Thermostatic valve in air cleaner test

[APPLEGREENVW]

[tzepesh]

Reviving this old thread. It is still not clear how this small thermostat is suppoed to work. My concern is that when I suck on the plastic pipe, there is air coming in from the bleeding hole on the back. I expected that air would be coming in through that hole only to remove vacuum when the flap needs to close. I never get to have the vacuum from the plastic tube to go to the brass tube...
Please educate me some more on the topic. I would rather have the hot air circuit not working than struggling with vacuum loss and not being able to tune the carb...
_________________
'74 1303S, L98B Viperngrun (extra glitter), German Look
'64 1200, Sea Blue, under restoration

[vamram]

Bit of a wild guess here Tzepesh. I think when cold the bi-metal strip contracts just enough on the side going to the air cleaner snout to allow vacuum to open the diaphragm. As the air heats up, the metal strip expands, closing the port and the snout diaphragm.

I suppose you could test it w/the car running. Pull the intake vacuum hose from the top of the air filter and plug it w/your finger. If there's a vacuum leak, this should immediately affect your idle. I think.
_________________
"Men are qualified for civil liberty in exact proportion to their disposition
to put moral chains upon their own appetites. -Edmund Burke
“If something cannot go on forever, it will stop.”
Stop Russian-Soviet Aggression!!

'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...languishing since 2022.
Click to view image
Save the Supers!!

[busdaddy]

I thought page two covered the function really well, yours sonds like it's gunked up inside, or needs adjustement since it's in hot mode even when cold.
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[tzepesh]

I took apart one of the two thermostatic valves Ihad, to understand ow it works and what the issue my be.
My observations: the vacuum leak will be there all the time, there is nothing to block off the tiny hole in the housing. So the carb must deal with that, and seems that it will affect idle tuning, as the carb will expect to be there.

The small pistion inside was moving very hard. It passes through a rubber boot or valve. I think the tube was also clogged. So I blew it with brake cleaner several times, and not it is moving easily and it blocks or releases path for vacuum. I think this is the issue with all units, as stated in this topic: it gets clogged with oil residues from air filter (the crankcase venting) and it becomes stuck. You need to be very persistent to make it move, alternate brake cleaner with WD40.

The bi-metal part that activates/decativates vacuum can be adjusted by the large "jet" with plastic ball. I have not atemped it yet, so no advice here.

It's easy to work with it dismantled, hopefully I can get it glued back and no leak. Otherwise I will get to cleaning the other unit, without tearing it apart.
_________________
'74 1303S, L98B Viperngrun (extra glitter), German Look
'64 1200, Sea Blue, under restoration

[vamram]

Great write-up, Tzepesh. Do you think these can be properly cleaned w/out taking them apart? Just alternating WD-40, brake cleaner and possibly compressed air thru the stems/nipples?
_________________
"Men are qualified for civil liberty in exact proportion to their disposition
to put moral chains upon their own appetites. -Edmund Burke
“If something cannot go on forever, it will stop.”
Stop Russian-Soviet Aggression!!

'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...languishing since 2022.
Click to view image
Save the Supers!!

[tzepesh]

I will let you know, I will try with the other one. I will be careful with compressed air in those tiny nipples, there is not much air passing anyway. I will try to do all through the large "jet" hole, but it will take me some time, now I'm helping a friend with his bug.
I managed to glue back this one and it is not leaking vacum (with all holes closed)
_________________
'74 1303S, L98B Viperngrun (extra glitter), German Look
'64 1200, Sea Blue, under restoration

[busdaddy]

Sounds like a job for an ultrasonic cleaner.
_________________
Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!

Слава Україні!

[tzepesh]

That is a very good idea! I will look for somebody who may help.
_________________
'74 1303S, L98B Viperngrun (extra glitter), German Look
'64 1200, Sea Blue, under restoration

[vamram]

[tzepesh]

A note on ultrasonic cleaner: pay attention what liquid you are using. There is a rubber valve inside (orange in one of the photos) and it may be affected.
_________________
'74 1303S, L98B Viperngrun (extra glitter), German Look
'64 1200, Sea Blue, under restoration

[AMS_Dizz]

I use my ultrasonic cleaner to remove any gunk from the thermostat. I just use water with a little degreaser, then blow air into the hole to remove any remaining water.