Strange coolant colour/behaviour

[nick9one1]

Recently my heating has been playing up. It started when I removed the coolant reservoir cap to have a look at the coolant level when it was still hot. There was a hiss and some gurgling but the level was fine.

Since then my heating seems to work fine when your driving, i.e over 2k rpm. But if you start it and let it idle at 900rpm and get up to 90deg (same on the gauge,vag-com, and the climate control) the heaters don't get hot until you rev it then you get a sudden burst of hot air. Then after a while it goes cool again till you rev it. It might be worth adding it never goes over 90deg.
Then I noticed my coolant light came on so I topped it up. I think it may be leaking as I can see the colour of the coolant that's collected below the bottle. But even being topped up it still has this strange behaviour.

My next question is has anyone seen gold coolant? The best way to describe it is like copper grease! It has a definite gold colour and you can see the metallic-ness in it if you rub it between your fingers.

Its been serviced every 10k by seat until 100k then by an independent garage for the last 30k

Am I right in thinking the Leon has an auto bleeding coolant system?

Nick

 

[andycupra]

yes its auto bleeding, ive emptied a few leons and refilled with no issues. easy.

It doesnt sound like taking the cap off has caused an issue, the hiss would simply be that when hot the system builds up pressure as the coolant expands...
The cold then hot sounds like a potential air lock, but then removing the cap shouldnt have caused that. Having to top up the coolant does sound like a leak..

copper colour coolant? has it always been this colour?
its not oil contamination is it?

 

[nick9one1]

I haven't owned it for long.

No I don't think its oil contamination, I've seen oil in coolant before and it looks very different. A distinctive yellow/gold colour.

 

[sssstew]

sounds like you might have a bit of an airlock in the system somewhere perhaps?

the coolant shouldnt be metallic, it should be a sort of clear pink colour.

 

[nick9one1]

Hmm, I'm going to give the last garage a ring that serviced it and see if they can shed any light on the gold coolant.

My cooling got worse today. I was driving quite hard.. 4.5k upshifts to see if my repair in the turbo > intercooler hose was sufficient and it started to overheat. got to about 105 before i noticed and turned it off. I popped the bonnet and loosened the cap. Some steam and gurgling as you would expect, screwed it back on and went to check the temp... 95deg. got back in and drove off. Temp went back down to 90 and was fine for my 30mins drive home.

still likely to be an airlock?

 

[Viking]

Sounds like a water pump problem to me. Is there any loss of coolant at all?

 

[nick9one1]

Some loss. But. It looks like its collecting below the header tank so I think it could be a leak. Water punp was changed 10k ago.

 

[MJ]

Sounds like a water pump problem to me. Is there any loss of coolant at all?

i must admit from whats been said i concur with viking, even if it was changed not long ago the part may have become faulty, it wouldnt be the first time.

 

[meltonlad]

could be that before you got the car the old owner may have put K SEAL in the coolant. as that is gold coloured with gold bits in it....

 

[platofan]

The fool that i got my car off had obviously used kseal because the coolant was dirty orange/gold and smelt like rubbish. Looked like chocolate milkshake!

 

[meltonlad]

smelt like rubbish. Looked like chocolate milkshake!

that could have been caused by using the wrong coolant... vag engines hate anything other than G12........

 

[nick9one1]

what makes them dislike anything other than g12?
Im starting to think it is a coolant additive issue now, i'll try to get a picture and let you all have a look!

 

[Viking]

It's not so much that the engines don't like anything other than VAG specified coolant, it's more that VAG coolant doesn't mix with other coolant. If you drain and flush the system properly then you can use normal antifreeze, but it's just not as good for the engine and components as the standard stuff. VAG coolant is specifically designed to be compatible with their engine components, and it's not that much more expensive anyway.

 

[nick9one1]

Ah I see.

well I've changed my mind about it leaking... past couple of mornings after its been stood overnight and is stone cold I have taken the cap off to see what the level is like, and there has been plenty of pressure in there still as I get a good hiss. The pressure that's being retained must mean there is no leak??

and strange how on my 35 min drive to work this morning it sat solid at 90 all the way.

could it be faulty thermostat?

