible as dampness.

If all of that is good, the only place it can be going is into the engine itself.

Hicap phill · Sep 11, 2022

When you say the level drops … by how much?

Soriano51 · Sep 11, 2022

Hicap phill said:
When you say the level drops … by how much?

Yesterday I

Soriano51 · Sep 11, 2022

Yesterday I did a trip of 25 miles and this morning had to add about 2 pints.

Turboman · Sep 11, 2022

Soriano51 said:
Yesterday I did a trip of 25 miles and this morning had to add about 2 pints.

That is a lot of coolant loss.
Should certainly be visible as wetness or steam from the heater box.

Soriano51 · Sep 11, 2022

Litch said:
Any suggestion that the coolant is leaking from the heater matrix?
Is there a smell of coolant when you turn the heater on or do the windows mist up?

No smell of coolant, no missing of windows

Turboman · Sep 11, 2022

Soriano51 said:
No smell of coolant, no missing of windows

Have you removed the plastic shield from the top of the engine, and been over all the hoses using a lighted mirror on a stick?

tottot · Sep 11, 2022

A mate had similar with his td5, changed water pump ect but it turned out to be a small pipe low on the block near the water pump. Hard to see.

Dippypud · Sep 11, 2022

Heater pipes ? try a pressure test, a pin hole will stay shut until up to pressure and it may be in a sneaky place squirting up yer bulkhead without trace ...

Buy some talcum powder and dose over half the engine at a time, the tracks may help find the source ...

robbie the greatl · Sep 11, 2022

fill my puma to level and it chucks about a litre. down the overflow so header nearly empty but doesnt lose anymore just a drop in header tnank and thats how it stays

Turboman · Sep 11, 2022

robbie the greatl said:
fill my puma to level and it chucks about a litre. down the overflow so header nearly empty but doesnt lose anymore just a drop in header tnank and thats how it stays

Your pressure cap has failed.

A Tdci shouldn't lose any coolant at all in normal operation.

robbie the greatl · Sep 11, 2022

turboman it dont cause me a problem as it is but thanks ill get a new cap is that the cap on header or rad

Shippers · Sep 11, 2022

Had the same problem with a 1.8tdi in my van it was a core plug in the head that had a pin hole in it only leaked when thermostat opened so didnt notice it when fault finding after topping up when cold...

lynall · Sep 11, 2022

Has it got an egr cooler?

robbie the greatl · Sep 12, 2022

Lynal i dont think so its strange as once it finds its own leve it dont get no lower

Turboman · Sep 13, 2022

robbie the greatl said:
turboman it dont cause me a problem as it is but thanks ill get a new cap is that the cap on header or rad

On the expansion tank.

payydg · Sep 13, 2022

Soriano51 said:
I have a Td5 90 which has recently had a new expansion bottle, water pump and hoses. The tank is filled to the correct level when cold but after every journey the coolant level drops. There is no evidence of a leak, the vehicle has been on the ramp at a local garage , engine running, which showed nothing.
There is no contamination of the oil, and the temperature gauge reads normal, just below halfway.
I'm at a loss to understand what's happening.

that’s a serious amount of coolant to be loosing. When you say the oil isn’t contaminated what have you checked? I don’t know the TD5 very well but I would check the engine breather for emulsified oil coolant - this was the only sign I had with a cracked engine block (200tdi). You can get a UV dye to put in that should easily show up if it’s a leak from a hose/radiator.

bluedog333 · Sep 13, 2022

Get a UV dye and torch kit, makes locating external leaks a doddle.
Edit… just noticed Ralph already suggested that ^^

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