Steam coming through the demister vents

[uktom]

Hi

I am getting steam through my demister vents mainly on the left side of the screen, it is quite heavy. My first thought was seeping heater matrix but it is all dry round there. Next was drain channels for heater box, but they are clear too. To save you looking at my profile the car is a 530i Touring V8 1994 with A/C.
It does'nt look like my head gasket is the problem either as I have done a CO test on the coolant system.
Any ideas?

Cheers
Tom

[DaveVoorhis]

Sure sounds like a leaky heater matrix -- unless the A/C evaporator is venting refrigerant, but I'd expect it to empty quickly. How's your coolant level?

[Ross]

If this indeed steam you are seeing then heater core or seals are the problem.
Since I don't know where you are it's not possible to know if you are using heat or a/c. A frosted over evaporator will some times cause mist out of the vents.
You should be able to smell coolant as well.

[uktom]

Sure sounds like a leaky heater matrix -- unless the A/C evaporator is venting refrigerant, but I'd expect it to empty quickly. How's your coolant level?

Hi Dave,

That was my thought but the floor is dry, as is under the matrix.
Interesting what you say about the AC evaporator as the screen seems slightly oily. But it is gradual release which may rule out A/C evaporator.
Open to ideas though!

[uktom]

If this indeed steam you are seeing then heater core or seals are the problem.
Since I don't know where you are it's not possible to know if you are using heat or a/c. A frosted over evaporator will some times cause mist out of the vents.
You should be able to smell coolant as well.

It does smell like coolant Ross. It doesnt see to be heater core though. Thinking about it if it was heater core would it not come out both sides as opposed to just the left sided vents?
I am in UK but it is quite mild at the moment 55-58f so no frosting. And def not using AC!

[DaveVoorhis]

If you smell coolant and have an oily windscreen, it's almost definitely the matrix or one of the pipe o-rings. The matrix is divided into passenger and driver halves, so one side can leak while the other side stays dry. It won't necessarily pee on the floor, either. Coolant can pool in the heater box until it overflows, or just steam out -- it took several weeks of leaking before coolant drizzled down the carpet in my previous 525i.

[Ross]

It's the heater core then or an o-ring. Prob the core.

[uktom]

Cheers guys, I'll give it another go as everyone seems convinced it it the heater core!

[liquidtiger720]

So, a wet floor/mat also points to heater core?


About 2 weeks ago, my passenger side floor/mat was SOAKED. No clue what.

[shogun]

So, a wet floor/mat also points to heater core?


About 2 weeks ago, my passenger side floor/mat was SOAKED. No clue what.
Not always. If heater core, you can smell coolant.
If no coolant smell, it is water, maybe from stuck sunroof drain hoses.