mystery cooling problem

[JDMPR]

So I noticed the other day that my coolant reservoir tank was bubbling, so I checked it out and found out that neither one of my fans were not kicking on, so I decided to focus on my cooling fan since I'm not using the a/c right now, so I pinpointed it to the fan switch or thermostat, I replaced both and the fan still doesn't turn on, I double checked the fan and fuse and they turn on with a paper clip, I don't know what else to do?

[GhostAccord]

Have you tested the fan relays?

You mention that you replaced both temperature switches. Just to clarify, those are the one located on the upper water neck and the thermostat housing right? Some people mistake the Temp sensor and Thermo Unit located under the distributor as the fan switches.

[JDMPR]

I replaced the thermostat, and the bottom switch that's on the thermostat, would I need to replace the switch that is above on the top radiator hose?

[Fleetw00d]

I'm assuming the engine was running when you saw the bubbles. At idle after driving a while? Or just sitting and letting it warm up? The system works on the fact that hot air expands considerably (coolant to a much lesser degree). As the system heats up, even below the temperature as which the coolant would boil, air in the system will expand and increase the pressure. When the pressure exceeds the setting of the radiator cap, it will allow air to escape back to the overflow tank (bubbles). When you shut the car off and the system cools, the remaining expanded air in the system contracts, reducing the pressure in the system below atmospheric pressure causing coolant at the bottom of the overflow tank to be pushed back into the radiator. This is designed so that the system will try to keep almost completely full of coolant. If operating correctly, when the system has been at operating temperature for a while, all air expansion should have taken place and you should no longer see bubbles. If you continue to see bubbles all the time, it may indicate a head gasket leak of air from the cylinders to the cooling system.

[johnl]

The system works on the fact that hot air expands considerably (coolant to a much lesser degree). As the system heats up, even below the temperature as which the coolant would boil, air in the system will expand and increase the pressure.

It is abnormal for any gas to exist in the cooling system, at any time. Gas can only enter the cooling system when the system is opened to air (and some coolant spills out to be replaced by air), or when it enters from a cylinder, or it is created by boiling. Note that gas produced by boiling expands to 600X the volume of the fluid that was vaporised to create the gas, though the higher the system pressure the less this will be.

When the pressure exceeds the setting of the radiator cap, it will allow air to escape back to the overflow tank (bubbles).

This will allow coolant to escape. Gas will only escape if gas exists (for whatever reason) in the cooling system, which it shouldn't.

When you shut the car off and the system cools, the remaining expanded air in the system contracts, reducing the pressure in the system below atmospheric pressure causing coolant at the bottom of the overflow tank to be pushed back into the radiator.

Coolant is expelled because the coolant expands as it gets hotter. It's the contraction of the cooling coolant that 'sucks' coolant back into the system from the overflow tank. Expanded gas will do the same as it cools (draw coolant back from the over-flow tank), but no gas should be present unless something is wrong. Note that the cap holds pressure up to X psi, but presents no restriction to flow in the reverse direction.

This is designed so that the system will try to keep almost completely full of coolant. If operating correctly, when the system has been at operating temperature for a while, all air expansion should have taken place and you should no longer see bubbles. If you continue to see bubbles all the time, it may indicate a head gasket leak of air from the cylinders to the cooling system.

Agreed, more or less. Except that gas should have no part in this, there should be no gas to expand or contract with temperature. If there is then the system hasn't been properly bled, or there is boiling at some point in the system (possibly very localised in the water jacket adjacent to the combustion chambers), or there is a head gasket leak, or a cracked casting.

[JDMPR]

What I really need to know is why my cooling fan won't turn on?

[oni_cb7]

Run power from the battery straight to the fan electrical connectors with some pieces of wire and see if they turn on. If they don't turn on with power direct to the connector, then the motors are dead.

[Fleetw00d]

What I really need to know is why my cooling fan won't turn on?

Where did you use the paper clip to test the fan, at the fuse box or across the switch? Did you check if there was power to the switch? Make sure there is continuity in the wires from the switch to the fan, and from the fan to ground.

johnl

I don't disagree with what you elaborated on. Ideally, the system remains full of coolant. I was trying to describe (albeit without stating explicitly) that a system with air (not completely filled for whatever reason and/or not bled well) will tend to purge the air from the system, then as you indicate, expanding coolant exercises the system). Also note that depending on the makeup of the coolant (ratio of water to coolant), if/when the system pressure exceeds the cap setting, the coolant may flash to vapor upon going from the high pressure in the system to atmospheric pressure downstream of the cap; this would potentially show up as bubbles in the overflow tank as well.

