Lotus Elan

Getting OGU roadworthy again

PostPost by: billwill » Tue Sep 18, 2012 9:18 pm

Ah, now I recall the cause of my problem, but not exactly how to cure it.

Some long time ago, the junction of the heater's water valve and the head, corroded the original head and one of those firms, that over the years, I have employed for engine work, resolved the problem by boring the hole in the head bigger and cutting a bigger thread (a parallel one). To match this he/they made a non standard bulb adaptor out of steel. Clearly they made it a very tight fit on the bulb and either glued it in or the two-metal junction has 'welded' the bulb to the steel. They interchanged the positions of the water valve and temp sensor.

I presume that the standard adaptor has the same tapered thread as the water valve. Can someone confirm this?

Here is a photo of a water valve next to my non-standard bulb adaptor.

WaterValve+TempSender.jpg and
A Water Valve for the heater plus the non standard temperature sensor.


Attempts to separate the bulb from the adaptor using extreme torque, as mentioned above, have failed and have damaged the flats and the brass collar.

DamagedBulb2.jpg and
Damaged Temperature Sensor


Rohan's suggestion of cutting the adaptor may be the only solution, but as you can see from the photo this is a tougher task than cutting the standard adaptor. This is hefty steel, not an aluminium alloy and it will be difficult to avoid sawing into the bulb.

Can someone tell me a source and/or the part number of the standard adaptor for the temperature bulb as clearly I will need to buy one to mate into my new head? The part does not seem to appear in any of the pictures here: http://www.rdent.com/manuals/index.html

Also does anyone know a good repair/renovation firm for this temperature instrument?
Last edited by billwill on Tue Sep 18, 2012 9:23 pm, edited 1 time in total.
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PostPost by: billwill » Tue Sep 18, 2012 9:22 pm

Matt Elan wrote:Re cost of heads - QED website says ?2275 inc VAT for a bare head, Burton catalogue says ?3700.....



My die is cast.

8)

But QED is ?2275 PLUS Vat.

http://qedmotorsport.co.uk/qed-shop/lot ... components
Last edited by billwill on Tue Sep 18, 2012 9:36 pm, edited 1 time in total.
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PostPost by: ardee_selby » Tue Sep 18, 2012 9:30 pm

billwill wrote: Also does anyone know a good repair/renovation firm for this temperature instrument?


Bill,

"Speedy Cables" got a mention here: elan-f14/combo-gauge-t20115.html

Maybe Roger could give you more info...

Good Luck - Richard
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PostPost by: billwill » Tue Sep 18, 2012 9:42 pm

QED have got the adaptors.

http://qedmotorsport.co.uk/qed-shop/lot ... sing-union

That does not look like a tapered thread to me.
Image
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PostPost by: types26/36 » Tue Sep 18, 2012 9:53 pm

From memory I dont think the adapter has a tapered thread but will have a look at one tomorrow although you can interchange the heater valve with the temp fitting.
Here is another one that may work; http://www.holden.co.uk/displayproduct. ... de=070.043
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PostPost by: garyeanderson » Tue Sep 18, 2012 10:19 pm

I looked at 2 parts manuals and neither netted me a part number. It is shown in the early parts book as PA8 but no part number found. Dave Bean catalog lists it as follows

Gary

Twin Cam mechanical water temp gauge adapter.JPG and


p/s/ - Glad to see you are getting the Elan back together
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PostPost by: billwill » Tue Sep 18, 2012 11:19 pm

Thanks Gary,


I found some instructions on how to cannibalise a bulb off a cheap NEW gauge and fit it to a classic display unit.

http://www.ply33.com/Repair/tempgauge

The working fluid is ether, so the trick is to cool the new bulb very cold in salt ice water, then having done all preparation possible before hand the old tube is cut and with an electric soldering iron (no naked flame) solder a copper tube sleeve over the old tube, then cut the new tube, insert it in the other end of the sleeve & solder it in. Better details in the linked article.


~~~~~

Looks like Speedy Cables can do the job if I find that I cannot. 8)
http://www.speedycables.com/calibration.html
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PostPost by: qedmotorsport » Thu Sep 20, 2012 8:54 am

billwill wrote:I originally placed the order with QED, but for various reasons they had not been able to deliver, in the end I got fed up with the lack of supplied information as to what was happening and I cancelled the order with QED. QED have probably resolved their difficulties by now.


Hello Bill,

Firstly apologies if we failed to keep you in the loop enough. The guy machining our heads had a major fire at his workshop some time back and although we knew waiting for him to get back on his feet and re-tool would take time, we didn't feel it would be fair to just drop him and find someone else who could get our heads back into production quicker.

I don't want to hi-jack this thread but with regard to the cam bearings, we make our cylinder head that way so that should the worst happen and debris gets between the cam and the journal, all you need to do is change the bearings. Otherwise you would have the line-bore the cam journals and get new bearings.

For anyone else interested, we've just received a batch of 19 new castings and dropped off 10 for machining.
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PostPost by: billwill » Fri Sep 21, 2012 7:30 pm

This week I've been taking off the front of the timing case, because when I assembled it last time in 2010, I realised afterwards that I had forgotten to put Loc-Tite on the two screws that hold the timing chain guide. It became academic as the head failed & the car was off road, but I would not be happy to put the new head on with that nagging doubt.

Turned out that with the silicone sealer that I had used as a gasket, there's no way those screws could have worked loose, but anyway now they have the proper stuff.

Put the case-front back on today using chopped off sections of a sump gasket set held on with silicone sealant for the sump and some orange liquid silicone gasket for the faces and the modular waterpump.

~~~~~~~

Anyway after doing that I decided to have another go at that temperature gauge sender (above). So by taking the instrument out of the dash, I was able to put the two flats of the sender bulb in a mighty big vice and then with WD40 and a big spanner and an unholy amount of torque to and fro, the non-standard steel adaptor/housing finally came free of the sensor bulb.

