Coolant (Water) Loss

[UpTheIron]

Is this likely to be air being sucked into the cooling system somewhere?

If it's not the head gasket, then where is the coolant going? How can air be sucked into a pressurised cooling system? Dodgy water pump?

Nothing obvious (to me anyway), and I can't see any signs of leak around any pipe, water pump gasket or anywhere else.

If I have to go to PistonFest in my A3 I will not be happy!

[UpTheIron]

My Chimaera (2000/W) recently went back to the supplying dealer after the running temperature shot through the roof on a motorway run. Ensuing investigation by myself found a loss of coolant, and after topping up and bleeding air would be sucked into the system (with expansion tank top off it would bubble through) and coolant lost.

No sign of any coolant leak anywhere. My initial thoughts were head gasket or worse. Car was trailered back to the dealer who 'phoned me up to ask how I managed to miss the leak from the hose at the top of the swirl tank. Quite simply, I didn't notice it - either is wasn't there or I had a blonde moment.

Anyway, the car is returned after assurances from dealer that this all is OK and leak has been cured and they have run the car for several hours to test.

A few hundred miles later, the same is happening. No sign of a leak under the car, no visible leak in engine bay, yet a full cooling system will lose a swirl tank full and more in 30 minutes of running.

My concerns are:

"Bubbling" up into the expansion tank says head gasket to me, but dealer insists that it was air just being sucked into the cooling system through the leaky pipe. I'm not convinced by this explanation. However, cooling system does not appear to be under significant pressure when engine is running, and oil level does not appear to be going up. No other signs of head gasket failure.

[tadpole]

Why don't you get the head pressure tested so that you can sleep at night / minimise any damage. You have probably already checked this but has the dealer bled the system properly after fixing the leaking hose? Did the dealer put the heater onto hot when bleeding to ensure the coolant filled the entire system?

[UpTheIron]

And the saga continues...

Now have new rad (bleed screw gave up after it was seemingly over-tightened).

And just stuck a new expansion tank pressure cap on for the hell of it.

Car & cooling system has now been inspected, pressure testing and given a clean bill of health by two independent garages.


As engine warms up (and coolant slowly expands) I still get a steadily increasing number of bubbles in the expansion tank - the hotter the engine the worse it is. Still no sign of water-in-oil, but coolant is dropping pretty rapidly (a 20 mile trip will empty a half-full expansion tank)

Car will be going back to garage tomorrow (only collected today) and I will demonstrate first hand my concerns.

I can't think of any other explanation (that I haven't already disproven) other than an internal water leak between waterway and cylinder...

Does anyone have any other suggestions?

(Thinking of trading in the TVR for something German)

[Leadfoot]

A few things:
>Is the expansion tank cap ok & is it on *really* tight
>What level are you filling the expansion tank to? Any more that 1/2 full & they seem to loose coolant - it appears that they fill up (with expansion) start to overflow & then a syphon effect comes into play & the whole lot is lost.
>The pipe to the bottom of the expansion tank runs very close to the steering rack (it rubs on it on mine)- maybe yours is the same & has worn thru' enough to become porous. Any leaks from here would be hard to spot as it's well buried.

[UpTheIron]

Leadfoot said:

A few things: >Is the expansion tank cap ok & is it on *really* tight

New cap and very tight

Leadfoot said:

>What level are you filling the expansion tank to? Any more that 1/2 full & they seem to loose coolant - it appears that they fill up (with expansion) start to overflow & then a syphon effect comes into play & the whole lot is lost.

Tried a selection of levels between 1 inch and half full.

Leadfoot said:

>The pipe to the bottom of the expansion tank runs very close to the steering rack (it rubs on it on mine)- maybe yours is the same & has worn thru' enough to become porous. Any leaks from here would be hard to spot as it's well buried.

Haven't checked but will do (please please please let this be the problem), but wouldn't this be shown up by a pressure test?

Thanks


Paul

[Leadfoot]

Just realised my post was somewhat incorrect - the pipe from the bottom of the expansion tank runs close to the anti roll bar not the steering rack.

Keep an eye on the timing chain cover on the front of the block as well.

Both might only show up when heat & or movement are involved.

[shpub]

Sounds like a head gasket causing exhaust fumes to enter the water channels... A hydrocarbon test is probably the next step.

[2 sheds]

You mentioned in the original post that the temp went "through the roof", how hot ? and is it still overheating ?
Tim

[UpTheIron]

2 sheds said:

You mentioned in the original post that the temp went "through the roof", how hot ? and is it still overheating ? Tim

Tim,

The temp gauge shot from 80 to 110-ish over a matter of seconds - presumably as coolant level became so low that hot air was circulating past the temp sensor? Probably more than sufficient to do head gasket damage.

