JobeJoe

After draining the old coolant on my 80 US auto, I began adding more coolant through the reservoir.

It took about 1.5 gallons of coolant before the reservoir was full. I ran the car shortly, expecting the thermostat to open and pull coolant from the reservoir. It stayed full.

The gauge goes from zero to real hot within minutes. I don't know how accurately this gauge is working, I don't see how the car could go from cold to overheating within a few minutes. The fuel gauge is super wonky too, with 5.5 gallons of gas it registers about 3/4 full most of the time.

At this point it's hard to tell what's going on, if the water pump has failed, which I see no evidence of. I replaced the thermostat and just the lost coolant from that operation was minimal. The reservoir was empty again, so I put in almost a gallon before it was full again. It still doesn't pull anything from the reservoir.

Maybe I'm missing something, maybe everything is working as it should and my gauge is faulty. Hard to say.

Any advice is welcome. Thanks!

ltoolio

It should take 4 gallons of fluid, 2 gallons of antifreeze and 2 gallons of distilled water, to refill the system after a drain.

Did you drain only the radiator? Or the blocks too?

JobeJoe

Good call, I only drained the radiator itself. But in that case the blocks should not be empty, especially if the system all draws from the reservoir.

If that logic follows, then what? Bad gauge? Bad water pump? Or possibly the coolant still left in the block is so old it's ineffective?

MainePorsche

The way the temp went up so fast, it sounds like the block had no fluid in it. Just curious, did you have the temp slider on your HVAC unit all the way to the right for heat when you were doing the maneuver ? This will open the heater valve. The volume of fluid in core and it's two lines needs to circulate and clear as well.

JobeJoe

That's scary. My heater blower (nor trim lights) is not currently working, possibly a bad relay or short somewhere. Just got it running for the first time in over a decade, and there are a ton of things to get working. Anyways, no I didn't leave the slider to the hot side, totally forgot about trying that.

If the block was empty, shouldn't it be pulling from the reservoir anyways? That is the only fillable point if I'm not mistaken.

MainePorsche

Sounds like you weren't sure of the coolant level status in the system. Is this right ? You could try and add some of your 50/50 mix of coolant and distilled water directly to the block. The large radiator hose on the Left side/Driver's side is the output from the radiator back to the block. Slowly with a flexible funnel try that just to get some fluid in there. Is worth a shot. Things may not work as designed if the block is bone dry. Make sure the heat slider is to hot. Even if your vacuum to it is dead, by default it goes to the open mode if the valve is functional. Also you can try turning the blower to MAX. If the resistor pack is gone it may still work at MAX. Not sure of the relays/electrics on pre S4's. If some of this doesn't work, the issue may be more profound (not circulating due water pump). If this were the case I would think more obvious symptoms would be present. Experts will chime in

JobeJoe

That is correct, I was not sure of the level. I was sure that after sitting all those years I needed to change it. Great advice, I'll give it a whirl after work tomorrow. How much should I try to add via the flexible funnel?

MainePorsche

As much as you can SLOWLY before it spits back out and makes a mess. Add some then let it find its levels in it galleys. To it again till saturation then close back up. You could put some in the other rad hose to the block in the same slow fashion. Will fill the other side of the 'V'. Hopefully it just needs to be primed like a pump and it is not the actual pump at issue. Best Wishes.

JobeJoe

I did wonder about priming lol, I'm a home brewer and often when I lose pressure or get an air pocket in the line, I lose prime. Thank you so much for the input!

Kiln_Red

Is there any heat in the cabin? Have you felt of the lower hose when the gauge creeps upward? Boiling in the expansion tank?

JobeJoe

Not sure about heat Kiln_Red, thanks for jumping in. Yesterday before changing the thermostat, I had it running for a few minutes, and when I got back in the cabin, I thought I noticed slight fogging of the windshield.

After I shut it down, waited a few minutes and twisted the cap slightly on the reservoir, it did boil when I released a little pressure twisting the cap slowly. It would have totally shot out if opened it more.

What am I looking for by checking the lower hose - heat or tons of pressure?

Kiln_Red

To see if it gets hot as it will when the thermostat opens. Also, you can help purge the system by squeezing this hose after the t'stat has opened.

If the lower hose is still cool to the touch and the tank is boiling over after you shut it down, then you either have a blockage or no circulation. It's most likely the latter. These cars don't always purge quickly, but the system doesn't get big air pockets that stop circulation in my experience.

MainePorsche

Didn't know you had boiling in the reservoir.
When the engine ran, did it run smooth or like it was missing on a cylinder ?
Any white smoke from the exhaust ?
Evidence of any leaking fluid and if so, where ?

Kiln_Red

^^^^^^^^^^

Check the oil, also. This could be a concern area. Make sure that the oil doesn't have the chocolate milkshake look so as to suggest mixing fluids.

MainePorsche

Hopefully not.
If so it is a defect in the head gasket.