Radiator fan not turning on

[micbrody]

I again just jacked up car; burped; even disconnected lower hose at thermostat to burb out any coolant; reattached ; burbed with front end on Jack ; burped again; burped ; flat; burbed with coolant prestone t- etc etc etc; couldn’t squeeze another drop into it;
Turned on and still no fan.


My next step: remove thermostat; inspect - probably get new one

[micbrody]

Does anyone have experience as to what a functioning thermostat looks like?
In other words: when I remove thermostat, what should I be looking at? I will boil it in water and expect “it” to open.....but question is what is “it”? A flap? Or something else that I can tell if whether it’s “fully opening” to specs.

Is this something I can see? Anyone have photos of what inside looks like?

[18Fiatsandcounting]

[SUBSEQUENT EDIT for another thought: I went and tested the thermostat in my '71 as I describe below, and since the thermostat seems to be working just fine in the car, it's probably a good example. With both the cold and hot tests, water would flow through the thermostat at pretty much the rate that I poured it in, which was from a faucet for the cold test and from a boiling tea kettle for the later test (using car not to burn myself of course). So, if you can pour this amount of water in without it appearing to back up, I would consider that fully opening and closing as it should.]

I don't have a picture, but if your thermostat is anything like the 3-neck version that I have on my '71, the inside configuration is rather complicated and so it isn't very obvious what exactly was happening when mine opened/closed.

What I did was take the cold thermostat and put water down each of the three holes (easiest with the 3 hoses connected). You should be able to tell which two ports are connected when it's cold, and those will be one to the water pump and one to the upper T-connection at the front top of the cylinder head (the other goes to the lower radiator outlet). Mark those two ports.

So, the question now is which is the water pump and which is the upper T-connection. So now you put the thermostat in a pot of boiling water, and by lifting it partially out of the water with a pair of tongs, you should be able to see which two ports are connected internally. One of those will be one of the previous ports you marked when you did the test cold, and that will be the connection to the water pump. The other port in the hot test in the one to your lower radiator outlet, and the remaining port is the one to the T-connection.

-Bryan

[micbrody]

I did order new thermostat and water pump. In the meantime, I took out old thermostat and inspected. It does seal. And when placed in very hot water (unfortunately did not use thermometer (but from hot water tap and the. On stove - not quite boiling but should have been about 200, it did open up - but first time not completely. I took it it and it closed. I then boiled water and put in and this time (it could be my imagination) but piston opened partially but slight tilt in valve plate- and then a tiny particle of copper stuff (Bars) floated from piston and the piston fully opened.
I’m wondering if the particles got stuck in piston and would not allow it to open fully.
I flushed everything in system repeatedly with garden hose; reconnected everything ; filled with tap water. No fan still; burped ; ran ; still no fan.
When I run the car in motion, it stays at 190. Only when sitting at idle does it increase - but still no fan.

So tomorrow: I will receive new thermostat and water pump. Try that. If it doesn’t go on, then I’m officially stumped

[18Fiatsandcounting]

Well, the way I'm looking at this is that your cooling system is working as it should when you're driving, as 190 is exactly where it should be. And when you're driving, the radiator (and coolant inside) is being cooled by air flow, and that all seems to be working. And besides, you got a new radiator.

But when you don't have air flow through the radiator from driving, the fan doesn't come on to cause that air flow, and so the engine eventually overheats. This could be because your water pump is pumping but not very well, or your thermostat was partially plugged and that was limiting coolant flow as well. And you verified that the fan comes on if you connect the two leads together that go to the fan switch at the bottom of the radiator. And burped this beast until you're blue in the face.

I know I'm just restating what we already know, but it helps me narrow down the issue. If the new thermostat and new water pump don't fix the issue, I think the only thing remaining is that the fan switch is bad. It may work in a pot of boiling water, but if it doesn't come on in the radiator, something's wrong with it.

There is one other remote possibility, and that is that your temp gauge is simply wrong and your engine temperature is fine.

-Bryan

[micbrody]

Replaced water pump and thermostat. (Tested okdmthermostat - it was working ; but figured I would try last two things.

Still no fan.
I’m gonna pull switch and bench test again. Maybe bad wire??! ?
Either way: I learned how to replace water pump, thermostat, radiator ......

[spider2081]

when I jump the blue and black wire, fan goes on (and horn always working)

As previously stated by others: the blue wire should be "hot all the time" battery power to the fan motor. The black wire should be a switched ground through the temperature switch located in the bottom of the radiator.
Jumping the blue and black wire together would do nothing if the temperature switch is not closed and would blow the fuse if the switch is closed. Are you sure your fan is wired per the wire diagram posted??
One can test the radiator fan operation by unplugging the radiator fan switch 2 pin connector (both wires are black) and installing a jumper in its mating connector (both wires are black)
I could be misinterpreting the qouted statement.

