scuttle vent

[HG_S-type]

Hi,

I noticed that my scuttle vent opens only a little bit when I press the AIR- and HEAT-button both.
According the manual pressing the AIR-button only should open the Scuttle vent as well.
When I switch off the engine the vent closed immediately. I think it's vacuum problem?

Is the reserve tank and Check valve the most likely root cause for this behavior?

Thanks,

Harrie

[cass3958]

If you think you have a vacuum leak there are a couple of places it could leak from. Check all the hoses from the dash switch to the various vacuum switches. I had a leak right on the end of one of my rubber hoses where it joined the vacuum switch on the bulkhead.
Next check the vacuum tank under the front left wing. Very susceptible to rust due to its position and it is not protected with a shield like the brake vacuum tank. I had a small leak where the mounting bracket is welded to the tank as mud and water gets into the V shape and it rusts. I had to repair this with araldite but have since found a very good replacement but as the original is not leaking at the moment I have not bothered fitting it yet.
Next check that the non return valve on the vacuum tank is working. The tank should hold a small vacuum after the engine has been turned off. David Reilly's S type would hold the scuttle flap open for about twenty mins before closing, mine holds it open for maybe 10 to 15 mins. If it slams shut as the engine is switched off it could be the non return valve.
Lastly check the hose that runs across the front of the car from the brake vacuum tank to the scuttle vacuum tank. Being at the front of the car it is in harms way from anything being kicked up off the road. I think from memory this hose is made up of two ends of rubber hose and the middle is a copper pipe. Also check the rubber hose to see if it is still intact ie not being crushed by the force of its own vacuum. If the hose is old and collapsing then the vacuum tank will not be forming a vacuum and your flap will not work.
I bought a vacuum pump off eBay which is used to bleed brake calipers but it allows you to connect it up to the rubber hoses and to check if everything is holding a vacuum. https://www.ebay.co.uk/itm/284354587655 ... BMyr6L-_5h

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If it is not the vacuum check that the hinge on the flap is well lubricated and the flap is able to rise and fall easily. You can do this by disconnecting the rod on the vacuum switch on the bulkhead and then working the flap by hand whilst spraying copious amounts of lubricating oil into the hinge area. You will have to remove the gauze screen, the flap top and the deflector panel inside to be able to do this. Not easy because of the access to the screws and nuts.

[HG_S-type]

Thanks Rob,

I will check these points

Harrie