How to restore a STV valve? 1964 coupe with factory AC

[Claus S.]

It is time for me to restore the STV valve so i wonder if some here knows what kind of solvent i should i use to clean the STV valve?
The GM instructions says to use Molykote Type Z.
I have never heard of Molykote Type Z and i do not know what it is
But from reading the GM instructions i guess where you use Molykote Z on the STV valve is where to use the graphite lubricant that came with the STV valve restoration kit?

The GM instructions says to use 525 viscosity oil to lubricate the inside of the wall, piston and the spring of the STV valve.
I have never heard of 525 viscosity oil so what kind of oil should i use? Can i use something like gun oil for that? Thinking that it is just for lubrication?

The kit i bought to restore the the STV valve does not seem to include the seal that is located between the absolute vacum regulator and the STV valve itself(seal number 15 in the digram)
Is there any members here that have restored the STV valve and knows if this seal for the absolute vacum regulator usually is included i kit?
I do not feel for taking off the absolute vacum regulator if i do not have the correct seal(number 15) to put back on
It looks like there is mostly O-rings in the kit i bought for restoring the STV valve, but the seal(seal number 15 on the diagram)does not look anything like a O-ring

[Mike G.]

Re: How to restore a STV valve? 1964 coupe with factory AC

Roger:

Use the supplied graphite powder in place of the Molykote Z, which is a similar dry powder lubricant made by Dow Corning (difficult to get in a small quantity).

If you are going to charge your system with R-12, you need the 525 viscosity mineral oil for lubrication. It's readily available from US suppliers of A/C related items. If you are using an original style A6 compressor, the system needs about 11oz of 525 oil for the initial charging. That's starting with a dry (empty) compressor. Use the oil to lubricate all the o-rings before installation, too. Do not use gun oil or any other type of oil.

The seal for the vacuum regulator is not included in any kit I've ever seen. I don't think there's a danger of damaging it during removal of the regulator. You could smear a light film of vacuum grease on it for reassembly, to help get a good seal.

For cleaning the body, after it's apart, a mild solvent and tooth brush should work for you.

PM me if you have other questions once you get into it. Mike

[Claus S.]

Re: How to restore a STV valve? 1964 coupe with factory AC

Thanks Mike
I came some graphite lubricant with the restoration set for the STV valve. I plan on using the the original STV valve for sure and most likely i will use a original compressor as well
I suppose maybe that 525 viscosity mineral oil something that companys that repair AC units for both cars and house usually have?

Can i use solvent like white spirit to clean the outside of the valve? The inside as well?

[Claus S.]

Re: How to restore a STV valve? 1964 coupe with factory AC

It says in the GM manual to use 525 viscosity mineral oil so i suppose i can use Mobil Vacuoline 525 oil?See the picture where i have marked the 525 oil blue

[Mike G.]

Re: How to restore a STV valve? 1964 coupe with factory AC

Roger: That stuff is not refrigeration oil, and it is not 525 viscosity. It's for use in heavy duty steel mill machinery.

Here is the question you need to answer first: what refrigerant are you going to charge your system with?? Freon R-12? 134A? Other?

Once you decide that, then the compatible oil is easily identified.

Mike

[Claus S.]

Re: How to restore a STV valve? 1964 coupe with factory AC

I am going to use a freon that can be used instead of R-12

What i mean is just to lubricate the spring and inside wall of the STV valve using the Mobil oil i asked about. So i can put the STV valve back on the evaporator/outer AC box that is placed on the table in my living room

Do i have to use the correct oil just for this? I am not thinking of putting it back on the car yet, just put the STV valve back on the AC box

[Mike G.]

Re: How to restore a STV valve? 1964 coupe with factory AC

Lubricating the spring with some oddball oil is probably OK since it's not going to contaminate the Freon. But you will need the correct oil to lubricate the O-rings before installing them. So you might as well get the compatible oil for your refrigerant and use it eveywhere you need a lubricant.

And to repeat, that Mobil oil you mentioned is not 525 viscosity... It's more like 100.

[Claus S.]

Re: How to restore a STV valve? 1964 coupe with factory AC

Mike can you have a look at the link to ebay? I did a search for 525 viscosity oil and what you see when following the link is what i found:
And if there is okay oil there which kind do you suggest that i use?

http://www.ebay.com/sch/6000/i.html?_nkw=525+viscosity+mineral+oil&_dmpt=Motors_Car_Truck_Parts_Accessories&_vxp=mtr&_rdc=1

[Mike G.]

Re: How to restore a STV valve? 1964 coupe with factory AC

Roger:

The FJC oil is the same oil I use with original R-12. If you have not done it already, make sure that your refrigerant takes 525 mineral oil.

Mike

[Claus S.]

Re: How to restore a STV valve? 1964 coupe with factory AC

I have not done anything with it yet because i want to use the correct products so i do not damage anything

[Claus S.]

Re: How to restore a STV valve? 1964 coupe with factory AC

Is this the FJC oil i can use? The one thing i am not sure about is that it says both R134 and R12. Below is what is says about the oil:
One 8 oz Bottle Of FJC Estercool Oil.
This Is The Most Technologically Advanced R134a And R12 Oil On The Market Today.
This Is Compatible With Mineral, Ester, Paraffin, and PAG Oil.
One Oil Used For ALL Applications.
Can Be Added To Any Existing R12 or R134a Mobile A/C Systems With Mineral, PAG, Paraffin, Or Ester Oil.
Made With An All Natural Ester Oil That Contains Additives Which Gives It The Ability To Lubricate And Protect
The System At The Same Time.
Prevents Acid From Forming And Inhibits Corrosion

If this is the correct oil how much do i need for the AC system on my car?

[Mike G.]

Re: How to restore a STV valve? 1964 coupe with factory AC

Roger:

I'm not familiar with this all-purpose oil. Probably OK.

Best thing is to first choose which refrigerant you are going to use, then get the type of oil recommended by the manufacturer.

On a stock system (A6 compressor), you will need about 11 ounces for a charge. You should follow the manual and add the specified amounts to the condensor, receiver/drier, and evaporator --as well as the compressor. Make sure you are starting with an empty compressor by draining it.

I would suggest that you have a specialist A/C shop do the initial evacuation, system charge, and leak testing. Money well spent.

[Claus S.]

Re: How to restore a STV valve? 1964 coupe with factory AC

Mike i tried too send you a PM but i do not think it got thru
This is what it said:
I looked for the FJC oil you said you used but in the ebay link i posted but i could not find any FJC oil
I did a ebay search today and this is the only FJC oil that i could find that is ok for use with R12

[Mike G.]

Re: How to restore a STV valve? 1964 coupe with factory AC

Roger: tell me which refrigerant you are going to use.

[Claus S.]

Re: How to restore a STV valve? 1964 coupe with factory AC

I am going to use R12 refrigerant. A company close to where i live have a refrigerant that is used instead of R12 and they guarantee that it works just like R12 refrigerant