air bleeding into the coolant

**na15575** · 09-10-07, 13:51

Hallo
I just open this forum because I need some help
I have a problem with my Q4
There is air bleeding into the coolant liquid of the engine .
Is this hapent to another one?
Is it possible to come from the turbo?

Thanks

**AlfaJack** · 09-10-07, 14:10

I am not sure what you mean....do you mean air pressure from the air intake is pressuring the coolant system?

**na15575** · 09-10-07, 14:19

there is air pressure into the coolant system
and i dond know from where the air is coming
is it possible to come from the turbo cooling?via a crack
thank you alfajack

**AlfaJack** · 09-10-07, 15:27

Do you have any leaks, or strange noises from the cooling system?

Can you hear any gargling noises?

When was coolant last re-filled or replaced?

**wrinx** · 09-10-07, 16:35

If the system is pressurising you may have a blockage or the head gasket has gone

wrinx

**na15575** · 09-10-07, 19:23

No leaks or noises
The coolant was replaced 8 months ago

I?m afraid that WRINX is right but I don?t won?t to believe it
Because the engine was overhaul 5000km ago
The casket is the original
And I thing that the problem was from the beginning
I don?t know if air can pass from turbo to coolant can you confirm it?
All the coolant system is brand new
if I tight the cylinder head again or more?
I haven?t push the engine since the overhaul

http://briefcase.pathfinder.gr/zoom/...s/29645/586212
http://briefcase.pathfinder.gr/zoom/...s/29645/586211

**wrinx** · 09-10-07, 19:37

Wow, very nice rocker cover and inlet!

I don't know how air can pass into the engine from the turbo...you could try tightening the head bolts but I would think the damage is already done

Is the car losing water?

wrinx

**na15575** · 09-10-07, 19:49

thank wrinx
no the car is not losing water. the air comes up to the coolant when the temp go to 90celsious

**na15575** · 09-10-07, 20:52

i mean if the air can pass to the coolant from the red arrow

**AlfaJack** · 09-10-07, 21:39

That is beautiful! Congrats!

I do not know for sure but I think air should not pass in to there - logic tells me it should be sealed - im not expert though..

**jimnielsen** · 09-10-07, 22:27

That engine looks great!! Can you post some more pics of it? especially ones where the whole unit is out of the car?

Thanks, JimN

**jimnielsen** · 09-10-07, 22:53

As the turbo has both an inlet and outlet for coolant, the coolant in the engine and the turbo are only joined across this pipe. The only place for a leak would be at the union of the coolant pipes and the turbo. If there was a leak via a crack at the turbo housing you would see coolant exterior at that point.

If the engine combustion process is pressuring the coolant via the head gasket you should see..

1. bubbles in the top tank.
2. steam in the exhaust gas even after full warm up.
3. a measurable increase in the pressure of the cooling system
4. reduction in coolant volume.

If you are having head gasket problems - as seems very likely, I would (with the engine cold) back off each head bolt in turn - then re torque - (maybe a LITTLE over spec) in the correct order.