Expansion tank virtually empty- should I be worried?

[HiAsAKite]

Checked the water in the Chim today. and found that the expansion tank was virtually empty..

Question is- should I be worried?

Not had the car long (200 miles maybe?) so don't have a 'feel' for what level it should normally be at. No puddles of the water anywhere or any obvious leaks, only recently (circa 50 miles ago) had a full 12K service and general checkup with a v.reputable specialist nr Guildford. Had no warning lights or anything, temperatures and pressures all seem fine .. appreciate thoughts..

Have topped it up to the halfway mark and will recheck it next time its been for run..

Car is a 95 serpentine 400 with separate swirl pot

Thoughts appreciated..

[V8 Animal]

Mine does the same and had the car 2 years.
I put it down to the heat in the engine bay i check it about once a month and put in about a pint.
Paul

[CLN1]

Mine seems to do the same on the Griff. Before I changed the rad it ran at about half full but now since the change it appears to settle at about 2cm from the bottom.

From what I've read in the past they all seem to run at different levels.... TVR ish really !

Colin.

[Cider Andy]

Half full as you have it now is fine, but keep checking and topping it up. If you overfill it, it will spit out the excess and find a level again. If you need to keep topping it up though it's likely there's a leak.

A lot of small leaks only appear when the system is pressurised (and therefore hot) and they evaporate without becoming visible. Check all the hose unions are tight and look for tell-tale marks of coolant loss on the radiator. They're more difficult to see on the aluminium engine casings.

Another cause could be a failed cylinder head gasket. This would tend to be accompanied by an emulsion of oil and water visible in the oil filler cap (resembles mayonnaise).

[glow worm]

You'll find that it sorts out its own level....get a stick and mark where it usually finishes up...then top up to that point ... if you fill to excess it just boils off...seems to be one of those things where you have to know your own car... but it always seems to be well down the expansion tank.

[HiAsAKite]

Ok- thanks all.. will keep an eye on it and 'monitor it'.. no sign of any mayo like emulsions so the gaskets etc should be ok, I guess most of the hose connections and rad are getting on 13 years now so there may be a bit of leakage under pressure from there..


Another stupid question- I'm aware that if there's too much water in there it 'boils off' and is vented- where is it vented from....had a look at the swirl tank and expansion tank and couldn't see any pressure release valve like things.. the expansion tank cap is just like the one I had on my old mk2 GTI and I'm sure this doesn't have venting release in it..

[crackedfinger]

HiAsAKite said:

Ok- thanks all.. will keep an eye on it and 'monitor it'.. no sign of any mayo like emulsions so the gaskets etc should be ok, I guess most of the hose connections and rad are getting on 13 years now so there may be a bit of leakage under pressure from there..


Another stupid question- I'm aware that if there's too much water in there it 'boils off' and is vented- where is it vented from....had a look at the swirl tank and expansion tank and couldn't see any pressure release valve like things.. the expansion tank cap is just like the one I had on my old mk2 GTI and I'm sure this doesn't have venting release in it..

The cap on the expansion tank does (or should!) indeed contain a pressure valve, and will spit & dribble hot coolant over any recently polished parts within 10 cm's if there is too much in the system.

[Cider Andy]

HiAsAKite said:

.. the expansion tank cap is just like the one I had on my old mk2 GTI and I'm sure this doesn't have venting release in it..

You're right, it is the same, it's a VW part and it is where it vents from.

[HiAsAKite]

Cider Andy said:

HiAsAKite said:

.. the expansion tank cap is just like the one I had on my old mk2 GTI and I'm sure this doesn't have venting release in it..

You're right, it is the same, it's a VW part and it is where it vents from.

Really?- didn't know that (and I had the GTI for 8 years!!!)

This would suggest if 'overfill' deliberatly (eg 3/4 full), and then just leave the car running I should be able to see it venting, if I then leave it until has finished venting, switch off and let it all cool down and check the water again this should tell me where the 'natural' level is...
..and may even be able to spot any other high-pressure leaks..

[Seasider]

HiAsAKite said:

This would suggest if 'overfill' deliberatly (eg 3/4 full), and then just leave the car running I should be able to see it venting, if I then leave it until has finished venting, switch off and let it all cool down and check the water again this should tell me where the 'natural' level is...
..and may even be able to spot any other high-pressure leaks..

