96 Nissan Sentra Coolant Consumption

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

Reply to
user132384
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The pump can leak to a spot such as a manifold and the coolant will evaporate while driving. Either that or a pinhole leak in a hose, hose is my best guess. Heater core anyone ?

Reply to
wws

Or maybe he has a heater core leak although he should see that much leakage. Perhaps some is running out the bottom instead of on the carpet as usual.

Reply to
Al Bundy

When you lose coolent does it pull it from the overflow tank ?

If it is that suggests that your system is pressure tight, otherwise it would pull air from the leak rather than fluid from the overflow.

I would look for a pinhole in a hose, opens under pressure, but pulls closed under vacuum.

I would have thought this would show up in a pressure test though.

Reply to
marks542004

If it is that suggests that your system is pressure tight, otherwise it

would pull air from the leak rather than fluid from the overflow.

I would look for a pinhole in a hose, opens under pressure, but pulls closed under vacuum.

I would have thought this would show up in a pressure test though.

It pulls the coolant in from the overflow tank. Thanks for the ideas. I'm going to drive it up on ramps, and get under it with a flashlight and look for leaks / residue of leaks.

I'm also going to take off the air intake tube tomorrow if I get a chance, and look inside there again, and look for any signs of leakage into the throttle body or intake manifold. I remember seeing some discoloration on the lower part of everything in there, but it was a brownish color, not a green antifreeze color.

Reply to
user132384

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