Plus Two Heater Hoses..

[G4ILN]

During a body off rebuild I fitted new 5/8" OD hoses to the heater as it's very easy to do with the body off. When I came to connect these hoses to the engine I found (yes you've guessed it) that the connections are 1/2" diameter and no amount of tightening of the hose clips will stop them leaking.

Is there a UK supplier of the correct hoses with different sized ends? If I can't get any I'll use some barb reducers, but that will require four extra hose clips.

Also what is the correct routing of the long hose? Ever since I've owned the car it's been routed under the inlet manifold, up through the hole between two inlet pipes and over the top of the cam cover to the thermostat housing. Works fine, but doesn't look good. To achieve a better routing across the back of the engine and along the LHS of the engine would require a hose with two sharp 90 degree bounds and it would run close to the exhausts. I'd also have to turn the thermostat connection through 90 degrees as at the moment it points upwards.

The manual and parts list are not helpful on this point as they show the heater as having connections on on each side rather than one above the other on the RHS.

Thanks, Graham.

[TeeJay]

With reference to the Heater Hose (long) routing.

On my +2 it goes behind the engine across to the LH side, then across to the connection by the Thermostat Housing.

Hopefully the photos will clarify the routing.

Heater Connections

Heater Connection on Engine

Engine Bay Heater Connection

The above photo is not my car, it was taken many years ago at a Donington Lotus Show.

[mbell]

When I checked ~1 year ago the hoses weren't available from the usual Lotus parts suppliers. On my car the 5/8 hose has some how been made to seal correctly on the 1/2 barb and I haven't touch it.....

If I was replacing it (and couldn't get a suitable hose) I would either try to get a 5/8 fitting for the connect to the front cover. I think it will be a standard BSP thread, so should be able to find a suitable connects from a plumbing place. Other wise I'd buy a 5/8 hose with a 90 bend and 1/2 hose with 90 bend. Then fit a barb between the two 90 degree bends in the bit of the hose that runs parallel with the rear of the engine bay.

The thermostat to heater core hose should run from the thermostat housing (front connector for some strange reason) to the rear of the engine, between the engine and the bulkhead and then do a 90 degree bend and on to the heater matrix. It shouldn't run around the front of the engine.

[JJDraper]

I got a set of Silicone hoses for my +2 from Cliveyboy a few years ago (in black not horrible blue..) which included the correct heater hoses, one with the 90degree bend. Quite expensive, but not for silicone and a reassuringly good fit, with some excess for cutting to fit. No leaks.

Jeremy

[worzel]

Hi Graham

Try Autosiliconhoses- they supply in black/blue/red. You probably need one of their "reducer" hoses plus a suitable nylon/plastic connector from them.

Regards

John

[CBUEB1771]

If I was replacing it (and couldn't get a suitable hose) I would either try to get a 5/8 fitting for the connect to the front cover. I think it will be a standard BSP thread, so should be able to find a suitable connects from a plumbing place.

A 3/8 BSPP to 5/8 hose barb adapter is not common, I searched fitting manufacturers on-line catalogues for quite a while until I found that Lotus Marques in Australia has them:
http://lotusmarques.com/parts/catalogue ... pump-parts
This allows a straight length of 5/8" heater hose to be used for the lower location. The top hose still needs a tight 90 degree bend at the heater housing end for correct routing.

[G4ILN]

Thanks for the replies and pictures.

I've emailed Cliveyboy who tells me that the hoses he supplies are for the Elan and are 1/2" internal diameter at both ends. However some of his customers have used them on Plus Twos. He's offered to supply me with a set of heater hoses on a supply or return basis, so I'll take up his offer.

I have in mind heating the ends in boiling water and pre-enlarging them by pushing them over a tapered mandrel which I'll turn up. I'll then move them directly to the heater connections before they cool and contract. That and a bit of lubricant might do the trick.

If I run into problems I'll probably fit reducing hose connectors from ASH:-

http://www.autosiliconehoses.com/silico ... lours.html

along with barb connectors.

I'll report back with results.

Graham.

[vernon.taylor]

Salut

You could also change the 5/8" brass bits (can't remember the name) to 1/2" - I've seen them on eBay in the past, and somewhere else.

http://www.classicsiliconehoses.com told me they could make up the hoses for the +2 - 1/2" hose enlarged to 5/8" at the thermostat end - I think the price was reasonable. You can also specify mat or lapped finish to look more in period.

