Removing a thermosat 99 Buick Century 3.1L issues

[Kevin Schmuhl]

I have a 1999 Buick Century 3.1L with a heating issue the heat get warm then cold in cycles of about 20 minutes or so. I have bled the air out of the cooling system using Eric’s video (Thanks). This helped some seems like it heats up faster now but still doesn’t stay warm. Checked the upper radiator hose while the car was cold and it got warm very quickly before the engine was even up to temp, leading me to think that the thermostat is stuck open. I don’t have scan tool to tell you the exact temperate. I went to go remove it. I found the two bolts holding it in, but an exhaust cross over pipe (large silver square tube) is in my way as well as the throttle body. Do I need to remove those, just to get the thermostat out.

Topic

[college man]

according to this diagram two fasteners hold the horizontal water outlet on and the
whole thing should come off.

http://www.justanswer.com/car/1bsd5-find-thermostat-1999-buick.html#re.v/447/

[Kevin Schmuhl]

Yeah I know where the two bolts are but the issue is I can’t get to them with a socket or a wrench. Because the exhaust is in the way. Do I need a special tool to get in their I tried a flexible extension but it didn’t have enough torque to break the bolts loose. The throttle body is the in the way on the top preventing me from getting a wrench on it.

[Glenn]

It kind of sounds like the set up for many of the 3.4l engines with the exhaust coming off the front and wrapping around the side of the motor (with a square looking heat shield over it). If so, you pretty much have to take the throttle body off to access it. It’s still tight in there going after the thermostat housing bolts. I’ve used a ratchet style box wrench to get after it. The challenging part is disconnecting the small coolant inlet hoses attached through the throttle body coming from the coolant bypass pipe (to remove the throttle body). Good luck with it…

[college man]

see if this helps. The guy does not show how he gets the bottom fastener out.
Have you tried a swivel under the manifold?

[George Gallen]

I will most likely be doing this in about a week on my sons car. So I ordered this from ebay:

Ebay – Wrench for lower housing bolt

Also, the housing for the lower bolt is slotted, so you should just have to loosen the bottom bolt, remove the top bolt and the housing should slid off the lower bolt…..should…..Guess I’ll find out next week!

GG

[George Gallen]

OK – just finished this thermostat job (3100 engine – 1999 malibu).

I used the Thermostat Wrench to loosen the bottom bolt to point that the wrench would
no longer fit over the bolt (no more clearance).

I also needed to loosen the two heat shield bolts.

I removed the top bolt by forcing an extension under the black tube which made getting the
top bolt off easy.

Then I used a screwdriver to pry the thermostat out of the engine into the housing outlet.

I never needed to take out the bottom bolt, but I did need to maneuver the housing around until it finally
slid off the bottom bolt.

My engine also had a bleeding tube to the overflow container. I wasn’t able to loosen the compression fitting
on the housing, but was able to disconnect it at the overflow, and pull the 3 front spark plugs to allow the
thermostat housing to be maneuvered.

It was NOT a fun job. BUT having that GM Thermostat Wrench did make getting the bottom bolt loosened and tightened much
easier than without it.

GG

[Brian]

I just did a thermostat last night on a 3400 in an olds alero.

Remove the air intake hose and upper and lower air filter box.

The lower bolt hole on the thermostat housing is slotted, but the thermostat protrudes into the housing enough to make the slot useless.

Use a short 13 mm combo wrench – the ratcheting wrenches are too thick walled to fit on top the bolt head between it and the housing. Sneak in the combo wrench under the exhaust pipe (after its cooled off) and get it in a spot that you can pull it up. It won’t move far, but after it comes out some, you will be able to put a ratcheting wrench on it to make slightly easier progress.

Use an extension on a 13mm socket for the top bolt. I pulled the crossover coolant tube up a hair to fit that socket with extension between it and the exhaust pipe. That bolt was way easier to remove.

I hope this helps.

[Author]

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