Air Filter Housing - Seized Hot/Cold Air Valve

Morning all,

Just giving the old girl a bit of TLC, much to the missus' distaste! Jealousy isn't a nice trait I keep telling her.

I noticed that the hot/cold air valve/flap has seized within the front part of the air filter housing. I assume that this would be contributing to the car stalling at random intervals after say a 20 minute constant run. Not allowing warm air to be fed up to the carb and causing icing?

I did unlatch some of the clips and manage to very slightly separate the two housing halves around the flap. This seems to give enough space for the flap to move freely. Once the housing is clipped back together, the flap sticks solidly again.
Is this a 'user serviceable' part and can this be rectified by simply taking apart and cleaning out any crud that may have accumulated at the flap pivot points?
More to the point… Can the air box be disassembled without butchering the plastic latches that hold the valve housing to the rest of the body?

Many thanks,

Gav

iirc you can split them, the clips make it fiddly. but it might be the diaphragm is the problem, and i dont think you cvan get the dome off easily. maybe try a few drops of machine oil down the vacuum hole and work the flap? this works for stick FPR on injection engines.

worst case just wedge it 3/4 open with a screw thru the side till you can get a replacement

Cheers John,

I managed to get the valve part of the housing apart with a bit of persuasion.

The pivot rod had accumulated just enough crud and rust to stop any free movement.
I cleaned up the metal rod and pivot points in the housing and put a small amount of grease around the friction spots. Works as good as new now.

Pics can be found here…

Photo and Video Storage | Photobucket

Just a couple of questions about the operation of this flap and the vacuum system…?

1) Is the flap supposed to drop of it's own accord when the vacuum is no longer sucking or is it forced shut with the flow of cold air from the front intake?

2) What is the correct way around for the dual thermostat to be fitted to the air box and which pipe goes to which nozzle? There is a brass nozzle and a plastic one. Which nozzle points to the front of the car? Just need some clarification if poss?

Many thanks,

1. it should close as soon as vacuum is lost
2. the rear nipple goes to the carb and front one to the air flap vacuum unit. I dont think it makes a difference which way round it is, but I found this:


and this random ebay pic I found seems to agree:

My hoses on my 1978 Mk1 Scirocco if any use?

Great help!! Cheers fellas. All the pipes run to the correct locations and the flap moves freely again.

Is there a way to test the vacuum / flap operation myself without the engine running? Not entirely convinced the vacuum to the air box is working properly.

Any advice greatly appreciated.

suck on the pipe

you can take the airbox off and start the engien if it helps with your troubleshooting. the flap should be open pretty much all the time

rubjonny said

suck on the pipe

you can take the airbox off and start the engien if it helps with your troubleshooting. the flap should be open pretty much all the time

Tastes lovely!!

Cheers for this, found that there was a split in the other vacuum hose on the airbox. Only very slight as I could still feel suction from the flap end of the pipework. Just ordered some new hose and will be going on a hose replacement spree around the engine bay.