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2006 Lucerne with 4.6 Northstar
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Discussion Starter #1
Hello to everyone. I own a 2006 Buick Lucerne with the 4.6 Northstar. About 8 months ago she started overheating with the gauge jumping up to the top and the message near the odometer saying that it has shut down the a/c then said to shut the engine off. I did notice that the hose leading to the thermostat was rock hard, so I replaced the thermostat. I purchased one from the local autozone in town and noticed it did not have the hole in top of the thermostat, so I purchased one from the dealer which was exactly like the original. Everything was fine after changing the thermostat, so I took it to the dealer and had them flush it and put new coolant in. The car has just turned 50K and it is starting to overheat again. I am puzzled because the coolant level is fine. When the temp is close to overheating, I put it in neutral and rev the engine. The heat in the car gets nice and hot like it should and then the temp gauge goes down to normal. I have noticed that the heat in the car does not blow that warm when it is getting close to overheating until I rev the engine. I want to say that the waterpump is bad but don't want to just start changing parts because I am unemployed until I can find a new job. Many thanks in advance.
 

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2006 XJ, 2000 Eldorado ESC--total loss :(
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Just looked up your 06 Lucerne with a V8, it looks identical to the FWD Cad N*. That small hose from the water pump bolt over to the coolant reservoir is your purge line... if that clogs the system can't get rid of air bubbles. With the engine cold, remove the hose from the reservoir nipple, put it in the filler neck and have someone start the engine. Water should be flowing through there. If not, pull the hose off the water pump bolt and check for clogs in the nipple.

Also check the small water pump belt drive (right above the water pump). Have seen the thermoplastic pulley(s) seize and then you have no water circulation.
 

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98 deville D'Elegance 86 Fiero 2m4 / 86 Fiero GT W/SBC
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Edited:


Then comes around and hooks into the thermostat housing. This nipple here is the smallest hole in the run. As mhamilton mentioned remove line from reservoir and check for flow. Your water pump pulleys are under the (green) cover. Don't look for the green cover though, you'll never find it. LOL
 

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White Diamond '03 DHS (with DTS floor shift)
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86,792 Posts
His ('06) purge line may be different from your '98.

Forget the WP. Check the purge line as mhamilton said.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,504 Posts
Basically, the purge line is a slow constant bleed that runs from the water pump housing metal bolt/nipple to the top side of the coolant reservoir. If the line or bolt/nipple is clogged the system tends to develop air pockets and the water pump starves for coolant, leading to engine block/head hot spots and poor heater operation.

The purge line should show a steady flow with the engine cold, reservoir opened, purge line disconnected at the reservoir and held in the open reservoir filler neck. have an assistant start the engine normally while you hold the line in the reservoir neck. No flow ??? Clean out the line and the hollow bolt/nipple. If the plastic line is uncleanable, a length of proper sized jacketed rubber fuel hose, from any parts store, can be used for replacement.

Depending on your coolant reservoir placement, there may or may not be long/short/plastic/rubber line. Wing it.
 

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2006 Lucerne with 4.6 Northstar
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11 Posts
Discussion Starter #9
Thanks guys for the quick reply. Unfortunately I am sick today and will check it out as soon as I feel better and report back. I'm just another Northstar owner getting nervous about the head gaskets.
 

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we've seen just about every HG issue (after the coarse thread update in late 2004) be caused by loose headbolts backing out from being too loose

the fix is basically the same HG job but without any drilling/tapping/inserting but with generous use of loctite or threadlocker when you put the new bolts in

don't see it very often but it does happen
 

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2006 Lucerne with 4.6 Northstar
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Discussion Starter #12
I can't thank you guys enough for the help. I am still sick and in bed. So you guys think that this line is plugged up or the bolt is plugged up ? This would cause the overheating ? As soon as I see the gauge go up from where it normally runs ( smack dab in the middle ) the heating ducts blow cool air. I rev the motor up and the ducts blow hot like it should and the gauge drops down to where it should be. This lasts for a few minutes and then goes back up. It mostly happens at a red light when the engine is at idle. It's only 26 degrees F out and I feel like crap so I don't dare go outside yet. I'm not a spring chicken anymore LOL ! It's really nice to belong to a site with members that help out. Many thanks again.

