Derf, want to do things systematically so decided to start from scratch and remove coolant I put in there. Didn't start the engine so everything is cold. Opened the valve on radiator and drained about two quarts. Everything drained out of resevoir which I don't understand because the hose from resevoir doesn't go to radiator. Removed lower radiator hose where it is attached to engine and where thermostat is located. Didn't get a drop out of there. Is that because the engine is cold and the thermostat is closed? I'm not going any further until I know. Would it be ok to start engine with that hose disconnected and no coolant in the radiator? I mean, just long enough so the thermostat would open if that is the issue or until temperature gauge begins to flash?

Do not run it without coolant trying to open the thermostat. The thermostat needs to be in contact with coolant or water to open. I'm going to stick my nose in here. I looked at all the hoses on Rock Auto and I do not see where the hose from the plastic tank connects to the engine. Rock Auto also says that a heater hose connects to the intake manifold. You may need to open the system there to let out air.

Ok, I won't do that. Why do you suppose the coolant resevoir emptied when I drained the radiator? I just looked at the hoses that run from the coolant resevoir. A very small one at the top of the resevoir goes to the intake manifold. The larger hose at the bottom runs to a T, one connecting to a metal tube and I'm not sure where it goes. The other one enters the engine just below the lower radiator hose where the thermostat is located.

So it is similar to my L series, the large hose t's into my lower hose between the thermostsat and the radiator. The small hose is the air bleed back to the reservoir. it is difficult to get these full without pulling a heater hose loose to let air out.

No, mine doesn't T into my lower hose; it remains separate and enters the block just below where the lower hose enters the block.

This is a drawing of the L200 system. It may help you understand the s series system. The coolant has to flow through the heater core. The coolant in the block and head has to get up to thermostat temp before full flow is allowed. The thermostat only allows coolant from the radiator to flow when the engine is up to temp. If you have an air lock in the heater core you cannot get the thermostat to open. I would open the system at the top hose and at one heater hose to let air out as you fill through the reservoir.Attachment 1456

There are several things that are different on mine. I assume my 98 SL2 is the same as L2000 but the drawing you put on is a bit different. As I said, the bottom hose from the reservoir does T off, one to a metal tubing and the other goes to and enters the manifold just below where the bottom radiator hose enters the engine. The metal tubing must go to the heater core. I didn’t have a radiator cap on the old one and neither on the new one. I will open the top hose from the radiator and one of the hoses that go to the heater core. I want to thank everyone for their time and patience. I thought when I got everything reassembled that the difficult part was over.

I poured coolant thru the top radiator hose into the block as Derf had recommended. Coolant in the resevoir was forced out the top. Does that mean the block is full of coolant? The engine temperature comes on in less than a minute after starting the car and I immediately turn it off. Is there any way to tell if the light is coming on when the engine is not actually too hot. I'd love to run it longer to see if the thermostat is opening but didn't want to chance it.