Missing hose? (BX16 petrol)

[mnde]

In the Haynes manual underbonnet shot of a BX16 RE, I've noticed there is a long cardboard hose running from the exhaust manifold to what I assume to be the thermostat housing. My J reg Meteor had no such hose, and the two garages I took it to never commented that there was a hose missing.

I assume it's a warm air hose, using heat from the exhaust manifold to channel warm air to somewhere or other to aid cold-starting in winter?

My eBay Meteor has no hose here either, but has a remnant of hose attached at the front. Were these often removed for some reason?

Cheers,

Mark.

[M]

, I've noticed there is a long cardboard hose running from the exhaust manifold to what I assume to be the thermostat housing.
...remnant of hose attached at the front. Were these often removed for some reason?

Cheers,

Mark.

If it was truly made of Cardboard i assume it will have perished away by now - and thats why its missing

[mnde]

Yeah whatever... whatever it's made out of... 2CVs have cardboard hoses... they catch fire sometimes

Now back to the question...

Mark.

[mnde]

Thanks Jon. Both my cars have the later arrangement with the air filter in a box to the RH side of the engine bay. You can imagine I don't know many people with a late petrol 1.6 non-injected BX to compare with!

Mark.

[cavmad]

Oh yes you do!

[mnde]

Oh yes I do! Same colour too I believe, Mercury grey?

Does your's have a hose connected to the exhaust manifold just infront of the bulkhead?

Mark.

[ken newbold]

My mums old 16tgs had an ally foil hose with like a paper/card covering which was there to direct warm air from the manifold into the engine via air cleaner.
Quite usefull this time of year.

[cavmad]

I don`t know mate but I`m going to find out for you asap, probably this evening!
Mines a rather fetching shade of dark grey but I don`t know the `proper` name for it.

[mnde]

Ta very much!

I obviously like this grey a lot, having two BXs in the same colour!

Mark.

[DavidRutherford]

I noticed that hose was missing too.... but then that's the same as my 19GT. The hose missing used to draw cold air from the nearside wing (there's a hole in the middle of the inner wing where it should go to) and blend it (thermostatically) with hot air from the exhaust manifold. The cold air hose being missing is no great problem, as it will simply draw air from the engine bay.

Is the hot hose from the exhaust manifold up to the flap thermostat also missing? The one on my GT is aluminium rather than cardboard, and so is still in good condition.

[AlanS]

I haven't had a chance to play with one of my favourite "hobby horses" for years until now, so here goes:

There are 2 reasons this hose between the hotbox and the thermostatically controlled air deflector box gets lost or discarded.
Firstly:- Slack mechanics too tired to refit it or have stood on it and destroyed it whilst it was off the car.
Secondly:- Over here, it seems there's this strange idea that "they don't need 'em, an' anyhow, yer'll get better fuel consumpshun without it." This is apparently based on the theories that the designers didn't know what they were doing and that it only applied in colder climates and one could be forgiven for thinking they seem to be of the opinion that 30 degrees in Sydney is hotter than 30 in London and -5 in Sydney is also much warmer than -5 in London; it's the only "logical" explanation.
Originally it was made of a wire reinforced cardboard as commonly used in Cits of the 70s and 80s but can be replaced using an aluminium concertina hose from memory about 70mm diameter.
What does it do? It allows the hot air from the outside of the exhaust manifold to flow to the air intake on the carby. As the air begins to heat, a thermostatic sensor bowl at the junction between this hose and one coming from under the wing, comes into play and progressively closes the flap until, given the correct set of weather influences, it shuts off the supply from the exhaust hot box. In cold weather, this flap will open and close to allow a constant temperature of air to be supplied to the engine.
In the case of a car with an automatic choke, this will also aswsist the auto choke to function efficiently.
Will it effect the overall running of the car? Yes. Late model dual throat carbies (I speak in particular of Weber, but suspect Solex would be the same) are supposedly calibrated at the factory to operate in a pre determined ambient temperature, so as soon as you alter this, you also alter the characteristics of the carby and hence the engine performance. There is one adjustment that is made at an ambient of 20 C +/- another measurement per 1 degree hotter or cooler. This is why this thermostatically controlled flap is so vital. The extent of the change to the performance can be judged with my own 16Trs that had been 'modified' prior to me buying it. I was getting around 13.75L/100 klms around town or 20 MPG which went as high as 15 on more than one occasion (18MPG). Detailed inspection showed that to make the car idle when cold, a 70 idle jet was installed instead of the standard 45 and the float level was high. By setting everything back to standard I improced this figure to around 9.5L/100 klms or almost 30 mpg and open road driving at 7.3L/100 klms/ 39 MPG with the air con operating.
My suggestion would be to replace the hoses using the universal fit aluminium concertina type hose/ducting and at that point also check the specs of the carby as there is a chance that you may be using far more fuel than you need to and it's not all that hard to rectify the problem, but don't swallow the fairy tale that it is unnecessary or that removing it will improve the performance; on the contrary, it won't.


Alan S

[mnde]

Thanks Alan for that info!

Earlier on I duly went to Halfrauds, having measured the diameter of the tube, and found it to be 50mm. Bought myself a 55mm dia concertina hose... only to find that the bloody thing wasn't long enough even when fully stretched out, and I split it while trying to stretch it further.

Maybe someone who's registered on that Citroen parts database could find out for me whether this hot air hose is still available from Citroen?

Mark.

[cavmad]

If you check with Directory Enquiries for a company called Safety Kleen you may have one locally.
They supply de-greasing baths and (spray) gun cleaning equipment, as well as other stuff, to the automotive and industrial sectors.
On the top of the spray gun cleaning equipment they supply they run a sort of tin foil extraction pipe and I have used this succesfully in the past to make the type of pipe that you require. It`s normally about 6 feet in length and quite flexible though will rip if you`re not careful. I can`t remember the diameter offhand, possibly about 4-5 inches but it can be squashed fairly easily to fit and as I say has done the job for me before.
Failing that would a rubber water pipe off a scrap car be suitable?

[jeremy]

There a couple of problems with rubber water hose that I can see - the first being that it may burn at the exhaust pipe end and it may be too heavy or inflexible for the existing mountings.

An alternative may be re-inforced plastic but again the overheating point is relevant. Some in this link - its available in other sizes - which are listed if you look hard

http://www.machinemart.co.uk/product.asp?p=051020157

jeremy