Need help locating an obsolete part

[kazoocruiser]

The truck is a 1981 C10 Scottsdale longbed with a 250 inline 6 with the integrated head.

The switch I need screws into the oil galley on the passenger side of the motor, about 4-6 inches to the right of the oil pressure switch.

It is a 2-port switch, which allows manifold vacuum to flow to the heater stove actuator, until oil temperature reaches 150 degrees F. It is called a EFE valve or switch.

The part number I pulled from the service manual is 866887. CORRECTION 366887 Thanks ElGracho.

Thanks in advance for the help.

[83GMCK2500]

Napa calls it a Ported Vacuum Switch, still available. If you know the temp rating that may help your search.

https://www.napaonline.com/en/search...=nol-veh-conds

[kazoocruiser]

Thank you for the reply, however, the switches showing on the NAPA website mount in the water jacket, probably on the thermostat housing, so they are too big to screw into the hole in the oil galley. I'd prefer to go back with what is coming out if I can.

[ElGracho]

Are you sure it isn't 366887?

http://www.gmpartswiki.com/getpage?pageid=59361

[kazoocruiser]

ElGracho thanks for correcting my typo. I fumble fingered it from a three to an 8, so yes, it is 366887.

Seems GM used a number i am having no success finding.

[83GMCK2500]

Interesting, what size thread is the switch you're looking for?

I see on this search: https://www.gmpartsgiant.com/parts/g...ch-366887.html that it notes the original P/N was superseded to 12388891. Looking for that number also leads to "discontinued" however there is one on ebay, the appearance is different from original, but the function may be the same...does this look like it is the correct thread dia? The one on ebay: https://www.ebay.com/itm/212-354-AC-...kAAOSwNxlbNVtQ

[kazoocruiser]

Hi 83GMCK 2500,

I just sent a message to the seller of the switch on Ebay you sent me the link for, to see if he could put a wrench across the flats of what he has to see if it is the same size as what is in there now.

I don't know what the thread pitch is on what I have, but I am pretty sure, because what I have now is 3/4" across the flats, that if I get something with 7/8" across the flats, that I am going to have to either use an adapter, or try to use the thermostat housing.

Thanks for the detailed help. The difference between a normal ported vacuum switch, which is normally closed until a certain temperature is reached, and what I need, which is an EFE, is that an EFE switch passes vacuum until a certain temperature is reached, when the vacuum is then shut off.

[kazoocruiser]

I just went to gmpartswiki.com and entered in 12388891. No results!

[Irish1941]

Originally Posted by kazoocruiser

I just went to gmpartswiki.com and entered in 12388891. No results!

Because that part number is too new. It replaced 366887 in 2002.

The one on eBay is correct but if you're still not sure I can look thru my junk and see if I have one in the 366887 box for comparison.
It was used on ALOT of GMs. Shouldn't be too hard to find one.

[ElGracho]

I have no knowledge of this company, but I found this one based on the interchange to an acdelco number from the ebay ad above:

https://www.stockwiseauto.com/acdelc...-vacuum-switch

Never mind, I missed the zero in stock...

If you search the ac delco number of 212-354 there are 3 on ebay...

[kazoocruiser]

Now that it looks like a replacement switch might be available, my next project is definitely making sure the one I have is bad. Anyone have any advice before I break an egg I can't unbreak?

Maybe I should take a poll.
1. Abandon the switch where it is, and relocate a new switch to the water jacket.

2. Restore operation to original location.

[kazoocruiser]

Here's an update. Things can change in a month. I got an offset crowfoot line-wrench wrench (Snap-on, no less) off Ebay to remove the old switch, and then the wrench went missing before I could pull the original switch, In the interim, I ordered another wrench off of Ebay (another Snap-on unit, that is now in transit from Texas). I did a search under the original part number on Ebay, and now there are TEN of these switches available as N.O.S. parts from someone I have bought from before. So things seem to be moving towards a good conclusion. I think EVERY 4.1 250ci I6 motor used this same switch.