White smoke from exhaust, Antifreeze smell in cab, A lot of heat on feet, No loss of coolant oil not milky

Got a 97 Chevy Blazer in March. Not sure when it started just when I first noticed it. About 3 weeks ago after about 15 to 20 mins on freeway/highway 60-65 miles per hour, WV so had some inclines, Notice my feet are extremely hot and start smelling antifreeze, also there’s white smoke billowing from my tailpipe. First thought is overheating even though my temp gage is low. I turn heat all the way up and set on high n Defrost. The smoke clears up n antifreeze smell dies down, I drive the 10-15 minutes left to home at about 50-55. Fluid check fine, oil doesn’t appear milky. A few days ago on same route n next time on freeway, it did the same thing, and I reacted the same way. Had the shop look at it today n explained what it was doing. They said they couldn’t find anything wrong, not thermostat, doesn’t seem to be head gasket, recommended I buy this head sealer stuff from Auto Zone. I did, let engine completely cool as it said, couldn’t get the cap off so took to them to do. Shops literally 3mins from my house. I pull it into the bay n turn off. Mechanic opens radiator it’s full, reservoir is full. So he uses a tool (looks like a turkey baster kinda) to remove a good amount of coolant around a quart or 2. Went to put in and I said wait said engine has to be completely cool and car has to idle as you pour in. He told me it take about 2hrs for my engine to cool completely, to go do what I needed n recommended I park it and put in sealant in the morning. So I hit the freeway this time turned heat on as soon as I got on. Same settings as before, Defrost high heat all the way up. Had a lot of heat on my feet shortly into drive, a little antifreeze smell it fluctuated between light, strong and none. On my return trip (heat on), a bit earlier than I noticed last trips, thick white smoke pouring out my tailpipe, Antifreeze smell, feet burning. I lowered speed 5-10 miles per hour, and smoke thinned, smell lessened but did not go away, smoke stayed visible this time. Finished to home n parked it. Had some friends stop over n visit, hours after my drive, asked my friend about it n they said let’s check it out. Open radiator cap coolants all the way to brim, so I start her up and it goes down I start to add the sealant only get about 1/4 cup before theirs no room for more. Turn off engine n ask my friend if they can drain some coolant. They said yes. They checked hoses, n reservoir. Noticed coolant in reservoir was really dirty, so removed some hoses drained n flushed. they swueezed some hoses and pushed coolant out of radiator (where cap goes), until it looked like was enough room to add sealant (reservoirs is empty) and removed hose he squeezed (think the one to reservoir). Focused on attaching another hose he removed, in under a minute coolant was back to the brim of cap opening. He finished attaching hoses, squeezed hoses n pushed more coolant from the radiator (Did a bit more this time). Coolant raised back up some but not much, started engine he poured in sealant and still couldn’t get it all in before radiator was full again. Put about 3 cups (what remained in jug being used to flush out reservoir) into the empty reservoir and let idol the 50 minutes the sealant instructions said to with heat on. Sorry so long just want to give good details so I get good educated answers/help. Okay so question is, what could be causing my vehicle to put off so much heat, Antifreeze smell and white smoke from tailpipe without overheating? Also how/why did the coplant in my radiator keep rising even with reservoir empty? Any ideas? I had another friend say clogged heater coil, my experience with a bad heater coil was white smoke coming out my heater vents and fogging up my windshield, could it cause what I’m experiencing now also? Could it be a cracked, busted or blown head gasket? Or something else entirely. Please help

I’m not a mechanic so I’m limited on what I can ask and tell. However, I did have a '97 Blazer and have some experience with the repairs I had to do.
Go ahead and reply with the mileage and whether an engine light and/or the trouble codes. Some other replier will ask.
The heat on your feet may not be a problem with the engine but the comfort system, like a blend door. I had similar issues that I had but never fixed prior to trading it in.
For the coolant loss, I had a “rear seal” replaced probably 10 years ago. I don’t recall all the details, but I remember I was losing coolant, it was not radiator leak, hose leak, or head gasket. Once that repair was completed, the coolant loss stopped.
I also had the heater core replaced. Coolant smell could be a symptom.
I did have a radiator replaced at some point.
With regards to the radiator sealant, I do have some advice for the future as you already added it. I have to do a bunch of troubleshooting in my day job, so I can speak with some knowledge. In my opinion, the mechanic that advised you to add the sealant did you a disservice. In general, it’s bad practice to start applying “solutions” to a problem that has not been identified. It may be more difficult to find the real problem/problems when the “solution” doesn’t work. Just something to consider for the future.

I agree that adding stop leak type products is a bad idea, especially if you don’t know what is really wrong. I wonder if you have the 4.3L. A lot of these were known for intake manifold gasket failures and maybe it is leaking and running down onto the exhaust. Check all around the engine, especially towards the back, and see if it is leaking.

I hate to say it but I suspect there might be some sort of engine issue like a head gasket leak or similar.

Have you done a pressure test on the system? Have you found any of the codes for the check engine light?

Pressure test the cooling system as mentioned above. That’s where I’d start. White smoke out the tailpipe may be a headgasket problem but can be caused by other things too, for example the intake manifold gasket. And coolant might not even be involved. One test you can do is warm the engine up, then drive up a freeway on ramp accelerating rapidly, with a friend following behind watching your tailpipe. If the white smoke really starts pouring out the tailpipe, whatever the problem is, it has to be addressed asap, b/c this can damage the cat.