Hi all,
I am sorry this is a long post but i want to give you as much information as I can.

I have a 2000 deville n* base model engine code Y. I read a lot on the head bolts and such but I think this is a different issue that i cant figure out.
A lady sold me this car because she didn't want to deal with what the dealer said was a head gasket.
it overheated once when she was driving and she said she pulled over and added oil. she cant tell me where she added it but she said she overfilled it and i suspect she added it to the expansion tank as we found new oil on the rim of the tank. She sold it to me for a grand.
I overheated it once and it shut off the ac. I think at this point it was In "crawl home mode" Stupid question but is there a reset switch after the motor goes into this mode? Runs great tho.
Here is what i did so far:
1. the t-stat was junk. rubber ripped open and buckled. Changed that.
2. Changed radiator because it was cold on one side and hot on the other. come to find out there was a lot of some sort of built up sticky substance.?.?
3. Changed the water pump because at this point why the heck not.
4. flush and fill with DEX
5. Pressure tested the cylinders. pressure holds. and all cylinders crank at around 180lbs.

We had a big issue with the coolant message on the DIC. We finally got the coolant to low liight to go out and we have a good amount of heat at idle. Temp doesnt rise above half way at idle either. and totalling about 4 hours of Idling too.
I get it on the road and the heat goes away and the heater motor will slow down when i slow down all within 4 miles. The temp is now 2 bars above normal. No messages on the DIC.
When we stop the car back at the garage, the radiator is cold, the fans are on, the tank isnt even bubbling, hoses are hot but not so hot that we cant
touch it. and the fans turn off within 5 minutes of stopping. Is this a temp sensor? if so where is it? or is it the same sensor thats in the bottle.

The only thing I think is odd is one hose out of the heater core by the firewall is hot and the other is not.

I think there is a huge air bubble in there but cant seem to get it out. How do i do it? and I checked the purge and it blew through but I will check by where it connects on the neck side. I dont think i remember seeing any coolant in there. I will dig deeper into that.

Tonight I will test for exhaust gases but if there is none, What do i do now?

Thanks all in advance

 

One thing at a time. Report back after you know for sure the surge tank purge line is transferring coolant. Burping a cooling system is different for most cars but general rule of thumb is to get the radiator higher than the engine (jackthe carup) start cold engine with pressure cap off, keep at faster idle 1200, 1500 RPM till coolant drops in holding tank, then while still idling high add coolant andquickly reinstall pressure cap. ( easier with 2 people) Did you add the GM sealant tabs into the lower hose as recommended? Replace the 9 year old pressure cap as well. PUT YEAR AND TYPE OF CAD IN PROFILE SIGNATURE PLEASE!!

 

Car is in my SIG. thank you for the reply i will let you know, i got delayed a few days...

Thank you for the reply

 

I fixed it. The purge line was clogged up tight at the t-stat neck side. Took all that apart and cleaned it out and it does not run above half way.

Thank you!!

 

Thanks for the final post. You're welcome!!