Lotus Elan

Heater Air Pipes S4 Elan

PostPost by: RichardHawkins » Wed May 20, 2020 9:11 pm

I am having difficulty fitting these flexibles. My car is an early S4 with an S3 crash pad. The flex tube I am having most difficulty with is from the front (engine side) side of the heater to the fresh air eyeball vent on the A pillars. There does not seem to be enough space between the heater and the bulkhead (firewall) for this pipe, I cannot manage to push the heater forward into position. Reading Buckland it seems this pipe is a different diameter from the pipe that connects the heater to the demister vents, looking in the parts list these two flexible tubes have different part numbers. I am using the flexible tubes that came off the car as they are already bent to shape, on the assumption that they are correct, but now I wonder if I might be the victim of a previous owners error. These tubes also rub on the steering column.

Can anyone guide me as to what diameter these tubes should be and how they should be routed?

Richard Hawkins
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PostPost by: oldelanman » Thu May 21, 2020 8:42 am

Hi Richard,
On my S4 the pipe diameter is 1.25" ID (1.4" OD) It fits directly onto the eyeball vent and the rubber elbow on the back of the heater without any other connector or adaptor so it should be obvious if you have the right size from that. Buckland says the pipe is 1" diameter which appears to be incorrect.
On my car, on the driver's side at least, (can't get to the passenger side to check at the moment) the route is pretty much direct from heater to vent. It passes over the steering column rising towards the outside of the car then sweeps back to the rear of the eyeball vent, there are no sharp bends.
The felt under and behind the heater box is thinner than that used under the carpet, maybe yours has been replaced with thicker material which is preventing the heater seating fully in the notch in the body ... or maybe the elbows for the air pipes have been replaced with something larger than the rubber originals and that is preventing the heater seating fully.
Eyeball vent pipe 01.jpg and
Driver's side pipe routing
Eyeball vent pipe 02.jpg and
Driver's side pipe routing
Heater 002.jpg and
Felt under heater
Roger
S4 DHC
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PostPost by: RichardHawkins » Thu May 21, 2020 9:26 pm

Roger,

Thanks for the reply, and particularly for the photos. I have spoken to Brian Buckland this morning, and he blames the printers for omitting the 1/4 in 1&1/4”. I have been looking at the whole assembly again today, I have dismantled the heater so that I only have an empty box and removed the rubber elbows and bungs so I can see right through. In this condition the air hose fits between the heater box and the bulkhead, but the holes where the rubber elbows fit are about 15mm too low to align with the air hose. It seems that the gap between the top of the transmission tunnel and the bottom of the plenum is too small. It seems I will have to reposition the holes in the heater case. I have cleaned pressure tested and overhauled the heater assembly it looks better than new. Now I need to butcher it so that it fits. Some days I hate Lotus.

Richard Hawkins
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