Cooling Question - First Gen.

[Bronco648]

OK, sorry everyone, I inadvertently started a bit of a firestorm. I thought that the '85 2.8s all had the same cooling system configuration and @AndyB. has proven otherwise. Let me do my best to provide more info and I'll post some pics ASAP.

In AndyB's post, with the three images from the shop manual, the middle image shows my set-up (albeit without much detail).

His image of the V6 on the engine stand (nice work Andy!) shows it even better WITH THE EXCEPTION that my intake manifold water neck does not have a t-stat (like an early Mustang 289/302 does).

I may have created some confusion (my bad) thru ignorance; my water neck has the coolant gauge sending unit and the electric fan sending unit (the switch to complete the circuit to turn the fan on). It does not have a t-stat to regulate the passage of coolant.

Per AndyB's post with the two t-stats; it's distinctly possible I bought the wrong t-stat (ignorance again). I have a Motorrad MOT 234-192 (Rock Auto) based on my receipts:

Rock Auto does not stipulate the location of the t-stat in their listings.

 

[Bronco648]

Here's a couple more images from my Ranger's engine compartment:

Upper water neck showing the two sending unit switches (that I originally referred to as 't-stats'):

The near one (on the right) is the sending unit for the dash gauge. The far one (on the left) is the switch to actuate the electric fan. The other difference between my 2.8 and AndyB's 2.8 is that my coolant bypass hose goes into the intake manifold while his connects to the water neck.

Here's the electric fan in question:

I have the fan supported by two pieces of aluminum angle (3/4" x 1/2") which are in-between the fan and the radiator core. I'm wondering if the fan shouldn't be right up against the core itself but I'm not a fan of those thru-the-rad-core zip ties that come with these kits.

I do have an inferred temperature gauge so taking temp readings, in various spots, shouldn't be too hard.

 

[AndyB.]

If you want a Ford thermostat, I’ll send you an NOS one free. No idea on the fan setup.

 

[Bronco648]

OK, after I got home today, I grabbed the inferred thermometer and took some readings (which I failed to write down - I'll do it again tomorrow and make notes). I did not see anything that would lead me to believe that the t-stat isn't working correctly nor that the heater core is clogged. However, I did not see any readings anywhere close to 200* which is when the electric fan kicks on.

I guess it's possible that I have air trapped in the water neck where the two sending units are. That's the only thing that would make any sense. ??

 

[85_Ranger4x4]

I question an air bubble.

Even in summer my 302 with a 19X thermostat doesn't get warm that fast. Driving it to work a couple weeks ago in with highs in the 30's and after 10 miles on the highway I was just starting to get heat out of the vents by the time I got to work.

You can pick on the precise nature of the 1980's temp gauge but your fan is saying something is screwy too.

Dunno how original it was but my February build '85 had the top thermostat. That lower hose design sandwiching the timing cover... no kudos given. I hope that engineer got audited. I hate to be that harsh but he went way out of his way to do it to himself.

 

[Bronco648]

I question an air bubble.

Yeah, I'm wondering what's going on myself.

I used an inferred thermometer to take some temp readings last night when I got home. Ambient temps were in the upper 50s and the fan had just kicked on after a five mile ride on local roads (max speed ~45 MPH). Here's what I recorded:

Heater Hose:
@ heater core/firewall: both ~175*
@ alternator: 150* & 130* (fan running, these locations are in the air stream)

Radiator Hoses:
Upper @ water neck: 165* (fan running, in the air stream)
Upper @ radiator: 160*
Lower @ t-stat housing: 93*
Lower @ radiator: 91*

I flushed the heater core before filling the system using water from a garden hose (under pressure). The coolant that came out was still green and the subsequent water stream was clear. The flow did not seem to indicate any sort of obstruction.

I can touch every hose (nothing is too hot to grasp/hold for 3-4 seconds). I'm beginning to wonder if the sending unit switch is defective or stamped wrong. It's supposed to kick on @ 200* (after the t-stat opens @ 192*).

 

[Shran]

I am here to tell you that I've played the electric fan game and lost. I bet I tried 3-4 different styles and brands of automatic temp switches and none of them worked right. The one I have now was supposed to be adjustable and I had it dialed down to about 160 degrees but eventually it just started activating the fan whenever it felt like it. I ended up just putting it on a bypass switch and remembering to turn it on when I drive the truck.

The previous fan wiring kits I got had constant relay failures and one of them got so hot that it melted the power wire from the battery and the fuse itself but didn't pop the fuse. I am not a big fan of aftermarket electric fans, I have yet to find a setup that works like it should.

 

[Bronco648]

I am not a big fan of aftermarket electric fans, I have yet to find a setup that works like it should.

That's certainly a disappointment. As I said, with winter here (Chicago), I'm not terribly concerned but once warmer weather arrives, I will be. Perhaps, in the meantime, I can install a temperature gauge to see what the coolant temp really is. An override switch is a distinct possibility.

I also don't have a real issue with going back to a mechanical fan either. But, I'll have to find one as the old one was cracked, in several places.