 

[andycupra]

Ah I see.

well I've changed my mind about it leaking... past couple of mornings after its been stood overnight and is stone cold I have taken the cap off to see what the level is like, and there has been plenty of pressure in there still as I get a good hiss. The pressure that's being retained must mean there is no leak??

and strange how on my 35 min drive to work this morning it sat solid at 90 all the way.

could it be faulty thermostat?

its unusual to get a hiss if the engine and coolant is completly cold...
Although it may be that opening the top few times is allowing an air lock to clear.

Have you taken top off, and run the engine for a good few mins? this can aid self bleeding.

 

[leonrob]

I haven't owned it for long.

No I don't think its oil contamination, I've seen oil in coolant before and it looks very different. A distinctive yellow/gold colour.

previouse owner might have put rad weld or something similar in coolant to stop leak this would explain the metalicness and that theres a leak also ?
just a thought

 

[muddyboots]

Maybe it's a faulty water pump (which is quite a common problem), causing coolant loss - but the previous owner misdiagnosed and tried to fix with some kind of leak-fix additive.
That coolant colour is definitely wrong; G12 should be pink.

The water pumps were fitted with a plastic impeller, which can break up or come loose on the shaft.

When I had the cambelt changed on my last Passat at 120k, my garage fitted a new water pump as they found a small leak from the original when they got the cambelt off.
Around 10-20k later, I started getting problems. I kept losing coolant and had to top up regularly. During normal driving, temp stayed at 90ºC all the time. But after a while things got worse, if I drove with a higher load - ie at high speeds, or up a long hill, the temp would suddenly shoot up. If I didn't ease off in time, the coolant would boil up, and whenever this happened, the coolant level would drop significantly and require topping up. Was barely any trace of coolant around the bottle though - unless you happened to stop and look while it was happening, by the time you did have a look later - it had all dried and evaporated off.

When I took the pump off, the impeller was loose on the shaft. I could spin it around with little effort. It had just enough grip to turn a little bit, so just enough circulation for normal driving (either that or it was thermo-siphoning enough through the rad without the pump's help). When the heat load got bigger though, there wasn't enough coolant flow and things got hot.

I've heard other stories of impellers that stay fixed to the shaft, but the blades break up. If this were to happen, I imagine the pumping capacity would be reduced, but flow would still increase as revs increased.
Maybe this is why you're not getting much heater output until higher engine RPM

Just a guess though...

 

[nick9one1]

MuddyBoots, that does sound very similar to the symptoms I'm having.
Yes I think the previous owner could have put rad weld in it. Although there isn't any leaks that I know of...

I'm going to make sure its nice and topped up/bled with the cap off for a few minutes before I leave from work tonight and see how it goes.

 

[nick9one1]

Got home fine with a solid 90degrees all the way.
Still having a problem with the heaters though.
When I'm moving its fine, i.e. 1700rpm+ But when I stop and let it idle the heaters go cold.

Water loss:
It has seemed to have lost some water on the way home but I did over-fill it (not noticing the min max lines till just now) Its gone from over-full to exactly on the max line. Could this just be it dispensing the excess out of the overfill pipe?
I'm going to leave it now and see if it goes down from the max line after tomorrows commute.

I think it could realistically be one of two things;

Leaking;
Water is leaking somewhere and the first thing to stop working is the interior heating as its the highest place in the pipework. Blipping the throttle turns the water pump faster and is pushing hot water past the airlock, causing the heaters to get hot. Then letting it drop back to idle stops water getting through the heating system and the heaters go cold.

Failing water pump;
as muddyboots suggests, the pump fins are loose/broken. This is stopping the
water being sent round at its correct speed, i.e. too slowly through the heating system. It takes more rpm to increase the flow of the water enough to get enough hot through to the heaters.

The pressure thats being retained in the system makes me think its unlikely to be a leak, as surely if there was a hole in one of the pipes the pressure would be low and completely disappear overnight. unless there are some kind of one-way valves in the system?

 

[meltonlad]

have a read mate.... sounds like water pump.
http://www.seatcupra.net/forums/showthread.php?t=233967