Antifreeze leaking inside cab of 98 chevy silverado

You have a leaking heater core inside the dash. You will need to remove the dash from the truck and replace the offending part. If you go to this LINK you will find full instructions with diagrams from the factory manuals.

the heater core is the only thing you havent replaced besides the thermostat so feel the carpets and floor around the floor heater out puts to see if there damp or sticky they may smell like a sweet smell as well.

First- When was the last time you checked it & it was full?
Second- Is a lot missing (1/2 gallon)?
Third- check the oil dipstick for any antifreeze in there or any white smoke from the exhaust,that would indicate a possible head gasket leak.
Fourth- Do you smell antifreeze inside the truck? Look for a small leak under the glove box in the dashboard for the heater core.
Hope this helps

Even though you do not feel antifreeze on the rugs. The only way
the smell of Anti freeze can get in the cab is, It's leaking from the heater core.
Maybe not enough to see a leak on the floor.
However, the heater core is inclosed, plus antifreeze will not
dry. it can sit at the bottom of the heater box, for a long time.
And the smell can stay in there for a long, long time.

heater core is leaking needs to be replaced

heater hose or heater core you can solder the heater core if you can find the leak oh and if the rest of it is good

Usually a smell of antifreeze in the cab when the heater is running is a sign the heater core is leaking. Just becasue you dont see a leak at this time doesn't mean there isn't one. It might small enough that the haet from the core is burning off the leaking antifreeze. I would suggest replacing the core before you get in one day and there is a puddle on your floorboard. Or if you go to a local parts store and rent a cooling system pressure tester, wait until the vehicle is cold, pressure the system to 12 lbs and then check for leaks. Hope this helps you out......

check for a wet tailpipe,which might indicate a leak between water jacket & combustion chamber.i.e.headgasket.check heater hose isn't leaking onto exhaust manifold,'cooking' the anti-freeze as it leaks.

think brake switcjh it is a dule part switch.. if bulb good then switch next culprit

the small radiator just inside the cab, where the hoses go to the heater is leaking. You may try using stop leak (many don't recommend this) or take off the heater radiator. it will probably get worse when you turn on the heater and fog up the windshield if not fixed. hope this helps.