Lotus Elan

vacuum pod leak down??

PostPost by: nomad » Tue Sep 14, 2021 8:08 pm

Is there a tried and true method of isolating a vacuum leak in the light vacuum circuit? Was thinking of putting a slight pressure on the system and using soapy water. Yes/No???

Kurt
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PostPost by: alan.barker » Wed Sep 15, 2021 5:24 am

If there is a leak i first remove the Vacuum Pod from car.
Put a little pressure inside and submerge in Bucket of water to check for leaks.
Many times it's bottom of Pod rusted through.
Fit new "T" take off.
Or bypass "T" to check leak is not in Chassis (rusted through tower/turret).
Alan
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PostPost by: wotsisname » Wed Sep 15, 2021 11:48 am

I have a gauge (amazon, ebay) and some push fit 8mm pneumatic fittings (straight, Tpiece and port block).. so was able to work my way through the "circuit" and look for leaks.. does require a vacuum source, in my case a working engine. I have left a tpiece and port block in line, out of sight, for future testing. I was able to isolate the leak to the dash switch (+2, pre failsafe).
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PostPost by: prezoom » Wed Sep 15, 2021 5:25 pm

Bypass the switch, connecting the tube from the pods directly to the front crossmember. The rubber block in the switch after all these years gets hard and the metal surface of the switch on which the block sits is less than flat or smooth. If that solves the problem, search for the post from Emma Knight on her repair of the switch in the archives. Works very well. Did mine 15 years ago and it will still hold the pods up for several days on my S2.
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PostPost by: vxah » Wed Sep 15, 2021 10:41 pm

Get yourself (or borrow) a Mityvac pump tool.
Then you can vacuum test all individual components and easily trace the leak.
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PostPost by: nomad » Thu Sep 16, 2021 6:14 am

vxah wrote:Get yourself (or borrow) a Mityvac pump tool.
Then you can vacuum test all individual components and easily trace the leak.






Seems like this would be most thorough. Vacuum gauge and each individually.

Thanks all for good idea's.
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PostPost by: oldelanman » Thu Sep 16, 2021 7:37 am

Another way to test the pod under vacuum out of the car is to suspend it upside down, push the actuating rod fully in to expel all the air then blank off the port(s) and suspend a weight from the end of the rod. If no leaks it should support the weight indefinitely, the more weight added the higher the vacuum created. Once the pod is proved OK you can use it to test the vacuum valve in the same way.

Vacuum switch testing 01.jpg and
Vacuum valve testing
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PostPost by: nomad » Thu Sep 16, 2021 1:40 pm

oldelanman wrote:Another way to test the pod under vacuum out of the car is to suspend it upside down, push the actuating rod fully in to expel all the air then blank off the port(s) and suspend a weight from the end of the rod. If no leaks it should support the weight indefinitely, the more weight added the higher the vacuum created. Once the pod is proved OK you can use it to test the vacuum valve in the same way.

Vacuum switch testing 01.jpg


Ah! Very innovative! Uses the pod itself to create the vacuum! Thanks.

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PostPost by: MarkDa » Fri Sep 17, 2021 10:25 pm

Here's
The link for Emma's repair

viewtopic.php?t=13457&p=60892
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