SanDiego928

I replaced this small valve forward of the heater control valve. Old one had a busted off metal line and was leaking. New one has both short metal lines coming off.

What does it do and can I leave it unpluged?
Should it be plugged?
Or connected to what?

I have no idea of what or where this should hook up too or if it shoud be.

I had a major coolant leak around this area and this looked to be the culprit. Looks like all is okay now with new valve. Test ride resulted in no leaks so far. System was pressurized and this was 1 of 3 leaks. All fixed I believe.

Thanks for the help. Much appreciated.

smiffypr

It is the "thermo switch for cold start valve" seen on the wiring diagram in column 12 on page 1. It should have yellow and brown/yellow wires connected to it. Note that they must be the correct way round.
Without it, the cold start injector won't work, and cold starting will be difficult.
If you never experience cold, you might not miss it as it only operates below 35 Centigrade.

chrly924s

That is actually a themo switch for the emmisions. It opens and closes a vacuum line that runs between the throttle body and the air bleed valve, which goes to the diaphram valve, which goes to the oil filler neck. I replaced mine a few years ago. WSM 24-208.

neilh

+1 on what Charly said... if that line is off and not plugged you would experience a vacuum leak.

James Bailey

I think it purges the charcoal canaster of vapors under certain conditions (decel)when the engine is warm. Or some such thing Hose goes to a vacumn pod switch on one of the larger hoses to the canaster out in the fender.

smiffypr

I should never have said "it is", should have said "I think it is". Never having seen a US version '81 I should know better than to assume anything.
As the "thermo switch for cold start valve" does appear on the US specific wiring diagram, where is that mounted on the US version?

SanDiego928

Many thanks to all. I will check again for leaks but looks dry so far back there. Great knowing what this is for. I did find it in the WSM. I see that it is in the 32v 1985 section 24-208. I imagine it is common for all years or at least my USA 1981 also.

At same time replacing this thermo switch I also replaced AFM seal and deleted the decel valve. Seems to be more responsive and idles perfectly which has been an issue for 1 year.

I owe a lot to this site and eveyone here. Hope to meet you all at the Shart Fest in Anaheim now that my 928 is running properly. I imagine this may be the first time in years this car ran so good.

Mark

Landseer

cold switch? thermo time, water bridge, screwed in axially, ie, towards back of car

SanDiego928

I am still not sure why it was leaking coolant during pressure test if it is a vacuum switch per se.

Does it actually come in contact with coolant by way of the adapter/housing for fluid flow into the HCV?