Air temperature regulator valve in air filter box - test?

Post by **Pootle** » 09 May 2006, 08:53

T25 1989 with 1.9 watercooled DG engine.

There is a temperature regulator valve in the air filter box. It causes the air filter to take hot air from around the exhaust pipe in cold conditions, but unheated air when the engine is warm. It does this by controlling a flap.

How can I tell if it is working? If I suck on the pipe with the engine off I can hear the flap move, but I can't hear it move with manifold vacuum because the sound is drowned out by the engine noise.

Also, how can I tell if the vacuum tubes have been connected the right way around?

What air temperature should it kick in at?

Many thanks,

Post by **ghost123uk** » 09 May 2006, 09:56

Lets see now, I suppose you could blank off the air intake that you think is supplying the air, with a rag or summat and see if the engine stops !!

From what I know, it only draws warmed air when it is very cold.

Also, though I wouldn't recomend this on most engines, apparently the engines in our vans never need the warmed air in UK conditions and I was recomended not to bother with it by a very experienced and well known on here VW mechanic, I have had no probs with carb icing even on cold Feb mornings so I guess he was right

Post by **Pootle** » 09 May 2006, 12:19

ghost123uk wrote:apparently the engines in our vans never need the warmed air in UK conditions and I was recomended not to bother with it by a very experienced and well known on here VW mechanic

I wondered about that. But the Bentley and Haynes manuals both describe how the valve may be tested so I guess that they DO function even in our mild climate.

What the manuals don't tell me is if the vacuum connections are the right way around (what if I'm taking in hot air ALL the time?) nor at what temperature they operate. They also tell me to listen for the flap moving as the engine warms up but I can't hear it - the engine drowns it out.

Thanks for your help.

Anybody have any more info on this valve?

Post by **ghost123uk** » 09 May 2006, 13:23

ghost123uk wrote:Lets see now, I suppose you could blank off the air intake that you think is supplying the air, with a rag or summat and see if the engine stops !!

A modification of this technique might be to put your hand over the air intakes in turn whilst revving up a bit, you should be able ti feel which one is sucking.

Re pipes on the right way or not, if the above test gives a correct result they likely are. Other than that get a peek at someone else's motor

Post by **Pootle** » 10 May 2006, 18:13

ghost123uk wrote:apparently the engines in our vans never need the warmed air in UK conditions and I was recomended not to bother with it by a very experienced and well known on here VW mechanic, I have had no probs with carb icing even on cold Feb mornings so I guess he was right

Well this has suddenly become a bit important!

I've just bought a stainless system from Bluebird Customs. I notice that the downpipe from the offside manifold doesn't have the heat jacket for the air filter hot air pickup.

Why not? What should I do with those air connections from the air filter?

Who made that recommendation ghost123uk? I'd like to get in touch.

--
Pootle

Post by **ghost123uk** » 11 May 2006, 08:40

OK Pootle

I have just spoken to my mystery"very experienced and well known on here VW mechanic" and he has OK'd me to revael his identity

It is of course.....
Wait for it....

Steve Shaw our host, guru and gaseous friend.

He did say it was OK to ring him to discuss, tho I often feel sorry for dragging a mechanic out from under a van, probably whilst holding a gearbox in place with one hand, trying to line up the bolts with the other, when the phone rings !!

He did confirm, that in his opinion, it was an unnecessary device on our vans.

Since I got my LPG conversion mine is not connected, but is still there, and it rattles at a certain engine revs !! - I want it off but ain't going to start undoing J pipes etc until I have to as the bolts are famous for shearing off in the heads !!

C&P from his website at http://www.gasure.co.uk/contact.htm =
Contact: Steve Shaw
Gasure.UK
Unit A7
Deeside Industrial Estate
Flintshire CH5 2JZ

Telephone 01244 288862
Fax 08707 061134
Mobile 07899 860126

Hours of business 9:00am to 6:00pm Monday to Friday

Email:
Sales sales@gasure.co.uk
Technical technical@gasure.co.uk

Post by **ghost123uk** » 11 May 2006, 08:45

Oh re Air inlet connections

Junk the ones that go to the box in the r/h rear cubby hole and the ones that go to the heat exchanger.

Might as well get rid of the stuff in the r/h cubby hole as well and when you have, check right up inside that cubby hole for rust as it's a well known rust trap ( best check the l/h side one as well ! )

The main air inlet can just be a bit of the corrugated pipe, fastened somewhere it can suck clean dry air in

Post by **Pootle** » 11 May 2006, 09:22

ghost123uk wrote:Junk the ones that go to the box in the r/h rear cubby hole and the ones that go to the heat exchanger.

8< snip >8

The main air inlet can just be a bit of the corrugated pipe, fastened
somewhere it can suck clean dry air in

Thanks for that!

I might not bother with an air inlet pipe at all, the air from the engine bay is as good as anywhere.

--
Pootle