 

[RonD]

Using a bung on lower rad hose with a 160-180degF switch is best location for temp switch, NO AIR ever, well unless engine has melted down, upper rad hose will always have some air, pretty much anywhere in upper engine will get air pockets now and then, shouldn't but WILL since everyone gets coolant leaks at some point, lol

180degF in lower rad hose means 195degF in upper hose(thermostat)
Radiators provide 15degF cooling without fan, 20-25degF with fan on or driving above 30MPH
Except on hot days electric cooling fan should only come on when stopped or in stop and go traffic
Above 30MPH air flow cooling thru rad is better than any fan can provide

You can install another relay to bypass temp switch, that relay is activated by AC Compressor on, and/or a switch on the dash
And if you have AC and add the relay then you already have a dash switch...................AC on

Radiator hose bung, needs to be grounded for switch to work: https://m.media-amazon.com/images/I/81j7wLld02L._AC_SL1500_.jpg

 

[85_Ranger4x4]

I have a painless wiring kit for mine, been happy with it for 10 years. It's currently running dual pushers out of a supercharged Mercedes.

 

[Bronco648]

Using a bung on lower rad hose with a 160-180degF switch is best location for temp switch, NO AIR ever, well unless engine has melted down, upper rad hose will always have some air, pretty much anywhere in upper engine will get air pockets now and then, shouldn't but WILL since everyone gets coolant leaks at some point, lol

Not to be argumentative but I recall using a mechanical water temp gauge in the two race cars I had ('67 A-H Sprite & '66 GT-350). Both were somewhere in the vicinity of the water neck off the cylinder head (Sprite) or intake manifold (GT-350). IIRC, we tried to get the oil temp and water temp within 20* of each other. 200-220* seems to ring a bell. The Sprite didn't have a fan at all, the GT-350 had a plastic fan driven by the alternator belt (that drove the water pump, too).

180degF in lower rad hose means 195degF in upper hose(thermostat)

I seem to be seeing significantly cooler temps in the lower rad hose than 180*. Perhaps the inferred thermometer isn't very accurate.

Radiators provide 15degF cooling without fan, 20-25degF with fan on or driving above 30MPH
Except on hot days electric cooling fan should only come on when stopped or in stop and go traffic
Above 30MPH air flow cooling thru rad is better than any fan can provide

You can install another relay to bypass temp switch, that relay is activated by AC Compressor on, and/or a switch on the dash
And if you have AC and add the relay then you already have a dash switch...................AC on

Radiator hose bung, needs to be grounded for switch to work: https://m.media-amazon.com/images/I/81j7wLld02L._AC_SL1500_.jpg

No A/C in my truck. Either I go with the manual switch or use the hose fitting adapter with the port for the sending unit (image linked above).

 

[AndyB.]

If we think about what the thermostat does, it opens or closes to allow water to flow either through the radiator or the bypass. I think a 180° lower hose would be normal if the thermostat is closed and coolant is flowing through the bypass circuit.

I think the upper water outlet coming off the intake is a good place for a temperature sending unit, since you’ll always have coolant flowing there, whether going into the radiator or through the bypass.

 

[Bronco648]

Was on vacation last week so I didn't have any time to tinker. Obviously, Ford put the temp senders in the water neck for a reason. Just seems so odd that the temp sender for the fan, which is supposed to be 200*, completes to circuit when it doesn't appear to be necessary.

I'm not sure if the temp sender for the dash gauge is correct either. There were so many incorrect parts, that came with the truck, that it may be wrong as well.

 

[4x4prepper]

Temperature readings and thermostats and that are all fine to check out, BUT, what are the OHM readings from the sensor at the various temperature readings?

Since this looks like a single wire, I would assume it closes a ground to energize the relay, so, I would make sure the relay is wired correctly and maybe you can test the sensor simply by attaching a beeping voltage probe by sticking the pointy end into the (+) battery terminal and clipping the other end to the male 1/4" connector sticking up. If you do not get a beep and a light, then maybe there is not a good ground to the housing. Maybe just running a ground wire directly to that bolt sticking up clamping the housing would solve the problem.

Maybe you need a switch that closes a ground to turn the fan on vs. one that sends a reading to a gauge.

 

[Bronco648]

Temperature readings and thermostats and that are all fine to check out, BUT, what are the OHM readings from the sensor at the various temperature readings?

I will need to check this when the engine is cold and after it's up to temp. Good idea!

Since this looks like a single wire, I would assume it closes a ground to energize the relay, so, I would make sure the relay is wired correctly and maybe you can test the sensor simply by attaching a beeping voltage probe by sticking the pointy end into the (+) battery terminal and clipping the other end to the male 1/4" connector sticking up. If you do not get a beep and a light, then maybe there is not a good ground to the housing. Maybe just running a ground wire directly to that bolt sticking up clamping the housing would solve the problem.

I believe the sending unit for the fan simply completes the ground when the coolant reaches a specific temp (200*). I've tested the ground many times. It's seems to be very good.

Maybe you need a switch that closes a ground to turn the fan on vs. one that sends a reading to a gauge.

You kinda lost me here. I have two sending units. The fan does run but seems to come on when the water is below its activation temp (200*). The gauge sending unit seems to indicate that the coolant temp is high (dash gauge caveats apply here). I can hold onto the upper rad hose when the fan is running (engine @ temperature), it sure doesn't feel like 200*. The lower rad hose is much cooler, right around 90*.