Lotus Elan and Lotus Elan Plus 2 Forums

I'm in the process of changing the heater hoses on my project S3 Coupe and find the plenum is really
cramping on the hose on the rh side. Also, I find the demister hoses are in the front of the flapper
ie, toward the dash. My S4 has them toward the rear of the flapper, ie, toward the engine bulkhead.

The numbers on the little plate that's riveted to the heater assembly is FHR4325/09 and F 465.

The Parts manual shows a different prefix for the S3 vs S4 heater but only illustrates the S4 / S4 Federal
one.

So, what is the correct heater assembly for 36/5727? Is the 'hose to flap' orientation correct?

Has it been fitted the correct way around?

Greg
My '67 S3 DHC demister hoses are positioned the same as yours, toward the dashboard.

elanfan1 wrote:Has it been fitted the correct way around?

I don't know. It may have never been removed or, removed and refittet during a resto 40 years ago.

Chris, do you know if your heater hose fits like this one (relation to the plenum)?

Greg
Too difficult for me to see.

Looking again I think the box is the correct way around as you?d never reach the hose connections at the back. This doesn?t mean the end plates haven?t been put on the wrong ends of the box. The gap to the plenum looks quite large considering it?s just a piece of thin foam. As to the hose I think I?d just sculpt a small piece out of the plenum to get a better fit.

The heater for my pre-airflow Coupe is in Florida and I'm already back in Ohio, so I can't check this out.
But, I am pretty sure you could take the heater box apart and reassemble w/ the end plates swapped around so the demister vents could be reversed. IIRC, both the demister vents and the heater hoses should be closer to the dash.

I think the difference between the S4 and early S3 is the heater box has 4 demister vents opposed to only 2 in the pre-airflow cars. Later S3's had face level vents also. The other difference I think is the later cars also had 2 speed blower motors and the later heaters had a resistor riveted to the box to make the 2nd speed.

Roger

Steve, I think you're right. The Parts Manual and some google images show a notched out plenum at that
hose point to, obviously, clear the hose. Mine does not have the notch.

Roger, that's most likely what I'll do (turn end plates around) when the heater comes out later.

Thanks guys

My heater box assembly on removal s4

Thanks Shaun!

Shaun
Looks like your heater box needs the refurb treatment you gave the carbs!

Shaun?s picture above throws up further queries or oddities. It?s the correct way around as it has the added brackets for the wiring harness on the front yet it also has the cut out with grommets in that are usually around the back that connect to the eyeball vents. Also note there is no fouling on the right hand water pipe

Early last year I had four elans in my workshop, a 66 S3 DHC, a 67 S3 FHC, a 71 Sprint & my 69 S4, on which I happened to be trying to rectify a persistent rattle from the heater box. This got me looking at the others to compare fitment. I had previously restored the S3 DHC for a friend, & remembered trying to work out which way the ends should be, ie vent pipe closest to dash or furthest away. We ended up copying my S4, which has them furthest away from dash. Anyhow, looking at all four heaters, no two were exactly the same. Two had the vent pipe closest to the dash & two the other way, (but we may have assembled my friends S3 opposite to original,) but under the heater flaps, there are louvres to direct the air flow. On two of them they were oriented to direct the air towards the vent pipe, on one they directed the air away from the vent pipe & on the other they were half & half to direct the air in both directions, splitting it outwards from the centre. At first I thought it was an illusion or the way they had been fitted to the box, but they were definitely pressed out differently. The Sprint & my S4 had the eyeball vent pipes coming from the rear of the heater box but the S3 FHC had no eyeball vents, but did have the grommets blanking outlets in the front like shauns above. The DHC had no eyeball vents & no facility for them on the heater front or rear.
I have no idea which, if any, is right & which, if any, is wrong, it could just be that in true Lotus fashion, yer pays yer money, yer takes yer choice, anything goes

Regards, Tim

Well here is a couple more pics, one of my S2 and two of my S3 SE when I had them apart, the water connection also a very tight fit on both cars.

I realise this post is a little dated but is the closest to the problem I am having refitting my heater core. My 65 S2 does not appear to have any solid mounting brackets or screws for the heater box. I rebuilt the heater box last winter and am sure I fitted everything back as it was but when I came to mounting it in the car I had 2 dense foam blocks, that I believe the bottom edge of the matrix sat on and a T shaped bracket, that also mounts the bottom of the dash, holding the front up so it makes a tight seal to the air intake box. Am I missing something or does it just sit there with the front resting on the bracket.

Thanks