2.0 D-4D Rattle/trickling Water Sound Behind Dash @ 2000Rpm

[nicebutdim]

Hi all and happy new year

Right then, I've had my 07 plate Corolla for about two months now and since I've had it, I've noticed a rattle or water tricking noise behind the dash. Now it seems to do it worst (most audibly and clearly) in the morning but also does it at all temps but curiously it seems in first and second gear at and around 2000rpm.

Reading on the forums suggests maybe air in the cooling system so to that end I lifted the radiator cap and attempted to 'burp' the system but nothing visible bubbled and I cant tell if it made any difference initially though I suspected it helped but that might have just been placebo effect.

Whilst I was rooting round around behind the glovebox noseying, I cleared plenty of vegetation from the cabin filter housing none of which made a difference.

What makes me thing cooling system is that is if you run the noise, and put your hear behind the glovebox it seems to originate from there.

I've read the 1CD doesn't suffer from HG problems like later engines and the coolant and oil don't look suspect for that. It drives well, maintains a good engine temp and returns a good MPG.

I've included a link to a recording of the noise, at each rev to 2000prm you can hear the noise, then I rev to 3000 and 4000rpm and you cant hear it. Sorry for the quietness, that's my phone. It will amplifying to hear clearly.

http://1drv.ms/1B94bMX link to audio

Any ideas on what it might be? Thanks for reading.

[nicebutdim]

UPDATE - I *might* have found the problem and fashioned a fix but its too early to tell.

Taking the glovebox out I can see a yellow thickish loom that goes to the airbag which also plugs near the glovebox lid. This loom is ribbed and I think it may have been rubbing on the radio inside the dash creating the noise. I have re-located the wire away from any surfaces and now just seeing how it goes. The initial drive home didn't result in any noise even at my attempts to force to problem to happen.

[nicebutdim]

Can anyone advised, a lot of reads there. The update I posted wasn't the fix.

I've taken off the dash facia and recorded a video of the noise, it is coming form the black housing behind, not sure exactly what it is, assume the heater fans or heater core?

Video link - http://1drv.ms/14Udofq

Its not affecting the car but the noise is annoying and offputting more so as I don't know what it is. It wouldn't be so bad if I knew the fix even if it is out of my capability.

Would a Toyota dealer be interested in the car given the age and are they likely to charge a ransom to book it in and listen to it?

[oldcodger]

Listening to your video I first thought it was the engine that was running, but then assume that is the noise your are getting.

To me, I would say its the blower fan that somehow coming on by itself, or if you have it switched on the motor is faulty or something is partically blocking it.

There is also the fans power 'resistor pack' which controls the speed, it could be faulty, as could any of the wiring etc

Assume you have checked the cabin filter.

As for a fix, what are your electrical abilities, do you have a multimeter.

The Haynes service manual details removal of the blower fan and testing of the Resistor pack.**

** if you have auto a/c then the resistor pack is replaced by an electronic control module.

If failing,that would be more likey to cause the fan to behave like that, imo.

[nicebutdim]

On the video, that is me revving the engine to 2000pm but it is the chattering you can hear that it the noise.

The fan works as normal and sounds nothing like the noise I'm getting, its a water sound.

Checked cabin filter, there was a bit of debris but nothing major.

I'm not good with electrics I'm afraid.

[oldcodger]

Listened to your vid several times to hard to tell if there are other sounds there.

Have you located your heater/ air con drain hose, its a small tube coming out of the passenders side of the heater box below the cabin filter.

It normally goes down under the carpet so any escaping water drops onto the road.

As the frozen matrix defrosts so the water escapes down that tube, if its blocked then the water could collect and you might get a dripping sound... ?

Try running the aircon for a good while , then 10 mins after switch off, see if a pool of water is visible under the car.

Assume your air con does blow cold ok ?

The other source of water could be a leak from the heater matrix, under pressure the more you rev it.

Have you checked the coolant level ? is it dropping ?

If all above ok, then perhaps try taking out the main fuse for these devices in turn and see if the noise goes.

The radio /cd player, the fan, the a/c system, the heating /cooling controls/motors

Last idea, you could have an airlock in the heater matrix, it could be flushed out, but to quickly prove the point, if the heater control is at cold, water should not flow though it, but if that control is not 100% some water could still flow, so get a couple of pipe clamps and place them on the 2 heater pipes where in the engine bay they go into the cabin, so stopping any water getting though, does the sound stop ?

[nicebutdim]

Thanks,I will investigate those.

[yossarian247]

Does the car use/lose any coolant at all? I've had this 'water trickling' noise on two cars over the years (a Citroen BX 1.9D and a Corsa 1.5D) and in both cases it was a very small head gasket leak bubbling tiny amounts of exhaust gas through the cooling system and the heater matrix. Both used to lose a bit of coolant slowly over time.

Also I've known aircon systems that are slightly low on gas to make similar bubbling/liquid noises when running.

[nicebutdim]

Thanks for all replies, I've not tempted fate but it stopped as of yesterday after a final 'burp' attempt Monday night although noting seemed to result.

It may come back so I'm monitoring it, but it so nice not to be hearing it!

[mcorban]

Did you try and bleed the system with the heater dial set to full heat?

get the car good and hot and then turn on the heat, and open the radiator cap.

A level surface also helps

[oldcodger]

get the car good and hot and then turn on the heat, and open the radiator cap.

Hmmmm.... rather you than me

[mcorban]

With the car switched, and use a rag. Never got burned myself.

[nicebutdim]

Just to put a bit of closure on this. It doesnt seem to bad now and when/where it did it most it doesnt now.

It falls in to the livable category now and hasnt bothered me for weeks/months.

Whatever it is will be a mystery!

Thanks for all replies.

[DeclanCorollaD-4D]

As has already been said I have this issue every 500miles or so and find the car needs 200-300ml of coolant added each time, I believe it's a small head gasket leak letting air into the matrix coupled with a slightly low water level that's causing the bubbling/trickling that you can hear.

Cheers

Declan

[nicebutdim]

Declan - I have to disagree with that. As I've not noticed the issue now for a while I closed this topic. I was hearing it very noticeably before hence the query here.

As for the coolant level, I've topped it up once in a year/25k miles. Its not losing a drop at all - if anything its due a change next year.