2002 Buick Century Custom SE new to me

Waiex191

Active member
238
86
28
Poplar Grove, IL
2000 Century
I'm not sure of the relative amounts of antifreeze in the radiator vs the rest of the system. I siphoned the radiator, heater core, and whatever I could suck out of the block when I had the manifold off. There are coolant drain bolts on the block, but a bit hard to get to, and mine were very rusty. I was afraid to remove them.

When I converted my other Saturn to Prestone, I drained it, filled with distilled water, and repeated that about 3 times. My Century already had the green stuff.
 

Count67

New member
28
7
3
Sanitaria Springs, NY
Buick Century Custom SE
I'm not sure of the relative amounts of antifreeze in the radiator vs the rest of the system. I siphoned the radiator, heater core, and whatever I could suck out of the block when I had the manifold off. There are coolant drain bolts on the block, but a bit hard to get to, and mine were very rusty. I was afraid to remove them.

When I converted my other Saturn to Prestone, I drained it, filled with distilled water, and repeated that about 3 times. My Century already had the green stuff.
I'll do the flush with Blue Devil radiator flush and degreaser from autozone first. Then I will add the auto zone yellow coolant concentrate with distilled water.

I just dropped the lower hose and will do this again as I don't want to mess with the drain plug and have that break.
 

chem_man

Buick Newbie
64
17
8
Fallston, MD
1999 Century
How much came out (assuming you drained it into a catch pan)? If you do not know, then while you are flushing your system, catch it an measure it.

There could be up to 4 - 6 quarts still left over in the block. A good way to replace the antifreeze is to pour in at least 6 quarts of straight antifreeze, not the 50/50 mix, and then top off with distilled water to bring it to capacity. That way you will have at least a 50/50 solution in your cooling system.

Also, a trick I learned long ago - fill the cooling system expansion tank with straight antifreeze.
 

Count67

New member
28
7
3
Sanitaria Springs, NY
Buick Century Custom SE
How much came out (assuming you drained it into a catch pan)? If you do not know, then while you are flushing your system, catch it an measure it.

There could be up to 4 - 6 quarts still left over in the block. A good way to replace the antifreeze is to pour in at least 6 quarts of straight antifreeze, not the 50/50 mix, and then top off with distilled water to bring it to capacity. That way you will have at least a 50/50 solution in your cooling system.

Also, a trick I learned long ago - fill the cooling system expansion tank with straight antifreeze.
I caught it in the drain pan, but the previous owner drove it to her mechanic and lost coolant due to the water pump and a pin hole in the lower hose. It was about 2 inches low from the top of radiator.

When I do the flush I will measure the amount that comes out and add straight coolant per ratio needed.

Thanks for the info!

Here’s a new question, is anyone familiar with the metal spring clips used to mount the interior over the door grab handles?

I got my interior from a special edition custom and the headliner has lit grab handles above 3 of the doors. The clips in the junk yard car get destroyed trying to take them out.
I’m hoping my custom se has the clips installed from the factory, but I doubt it.
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Last edited:

Count67

New member
28
7
3
Sanitaria Springs, NY
Buick Century Custom SE
I caught it in the drain pan, but the previous owner drove it to her mechanic and lost coolant due to the water pump and a pin hole in the lower hose. It was about 2 inches low from the top of radiator.

When I do the flush I will measure the amount that comes out and add straight coolant per ratio needed.

Thanks for the info!

Here’s a new question, is anyone familiar with the metal spring clips used to mount the interior over the door grab handles?

I got my interior from a special edition custom and the headliner has lit grab handles above 3 of the doors. The clips in the junk yard car get destroyed trying to take them out.
I’m hoping my custom se has the clips installed from the factory, but I doubt it.
I stopped by after work toady and took the old headliner and rear deck dash out.
I need to get 4 of the spring clips for the new rear grab handles. I was able to find the connector for the wire harness with ease today after learning in the junk yard yesterday. So tomorrow I'll go to the junk yard and figure out how to take the clips out and on friday get the interior back together.

I do need to get new speaker grills, mine are broke and the ones in the junkyard are so brittle from age its hard to get them out before they crack. I hope to find some that haven't got so much sun/UV ray damage. I also need new christmas tree clips as well for the rear tan molding and rear top of the headliner by the rear window.
 

Count67

New member
28
7
3
Sanitaria Springs, NY
Buick Century Custom SE
Last night at the junkyard I didn't have any luck getting the clips out to mount the new handles for the back seat. So I took a walk around the yard and came across a 2002 Impala that had the same type of handles the Buick has, so I took one off to see if it had different type clips and it did and they were much easier to get out and reuse. GM should standardize their parts for stamped parts like these. I'm just so happy that they work and the handles are in and solid and light up.

Today I took the day off and have the headliner, carpet, two front seats and the middle console installed. My one problem was the sun visor clips did not install proper and think I need to buy 2 new outside pieces so they retain into the sheet metal thru the headliner. I did not put in the back seats because I need to figure on what to do with the speaker grills that have deteriorated. I'm thinking about making a frame and covering it with speaker grill cover. So I have the rear deck out and will use the bolt pattern from the original grills.

