Other day suddenly there's an smell of antifreeze in the interior.
First you'd think it's a radiator leak, a heater core leak, or some
other sort of blockage. I've poured through the forum here looking
for troubleshooting and other clues, but nothing quite matches and
all the tests I ran based on what's in here haven't provided a clue.

It's coming through the venting (too cold for A/C) randomly, which
is even more maddening. You get it heavy at start and idle, then
at freeway speeds it'll go away for awhile. Presumably the higher
speeds flush the system out so it's minimal and when you slow back
down or stop we get the really heavy fumes.

Checked the thermo - 195ish and never wavers once fired up. From
the first day this 98 has had hellacious heat and never been a problem.
It's not running hot, we see no leakage from anywhere, new hose on
top, bottom hose nearly new and all clamps and joints in perfect shape.

Checked the heater hoses (as mentioned here) and the temps there
are correct, no hot/cold mix indicating a blockage.

Checked the heater core area w/out opening it up and making a
mess, all of it's dry and nothing puddling up around the floorpans
on either side so it doesn't appear there's a leak there.

Checked the fresh-air intake, thought there was a hose that ran
to the front like other vehicles I've had and I can't locate anything
like that so it's not a front core leak where the smell's being picked
up too!

So we're a bit stumped as to what could be causing this, one
thing to determine is where the fresh air intake's at that could
be picking up the smell to determine where it could be leaking.
Overflow tank's fine, radiator core's in perfect shape, dexcool
loaded to the top and the cap/overflow hose area is perfect.

When running we don't see any leaks on the core itself, nothing
puddling under the vehicle so whatever it is evaporates on the
spot or it's hidden somewhere we can't find but not enough to
puddle and show up as wet spots inside or out.

Got Bars Leaks, the right kind for this vehicle compatible with
Dexcool, but the system's filled enough we have to remove
some fluid to get it in there and see if that seals any pinhole
leaks not easily visible so that's the only thing beyond tearing
into it that hasn't been done yet.

Anyone have any ideas on things to look for not mentioned
as already checked in here? It's not running hot or cold, the
heat's producing like crazy and once in a rare while when it's
cold outside you'll get a fog from the defrost and that'll clear
shortly afterwards and work normally the rest of the day, even
though the smell's still there heavy on and off.

Dave

I have the 99 model blazer and have the same issues. I am going to follow this post.

Smell from heater vents points to heater core leakage.
Any fog or steam to go with the smell?
Any smell under hood area?
Will it leak in the heater core area with a pressure test?
They also make a dye to put in the coolant to test for hard to find leaks.

One other area to check is where the heater hose goes onto the heater core.
Sometime a lose heater hose there will squirt coolant back into heater core box.

Stop leak is only a band aid and may cause other major problems.
MT

Could be head gasket or intake and it going into the exhaust. Mine did that and it smell the cab up Come to find out I destroyed the motor If its not in the cooling system do a compression test.

i had the same problem, and i have JUST blown my motor, it was the intake gasket, i could smell the coolant inside and outside the truck, there was NO leaks, but i had to keep putting coolant in, one day i check the oil dip stick to find out there was to much oil in the motor, but it wasnt white, the wife took the truck out and it died, got it home and the oil was white (all within a week) changed the gasket last week, drove the truck till last night when the piston slap start, and i mean PISTON SLAP. so dont monkey around with this it could end up cost you alot of money, as it s going to cost me, but i hope this isnt the problem and its just a heater core

All good stuff, seriously hoping it's not a head gasket! But the
thing is - no leaks. No reduction in fluid levels at all, been checking
that daily to ensure it's not leaking somewhere else. This has to
be a pinhole somewhere along the system that's burning up right
away and causing the smell.

As I mentioned, it mostly goes away (if not totally) at highway
speeds and that additional pressure would cause a greater smell
if it was a head gasket, or some other visible signs. Exhaust is
clean, tailpipe isn't leaking any fluids or no discoloration you'd get
from something foreign in the exhaust. Head gaskets usually can't
get absorbed the cat converter and you'd see some whitish or
rainbow discoloration at the tailpipe - nada.

Also not running hot, oil is totally clean when I check it, that's
why I mentioned what I did originally. And also why it's a stumper.
I did check the heater core hoses, in fantastic shape with no
corrosion, both lines hot when running and no visible problems
up in the engine compartment.

That's another thing checked, virtually no smell up front at
all. It appears the fresh air intake's up on the hood area by
the wipers, no other intake hoses I can find anywhere, so it
really points towards the heater core BUT no interior leakage.

To me that leaves a pinhole in there somewhere causing a
little pooling but when the heat builds up it's evaporating the
remaining fluid and eventually it's reducing the smell. More
fresh air at 70ish MPH means greater dissipation of the scent.

Stop Leak - kills. Bar's Leaks original formula with the rabbit
crap pellets is a completely different story. I've never had a
single vehicle I've ever used it on have additional issues from
it's use. Alumiseal and junk like that - seisures. Only problem
is that the radiator's core comes up to the fill neck? Never
seen one like that and it makes using this stuff near impossible.
But I managed to get a small amount in and noticed a difference
in the smell! Not totally gone, but reduced so it appears it
may have found the hole and plugged it up a bit.

Haven't run pressure tests or anything, that may be on the
books next depending on how this improves or doesn't. Since
there's no fluid reduction or loss, hasn't been a reason to run
such a test if it turned out to be something simple.

i have something of the same issue. i was looking at my transfer case today and noticed some antifreeze coming from the top of my transmission. nothing is leaking no hoses or my heater core. there isnt any water in my oil, could this be a head gasket or maby a freeze plug?

i have something of the same issue. i was looking at my transfer case today and noticed some antifreeze coming from the top of my transmission. nothing is leaking no hoses or my heater core. there isnt any water in my oil, could this be a head gasket or maby a freeze plug?

Always check the date on a post before replying to it.
This post is almost a year old.
Let old post lie in piece.

On your problem start a new thread/post and someone will help.