[johnl]

johnl

I don't disagree with what you elaborated on. Ideally, the system remains full of coolant. I was trying to describe (albeit without stating explicitly) that a system with air (not completely filled for whatever reason and/or not bled well) will tend to purge the air from the system, then as you indicate, expanding coolant exercises the system).

Agreed. I've yet to come across a cooling system that won't 'self-purge' a relatively small amount of gas (left in the system due to incomplete filling). A large pocket of gas on the other hand may cause problems before it's all been expelled.

Also note that depending on the makeup of the coolant (ratio of water to coolant), if/when the system pressure exceeds the cap setting, the coolant may flash to vapor upon going from the high pressure in the system to atmospheric pressure downstream of the cap; this would potentially show up as bubbles in the overflow tank as well.

A good point, and I can see the possibility of such a thing occurring. I've never actually seen it happen though, in my experience (not comprehensive) bubbles expelled have always been due to residual gas (which will go away in a few heat cycles), boiling (only occurring in a specific circumstance), or gas introduced from a cylinder (in a specific circumstance, or all the time).

[johnl]

What I really need to know is why my cooling fan won't turn on?

If worst comes to worst and you can't find the cause, you could just wire the fan into a feed that is live when the ignition is on, and run the fan all the time. It would be good practice to do this through a relay. I've done this before, and it caused no problems, worked fine.

Alternatively, you could fit a thermal switch in the upper radiator hose. With another car I've used a short length of metal tube inserted into the middle of the hose, with a fitting for the switch attached to it (silver soldered, or welded, whatever works).

[JDMPR]

[QUOTE=fleetw00d;3222926]Where did you use the paper clip to test the fan, at the fuse box or across the switch? Did you check if there was power to the switch? Make sure there is continuity in the wires from the switch to the fan, and from the fan to ground.

I did the paper clip test at the switch that's at the thermostat housing, and the fan turned on, so if I put a new fan switch and thermostat should it not turn on? Could the radiator be clogged? What else could this be? There's another switch up on the top radiator hose, could this be the culprit? Today I checked to the radiator, I took the radiator cap off and let it run, as soon as I did that the fluid just rose up and out for a little bit and that's it

[djcaz_aom]

Have you tested the new switch? Let the engine idle until you reach operating temperature. The fan should turn on at some point. If it is, then you have a problem somewhere else.

I suggest buying a Helms manual so you can trouble shoot the entire system.

[Fleetw00d]

[QUOTE=JDMPR;3223047]

Where did you use the paper clip to test the fan, at the fuse box or across the switch? Did you check if there was power to the switch? Make sure there is continuity in the wires from the switch to the fan, and from the fan to ground.

I did the paper clip test at the switch that's at the thermostat housing, and the fan turned on, so if I put a new fan switch and thermostat should it not turn on? Could the radiator be clogged? What else could this be? There's another switch up on the top radiator hose, could this be the culprit? Today I checked to the radiator, I took the radiator cap off and let it run, as soon as I did that the fluid just rose up and out for a little bit and that's it

It is easier to use the paper clip across the switch connector than to dig out the multimeter. If the fan turns on, you know all the wiring is good. If not, then start checking voltage to the switch and the wiring. The switch at the thermostat is in the 195 range (I think); the one at the water outlet at the front of the head is 210 (maybe?). If you want to check the switches, you can remove them and immerse them in water as you heat it up (use a thermometer to monitor the water temp) and note when the switch closes (resistance will drop very low). I have an infrared thermometer that I can point at things to get an idea of the temperature.

Did you take the radiator cap off after it had heated up or before? How cold is it outside while you're doing this?

[JDMPR]

well looks like im gonna have to take the wagon to a mechanic and see what the hell is wrong with it, hopefully its the ecu, then i can just find one and get this nightmare over with.

[GXZ]

I would suggest that you take a really good look at the insides of the connectors of each switch, to be sure there is no corrosion making a bad connection. And make sure there is no crud getting in the way when you connect them together stopping them from getting a good locking click. Also try making sure the wires going into the connectors are solidly connected and not loose

Once again, look for corrosion inside the connectors, even if you dont think there is any, try cleaning them with a tooth brush and a mix of baking soda and water, then rinse it out and blow the water out with compressed air, and then go to a auto parts store and get a little $0.99 packet of dielectric grease and put some in each connector to prevent corrosion

Or check the fuse AGAIN, maybe even test it with a multimeter or try another fuse