Then it became obvious why it sticks, even for everyone else, The brass collar at the top of the bulb is a tapered cone. So in fact it would probably be best to just use a bit of PTFE tape on it as a seal. In my case that taper plus the fact that the through hole in the steel was too tight a fit is what caused my problem.

Well its off now though I'm not sure that it will be OK as I can smell Ether, so I'll probably have to repair it or get it repaired. If I can get hold of any ether, I can probably do it myself (carefully, in open air).
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PostPost by: types26/36 » Fri Sep 21, 2012 7:43 pm

billwill wrote:
Then it became obvious why it sticks, even for everyone else, The brass collar at the top of the bulb is a [b]tapered
.


I have not seen a tapered one although there is a "raised section" as this pic shows.
Attachments
BULB RAISED SECTION (Copy).JPG and
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PostPost by: billwill » Mon Oct 22, 2012 5:53 pm

I haven't done anything on my Elan over the past month (been building a stud wall to make a pantry for my kitchen) while waiting for my engine man to assemble my new head.

But the thought of my leaking temperature gauge has always been with me and on impulse I walked into my local pharmacy today and asked if they could get me some ether. They just looked at me aghast and said not possible, but no real reason why not. :?

So I decided to do an internet search and having checked that the desirable type of ether is diethyl ether (http://mgaguru.com/mgtech/dash/dt102a.htm#top), I did an internet search. I found it used to be used for making model engine fuel and I do have vague recollections of that (might be able to get some in model aircraft shops).

I also found that ether is in the easy start spray cans, but probably as a mixture & not sure which ether it is. :?:

I found this site
http://www.ebay.co.uk/itm/1L-Diethyl-Et ... 337d21d4f4
selling it in whole litres, but that is way too much at ?39.99 +?6.99 carriage, except as a very last resort. :shock:

A bit more hunting and I found a site that does 50ml bottles at ?7.99 +?3 carriage
http://www.shop4glue.com/50ml-diethyl-e ... c-85-p.asp
Which is a more realistic quantity.

I haven't ordered any yet, but I now sort-of feel that it will be possible to cut off the bulb, allow the existing ether to escape and then drill out the cracked capillary tube, safely. then clean & resolder the tube in place and finally refill it through a tiny hole drilled at the blunt end, which I will then solder over while cooling the tube end of the bulb with crushed ice (or some-such).
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PostPost by: UAB807F » Mon Oct 22, 2012 8:35 pm

Yes, it is possible along the lines you describe, although I haven't done it myself. This type of repair is dealt with by Peter Wallage in the Osprey restoration series (#11, Instruments) where he runs through the process and the need for subsequent calibration. If you haven't got the book I'm quite happy to scan the relevant pages.

He talks of a couple of fluid ounces of ether being required, introduced by warming the bulb in boiling water to expel air, then holding the tube under ether to allow it to fill as you then move the bulb to cold water. I'd guess surface tension is too great to allow you to simply pour ether inside through such a small capillary tube ?

I'd have loved to see the reaction when you asked a pharmacist for some ether. As you say, there's no law as to why you shouldn't have some and there's no doubt at all that a chemist will have stock, but there's a classic case of "oh no..... you're not competent to handle such dangerous chemicals sir". Kids in night clubs are knocking back cocktails made with liquid nitrogen and losing their stomachs (and almost their lives) yet you can't buy 20ml of ether. It's a funny old world.

back on topic - if the pages are any interest, just shout & I'll scan them.

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PostPost by: billwill » Tue Oct 23, 2012 1:58 am

Aye, I'd like to see those pages.
Thanks


I doubt if pharmacists have any in their stock even; I don't think any of them have done their own pill or potion making for over 30 years.

8)

More likely to find some ether in a School Lab or University Lab.


~~~
Ether is probably far less dangerous than petrol & I can quite easily buy that 60 or more litres at a time.

:roll:
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PostPost by: UAB807F » Tue Oct 23, 2012 6:23 am

Hi Bill,

pm sent (or at least I think it has....)

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PostPost by: billwill » Tue Oct 23, 2012 8:02 pm

I've read the Peter Wallace pages now thank you and he does stress the point that the gauge end of these capillary instruments often have a filling tube also connected to the gauge, and sometimes its a second tube off the sensor. I don't recall seeing one on our Elan gauges, but I'll take another look soon.

If there is a filling tube it will be soldered shut, but the tip can be cut off again. Then it is fairly easy to get the Ether in by dipping the filling tube in a bottle of ether and then putting the bulb end alternatively in boiling water then in ice. The heat drives the air out as bubbles in the Ether bottle, then as you cool it it sucks ether in through the tube.

Peter W then talks of recalibrating "depending on how much Ether you managed to get in", but personally, I think he has this bit wrong. He seems to think that you should try to fill ALL the interior with ether. But in my opinion if you were going to do that you would be measuring the expansion of a LIQUID by using the Bourden gauge and frankly you might as well use water for that.

Nope, I used to think that too, until I read other articles on the Internet and realised that the essence of this gauge type is that you only part-fill the bulb, so that the Ether evaporates to form a mixture of vapour and liquid Ether. As such the pressure of the vapour is directly related to the physics (or chemistry) of the fluid and as mentioned in http://mgaguru.com/mgtech/dash/dt102a.htm#top is 107 psi at 100 deg C. As such, if the Bourden indicator gauge was correctly calibrated before the repair and if you use the same fluid, it should still be calibrated after the repair. :roll:

Of course the process of checking this be so is exactly the same as re-calibrating (put the sealed bulb in boiling water and look at the indicating needle on the gauge), but we might as well get our thoughts straight. 8)
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