Inexplicable coolant loss???

[Arrkon]

Im losing coolant from somewhere (fill it on Mon morning, by the end of the week it's down to min. Has dropped so far at occasionally that the DIS warning comes on).... no idea where to start looking though.

• HVAC works great hot and cold.
• Coolant temp never above 90, and doesnt move...
• No apparent leaks
• No white smoke/steam

any suggestions where to start looking?

Car is a 1.8T APU, and G12 is getting expensive with the amount ive gone through

(on a side note also, how much oil should a 1.8T go through/lose?)

 

[Oranoco]

Check the plastic pipe at the back of the engine and for signs of leaking on top of the gearbox

 

[ScottD3]

How's your carpets?

 

[B5NUT]

Have you checked the expansion tank overflow? I had the similar fault on my TDi and it turned out to be he head gasket, exaust gasses going into the coolant system and it was being chuck out the expansion tank.

 

[Arrkon]

Carpets, bone dry. Gearbox was out only a few weeks back to do the clutch conversion, no obvious signs on or around that. Expansion tank "overflow" I've not looked at, will check that when I get a chance. Though the header doesn't smell "exhausty" even after a thrashing, just smells of g12 lol

 

[Bradderz_1988]

Easy way to check is get someone to use an emissions tester over the header tank that will rule out the headgasket.

 

[THE MONSTER]

Im losing coolant from somewhere (fill it on Mon morning, by the end of the week it's down to min. Has dropped so far at occasionally that the DIS warning comes on).... no idea where to start looking though.

• HVAC works great hot and cold.
• Coolant temp never above 90, and doesnt move...
• No apparent leaks
• No white smoke/steam

any suggestions where to start looking?

Car is a 1.8T APU, and G12 is getting expensive with the amount ive gone through

(on a side note also, how much oil should a 1.8T go through/lose?)

I presume you have your under tray on have you checked to see if that is full of water or any water in it lowest point and all that..

That amount must be visible and going somewhere..

 

[Bradderz_1988]

Also check for a pink crusty residue of coolant on the system also near the water pump and at the oil cooler pipes !

 

[Sandip]

I had this on my S3, put some red food colouring into your coolant, go for a drive, then pull you plugs out one at a time. If the ceramic on any of the plugs has turned pink then you may possibly have a hairline crack on the cylinder head.

Or like Bradderz says, hydrocarbon test the coolant

 

[salad.dodger]

I had coolant lose on a 5 series BMW, works out the head was leaking right at the back, could see water marks

 

[B5NUT]

A very easy test to check if your getting exhaust gasses into the coolant system would be to take it for a quick drive and get the engine almost upto temp and check the hoses for pressure, if they are solid then gasses are getting into the coolant system, and you are looking at either a HG failure or damage to the cylinder head.

The top water hose on my car was just about solid even after a quick drive and the engine was around 80 on temp.

One other possible cause is the expension cap has failed and needs to be replaced, a quick pressure test would answer that question or just get one from a breakers for a couple of quid.

 

[Arrkon]

Ah well i have just squeezed the hoses and they are still quite soft so hopefully not a HG problem

 

[tdia4]

Leaking from a Core plug maybe?

 

[Mike B]

Take off the header tank and check at the back for acrack.This is where we found a leak and the new tank was £12

 

[Arrkon]

Leaking from a Core plug maybe?

How do you mean a "core plug" ?

 

[ScottD3]

How do you mean a "core plug" ?

Round metal disk pushed in to the side of the engine. It Blocks up the old holes used during the manufacturing process.
They can become thin and leak (happened on my land rover) or fall out.

 

[bmarshall]

Welsh plug

 

[Arrkon]

After having a good look, i may have found the issue...

Take a peek at the pics on FLICKR and tell me what you think... its like a pinky white sticky paste.... could be some coolant residue?

Cheers guys...

 

[ScottD3]

Yup, I'd say thats coolant.

 

[Arrkon]

thought so... have added a diagram of the area with positions i think the leak may be coming from... any ideas? I suspect No 3 is at fault... or hopefully duff pipes...

 

[ScottD3]

it looks like its coming from coolant pipes on number 14 of your diagram.
Possible a split pipe or the metal pipe work in side has rotted away.

I'd take the coolant pipes off, give the area a good old clean, replace the spring clips and try again.

 

[Arrkon]

yup was thinkin that... Cheap fixes win

 

[ScottD3]

yup was thinkin that... Cheap fixes win

Deffo.

I just need to find out where my coolant smell is coming from now.
I'm off to check my oil filter housing.

 

[Arrkon]

if its strong interior smell. could be the HVAC exchanger.

 

[ScottD3]

if its strong interior smell. could be the HVAC exchanger.

I do hope you don't mean this

 

[Arrkon]

yep thats what i meant... is that pic yours???

 

[ScottD3]

yep thats what i meant... is that pic yours???

Nahh Google image.
I hope its not.
I really don't want to take my days out.

 

[Arrkon]

Days? Did you mean dash??? Haha

 

[ScottD3]

Days? Did you mean dash??? Haha

LOL.
Yeah Dash.

The fact that it only smells when it pumps out warm air has me even more worried now.

Know of any other way to check it?
All my carpets are dry.

 

[Arrkon]

Pressure test maybe?