Automatic Level Control O-Ring Wanted + Switch

[SaltLife97]

Hello friends, another post here. I rebuilt the compressor for the Automatic Level Control and amazingly the diaphragm inside was in perfect condition. Piston never cycled though. Reservoir was white and rusty inside and I cleared that up to brand new and then sprayed it with rust inhibitor. After a bath in Evaporust, the whole thing looks brand new after the rebuild. The cork gasket was original and destroyed so I used gasket maker and made a bead which worked perfectly. Went to leak test it at 98 psi and the bubbles show one area between the tank and second stage housing flange.

I need the o-ring that goes inside it, it is original and showing cracks. I can't seem to find one as thin as that, since the thicker ones do not allow the tank to mate up flush. Any ideas? This compressor now works like brand new and the piston is happily cycling inside...just wont build or maintain pressure well due to this one lil ole leak due to the o-ring.

Also, the blower delay switch that closes the ground when the engine is 120 degrees or high is now broken so the blower doesn't run in off, lo, hi. Open circuit when the engine is warm. Where might I find such a switch? Ebay hasn't been much help..

["Cadillac Kid" Greg Surfas 15364]

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Greg Surfas

[Highwayman68]

I got mine at NAPA for around $5. Take your old one in and ask to see the O-ring case and find the one that matches the best.

[Bob Hoffmann CLC#96]

Kristof,
What year is your car?

[fishnjim]

O-rings are pretty standard, square or round profile.  Different materials, but most are "rubber".
Measure with micrometer for profile size (diam) then compare to the ring OD from a kit.   There's a size cone for that, but just make sure it's visually round or measure the groove OD.   It's probably in 32nds, and not as prevalent as 1/8.   
A local bearing or seal supply house could match.   No good to try NOS because it's rubber and will probably be toast.
www.allorings.com

[SaltLife97]

Gentlemen it is a 1973 Eldorado. I'll takethe old one into napa and ask them and check that website. The Diameter appears to be 3 3/8" inside.

[Highwayman68]

That is one receipt I should have kept for future reference. But it was only like $7 so it didn't seem worth it. Now the product information is worth more than the price of the product.

[SaltLife97]

I found the o-ring and it fixed that leak but I will have to fix the small one coming from the high pressure line. The problem is the compressor doesn't build up the proper pressure within the allotted time. The book says to deflate tank to 70 PSI and observe a minimum of 100 psi after 5 minutes of run time. Mine gets to 82 PSI. Is this indicative of worn piston seals? I notice that is a maintenance item and the seal does look a bit scored I'm assuming from constantly cycling if its leaked in the past. Any chance similar seals for small pistons like that are sold today? There's gotta be similar compressors that use that method to seal off the piston.

[SaltLife97]

IDK why this thread got moved because aside from my title, I'm not looking for someone to sell me the o-ring, I just needed to know where to get it lol. Anyways,

I think the internal piston seals are worn from a leaking compressor in the past because everything else checks out. Canister holds 90 psi and doesn't leak down after fix, no internal check valve leak based on the test from the book, and I have roughly 16 inches of vacuum off the PCV line. My guess is the piston can build about 5 pounds of pressure before just constantly cycling and the rest of the pressure is lost as blow by. Now to find the seal...

[SaltLife97]

OOP I lied, I took apart the whole kabootle because I'm determined and I manually pumped the piston which produced great pressure...that vented out of the intake vale up top. Any pressure it made is bled off into the valve cover up top. Makes sense. Now the question is how to fix it...I put a new o-ring in there and sucking on it (I know) will bring the piston up which means air is getting past that valve!