Aux. Radiator Fan ???

[Ken K]

With a digital mutual meter in hand, go to youtube and search for DC voltage drop tutorials. As posted on page one, the cooling fan pulls 25-35 amps, way more than the internal DMM fuse will handle. My $500 Fluke 87 type5 RMS DMM, will handle 15 amps, but you need a amp clamp for actual reading. What size fuse is in the fans relay circuit? That will tell you something.
Voltage drop will tell you almost everything you need. Just hook up your meter leads before starting fan, with one lead on both ends of any wire. This tells you the condition of the wire. If you go across the fan (1 positive and 1 negative) the fan consumes all of the voltage in this series circuit, but wires, connectors, relay contacts and fuse all have a tiny amount of voltage loss across them, even when new. All add up to battery voltage available. It is quick, never lyes, gives accurate quick readings and if the meter leads are backwards, it will just show a (-) negative symbol in front of the reading on your meter...the same correct amount.
During 7+ years of teaching 2 day classes for ACDelco, this was most of EL-2. I would bet I taught that class over 140 times, in the upper mid-west. It's about getting use to your DMM and comfortable with the readings your seeing.

 

[bugdewde]

During 7+ years of teaching 2 day classes for ACDelco, this was most of EL-2. I would bet I taught that class over 140 times, in the upper mid-west. It's about getting use to your DMM and comfortable with the readings your seeing.

Ken K ....
I'm jealous.
My father was an electrician and i didn't pay much attention to his teachings as a teenager ..... I'm regretting many of my choices in life now that he's gone.
As I grow older, he became much more smarter and capable than I can only imagine.

I'll soon be looking for a clamp on type ammeter and hope to brush up on some YouTube instructions on doing some voltage loss testing as well.

I know I'm not contributing anything to the OP issues, I just have to say Thank you for your very valuable input. .... AND all you other guys that are willing to share your knowledge.

 

[Ken K]

I bought several digital readout amp clamps over the years. Compared to a Fluke amp clamp that has to plug into a DMM for a reading, I was surprised how close the where in accuracy. One, I bought at Sears' that the digital bars are getting wonky, but readable, but a pico amp clamp, and something else. I have a whole large drawer tool box dedicated to just electrical, but have one drawer for quick access electrical tools. Got way too much stuff and counted like 5 amp clamps, 3 multi meters including analog from Yamaha I bought while at the dealer as a tech in 70ish. We where the only dealer and I was the only tech on motorcycles. Man, was I busy. I have guys who raced, slip me a $20 to get their bike with a broken primary drive gear fix before the weekend or next race.
Digital read out amp clamps take the guess work out of checking a circuit as you get answers now. I always went by the fuse size, so inrush current is high as a copper coil is cold, but current drops quick as it heats up to work. So, if you cooling fan is "Not" popping fuses, say 30 amp, then you have a connection or wire with high resistance. A voltage drop will show that. Just remember, a series circuit is one part in a single circuit and is designed to consume all of the voltage in the circuit. So, going from positive to negative side of motor, turn it on as a voltage drop will only work is current is flowing. Just like it is designed to. Perfect, but while running, you see 12.9 volts across it and battery while running is 13.4, you are gold. But if turns hard, bad bushings, etc., then it will still be 12.9 but current will be near of at the fuse rating. Too high. Fuses are thermal not current sensing.
Voltage drop effect that part of the circuit that has high resistance. From end of a wire to the other end while current is flowing thru it. I do not like to disturb connectors if possible, then problems disappears. Same with relays. Dealers don't stock every relay and only relays with the same P/N are the same for swapping. But, I would install 5 inch jumpers with the relay off on the side. I would do a voltage drop across the 85 /87 terminals as this is the contacts. Less than 0.050 DC volts is fine, but repeat. Off, on, Off, on, then all of a sudden, you see 2.1 volts, the relay contact is bad. It's like an "Automotive Court of Law" Can you provide the relay was bad? No, I just swapped them and it works. How long will work? A week? I don't know. Guessing or do you know for sure? Guessed. Go to jail.
A dedicated ground is used on sensors like TPS, MAP, MAF to provide a ground to the computer, to keep it on the same level. It passes thru the computer, out a terminal, thru a wire, to engine ground, then back to the battery. Voltage drop a sensor ground back to the battery is 0.400 volt DC is industry standard. Lower, better, higher bad. The good part a voltage drop test will allow you to work backward until you isolate it. Just start where it is easy to get to, then go from there on a vehicle. It's quicker. A cooling fan circuit is limited, so go straight to it.
Sorry to hear you lost your dad, but I have two sons. One is not into cars while his younger brother is. He can take stuff apart, but refuses to learn what he is seeing, how it works or why, just tell me how to fix it he yells at me. People learn 3 ways, being shown, talking about it or doing it with guidance.
Being open to learning, is something a good tech looks forward to every day otherwise, it is boring...at least to me. I am self taught also. It will click and learning will have occurred.
Best of luck, bugdewde

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[PlayingWithTBI]

Here's the Fluke amp clamp I bought about 20 years ago (0-150A)

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. I remember 1st learning on a Simpson VTVM, lol

 

[Ken K]

All of the first design analog volt / ohms meters where named "Simpson" as he was credited for inventing them. I have one as well, just say Yamaha on it for testing the points when closed. Still have "SnapOn" points cleaning fiber files in a box. Like a flexible sand-paper on a stick. Points seemed to have a coating on them for storage.
I will see your "Simpson" Volt-Ohm meter and raise you 8 distributor wrenches!

