TOTAL MYSTERY Coolant Loss!!!!

Hello everyone
Try this teaser...!!! I am hoping someone out there has actually had an identical problem, cos, nobody has managed to solve it yet

Since i had my td5 (2yrs and 30,000km) the coolant level in the header stays right at the bottom. It runs perfectly, thermostat always spot on. If I top it up (2litres) it loses it all within a 10km run but then settles down and stays like that for thousands of km's. Eventually I have to put more in cos it stops getting through to the heater matrix...I guess cos its too low to be pumped through at low revs.

To my mind, its like there is a leak high up in the system and once it drops to that level, it loses no more

• the 'steady level' is about temp.sensor level and the outlet flow pipe to the rad. is usually running half full
• there are no external leaks
• there are no signs of heatr matrix leaks
• it is definitely not coming out of the overflow
• no steam from exhaust when its losing coolant fast
• its not getting into the engine oil
• no head gasket issues; coolant is clean, no combustion gases and pressure not high; if anything, system pressure always seems very low

So................anyone come across this?

cheers
Mike

Check the fuel cooler, (cylinder under inlet manfold) the o-rings can fail and it will only loose coolant when engine off (seals shrink) and it is a little at a time not dripping

whats happens if you mixe more anti freeze with the mix?? dad told me to do that when my series 2 did that ?? cant say why or how but it worked althought the sereis two 2.225 dengine cant reali be compaired to that of a 2.5 td5

Manicinfrance said:

Hello everyone
Try this teaser...!!! I am hoping someone out there has actually had an identical problem, cos, nobody has managed to solve it yet

Since i had my td5 (2yrs and 30,000km) the coolant level in the header stays right at the bottom. It runs perfectly, thermostat always spot on. If I top it up (2litres) it loses it all within a 10km run but then settles down and stays like that for thousands of km's.
Mike

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Mine's been the same for 6 yrs, though I havn't had heater failure yet. I top mine up every 6 months. I look forward to finding where the leak is.
The leak is so small I've resisted the usual cure of Radweld, after reading this forum, if you've got a TD5 don't use Radweld. TD5's & Radweld don't seem to work.

Airhook

Get you cooling system pressure tested first. One thing's for sure - Its going somewhere and that ain't normal

T

I did a pressure test myself and it does not retain pressure - but then as you rightly said, it has to be leaking somewhere so you wouldn't expect it to pressure test ok.I suppose I need to get it pressure tested by a agrage that can then search for where its losing pressure?

Manicinfrance said:

I suppose I need to get it pressure tested by a agrage that can then search for where its losing pressure?

Click to expand...

Correct

I have just thought......CAN I CLAMP OFF THE INLET AND OUTLET HOSES TO THE HEATER MATRIX WITHOUT AFFECTING THE REST OF THE ENGINE COOLING?? Don't want to bugger-up the engine.
That would at least allow me to eliminat ethe heater matrix as the problem

Yes you can. 15mm copper pipe + jubilee clips.

T

Cheers.. I will do that first. Not quite sure what you mean by your method as I was just going to use a couple of jaw clamps on the pipes to squash then shut - did you mean to use the copper pipe between outlet and return on the engine side so that the coolant is still circulating but the heater is out of the loop?
mike

I would go for the option of keeping it circulating, did you check your water pump?

Jezath said:

I would go for the option of keeping it circulating, did you check your water pump?

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No I have not checked the pump because it is well below the level that the coolant settles out at..if it were a leak below that level, the coolant would continue to drop...it doesn't...it drops VERY quickly to the botttom of the resevoir, a loss of well over a litre in just a few miles of use, then stays there... to me, that suggests its disappearing from somewhere at the very upper levels of the cooling system, but if there is some way a leak low down could do the same, i am keen to hear opinions

Could it be the resevoir / expansion tank itself that is leaking? I have heard of these tanks splitting.
Mark

squizzel said:

Could it be the resevoir / expansion tank itself that is leaking? I have heard of these tanks splitting.
Mark

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Yes thats a good suggestion, but unfortunately it's not the tank, and oddly, there is never any sign of a leak...I once topped it up and left it running at 1500rpm on the drive for an hour, jammed a stick on the accelerator... then stopped the engine, let it cool, checked the tank...it wasn;t empty but was way down and NOTHING on the drive...GRRRRRRRRRRRR

its not yur bleed valve leaking under pressure? or a split pipe or pipe end that only opens up once the sysytem is under pressure?

felt the rad to see if water is coming off on yur hand?

just brainstorming..

thats so weird the water has to be going somewhere unless you have some airlocks?

Did the tank bubble up before dropping straight down? thats a good sign of airlock, im having a nightmare with airlocks atm

Manicinfrance said:

Cheers.. I will do that first. Not quite sure what you mean by your method as I was just going to use a couple of jaw clamps on the pipes to squash then shut - did you mean to use the copper pipe between outlet and return on the engine side so that the coolant is still circulating but the heater is out of the loop?
mike

Click to expand...

Yes Mike, that's what I mean

T

I think he is suggesting creating a by pass loop/link which technically would be a better option and you could monitor the new joints for leaks which would be harder with the clamp solution. (kinder to ageing rubber hoses too).
If it does turn out to be the fuel cooler, and you want to try the excellent DIY solution from Urban Panzer's site I do have some spare O-rings, now that Winter is here it might be good to fix it.

Jezath said:

thats so weird the water has to be going somewhere unless you have some airlocks?

Did the tank bubble up before dropping straight down? thats a good sign of airlock, im having a nightmare with airlocks atm

Click to expand...

Yes it does have airlocks..but where is the water going as its not out of the overflow???:doh:
I filled it this morning and revved the engine; lots of bubbling up so level dropped. Repeated this, and used air bleed screw, with heater on full until steady level and system full (2 litres used)...its sat on the drive now running and will eave it like that for a couple of hours....watch this space

Right...here is what happened........ARGGHHH! Lost half a resevoir of fluid after several hours running on the drive, some at high revs and though I did find a SMALL leak (a) it only dripped about 100ml into the tray I put under the car all day, and (b) its on the pump outlet hose so its so low down it can't be the reason I have been getting a stable but very low resevoir level for the past 2 years/30,000km, but it is obviously the reason that just recently the level has started to drop lower until the heater no longer works.....so I have at least found the NEW problem but am no closer to knowing why the OLD problem occurs..... I have fixed the leak, pressure tested it to just below cap release pressure and it is definitely pressure tight, including the heater matrix.
DOOOOOHHHHH!!! Where the **** is this coolant going

I have a 2001 Td5 with 220 K mls on the clock .
It was losing coolant and I could see traces around the oil cooler .
Removed the oil cooler and replaced gasket . The gasket had worn away to nothing at one point .
But I still had a leak .
Then I noticed some traces on the cylinder head - there is like a big plug screwed into the side of the head on exhaust manifold side. This apparently was leaking .
Leak then got very bad for a few days . I rembered a 'trick' I had used one time on a friends VW dsl : top up as usual , tighten cap and go for a drive to get engine up to normal operating temp . Then stop and loosen cap until you just hear a faint hiss of escaping pressure . Leave it at that . And the car could then go for weeks without topping up .
So I tried it on the Disco - and it worked pretty well .I now go for a few weeks between top ups - and then only a little .
I had changed the pressure cap for a new genuine item - but that hadn't solved it .
I know I still haven't really solved the problem ...... but will do for now .
And regarding taking the heater out of the system - be sure to link the 2 heater hoses so that coolant flow is maintained .