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purchased car with cracked radiator... very small leak so I changed the radiator, thermostat to a 180, new upper and lower hoses and flushed the whole cooling system but now when I shut it off I hear a bubbling sound coming from coolant expansion tank but don't seem to be losing coolant....
any ideas?
car is a 2000 Bonneville ssei supercharged

Replace your rad cap

Replaced rad cap when I replaced rad.... got the premium one...
Do u think I could've gotten a bad cap?
Car runs and drives great but has a slight miss at idle....

What pressure rating is it?
What temp does your car run?

16 psi

Did you make sure the bleed the system thoroughly?

the cap is 16lb the car ran at 200 before I changed everything now it runs at just under 200 on the gauge.....
bled the cooling system several times before driving it but bleeding it with the cap off it would stop bubblining for a few min then start bubbling and pushing small amounts of coolant up outta the cap area then I put the cap back on and bled it thru the bleeder screw on the thermostat housing till just coolant came out and it bubbles air thru the overflow tank while the car is warm and when you shut it off it bubbles for a min or 2 then stops..... also top and bottom hoses stay hard once car is warmed up till its cold but stays hard while running around 180-200 deg... nothing coming out of exhaust and oil still full and not milky.... any ideas or questions??? I,m pretty lost at this point.... thanks for the help by the way.....I bow to the Bonneville gods..........

I spoke with one of my mechanics at work and he also said he would try another radiator cap.

Should have new cap in this afternoon... parts store had to order a replacement in.... I'll let ya know how it turns out

Any idea if the water pump has been replaced?

Got new cap today and put it on and drove it till warmed up to 180 or so and stopped and checked the overflow tank and it was bubbling ... shut car off and it bubbled for 30 seconds or so then stopped...... car doesn't overheat and runs just under the 200 mark on the temp gauge and stays there either idling or driving...

Shot in the dark...did you make sure to crank the heat, could just be air trapped in your heater core getting pushed out through system.

Yea had heat on 90 and full blast heat... heat works great also ...
Car has a bad miss the first min of running when u start it also but it idles up to 1500 then smooths out and runs great but with a very slight miss... just changed plugs wires coils and ICM with no luck.... maybe the two problems have the same cause?
Any other questions I'm happy to answer... I'm up for whatever ideas anyone has

so I wnt out today and did a compression test on all cylinders twice and got the following readings..
cyl#1 115lbs and 113lbs cyl#3 105lbs twice cyl#5 121lbs twice cyl#2 110lbs twice cyl#4 83lbs and 78lbs cyl#6 140lbs and 125lbs and had a few drops of coolant in the compression tester when I took the end apart that screws in the spark plug hole......

so bad head gasket?

....or cracked head......tear down time.

What gaskets should I get when I get the heads off this and put it back together?
There's a lot of different options I just wanna get the right ones the first time.... thx. Wanna get everything ordered before I tear it apart.....

So if I do have a bad head gasket I don't understand why coolant isn't in the oil or coming out the exhaust and no puddles or drips and no smoke coming out exhaust and other than the dead miss it has for maybe a min after started then turns into a very slight miss and it can sit an run or be driven and runs right under 200 deg no matter how long it runs... but the cylinder with the 83lbs of pressure had a half melted spark plug in it when I got the car and you can drive it for days before it will set the p0300 code... only seems to set code if u rev it up when its missing after just starting... but either way it goes away right after it runs for a min....

I can't answer that but I do think you are fortunate that a connecting rod didn't get bent. - BC

So I have motor apart and cleaned for new head gasket set and ready to put motor back together but only book I can get says nothing about supercharger.... anyone have those directions? Please help

the torque specs for the for the SC bolts are 17 ftlbs starting from the center bolts and working your way out. also you want to make two passes when torquing...first pass being 10 ftlbs or so and the second time go up to 17 ftlbs theres one long SC bolt that goes next to the throttlebody on the firewall side, and then two smaller ones that retain that black electrical box(not sure what it is) make sure to clean bolt threads, bolt holes, and use thread locker