if they give you any trouble, just cut the heads off with a disc and use a stud puller after removing the housing and a little heat and penetrating oil.
the plastic housing have a life as well.
they are $24 brand new on eBay or you can replace with the cast Syncro version and not have to worry again. Temp2 and temp gauge connectors must be changed to Syncro style, super easy.
I had two plastic housings fail this last winter in very cold conditions.

dylan

----- Original Message ----
From: Frank Condelli <RAlanen@AOL.COM>
To: vanagon@GERRY.VANAGON.COM
Sent: Thursday, May 29, 2008 5:36:04 AM
Subject: Re: thermostat housing

In a message dated 28/05/2008 10:07:37 P.M. Central Standard Time,
LISTSERV@GERRY.VANAGON.COM writes:

i am  replacing my 1987 thermostat housing. does any know what size bolts
holds it  on to the engine. is it allen,torx or triple square??? also if there
any tips  in replacing this?

Patrick,  those bolts may be hard to remove.  They are allen head.  Insert an
allen head socket key with a long extension and then bang on it hard with a
heavy hammer to try to loosen the threads and corrosion around the shaft of
the  bolt before trying to turn it out.  Going slowly left & right may be of
some help to loosen them also.  If you get them out, replace them with
stainless steel ones.  I have them or you can find them locally.  From  my _Vanagon
Items Forsale_ (http://members.aol.com/Fkc43/sales.htm)   webpage >

Stainless Steel hex socket bolt for T-stat to head, M8 x  50mm   -  $1.25
Stainless Steel hex socket bolt for  T-stat to head, M8 x 60mm   -  $1.50

Cheers,

Frank  Condelli
Almonte, Ontario, Canada
'87 Westy & Lionel Trains (_Collection for sale_
(http://members.aol.com/Fkc43/trainsal.htm) )
_Frank Condelli &  Associates_ (http://members.aol.com/Fkc43/busindex.html)
- Vanagon/Vanagon Westfalia Service in the Ottawa Valley
_Vanagon Stainless Steel Exhaust  Systems_
(http://members.aol.com/Fkc43/exhaust.htm)
_BusFusion_ (http://members.aol.com/BusFusion/bfhome.htm)  a VW Camper
camping event, Almonte, ON, June 12 ~ 15,  2008