Intermittent knocking / clicking behind dash

For a few weeks now as the engine warms (oil temperature gauge comes off the zero stop) I get what sounds like heat expansion noises from behind the dash. Mostly over toward the passenger side but sometimes also drivers side. The noise tends to be in pairs - first a loud then a quieter click. For everyone with water central heating at home it sounds similar to a radiator warming up. When the engine is fully warm no more noise.

It's not electrical, as I first wondered, as I hear this occasionally after parking and getting out. Not cabin fan related as no affect changing speeds / switching fan off.

I drained the system and fitted new underfloor pipes from radiator to engine in summer, topped up with the required coolant and changed the heater control valve. Now that morning temperatures are dropping I get this very annoying noise.

Has anyone come across this? How did you fix it, or it there no fix?

This sounds just like my TF . It does it when it's stood after a run so I just put it down to the car being warm and just relaxing as it cooled off . At first I put it down to the flexing of the body and then I got paranoid thinking that I had left something loose but it doesn't rattle when it's on the move . The noise is quite loud when it happens but ......:nonod: I dunno what it is . :nonod:

John

Thanks John, I'll see how it goes with mine. At least I'm not alone!

Nick

I have heard that clicks and groans behind the TF dash can be caused by failed welds on the strengthening brace.
The brace is part of the upgrades to the original F to stiffen the chassis along with the front subframe brace and engine bay brace..

Thanks David, I'm going to open up the dash and run the engine up to normal operating temperature to try and get a better idea of what may be happening. Keeping the car stationary and still getting the noise will give indication that it is not structural. It's always intermittent and rarely matches any car movement on the road or mechanical change (gear change / braking etc.) so I'm hoping I can rule structure and drive train out.

Nick

I thought most cars make this kind of noise as they cool down Nick.
Could it be coming from the heater matrix? or perhaps if you have air con could be the compressor, neither of my cars have air con; so just fishing really.

No aircon so will have to see when I can warm the car up with the center console removed from the dash. It's a recent thing and can be quite loud, I'll pot an update in a few weeks when I can get to this. Thanks for the suggestions though, all very welcome.

Nick

The noise on my TF is a real hefty clonk while stationary . When I next get the chance I want to put it over the pit in my garage and while under it wait for it to make the noise to try and locate it . The thing is it will do it without warning so it will be like watching paint dry !