@+

Vernon

[G4ILN]

I'm confused by the last reply. The connections at the heater matrix are 5/8" diameter and to change these to 1/2" diameter would require some kind of soldering job.

The connections to the thermostat housing and water pump are 1/2" diameter. These could be changed to 5/8" diameter by changing the BSP to barb fitting ( so long as these can be easily obtained), but I have chosen not to go down this route. There'd still be the problem of turning the 5/8" long hose through a 90 degree bend at the heater end.

Custom hoses from CSH sound like a good idea with the hose enlarged to 5/8" at the HEATER end, but I'll try the Cliveyboy hoses first rather than incur a manufacturing delay.

[alan]

you can slide a copper pipe 90? elbow Inside the end of the hose where it connects to heater. This stop the hose from flattening. When i bought my plus2 the previous owner had done this

[Higs]

I found this source for the 90 degree bend on a 5/8" (or 15mm) hose:

http://www.carbuildersolutions.com/uk/15mm-id-90deg-rubber-hose-bend-with-1-mtr-arm

It fits well and seems to seal ok at the engine off-take end.

Hope this helps.

Richard

[G4ILN]

I fitted the Cliveyboy hoses today.

Attaching the hoses to the heater is easiest if the body is off the chassis, the engine is out, or the dashboard is removed. However it was too late for this in my case, so I removed the carbs and starter to improve access and visibility.

Being intended for the Elan, rather then the Plus Two, both hoses have 90 degree bends at one end. This can be cut off the short lower hose as it's not needed.

After copiously lubricating the heater barb and the inside of the lower hose with washing up liquid, I had no difficulty in pushing it about one and a half inches onto the barb. It was then routed under the fuel pump inlet pipe - behind the fuel pump bowl - under the HT leads and under the distributor to the barb on the water pump.

Fitting the 90 degree bend of the upper hose to the heater is a bit more difficult as the engine is in the way. I cut off the end of the bend to leave about one and a half inches of hose measured from the inside of the bend. I then pushed this onto the barb with the hose vertical and rotated it to the horizontal position behind the engine. This wasn't easy and it's important not to push the hose on too far or the barb will block it. Clearance is tight here and I noted that the aluminium radio interference shield had a groove in it where a previous hose had obviously chafed. Protecting the hose close to the bend with a few layers of plastic tape might be advisable. I left quite a bit of slack on this hose and it's sitting on top of the bell housing. I may shorten it later and fit a 'P' or 'R' clip by the screen washer bottle.

The barb on my thermostat housing was pointing vertically upwards, so I had to tighten it by about 60 degrees to line up with the end of the upper hose. This is a tapered thread and was exceedingly tight. I was concerned that I might strip the thread or break the fitting, but all was OK.

Fitting hose clips to the heater end of the hoses is not easy. I first tried a 7mm hex flexible hose clip driver from underneath the car, but it wasn't long enough or flexible enough. I did no better with a quarter inch square drive 7mm socket, extension rod and UJ. It might have worked if I had had an assistant, working from above, to guide the socket onto the screw. Finally I had success using the ring end of a 7mm combination spanner from above. If you do this, tie the spanner to a piece of fishing line, because if you drop it, it's 100% certain to drop into the vertical gap between the chassis and the body. You can guess how I know this.

It is possible to push lubricated half inch RUBBER hose onto the heater barbs, But if you do this you'll have to route the upper hose up between numbers 2 and 3 inlet tracts and over the cam cover to the thermostat housing.

[TeeJay]

Graham. Good to hear that you have managed to fit new hoses, even if it was a little fraught.
Hopefully they will be without leaks.

After your experience I am thankful that I can fit my hoses while the body is off.

[KevJ+2]

Very interesting write up Graham and well done.
I notice that SJ sell a 90 degree bend heater hose part number SJ050P0001 - ?12.65 + vat how does this compare to cliveboys?
This is a job I have to do before the body goes back on so I'm lucky to have the time and room to do it.
Kev.

[alan]

i fitted a hose from sjsportscars on my +2s and it fits very well.
To tighten the clips i used a long screwdriver from the exhaust side. I slide it between the back of the cylinderhead and bulkhead