patrick1974

Hey everyone,
So I had my C3 out for a drive yesterday and noticed after 15 minutes the temperature was climbing past 200 and nearing 260, I got it home in time to find water pouring (basically boiling over) out of the overflow tank. there was no coolant in the liquid boiling out it was almost clear and I could hear it bubbling for a good 15 minutes after I shut the car off. I decided to do a flush of the cooling system and nothing but water came out of it, not sign of coolant in what came out - other than the slight sweet smell. I went to change the thermostat and only the top piece of the old thermostat was under the cover, I checked with my fingers and a flashlight to see if the bottom had broken off into the manifold, but it just wasnt in there - I completed my flush and topped off with new coolant ran it again for the same amount of time today and the temp needle hovered around the 200 range, when I shut it off I could hear a slight whistling and there was a trickle of coolant coming out of the thermostat housing- any idea as to why the original set up would be this way? also the housing has two different and mostly corroded sensors coming out of the top of it - I am not a mechanic, but I have never seen so many vacuum hoses in my life of tinkering and never seen two sensors? coming out of the thermostat housing.
Help me understand?

C6_Racer_X

You don't say where you are in this world, or how long you've owned this one.

I'm not sure where the rest of the thermostat went. Usually when someone removes the thermostat, they remove all of it, unless it's one of the newer ones that has the seal as part of the thermostat.

To me it sounds like your radiator cap is not holding pressure. That would explain the loss of coolant and the boiling. It also sounds like it's been that way a while, and someone was just putting water in, not a 50/50 mix.

MelWff

the original set up was that way because a prior owner had an overheating problem and didnt know how to resolve it correctly.
I assume you installed a new 180 degree thermostat?
I assume you did a 50/50 mix of coolant and water?
are all the seals around the radiator in place?
on a cold engine that is not running, can you spin the fan and it stops after no more than 1 1/2 turns?
You make no mention if this car is new to you.

patrick1974

I am out in North Carolina, have owned this car a little over a month now - it sat forever, being started frequently but not driven - yesterday admittedly I gave it a good run through - couple of spin outs - just to make sure all was good and to get it at a running temp, the guy I bought it from was dying so he couldnt tell me much about it.

patrick1974

I did a 190 degree thermo, which was recommended if I didnt do a lot of driving of the car ( I dont) all seals are in place in the radiator - no leaks other than the trickle after I installed the new thermo and gasket, yes I also did the Peak 50/50 mix - car is new to me, sat for a very long time, but was started frequently not driven- is what I was told.

I can spin the fan continuously (i just went out in the garage didnt feel like it was getting tight in either direction after two rotations)

C6_Racer_X

That sounds like the fan clutch is dead. A final test, if you want to absolutely confirm it, is after a drive, with the thing at operating temp, let it idle for 2 to 3 minutes after stopping. While it's parked and idling, go find the tube from a roll of paper towels. Take that to the car. Use the paper towel tube to try to stop the fan. If it goes "thwap thwap thwap" and stops quickly, the fan clutch is dead. If it shreds the cardboard, it might still be OK.

I'd replace both the water pump and the fan clutch together as a unit. They tend to have the same service life, and a warranty claim on either these days requires proof that you did both together.

As for the leak at the thermostat gasket, either you didn't get the surfaces clean, or maybe you overtightened the bolts there. Or maybe you didn't tighten them enough. Hard to say. Take it apart, inspect, clean as necessary, use a new gasket if in doubt, and torque it to spec when you put it back together.

patrick1974

Thanks, the two sensors coming out of the housing - they cant both be for the temperature gauge right? I have seen housings for sale where you can close them off - I dont want to do stuff like that unless it is necessary or makes no difference in how the car runs and drives

looks like they are both Vacuum purge switches?

C6_Racer_X

Is this the original engine? What year?

Later models had a sensor for the gauge and a sensor for the ECM for the fuel injection. I'm assuming this is a carburetted C3? Without knowing the year, I'm not sure at all.

patrick1974

Original engine yes 4 barrel quadrajet, 350, 1980

C6_Racer_X

Looking at some online parts sources, I'm seeing the thermostat housing/water outlet definitely has two threaded ports.

I'm also seeing a coolant temperature sender (for the gauge) and a radiator fan switch. Does yours have an electric radiator fan?

UPDATE: I'm also seeing a ported vacuum switch which might go in one of those locations. For some reason, I'm thinking the sender for the gauge is in the head on that year.

lionelhutz

Gauge sensor would be in the head or it wouldn't read right during warm-up.

The vacuum switch to purge the carbon canister makes sense in the thermostat housing.

I thought the switch for the aux cooling fan was in the passenger head.

Big2Bird

Correct

drwet

I believe in the '70's many thermostat housings had two TVS (thermal vacuum switches). TVS switches served a number of purposes on these smog motors. They controlled the EFE valve, vacuum to the charcoal canister purge valve, the hot air door on the air cleaner, and on some cars, vacuum to the vacuum advance can. Not sure exactly which years this is true for.

7T1vette

With only water in the system, the thermostat may have corroded itself to death. There are more reasons for having coolant in the system than just raising the boiling point (and lowering the freezing point).

terrys6t8roadster

In reading this post I was wondering what year the car is. First clue was the vacuum sensors in therm housing, but not until #9 did the owner finally tell us [B]what year[B] the car is. Oh the suspense of it all. T

derekderek

OP, did you taste the coolant that originally came out of the engine? Sure-fire way of telling if there is any coolant left. North Carolina, you don't need much, but this winter you needed some. There is a possibility of engine freeze damage with the winter we just had. You need to check coolant level and engine oil EVERY TIME the engine heats up for a couple of months. First place small blocks crack is under the intake manifold, about in the middle, front-to-back and halfway between lifters and head gasket.

patrick1974

Hey, nope didn't taste it - just looked at some I collected on my hands when I pulled the drain plug and when I wiped the puddle off of the floor - almost completely clear, with the "sweet" smell lingering in it.
Thanks for the advice, I will definitely do that - I have only driven the car a hand full of times since I bought it and have yet to take it out of my neighborhood - and only on nice days like yesterday and the day before.

I am still planning on having a mechanic look at it in the next week or so.

patrick1974

I apologize, I have to stop thinking people can read my mind

patrick1974

The thermostat housing is a macabre specimen all on its own - I cant make sense out of just the top part of the thermostat being under there.

jim-81

Pictures!