Lotus Elan

Leaking water valve - stuck away from home!

PostPost by: pabbage » Sat Jun 22, 2019 6:39 pm

Hi all - clever souls can you help!

I drove down to the see the parents this weekend and had a few 'challenges' over the journey?. one of these 'problems' was that over the course of the journey I had to fill the radiator up twice.

I think I have tracked this down to a leaking heater valve (where it enters into the engine - the water is pouring out and theres a lot of play to it.

img_0392.jpg and

Can someone suggest the steps I'd need to do to fix it? Does it just screw in with some plumber tape? OR is it a more complicated set up?

I'll need to drive the car back (Suffolk to Nottinghamshire) on Monday so any help would be appreciated!

Thanks in advance!!
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PostPost by: richardcox_lotus » Sat Jun 22, 2019 9:26 pm

It depends if the valve thread is fractured. If not too bad PTFE tape on the thread may help.

In an Elan, you can remove the entire valve, or also Bypass the heater circuit entirely if you also remove and plug the other heater hose in the timing chest near the oil pressure gauge fitting in the block.

Others with better memories can advise of the valve thread size - I believe it?s a BSP fitting so you could get some hardware for a plumbers merchant!

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PostPost by: rcfurse » Sat Jun 22, 2019 9:32 pm

I think it is 1/2" BSP. I would take the hoses off, unscrew the unit and then try putting it back with PTFE. If it still leaks I would suspect you have a bigger issue. If the water is being forced out under pressure it infers the system is pressurising and that means it is getting too hot. Why?
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PostPost by: billmoore42 » Sat Jun 22, 2019 11:12 pm

Remember you will have to loosen the motor mounts on the side the heater valve is on and jack the engine up a bit to clear the body enough to unscrew the valve.
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PostPost by: elancoupe » Sat Jun 22, 2019 11:32 pm

I have witnessed a few of these valves fracturing at the end of the threads, resulting in a difficult job to remove the remaining piece.

I put an elbow in the head, and run an in-line heater valve. The heater cable hooks up just fine.
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PostPost by: rgh0 » Sun Jun 23, 2019 12:13 am

You should be able to reseal it with ptfe tape at least temporarily. i would use Gas tape ( it may be coloured pink or yellow) as this is thicker and stronger than the normal white water pipe tape. The threaded connection is tapered so screwing it in another turn should get the needed engagement and sealing

You will not be able to turn the valve without jacking up the left side of the engine and maybe releasing the engine mount as the flange on the valve hits the footwell.

If you leave the cap loose on the radiator you will run the cooling system at atmospheric pressure and minimise any leak also. This alone may be enough to get you home.

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PostPost by: pabbage » Sun Jun 23, 2019 7:12 am

Thanks for all the replies, really helpful info - I hadn't realized i'd need to lift the engine up?. I only have a handful of spanners, screwdrivers, and a car jack.

Could I make this work with a car jack?

Failing that I guess I'll look for a nearby garage and limp there. Any ideas on garages in the Suffolk (nr Framlingham area)?

Cheers again, Paul
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PostPost by: SENC » Sun Jun 23, 2019 12:10 pm

Yes, you just need something to spread the load as you will lift the engine by jacking up under the sump pan. You're only looking to lift it the slight bit needed to allow the valve to make a full rotation so you can unscrew it from the head, so my not need to remove the mount on that side. I think those mount nuts and bolts are tough to get to unless you can get under the car, so keep that in mind, too.
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PostPost by: pabbage » Sun Jun 23, 2019 6:58 pm

Thanks to you all for your input - really helpful and given a few more tools I'd have attempted a roadside repair. As it is we limped it 5 miles down the road to a classic car mechanic (with an interest in Lotus and who replied to an email on Sunday - what a legend!)

He's going have a look but he didn't seem confident it was a simple fix and was concerned for engine given the fact it had an episode of overheating too?. I'll keep you all posted. Thanks again for the support everyone.
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PostPost by: el-saturn » Sun Jun 23, 2019 7:57 pm

mike - u can also ift the car, put a sufficiantly stiff an long tube under the area in question, lower the car by 10 to 20 mm whereafter you have enough clearance to turn the valve. rise, remove tube and lower car -- if your mounts are old or of mediocre quality it may not work - mine always did sandy
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PostPost by: 10kph » Sun Jun 23, 2019 9:48 pm

having taken apart one of these valves I would say that the leak is from the rubber diag phram inside. Trying to remove the alloy valve could end with the neck breaking in which case plug the hole with a tapered piece of wood and also blockthe rubber pipe. Or, ...remove the rubber pipe and squirt into the valve enough silicone sealer to block the unit Or,....Remove and open thermostat housing . block back of valve with a plug of sealer or polythene bag plug and do the same with the pipe.
Many a temporary bodge will get you home I would choose the last idea.. cheap and quick
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PostPost by: Maulden7 » Mon Jun 24, 2019 8:12 am

You also posted this problem on the Elan Facebook page & I have responded there.

You do not have to lift the engine to remove / replace the valve (either to seal the thread in the head or replace the diaphragm) The valve is manufactured in two sections, & these can be separated simply by drilling out the pop rivet & then rotating the outer section by around 20deg.

This then allows the section that screws into the head to be removed, or the diaghram to be replaced (from a new valve which has been dismantled in the same way)

I have very recently done just this myself to replace a leaking diaphragm (I have always used ptfe plumbing tape to seal the threaded section in the head)
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PostPost by: RichardHawkins » Tue Jun 25, 2019 7:32 pm


I like the idea of being able to take the valve apart. Could you expand on your comment about removing the pop rivets? The valve on my car does not seem to have any pop rivets, the two parts are crimped together. Looking again at the photo in the original post that valve looks similar to mine. What am I missing?

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PostPost by: marklowe » Tue Jun 25, 2019 8:50 pm

I have circled the 1 pop rivet. It stops the steel outer part of the valve rotating. So keeps the crimps in mesh with the main aluminium part of the valve. I?ve never tried to separate the parts myself, so couldn?t comment on whether the internals complicate maters.

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PostPost by: billwill » Tue Jun 25, 2019 8:55 pm

I seem to remember making such a repair 'on the road' by fitting a diaphragm that I made from an old leather glove or piece of sheet rubber that was in my odds & sods bag in the boot.

fortunately I think I had previously replaced the pop rivet with a tiny nut & bolt.
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