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Just another question guys. I have read that after a coolant flush, some people put pellets in the lower radiator hose or some gold sealant. When I had the system flushed at the dealer, I don't see anything on the bill where they added anything. What do you suggest I do ? It's been about 8 months since the flush. Should I add anything ? Thanks again
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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GM quit using the tablets, Bar's Leaks #HDC or the equivalent powder, Bar's Leaks #G12BP sometime around 2003 - 2005. They were used to possibly seal production line nuisance weeps, lowering warranty 'comebacks" to dealer shops. If the system was not leaking before the coolant change, there's no real need to continue adding sealants.

I have not used the stuff since 2005, change the coolant every 3 years, and the system does not lose one drop between changes. Monthly cold level checks. 50/50 DEXCOOL.
 

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White Diamond '03 DHS (with DTS floor shift)
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So you guys think that this line is plugged up or the bolt is plugged up ? This would cause the overheating ?
Yes it would.


As soon as I see the gauge go up from where it normally runs ( smack dab in the middle ) the heating ducts blow cool air. I rev the motor up and the ducts blow hot like it should and the gauge drops down to where it should be. This lasts for a few minutes and then goes back up. It mostly happens at a red light when the engine is at idle.
That's a definite sign of air in the system. Hope and pray that it's just "air".



Just another question guys. I have read that after a coolant flush, some people put pellets in the lower radiator hose or some gold sealant. When I had the system flushed at the dealer, I don't see anything on the bill where they added anything. What do you suggest I do ? It's been about 8 months since the flush. Should I add anything ? Thanks again
:tisk: DO NOT add those tabs. As Sub said, GM even quit using them. They are the cause of clogged purge lines. That said, yours should not have had any in it in the first place.
 

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2006 Lucerne with 4.6 Northstar
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Discussion Starter #15
Hey guys, I just want to say thanks to all who helped me out. I was finally able to get my butt outside and check out my overheating Northstar. I disconnected the line from the waterpump and the coolant bottle. I tried to fish a 3 foot piece of weed wacker line through the the hose and it kept getting stopped up at the part where the line goes from rubber hose to metal line. I'm not sure I had a blockage there, I think it was just hanging up where the metal line was crimped to the rubber hose. I am fortunate enough to own a compressor and blew some air full blast through the line for a while and all was clear. I also removed the hollow bolt with a 15 mm wrench and all looked clear but blew it out anyways. I put everything back together and the car is running fine smack dab in the middle of the temp gauge. The overflow tank was a little low so I topped it off and all seem to be well for about 50 miles the car has been driven and heat inside the car works like it should. This entire repair took maybe 30 minutes and that includes cleaning tools and putting them away. I'm not really sure if the line was plugged or not. I didn't see anything come out of the line other than anti-freeze but maybe it did but just didn't see it. Thanks a million again guys and I hope all is well.
 

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98 deville D'Elegance 86 Fiero 2m4 / 86 Fiero GT W/SBC
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Couldn't get a cheaper fix than that. Glad to hear you got it straightened out.
Thanks for the update
 

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purge line is always one of my first things to mention that people check when they have an overheating northstar ... usually they go straight for the worst case scenario but it's good to try a few other things first before thinking the worst
 

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White Diamond '03 DHS (with DTS floor shift)
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It's very odd that an '06 would have a clogged purge line since it's usually the sealant tabs that clog it and GM quit using them around '02. :hmm:
 

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98 deville D'Elegance 86 Fiero 2m4 / 86 Fiero GT W/SBC
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antifreeze not being changed enough and lost the rust inhibitors???. Rust build up???
 

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Something is squirly about the 2006 Lucerne CXS Northstars. I own one and it's a total lemon. I'm not sure if they were using up old stock motors or what but they really seem to be crummy compared to the DTS, even though it's essentially the exact same setup.
 
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