No overheating problems now as long as I keep an eye on the coolant.

I am fairly convinced that it is a head gasket (or worse - head or block) problem but when it originally went back to the supplying dealer they dismissed this and claimed they found a leak, fixed it and all should be OK.

I would rather like it if someone could persuade me that my train of thought is incorrect and that the problem could be less severe - i.e external leak.

The problem I now have is that if it is major work I have no confidence in the dealer to fix - after all they couldn't spot the problem even when I told them precisely what to look for. Car is under in-house warranty from that dealer.







>> Edited by UpTheIron on Wednesday 25th June 08:36

[DRS]

hmmm, this sound s remarkably similar to the symtoms I had on a 98 450. Bascially the harder you drove it the more water it used. Are the radiator hoses pressurising more than normal? If so I would think that head gasket is to blame. Mine turned out to have a leak in the head gasket at the back of the right hand cylinder bank, not very much but enough when driving hard to start pushing gas in to the water system. Had the head skimmed and new gaskets fitted, has not used a drop water since, about 25000 miles ago. Also had recored rad fitted at the same time with an extra row of core, temp has never been much above 85 C since. In mine, when cold, the water level in the header tank is only about an inch deep.
Cheers
Donald

[UpTheIron]

DRS said:

hmmm, this sound s remarkably similar to the symtoms I had on a 98 450. Bascially the harder you drove it the more water it used. Are the radiator hoses pressurising more than normal? If so I would think that head gasket is to blame. Mine turned out to have a leak in the head gasket at the back of the right hand cylinder bank, not very much but enough when driving hard to start pushing gas in to the water system. Had the head skimmed and new gaskets fitted, has not used a drop water since, about 25000 miles ago. Also had recored rad fitted at the same time with an extra row of core, temp has never been much above 85 C since. In mine, when cold, the water level in the header tank is only about an inch deep. Cheers Donald

Donald.

Sounds exactly the same. My gut feeling is that the harder it is driven the worse the problem is. Dare I ask how much it cost you to put right? Steve Heath has mentioned a £700-odd figure in previous posts.

Cheers


Paul

>> Edited by UpTheIron on Wednesday 25th June 08:51

[shpub]

A hydrocarbon test kit is about £20 from Frosts and will detect if exhaust gasses are getting into the coolent. You could even do it yourself and then show the dealer. Saves the cost and expense of taking the heads off and finding out it is something else.

[2 sheds]

Yes and you should also do a pressure test, most good mechanic workshops have these, sorry if you've already mentioned / done this.
Tim

[JonRB]

I had a very similar problem to yours when I first got the car almost 2 years ago.

My dealer replaced the radiator under warranty but it didn't cure it.

Then Dave Batty worked his magic on it and also fitted a lower temperature otter switch and thermostat and I haven't had any further problems.

[DRS]

Paul,

I think for the whole job, inc machining of the heads, was around the £600 mark, not done at dealer but by an idependant.
As mentioned previoulsy try and rule out all other possibilites as this is an expensive option!
I tried the a new radiator, lower temp otter, new pressure cap etc. All this was fine if just pootling about, ie no overheating and negligble water usage, but as soon as you did a blat on the motorway it started getting gas in the system and as soon as you slowed down up went the temperature. As I said before the pressure built so much that the rad hoses became rock hard. The final straw was when it blew the seal out of the water pump after a blat through Germany at speed!
Hopefully yours is something simple. Let us know.

cheers

Donald

[UpTheIron]

JonRB, I read through some of your cooling woes previously - does sound similar.

I've got a new compression tester (mine broke!) and a hydrocarbon test kit being delivered tomorrow, so hopefully will have a better idea by tomorrow night.

It looks like PistonFest will be done by train unfortunately.

[UpTheIron]

OK, hydrocarbon test comes back clear. Not what I was expecting.

Have now spotted what looks like the beginning of a leak where the water pump joins the block

Evidently this would explain the coolant loss, but surely this wouldn't also suck air in for it to bubble up through the coolant????

Car is going back to the dealer on Monday. Aaaargh.

[2 sheds]

If you get any air in the water pump it will certainly cause bubbles or foaming, fingers crossed its that.
tim

[shpub]

UpTheIron said:

OK, hydrocarbon test comes back clear. Not what I was expecting.

No but at least it is not the head gasket! Sounds like you may have found the problem. New water pump and gasket by the sound of it.