Thank you for posting this. I struggled SOOO much with my 1987 S4 and the stock/replacement valves in Florida during the summer that I DO NOT want to go back through this pain on my1990 S4 (I've not had a summer with this car but we don't really have winter in FL either ).

I ordered this from Amazon for $8 and will see if I can put it in front of the currently working (at least in the current climate) valve.

What hose do I need.... 5/8 inner diameter?

 

If you're confirming the o.d. of the valve, correction: it's 3/4" - the i.d. of the hose. Unless your stock hoses need to be replaced, swapping this valve with the stock valve doesn't require any additional hose, clamps or hardware. You just need to plug the vacuum line that you won't be using with this petcock valve.

I've taken a look at the run of hose along the firewall that runs under the AC lines that's between the stock valve location and the point on the driver's side that goes into the cabin.
I'm seriously thinking of splicing in this petcock as a second valve along that run. It looks like it can be located right at the bend where the hose goes into the cabin. Of course this would require cutting the hose and using two 1" hoseclamps, but it should fit just fine.
Accessing the screw-down would still involve removing the air filter housing, but that can be done in minutes - & with the valve in place the cooling system wouldn't have to be 'opened' every summer/winter.
I'll post pics if I end up doing this.

 

Great plan JP ... I just ordered one too and will check that location you are thinking of. Not sure how the handle atop is fastened, may get my neighbor to weld a nut to it so can just reach in there with a socket on an extension to operate it.

BTW, do you think it matters which valve is closest to the engine, the vacuum-operated one or the shut-off?

 

I don't see how it would matter. The stock valve would be operating under vacuum as normal. The downstream petcock would simply be blocking any 'bypass' coolant that the stock valve may be letting by; or in the case of a properly functioning system, preventing hot coolant from going into the heater core when the engine is shut off during Summer months.
I was thinking of somehow attaching a flexible shaft to the valve & running it up through the air filter housing (similar in function to an old mechanical speedo cable). I'm trying to think of a basic tool that's a flexible spring-like drive. Something like this:


EDIT: I've found an old thread in which this issue is discussed in detail. The initial discussion is to use a solenoid and reverse the vacuum electrically at the heater controls, but in post #29, Zeus touches on what we're talking about here. He references a valve that operates in an opposite fashion [vacuum/open & no vacuum/closed] from the stock valve. Using this second valve wouldn't cure the leaking stock valve that so many of us are experiencing, however. It would only be used in a properly functioning system to prevent heated coolant from flowing into the core at engine shut-off. Therefore it couldn't use the heater control vacuum source - it would need uncontrolled/unmetered vacuum - from the intake for example.

 

Crap. I'm telling you guys the hose is 5/8" when in fact it's 3/4".
Tom & Trey, if you guys already ordered the 5/8" valve which is the part number that I initially gave, I'm really sorry about my mistake here. The correct Four Seasons number is #84707; NAPA is BK 6601413 (3/4" hose).

 

Got the right sized petcock and installed easilly... No more hot air blow through when I get on the throttle and overall much cooler!

Thanks JPTL

 

Wow, my 'petcock' is too small, damn! I'm going back to Amazon and signing up for 'enlargement' ... LOL!

 

I went with the 3/4 inch model and experienced the simplicity of Amazon returns on the 5/8 unit.

 

NAPA Canada has different part numbers for these valves and they can't cross reference the numbers. Anyone know what vehicle are the two valves for?

 

I agree. I like having cold air, hot air, or sometimes a purposeful mix at my finger tips. No cutting, untying, etc...
Have had 928's since 2002 and the only issues I've had were with the hose or the vacuum line. I've had an 86.5 in the Desert Southwest, and now my 87 above the 48th parallel. Blew the short hose on the 86.5 2nd day I took it over. Had a vacuum line defect on the 87 2 or 3 weeks after taking this one. Since I maintain the car, never had an issue. Yes the valve is plastic. Yes it is exposed to heat...
If one is vigilant, one won't have an issue. The valve is easy to replace. The function is easy to diagnose with a Mityvac. The valve costs 25 bucks. Worth it to have normal, non-troublesome, temperature function.

 

'92 Dodge Caravan

 

Thank you!

 

.., Is this the type of valve your referring to Bob, do you know if the outlet/inlet are 3/4inch ?


http://imageshack.us/photo/my-images...age760dec.jpg/

Ken
80 928 S
5 Speed

UK

 

Same here. But I always buy at least 2. The next one lasted 5 years and still works perfectly. I used standard hoses. I've had better experiences with the flying saucer one than the other. Cheap a d reliable . Iirc it's from a Chrysler minivan.

 

My first choice will be the all steel one too. Looks more robust than the plastic. I'll ask for an early '90's Caravan.