Coolant / heater concern

[BabyG]

My car's got a strange collection of symptoms and I can't quite figure out what's going on. They may be unrelated but here goes..

Out driving today I heard a strange intermittent gurgling noise coming from under the dash (when heard from inside and under the bonnet). Happens when you rev the engine from idle (when warm). Sounds like water bubbling through a pipe that's got some air in. This gurgling repeats for a few seconds when the engine is switched off.

There's a hissing from the coolant cap when the engine is switched off. Trying a new cap seems like a good starting point ;)

The heater pumps heat through perfectly when set to max (32deg), but as soon as you drop it down to 31 or lower it comes out cool. Happens both on auto and manual control of the heater.

Checks I've had done:
- Car isn't using any coolant
- Coolant system has been extensively pressure tested by HUK and there's absolutely nothing shifting. They've also checked it's properly bled
- Starting from cold the water gauge starts to move after a minute or two, and is up to it's normal level (slightly below horizontal) in 5-6 mins depending on what the engine's doing. It doesn't move once up to temp
- A new aspirator fan was fitted before Christmas

The car is used frequently. The heating's been off colour for a while but I've not noticed any noises before.

HUK can't find anything - any thoughts on where to start?
Cheers,
Rich

[Sudesh]

Out driving today I heard a strange intermittent gurgling noise coming from under the dash (when heard from inside and under the bonnet). Happens when you rev the engine from idle (when warm). Sounds like water bubbling through a pipe that's got some air in. This gurgling repeats for a few seconds when the engine is switched off.

This could be the drain pipe at the bottom of the heater. I had a small problem last year where the pipe got blocked and the water drained into the passanger side foot well, instead of out to the ground. Lucky I caught it in time thought! Not sure why its gurguling unless there is a blockage or maybe the pipe has come free, worth check the carpet on both foot wells to see if there is any damp. Check out here: http://nsxcb.co.uk/testvb/showthread.php?t=5168&highlight=Damp+carpet



The heater pumps heat through perfectly when set to max (32deg), but as soon as you drop it down to 31 or lower it comes out cool. Happens both on auto and manual control of the heater.

This problem could be the the little "fan" or cabin sensor that sits behind the small grill at the tip of the hand brake button. If this has gone faulty then it may cause the problem you mentioned! Maybe worth checking that out.

[Kaz-kzukNA1]

Hi, Rich.

Just a matter of interest, when did you change your coolant last time?



Checks I've had done:
- Car isn't using any coolant
- Coolant system has been extensively pressure tested by HUK and there's absolutely nothing shifting. They've also checked it's properly bled

Please allow me to ask you this as I couldn't figure out the timing of the post, the date you heard the gurgling noise and above 'Checks'.
Did you and HUK check these things after you heard the gurgling noise?

Regards,
Kaz

[BabyG]

The pressure checks were done back in October, well before I heard the gurgling noise, I guess something may have changed since then.

Coolant was last changed just over a year ago.

Ref the sensor by the aspirator fan, I've just had a new aspirator fan fitted, hmmm.

A little more research has shown that the heater blowing cold on all settings other than 32deg is symptomatic of the capacitors on the climate control unit having let go, think that may be the next port of call to sort the heating. Doesn't explain the noise though...

[Sudesh]

Doesn't explain the noise though...

Have you checked the AC drain pipe and looked to see if the there is a blockage? If there is a blockage water will build up and start gurguling.

As mentioned above in the link I left, I would have a quick look.

Also check to see if there is any water draining out under the car with the AC on.

[BabyG]

Will do, thanks for the heads up!

[Sudesh]

No problem!!

Also as mentioned, Its worth checking the carpet to see if its damp. When I was doing a it of research, it seemed like it was one of those common problem as, quite a few had come accross the same issues.

It could also take a while for you to actually notice any damp, as the sound proofing below the carpet can soke up quite a bit before it comes through.

Steamey windows in some cases can also indicate damp in the car.

[Kaz-kzukNA1]

Hi, Rich.

Let us know when you had a chance to check the points that Sudesh mentioned.

I'm quite sure you feel the same but I don't like the fact that you can hear the gurgling noise at the front section even after the engine was stopped and the hissing sound from the coolant cap when the engine was stopped. Also, the following comment

- Car isn't using any coolant
- Starting from cold the water gauge starts to move after a minute or two, and is up to it's normal level (slightly below horizontal) in 5-6 mins depending on what the engine's doing. It doesn't move once up to temp.
makes me wonder as it seems the temperature gauge starts to move too early under this cold winter condition.

I have several ideas but I would like to wait for your investigation before start writing it.

Regards,
Kaz