I've found two in my 87 XJ-S 5.3L V12, one on the fuel rail, and another on the RH rear cooling manifold.

The one that came off the fuel rail (on the right side of the photo) is missing it's "cap", and thus its part number. Testing it, I find that it activates at 90 degrees C, 195 degrees F.

The other one that's off the cooling manifold, shows part number EAC4083. This gets somewhat confusing, since the reference I'm looking at says "from (V) 179737" (mine is 134879) but the intro page says the part #'s should be good for my VIN and engine number.

I suppose the above isn't as important as if the things are working right. I've not found documentation on what temperature each is supposed to activate at...are mine close?

Finally, what is the one on the coolant manifold supposed to do? I've seen a few pics of different cars with the switch there, but the vacuum lines no longer attached.

Thanks,

John
1987 XJ-S V12, 62,000 miles

 

the one on the right is for the air pump plumbing. and I think has a small roll with the vac advance vac lines. I just removed it and in it'd place put in a mechanical temp gauge sensor. that whole air pump system is really useless by now on your car anyways.

 

Other way round :-)

The EAC4083 (on the left) is for the emissions/air injection.

The fuel temp switch is (EAC5086) is on the right.

Cheers
DD

 

I think it opens the air injection divertor valve. Can't quite remember.

Go to the "How To" thread at the top of this section and then to "Downloads". Look for the "S58" manual. The operation of the switch might be explained in that manual. (Good reading even if the operation of that switch isn't mentioned)

Cheers
DD

 

Thanks for the replies.

I wish the fuel line switch didn't have the end broken off of it. I see that they are NOT cheap ($100 + or so), and I'm scratching my head trying to figure out how to fix it. My experience with JB Weld is that it doesn't seem to like (as in adhere to) plastic very much.

Thanks,

John

 

Try going without the fuel temp switch. You wouldn't be the first. Just run your vac hose from the regulator directly to the manifold nipple.

If you have problems with vapor lock you can spend the $100

Cheers
DD

 

Excellent idea Doug...should have thought of it myself!

Thanks,

John

 

Well darn, she vapor-locked on me this evening.

No big deal. Ironically, I was at the auto parts store looking for another lug nut (which I didn't find), went out to go home and no-start. Popped the bonnet, waited 15 minutes, started just fine.

I still don't want to spend the $100 :-)...and I wouldn't have to if there was a glue/epoxy that would stick to hose material and whatever plastic the thermal valve is made of.

Just had a (brilliant) thought...what if I just switch the thermal valves? Since there is no air pump on mine, and thus the valve is serving only to plug the hole in the water manifold, any reason to expect bad things would happen if I use it on the fuel rail?

Thanks!

John
1987 XJ-S V12, 62,000 miles