I have a 96 Sentra which is using about a quart of coolant every 150
miles! There is no visible leak, no drip, no puddle. But there is
sometimes a smell of antifreeze while the car is driven. A mech told
me he noticed a sweet smell from the exhaust, but I do not notice it.
There is no smoke of any color from the exhaust pipe.

I had the cooling system pressure tested at a repair shop. They said
it was fine, holding pressure well, and that the head gasket was OK,
since the pressure didn't flutter while it was running. They tested it
with the engine off and with it running.

I pulled all 4 spark plugs. They look normal, just brownish/ rusty
from being run for about 60K miles or so. (The mech said they looked
normal, too). Each cylinder has some carbon deposition, and they all
look about the same. (No "gleaming clean" cylinders cleaned by burning
coolant.)

Since tyhe cylinders don't look "steam cleaned", I am hoping I am not
burning coolant internally.

Since I can sometimes smell antifreeze while driving, I think it is
leaking out somewhere and burning up right away. I've watched it idle
and looked all over for a leak, or steaming coolant, never saw
anything.

The oil looks normal too.

I haven't yet driven it up on ramps and looked at it from underneath
while it idles. That's next, I guess.

The car runs fine, and the temp is normal.

Radiator cap is fine, according to the mech. (But it is awful easy to
put on and take off).

No bubbles in overflow reservoir.



Any comments welcome! Thanks