heating/ ac problem

Im not sure what is going on, it all started with no heat, so i checked coolant, level was low, i refilled the resvoir, bled system, heat was fine, ordered new climate control unit, mine leds were out on one side, so all lighting works now, blows out heat but blows out hotter when the a/c is on ? Dont see any leaking coolant, no wet floor boards, no puddles under car, temp gage gets to 200 and stays there, it doesnt seem to cool down very quickly though, like it can sit for hours and start it and its already warmed up, and at times u can smell coolant and then resvoir is low at times also, not sure what to do or where to start, its a 01 bonneville 3800 , any help would be apreciated

Did you figure out what is going on with your heating problem? Last night in my '97 Bone (non-sc) my heater stopped blowing hot, the temp rose on the guage, and the coolant reservoir drained somewhere to empty. No puddles anywhere under the car, dry floor, etc. Filled it up at Autozone, drove home a couple miles, but it was way low again so I parked it until I have the time to look into it. Still no indication of any leak anywhere.

JB

sounds like the same thing with me , can never find a leak anywhere but get no heat, then once filled again no heat until bleed the valve ontop of the water neck, then everythign seems fine, i figured maybe the little dome that open and closes inside the filtratin system above the fan was stuck and wouldnt switch fomr hot to cold, but thats not the case, not sure whats going on still but as long as there is coolant everything seems fine in mine,i havent had to add any in about a month but shouldnt have to keep filling up the resvoir so i dont know ?

Thanks for the reply.

I replaced the water pump and hoses about a month ago, but I did not change out the thermostat. I'm going to try that today. Seems a little strange to me, but the temp gauge is going up and down erratically, and I have only seen that before with a thermostat prob.

JB

How many miles are on these motors, folks? You really, really need to check the oil for coolant mixing in it. You may have experienced gasket failure due to dexcool. This is unfortunately very, very common. The dexcool is not compatible with the Nylon 66 used in the gaskets by GM and eventually causes failure. There is a class-action suit against GM over this since its so common.

See: http://www.dex-cool.net/

The only way to fix is to replace the upper and lower intake manifold gaskets with aluminum-enforcements and quite often the upper manifold itself.

See: http://www.pontiacbonnevilleclub.com/forum/viewtopic.php?f=53&t=3591

Got the thermostat changed out, and the temp is now solid as a rock at 180. However, now the oil pressure is fluctuating between 38 - 42 at 65mph (used to be significatly higher with no fluctuation), and I am hearing what seems to me to be some audible main bearing clatter at startup with most of the clatter calming down after a couple seconds. Still above the red at idle, but never ran low in the past. Could be the beginning of the end for this motor...

JB

Eric,

I just rolled over 100K, and I have been on the lookout for exactly that condition (coolant in the oil). Nothing yet, and I have always run Castrol Syntec in this motor. As I said, I think it is on the way out. What do you think?

JB

Eric,

Forgot to mention this motor has had the intake manifold changed out. I will have to see if I can determine if the upper and lower gaskets were changed.

JB

Current status:

It appears I overrev'd and probably floated the valves (guessing here), and I now have a lifter clacking. My own fault as I had to stomp on the gas to get out of the way of someone. I'm going to try using some Lucas oild to see if resolves itself.

I still have oil pressure that is well (10PSI+) lower than it normally is. Ever seen lower oil pressure associated with a malfunctioning lifter?

JB

Current status:

Car overheated and quit running on the freeway, had it towed to the shop where it was apparent the new upper intake manifold had been improperly installed (probably wrong torque), it failed/cracked and introduced antifreeze into the motor so there was white smoke/drained the reservoir dry and the tow was required.

Replaced the upper manifold, and still have oil pressure that is 10 - 20psi below normal, with what sounds like a lifter clacking when cold...

JB

i finally figured out my heating problem, no leaks anywhere jsut sometimes woulwd work and sometimes wouldnt, blower was fine and everything else, it was the control unit itself, my light on the face of it went out so i just chagned unit because of the leds in it, anyway heat still didnt work, but was messing around one day n bumped it n it worked, i found out that the unit sometiems sits to far in the dash and bends the ribbon harness n makes it not work, anyway al i did is grab the knob n pull it out a little and it works fine everytime