[micbrody]

The wiring in this car has been “mildly” changed when I bought off Craigslist in 2014.
The leads going to fan switch are black/blue- however: the blue wire comes from another wire with a connector.

Regardless of the nature of the wiring: when the connector that attaches to the fan switch is “jumped” (The two wires shorted or connected to each other), the radiator fan goes on. Whether it’s a hot circuit vs. a ground circuit shouldn’t matter. The fan switch closing should power on fan regardless. And it was wired like this when I got car; and haven’t changed it; and fan switch worked (fan turned on)

It’s easy enough to remove fan switch; bench test it but also bend/move the wires. Maybe there is a bad connection in the fan switch wiring or internals making it flakey. I will also check again the old fan switch.
(I have also learned to just use water during this process until I figure everything out - then the antifreeze.

P.S. the old water pump seemed fine; some of the blades had some crud stuck to it; but not enough imho to significantly affect flow rate

[18Fiatsandcounting]

It sure seems the evidence is pointing to a bad switch, as you've replaced or checked just about everything else. A couple thoughts, and these are long shots:

1) You aren't using "waterless coolant" or the like, right? I've heard this stuff does funny things in terms of cooling efficiency.
2) I have seen people push the connectors to the fan switch so that the plastic outer sheath of the connector is wedged between the metal lug of the switch and the outer plastic covering of the switch. In other words, no electrical contact although the wire appears to be "plugged in".

If the switch turns out not to be the problem, then you really have got me stumped. About the only thing I can suggest at that point is that your gauge simply reads high, and the engine isn't getting to the temperature it needs to turn on the fan switch. Especially now that you've got an awesome cooling system with a new radiator, thermostat, water pump, etc!

-Bryan

[micbrody]

The connector thing can be a real issue. The old switch was a spade connector; and the PO did have a separate connector with original connector on one side; and spade connectors on other ends of wires.

When I went to connect new switch it had the traditional connector- and it was very difficult to insert.
I eventually was able to pull back outer part of connector on switch side so the internal were exposed. I connected them directly to car connector; shorted the switch side connectors to ensure connection (fan went on) and then slide outside insulator back over leads.

So is a possibility that during this journey (where I have reconnected a few times), maybe it is the connector.

But I’m fairly sure that I have been extremely vigilant in reconnecting

And for coolant, now it’s just using water until I can figure out stuff

[18Fiatsandcounting]

Which radiator fan switch do you have, the old style ('77 and older), '78 only, or the new style ('79 and newer)?

Old Style: https://autoricambi.us/radiator-fan-swi ... fe2d666e81
or
1978 only: https://autoricambi.us/radiator-fan-switch-1978-only/
or
New style: https://autoricambi.us/radiator-fan-switch-1979-85/

If your car is an '81, the new style would be the right one although you can use the older styles but have to change the connectors.

-Bryan

[tima01864]

On my car last time i changed the coolant fan did not come on. It turned out to be the bayonet connecter was coroded, I cleaned it and all was well. Worth a look.

[spider2081]

Regardless of the nature of the wiring: when the connector that attaches to the fan switch is “jumped” (The two wires shorted or connected to each other), the radiator fan goes on.

This is what I was trying to confirm. The fan itself and its power and ground appear to be good.
Have you checked the switch with an ohm meter when the cars engine temperature is in the 200 degree range?? This can be done with out removing the switch from the radiator. I would check it at the mating connector to the one you jumped to make the fan run.

[micbrody]

I removed fan switch and carefully tested . Pot of water with thermometer on stove .
It turns on at 211 deg F. Tested old switch; went on at 200.

I think when I originally tested I was just adding hot water to a measuring cup with thermometer. Probably hot and cold spots- so switch turned on above 200- but obviously underestimated the temperature.

So I put old switch back. Everything works perfectly.........


Except leak at metal heater pipe to water pump connection. It seemed to be flush. Any easy fixes?

[18Fiatsandcounting]

Except leak at metal heater pipe to water pump connection. It seemed to be flush. Any easy fixes?

This connection is a fairly common source of problems. I assume you used a new gasket for this, and since your water pump is new and its mating surface should be flat, there are several possibilities:
1. The nuts on the studs are not tight enough, or too tight so that the flange warped slightly. The nuts should be around 7 ft lbs.
2. The flange end on the heater pipe is corroded (common), or the weld joint has a leak (not as common).
3. The flange on the heater pipe was indeed warped a bit. Maybe not visible to the eye, but that gasket isn't very thick and it can only "correct" for minimal warping.

I'd first try a new gasket and some sealer like Permatex or the like. While you have it apart, put a straight edge on your flange and see if it looks warped.

-Bryan