Water leak that isn't there.

[smccormick]

Hi,

I'm hoping you kind folks may be able to make some suggestions to help me with an issue I have with my 406 estate (2002 Rapier) before I throw it in the bin.

The car developed a water leak that my usual mechanic who is very good and I've used for past many years has failed to locate where the leak is which is highly annoying as you can imagine.

The water leak is determined by the red light on the top right of the dash coming on at regular intervals and the header tank needing topping up. Usually with approximately 1 litre of water.

Now a little around how many miles before the light comes on etc. It varies depending on the type of driving being done. Recently I drove from Epsom to Wrexham without a stop i.e. switch off, cup of coffee or similar, and the light did not appear. From Wrexham back home a number of stops were required to top up the level.

Short stop start type journeys tend to get the light to illuminate faster than a longer trip.

So what has my mechanic done to locate the fault. Pressure tested, and sniffer tested the car, no leaks visible from anywhere. Pulled the header tank out and checked it. Changed the cap of the header tank. Used various types of rad weld or similar. I gather some will go ohhh no not that stuff but options where running out.

Head gasket..checked, car pulls very well, no loss of power, no emulsification in the oil and the sniffer test was negative.

Only other options are around a crack in the head or other similar item which is the conclusion at this point in time.

So before I pitch the car onto eBay for last ditch ideas/hints/tips before I get rid of an otherwise perfectly good car.

Thanks in advance.

Steven

[dirtydirtydiesel]

Hi Steven & welcome .
I'm sorry that you join us with such woes.
If you've had it properly presure tested as you state, then the only advice I can give is this.
Try taking the car out for a good run, 20 miles or so to get the water & oil up to temp ie: 90 & 90.
Then find somewhere where there is nice dry concreate to stop on (this is to look for drips).
Without turning the engine off open the bonnet & run at a fast idle approx 1500-2000 rpm's untill the fan kicks in, all the time looking around the engine bay for leaks.
If you do not see any spraying of water or rushing of steam then due to the fact that you've had a sniffer test done I wouldn't worry to much.
But if you have a good look all around the engine bay you should be able to spot any tell tale signs of leaking by looking for dryed anti-freeze.
That is assuming your's has the correct amount in (when the engine is warm & dry it'll look wight & powdery) where it has leeked & dryed out.
The rad's a quite a common rotting point on these car's & tend to get overlooked.
Hope you get it sorted, all the best DDD.

[annie10]

i had a 405 years ago that did this and there was a crack between two cylinders and the water jacket. took a strip down to find it in the end

[dirtydirtydiesel]

i had a 405 years ago that did this and there was a crack between two cylinders and the water jacket. took a strip down to find it in the end

If that's the case a sniffer test should so it up & you'd find the cooling system getting presurised by the combustion gas.

[8Jb9]

I had a similar issue when the water reservoir developed a leak in the plastic weld. That's one place to look.

Another option could be to add some coolant compatible UV-dye and try to trace it that way.

[jasper5]

Have you looked inside the car for a leak on the heater matrix?

Have you looked around the water pump?

[mjb]

Radiators can spring tiny leaks which only let steam (not drips) through, and with the fan(s) going you won't even see that.

A high concentration of dyed antifreeze may help to track it down, but a new radiator might be cheaper

[Welly]

So before I pitch the car onto eBay

If you were to sell it you'd have to list it as 'spares or repair'.

Heater matrix is a good place to check as is the radiator (this might have lots of tiny leaks) and also check if the main coolant hoses to/from the radiator feel like they're fit to burst - this would indicate a HG failure, sniffer tests don't always find the problem straight away (any steam from the exhaust on start up?).

HDi's suffer if the coolant is not changed and flushed regularly.

[trufflehunt]

The most common cause if you're losing coolant, and there's no obvious sign of a leak.., is head gasket failure.

OP mentioned Radweld....

There are a variety of pour-in products for head gasket repair. Radweld is not one of them, it's an old product that's
only suitable for small radiator leaks.

[jasper5]

The OP mentioned the head gasket had been checked.

I've never known any of those magic head gasket repair solutions to work.

[Welly]

I believe K-Seal might buy you a few hundred miles but yes Rad Weld should really be retired to the Slick-50 home for retired chemicals.

[jasper5]

I believe K-Seal might buy you a few hundred miles but yes Rad Weld should really be retired to the Slick-50 home for retired chemicals.

I had a head gasket fault on a Kia, so, I thought I would give K Seal a go to buy me a little time....nope nothing doing, just didn't work.

I took off the head and noticed the broken gasket just hadn't got any K seal in it.

Rad Weld has never been of any use!

Bars leak stopper is the best sealer, but not for head gaskets.

[trufflehunt]

I believe K-Seal might buy you a few hundred miles but yes Rad Weld should really be retired to the Slick-50 home for retired chemicals.

If OP tries K-Seal, I think he'll probably find that it either fails to make the seal, and he'll know it because nothing much will change.
Or it makes the seal and lasts for a considerable time.

[smccormick]

So before I pitch the car onto eBay

If you were to sell it you'd have to list it as 'spares or repair'.

Heater matrix is a good place to check as is the radiator (this might have lots of tiny leaks) and also check if the main coolant hoses to/from the radiator feel like they're fit to burst - this would indicate a HG failure, sniffer tests don't always find the problem straight away (any steam from the exhaust on start up?).

HDi's suffer if the coolant is not changed and flushed regularly.

Hi,

If came to selling it it would be sold as spares or repair. I would not want to buy something in this condition without full disclosure being given. Goes around comes around etc.

Posting here is a last ditch attempt to fix it rather than give in and bin it.

Heater matrix has been checked, toasty and warm in the car, no leaks, checked.

I'll check the coolant hoses.

Thanks for your comments.

Steven

[smccormick]

Have you looked inside the car for a leak on the heater matrix?

Have you looked around the water pump?

Hi,

Yes water pump checked and heater matrix checked