Hy Folks,

98 Blazer 4door 4.3 Vortec AWD
Symptoms: First no heat out of the heater, 50 miles later fluctuating engine temperature and on the high side
What I tried to fix: Flushed Heater Core and burped - same ..... Flushed whole cooling System and replaced with new antifreeze and burped - same

what I find curious: everytime a lot of air came out of the cooling System when burping it, after second burp the Blazer ran 1 hour in idle - everything perfect (engine temp and heater core temp) then when I took it on a test drive on the Highway, after 20 minutes of no Problems heat in car suddenly turned icecold. But engine temp was absolutely steady. Burped the System again and air came out again (but way less than on the first burps)..after burping again heater core stays perfectly hot in idle....after testdrive - ice cold again...so maybe something is pushing air in my cooling system when the car is on higher rpm for a while

what to mention: no white smoke out of exhaust (just no smoke, toatally perfect), no coolant in oil or vice versa, no leaks, coolant quantity stays steady engine runs perfect

would be cool if you have some ideas for me, i know the cooling System is a common prob on these blazers but I think my prob is a little more Special so i gave it a new thread. Thanks a lot guys! Bernie

 

I had a problem last year with my heater core getting clogged. Flushed it about 4 times and had a full antifreeze system flush, worked good but had to flush it a 5th time myself before I was able to unclog whatever was clogged. I now have a problem with loosing antifreeze, there are no signs anywhere, even checked the oil to see if any got in through th engine, good at that end.

 

DonL
If you haven't done so already check your radiator cap, a weak cap can mist away coolant with no noticeable signs also the weep hole in the water pump will do the same way before pump failure

 

Newer rad, new cap, new water pump, all last summer shortly before the full system flush.

thermostat was replace shortly before all the work above. I will be doing another flush of the system shortly as there was still a little bit of brown in the system after 30 minutes of flushing the system.

 

Hey guys. Problem solved, flushed the heater core again and installed a new rad cap. The Blazer is now hot as hell. Thank you all! Bernie