I then put new hoses on the radiator and the small formed hose by the water pump and added water and blue devil flush and degreaser. I ran the engine and my heat never got hot and the temp stared to climb, so I shut it off and am quite sure I need to do the dreaded thermostat on the 3.1 and 3.4. So has anyone bought the GM thermostat wrench? It's designed to get the bottom bolt.


I pulled these codes off it.

P0141
P0446

I plan on changing both O2 sensors.

The emission code will require more time.
 

Count67

New member
28
7
3
Sanitaria Springs, NY
Buick Century Custom SE
The special thermostat wrench for the 3.1 and 3.4 engines is well worth the money! I heartily recommend them for anyone who works on either engine!
What thermostat do you recommend for the 3.1? Is Gates a decent one or the autozone duralast gold?
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chem_man

Buick Newbie
64
17
8
Fallston, MD
1999 Century
I use Gates or Stant. If I can't get either of those, I would then go ACDelco.

NOTE: Gates and Motorad often make thermostats for one another. I discovered that when I opened the box for a Gates thermostat and found a Motorad thermostat in it's place. I called Gates Tech Line because I was concerned about counterfeit parts and I was told that Gates & Motorad are often strategic partners.
 

Count67

New member
28
7
3
Sanitaria Springs, NY
Buick Century Custom SE
I use Gates or Stant. If I can't get either of those, I would then go ACDelco.

NOTE: Gates and Motorad often make thermostats for one another. I discovered that when I opened the box for a Gates thermostat and found a Motorad thermostat in it's place. I called Gates Tech Line because I was concerned about counterfeit parts and I was told that Gates & Motorad are often strategic partners.
I went with the Stant and bought the wrench.

Thanks for the info!
 

Count67

New member
28
7
3
Sanitaria Springs, NY
Buick Century Custom SE
I was posting a new problem in another thread that someone else had the same problem with the horn blowing. My problem I do believe was water related and seems to been back to normal, so now I can continue with the cooling system.

I ran the engine for almost an hour today without overheating. I opened the bleeder screw on the thermostat housing. This helped so much, because on Monday the temp was heading to the 3/4 mark on the temp gauge. I thought I might have a problem with the fans, but no problem they came on today and kept it at around the 5/8 mark but no heat. Then it final went to the 1/2 mark and I could feel heat. I'm glad I bought a new thermostat and will put that in after I flush the system out. The coolant and flush mix is very dirty in the overflow tank, the blue devil flush is doing its job. I will flush it 2-3 times or until the water is clear, then put the new thermostat in and the coolant. I have to wait for my new wrench to get here, its scheduled for the 14th-17th of this month.
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chem_man

Buick Newbie
64
17
8
Fallston, MD
1999 Century
Sounds good to me, and glad to hear you got your wonky horn working properly.

Just to make you aware, the 3.1 engines run a little hotter than any other engine I have ever experienced. Our 99 Century runs between 195 - 205 routinely and loves to stick right around the 199 - 202 zone. From what I have read in a couple of places, this is normal for the 3.1 engine.

Be sure and remove the coolant reservoir and clean it out too.
 

Count67

New member
28
7
3
Sanitaria Springs, NY
Buick Century Custom SE
Sounds good to me, and glad to hear you got your wonky horn working properly.

Just to make you aware, the 3.1 engines run a little hotter than any other engine I have ever experienced. Our 99 Century runs between 195 - 205 routinely and loves to stick right around the 199 - 202 zone. From what I have read in a couple of places, this is normal for the 3.1 engine.

Be sure and remove the coolant reservoir and clean it out too.
I planned on spraying the coolant tank out and I’m putting a new bleeder valve on the water pump side due to the fact it’s broken off. It’s nice they sell these for $10 for two of them. These make such a difference on making the car run cooler.

Thank you!

Eric
 

Count67

New member
28
7
3
Sanitaria Springs, NY
Buick Century Custom SE
I took a half day off today to go to the junk yard and found a rear interior dash with the speaker grills intact. I got it for $8.50! Great find and then I went and put the thermostat in and what a pain to get the lower bolt back in. This was the hardest part. The new wrench was alright, it hit the transmission casting with very limited movement. My son who is a lefty stopped by and thank god he did. He was able to get the bolt in!! I was so thankful and he said Dad you have always been there for me to help out with my cars.

I ran the car for around 30-40 mins and the temp gage was under the 1/2 mark. It did take a long time to get heat, so I do believe I need to back flush the heater core. What hose should I put the garden hose on to back flush proper?
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Count67

New member
28
7
3
Sanitaria Springs, NY
Buick Century Custom SE
I would run water from the hose through both hoses. That way if something gets "stuck" going one way, it just might come loose going the other way.
I ran water through the heater core in both directions. First I did the inlet hose, but then I noticed some sludge in the hose, so I cleared it out before I put the hose to it. Once I cleared it out I ran water through it with a light pressure and then I did the same on the other hose until it was clear water. Then I blew the water out of the heater core, I then ran water through the steel tubing that the hoses hook to, the water passed right through the radiator and out the bottom lower hose part of the radiator. I removed the lower hose to drain the radiator, so it was able to drain through there.

My coolant tank has a lot of hardened sludge on the sides and now I going to stop by the junkyard tomorrow and see if I can find a cleaner one. I dont want to have the sludge flakes flushing back into my clean coolant.
 
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