Where is my coolant going?

[Stingray1967]

Originally Posted by DRM500RUBYZR-1

With luck, perhaps the level was low and all worked as it should restoring it to full, emptying the tank.
If it is continues, then further search is required.
Until you get that cap off, you are a bit in the dark.

At the age of these cars, I would also suggest exploring around the heater core.
They are now at or beyond the age of failure.
Any fogging of the windshield or interior odor?
Carefully look around passenger side footwell for any trace of coolant.

Explore around the lower radiator hoses. A small leak there is almost undetectable, but will leave traces. Has you temperature been running a bit higher?
The first sign is losing pressure which results in higher temp s and more variance in the temp.

Lastly, get a quality pressure gauge and test the system once you have dealt with that cap.
Don't take it past 15psi to avoid overtaxing the heater core.
It should hold to 15.
If it does not, you indeed have a leak somewhere.
Good luck and keep us posted of progress.

Marty

Marty, thanks for all the suggestions. My car has an aftermarket Fluidyne radiator in it. I drove it to work most days this week. Ambient temp was in the 50s-60s. Coolant temp runs usually around 192. Although climbing a long slow hill on the interstate out of the river valley saw 200.

I have had the car in the air lots of times (have a lift at home). Have seen no signs of leaks. I added a little bit of coolant to the upper black reservoir to make it just below the overflow pipe opening, and I added a little bit to the lower white tank. When I checked the white tank dip stick today, it did have a little moisture on the bottom, so it isn't totally empty. Maybe there isn't an issue here. I'm still baffled at how the coolant goes down AND up that single pipe to the lower white tank.

I pulled the passenger floor mat out and felt all around. Even up under the hard plastic dash lower trim. Totally dry. I also looked from the top side at the heater area and saw nothing. There is no fogging of the windshield and no odor in the car.

[XfireZ51]

Have u checked the oil? Coolant can bet into the combustion chamber being sucked into the #1 and #2 cylinders from the coolant passage in the cylinder head going into the injector housing. The separation between intake tract and coolant path is not very wide and over time the IH gasket may give way along coolant to enter intake. White smoke would show up when you ?get on it?.
Also, pull those plugs on the first couple of cylinders for each bank. Are they steam cleaned?

[Stingray1967]

Originally Posted by XfireZ51

Have u checked the oil? Coolant can bet into the combustion chamber being sucked into the #1 and #2 cylinders from the coolant passage in the cylinder head going into the injector housing. The separation between intake tract and coolant path is not very wide and over time the IH gasket may give way along coolant to enter intake. White smoke would show up when you ?get on it?.
Also, pull those plugs on the first couple of cylinders for each bank. Are they steam cleaned?

I haven't noticed any white smoke when I get on it.