Air Intake pre heating

[Steve Lunn]

1983 T25 water Cooled VW. I have just bought my first VW, I notice there are several air pre heating boxes on the right as you look into the engine, but no pipework? I can get the ducting but which bit conects to which??? HELP!!! Steve

[ghost123uk]

Welcome to this place where you will find all you need to know (and lots you don't need to know too )

There should be just 1 pre heat box on the front r/h J tube (assuming you have a pre 85/6 exhaust)

I wouldn't worry about it though, in my experience our flat 4 watercooled engines don't seem to suffer from carb icing due to a lack of pre heated air, even in the winter. (mine has had no pre heat box for the last 3 years and no problems).

[lloyd]

Most of the time preheat isn't needed. Our van is gassed and on a couple of occasions I've had icing symtoms in last 2 winters down here. Occasions were with temps near/below freezing and high humidity/at dewpoint.. sleet/fog/snow (perfect conditions for icing).

As stated, this has only been a couple of times and I'm not worried about installing any preheat system.

[Ian Hulley]

We live in the Peak District and I've never had anything stop working due to icing

Ian

[lloyd]

Van didn't stop working. But did show the symtoms of intake icing... ie, boggy throttle response, more throttle needed for same performance, etc. Icing occurs when temperature is near or below freezing with very high humitity like fog and will become more noticable when running for long periods under throttle. http://ibis.experimentals.de/images/car ... assl14.gif" onclick="window.open(this.href);return false; Carb icing occurs when there is humid air, and the temperature drop in the venturi causes the water vapour to freeze. The ice will form on the surfaces of the carburetor throat, further restricting it. The farther from heat the carb is, the easier this problem can occur. Our engines have carbs quite far from engine heat. Injected engines usually don't have any problems with icing. As said above, it's not a common problem, but can occur.

[Ian Hulley]

Van didn't stop working.

It was a joke Lloyd

[lloyd]

Out of curiosity, have you ever had any symptoms of icing up there? I've lived in some pretty extreme winter inviroments and it's usually not much of a problem.

[Ian Hulley]

Out of curiosity, have you ever had any symptoms of icing up there?

Nope, I let The Bus warm up before setting orf in a morning ... more to do with being a nesh old gite than owt else ... but setting off from work (started & running on gas) it's alway's been 100% fine.

Ian.

[lloyd]

Thanks for the info.
Never had any problems starting and running. Only time last winter was driving from Torbay over Telegraph hill on way up to CJ's about 10pm one evening... Gritters were out and it was cold and wet. We had a few inches of snow on ground next morning. Noticed the icing cruising at 55-60mph pulling the hills full throttle. Didn't notice any other times this winter. Somebody suggested maybe the manifold preheater (12v thingy in maniflold under carb) might not be working, but I've never bothered checking.

[Steve Lunn]

Hi thanks for the info, would still like to connect it all up if someone knows what goes where?