1990 thermostat replacement help
Thread Starter
2nd Gear
Joined: Sep 2013
Posts: 2
Likes: 0
1990 thermostat replacement help
Hi everyone, ive been lurking for a while, and was able to replace my water pump thanks to the posts on this site. now that the wp is taken care of im trying to replace the stock (20+ year old) thermostat with a 180 (i know there's a big debate about 180 vs 160 vs oem) but what i need to know is how to remove the thermostat housing. the front bolt looks easy enough to get to but the rear bolt has a number of cables and wires on top of it. i disconnected one plug that but there's a broad flat rubbery "plug" in the way. i gave it a decent tug but it didn't budge and im afraid to pull any harder with out knowing what it is. can any 90 owners help?
I search all night to find a thread that has this answer but all i found was threads that talk about the lt1 or that don't go into any detail about th l98 procedure. thank you all in advance.
I search all night to find a thread that has this answer but all i found was threads that talk about the lt1 or that don't go into any detail about th l98 procedure. thank you all in advance.
Pro
Joined: Oct 2010
Posts: 695
Likes: 55
From: Palm Desert California
I have a 91, same car. the wires and cables you are talking about are just on a bracket that is held in place by the thermostat housing bolt.
My FSM states this to remove the thermostat housing.
1. disconnect battery
2.remove air cleaner and intake duct.
3. remove surge tank pressure cap.
4. Drain cooling system.
5. disconnect upper rad hose from outlet.
6. disconnect coolant hose from throttle body.
7. disconnect electrical connector and vacuum harness at EGR solenoid.
8. Remove housing bolts and housing.
9. remove thermostat.
My FSM states this to remove the thermostat housing.
1. disconnect battery
2.remove air cleaner and intake duct.
3. remove surge tank pressure cap.
4. Drain cooling system.
5. disconnect upper rad hose from outlet.
6. disconnect coolant hose from throttle body.
7. disconnect electrical connector and vacuum harness at EGR solenoid.
8. Remove housing bolts and housing.
9. remove thermostat.
Race Director
Joined: Sep 2003
Posts: 16,838
Likes: 341
From: Database Error Indiana
Dont panic if you snap the bolt off. When a steel bolt has been in aluminum for a long time, it can become pretty much welded in place. Ive snapped a couple off. I just drill them out, re thread beck to the 3/8 size and install a stud and use a nut to hold the housing in place.
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 412
From: WV
I alway found it much easier to also remove the throttle body.. It only takes a little longer, then you have nothing in your way , plus it makes it easier to scrape off the old gasket.....
...Don't forget you have to burp the cooling system when your done.....WW
...Don't forget you have to burp the cooling system when your done.....WW
Thread Starter
2nd Gear
Joined: Sep 2013
Posts: 2
Likes: 0
I have a 91, same car. the wires and cables you are talking about are just on a bracket that is held in place by the thermostat housing bolt.
My FSM states this to remove the thermostat housing.
1. disconnect battery
2.remove air cleaner and intake duct.
3. remove surge tank pressure cap.
4. Drain cooling system.
5. disconnect upper rad hose from outlet.
6. disconnect coolant hose from throttle body.
7. disconnect electrical connector and vacuum harness at EGR solenoid.
8. Remove housing bolts and housing.
9. remove thermostat.
My FSM states this to remove the thermostat housing.
1. disconnect battery
2.remove air cleaner and intake duct.
3. remove surge tank pressure cap.
4. Drain cooling system.
5. disconnect upper rad hose from outlet.
6. disconnect coolant hose from throttle body.
7. disconnect electrical connector and vacuum harness at EGR solenoid.
8. Remove housing bolts and housing.
9. remove thermostat.
Thank you for the quick reply! I wasn't sure what the name of the things I was looking at we're called. From your steps above I'm stuck at sept 7 I tried tugging pretty hard on the egr vacuum lines and it didn't budge I'm afraid to pull to hard and brake it. Is there a trick to disconnecting it? Really don't want to have to hunt for a discontinued part again if it breaks. Thanks again