Nope.. it will only vent when your not looking

[SmokinV8]

Seasider said:

HiAsAKite said:

This would suggest if 'overfill' deliberatly (eg 3/4 full), and then just leave the car running I should be able to see it venting, if I then leave it until has finished venting, switch off and let it all cool down and check the water again this should tell me where the 'natural' level is...
..and may even be able to spot any other high-pressure leaks..

Nope.. it will only vent when your not looking

Tvrs' are known to be shy when having a leak, unlike land rovers that want everyone to see!

Edited by SmokinV8 on Monday 21st April 08:47

[Chequred Demon]

If I over filled mine I could hear a faint "hissing" noise coming from the expansion tank cap after I had switched off the engine.

[WazzaL]

HiAsAKite said:

Checked the water in the Chim today. and found that the expansion tank was virtually empty..

Question is- should I be worried?

Not had the car long (200 miles maybe?) so don't have a 'feel' for what level it should normally be at. No puddles of the water anywhere or any obvious leaks, only recently (circa 50 miles ago) had a full 12K service and general checkup with a v.reputable specialist nr Guildford. Had no warning lights or anything, temperatures and pressures all seem fine .. appreciate thoughts..

Have topped it up to the halfway mark and will recheck it next time its been for run..

Car is a 95 serpentine 400 with separate swirl pot

Thoughts appreciated..

I have one of Steve Heath's pressure pump things. Allows you to pressurise the system when cold.Not sure where you are based, but if anywhere nearby, could borrow it. Otherwise, might be worth the £25 or so to get it. - Was well worth it when my new rad started leaking.

[HiAsAKite]

Update...

Topped it up the other weekend (when I wrote the original post)..managed to take it out for its first proper run yesterday (circa 170 miles)..
Oil pressure hovered around the 30 PSI mark for most of the journey with water temp between 87 deg and 93 deg for most of the time..
..had to negotiate Brighton Saturday rush hour on the way out which took around 45 minutes of being stuck in traffic during which the water temp crept up to about 98 deg and stopped dead and the oil pressure dropped to around 22 psi, on clearing Brighton and traffic temp rapidly dropped back to the 90 degree mark and oil press came back up to 30psi...

On checking the water today following yesterdays run, the expansion tank is again almost empty (I think there is maybe 1cm of water in the bottom)..infact I suspect there is exactly the same level now as there was last weekend before I topped it up

Appreciate anyone's thoughts on whether the above sounds normal... car itself never missed a beat and sound great (aside from the seat belt- see separate thread!)

[DavidK71]

Mine is much the same - the expansion tank is always nearly empty. Back when I first bought her I tried topping it up to about half-way up the expansion tank, but after a few runs the excess had been pushed out of the expansion tank's pressure cap and it was back to almost empty. I had my garage pressurize the system to be sure, but they found no leaks and I haven't worried about it since :-)

[HiAsAKite]

DavidK71 said:

Mine is much the same - the expansion tank is always nearly empty. Back when I first bought her I tried topping it up to about half-way up the expansion tank, but after a few runs the excess had been pushed out of the expansion tank's pressure cap and it was back to almost empty. I had my garage pressurize the system to be sure, but they found no leaks and I haven't worried about it since :-)

Ok..cool, maybe I don't need to worry then.. I assume to check the water level you check the swirl tank?

[DavidK71]

I generally just make sure that there's some dampness in the expansion tank - I've never managed to get the lid off the swirl tank, despite once trying hard.

[crackedfinger]

HiAsAKite said:

DavidK71 said:

Mine is much the same - the expansion tank is always nearly empty. Back when I first bought her I tried topping it up to about half-way up the expansion tank, but after a few runs the excess had been pushed out of the expansion tank's pressure cap and it was back to almost empty. I had my garage pressurize the system to be sure, but they found no leaks and I haven't worried about it since :-)

Ok..cool, maybe I don't need to worry then.. I assume to check the water level you check the swirl tank?

The swirl tank should be full.

[Cider Andy]

Even after thoroughly bleeding the system there may well still be residual air in it. Under your driving conditions yesterday it will probably have shifted it. Top it up again and keep monitoring. It may well be ok at the level it's at but it seems low to me.

[HRG]

DavidK71 said:

I generally just make sure that there's some dampness in the expansion tank - I've never managed to get the lid off the swirl tank, despite once trying hard.

I use a pick axe



Seriously, it actually works. Not in a swinging motion obviously, but the thin blade fits the slot perfectly and you've got a metre of unbending leverage