OK..maybe this is covered in the archives and mebbe not...if it is? this a
refresher..

COOLING SYSTEM..
2.1 liter
I've got a 1990 2.1 that the PO gave up on due to terminal overheating..he'd
done EVERYTHING..heads gaskets water pump thermostat.....Thermostat?...Hmm
the housing is actually melted though...wow..what are the chances of THOSE
heads being any good???
Well the top outlet is better than the one I was going to install and I take
the top half off..ther sits and shiny brass and chrome thermostat..even has a
little "jiggler" valve for bleeding off the air..a nice piece..sez "WAHLER
made in W.Germany" right on it..
I peer in the bottom and WHOA..the bypass valve does not fit over the bypass
hole in the housing..the valve (a flat circular plate) is bottomed about 1.4
inch up on the tapered sides of the housing! The thermostat will still OPEN
(the valve is spring loaded..BUT the valve will never get any closer to
sealing off the bypass!!!
I pull the one from my van.."Berh-Thompson Made In Germany" on the top (and a
handy little arrow point the way position the thing in relation to the
outflow hose...)
On the bottom...025 121 113 E  with  the VW and Audi symbols and "2.111.87"
("One hundred and eleven days has February"?..) the bypass plate is a formed
and shaped plunger that looks as if it will pilot in the actual bypass
hole...it's 32 mm in diameter as opposed to the 42 mm of the other one.......
Now..I've had Indian themostats made by Stant that wouldn't even fit in the
housing..but this??? yeow...

http://members.aol.com/notajeep/thermo.jpg

the scanner makes everything egg shaped but you can pretty well get the
idea....
<plonk> the WAHLER hits the bin and I'm back to work..

Steve
"Hey! nice Jeep, Mister! "
"Look kid, it's NOTAJEEP! "