 

[Schurkey]

I have one as well, just say Yamaha on it for testing the points when closed. Still have "SnapOn" points cleaning fiber files in a box. Like a flexible sand-paper on a stick. Points seemed to have a coating on them for storage.

I hate points. God Bless magnetic pickups. I suppose Hall-effect is also an improvement, but they're harder to test than magnetic.

Points...well, quality points anyway...were plated with a thin layer of Tungsten to reduce burning and extend service life.

If you file them, they're ruined.

If you remove the metal build-up that transfers from one point to the other, you've reduced the surface area of the points and what remains will burn faster.

GM used to recommend that the "cone" of transferred metal not be disturbed, and the points not replaced until the cone was taller than the point gap.

The "cone" of transferred metal is due to an imperfection in the "sizing" of the condenser (capacitor) due to manufacturing tolerances. (I bet + or - 20% from nominal value was common, but I haven't tested a condenser for decades.) Either the condenser is too low in capacity or too high in capacity by some tiny amount. If the condenser were EXACTLY right, the metal transfer from one point to the other would take a zillion miles. The metal transfer from the stationary point to the movable point, or from the movable point to the stationary point tells you whether the condenser is under- or over-sized. I've LONG forgotten which way the metal transfers means "undersize" and which way means "oversize".







Ken--You taught automotive training clinics? I bet we've met. I went to a couple sponsored by the local Chevy dealership. That was several years ago

 

[Ken K]

Possibly in one of my classes, but at Iowa Western or 12 others.

But, points may have a slight convex shape, but the condenser is used to give the eletromotive force a place to go to when the points opened. This was to reduce spark across the gap and make the point last longer. As points wear, the surface area of contact get larger anyways, so that rule for sizing a cap is gone.
But, I will see you theory on points / caps and raise you two large tubes of ACDelco points grease still on box. I have a 3rd I use for other points of lubrication. Don't forget to check your advance weight pivots for wear. That reminds me, I have a die-cast chrome plate Tach / Dwell meter as well. It is sitting next to my "PCV" flow tester, next to my single carb air flow tester and two water manometers. One is a "Bourdan Tube type" and the other is hose type on metal plate with graduations for vertical use. Used on Diesel engines dipstick tube for blow by and handy for natural gas or propane setting as well, but I used them on the Ford VV7200 carbs. Man I am old.

 

[PlayingWithTBI]

I will see your "Simpson" Volt-Ohm meter and raise you 8 distributor wrenches!

You win! I only have 1 but it has 1/2" & 9/16" on each end with a 3/8" sq drive coupler in the middle.

 

[Ken K]

The distributor wrenches are all SnapOn, but I made 3 different open-end-angled wrenches for removing carbs from mostly imports. Even the Solex used on early Chisler products that sold top half or bottom half. The problem was the choke opener which was a wax pellet. The wax pellet practice was common on Vacuum-Switching-Valves or "VSV", but the Solex carb used it to push open the choke on a gear driven bell-crank and huge large ass spring. The wax pellet housing was sealed, but had an adjustment screw. Later models, they placed a hardened piece of steel over it to comply with "Tamper-Resistance" laws. Grind or pry the two rivet off, remove steel plate and there was the same adjustment screw with lock nut.
This info will come in handy if you get a 1980 "K" car or original D-50 Dodge Ram mini pickup up to 1986. If the choke will not open fully with hot water piping still hooked up. Also used by Mercedes Benz on V8's to close off idle air flow from 1978-1984 SEL-400 & 450's.
The Cadillac Seville in 1976 V8 used a twin magnets in the base of the distributor to reed switches that triggered left bank or right bank injectors. Key-on, Engine-off, run the TPS from close to WoT. The injectors would trigger 21 times. If suffering from lean-mixture-rough-idle, there was no cleaner back then, only new injectors from the dealer at $175 each. The easiest solution was a 4-gas in tail pipe, and potentiometer with a sewing needle soldered onto the center / common and one end. Stick the needles into the intake air temp sensor (Pass Rear Intake Runner) in parallel with the sensor. As you turned the pot to add more resistance to the sensor circuit, it would think the air was colder, increasing injector on-time. Once the CO came down to less than 0.3% PPM and the engine ran smooth, carefully remove your "Pot" and measure total resistance. Open your selection box from Radio Shack, pick the resistor closes to the reading, then solder in place in across the two wire sensor in parallel.
The only other EFI car was the Datsun 280Z in 1976, that used 7 injectors for the 6 banger. The 7th injector was ran off a "Thermo-Time" sensor in the coolant jacket. It had time and temp stamped on the side. So, cold, it would spray the injector #7 for up to 18 seconds, warm or hot, nothing. I guess this is why they called a few of us "Legacy Instructor" in Detroit / Troy meetings. A nice way of saying old!

This is information only and not intended to harm any cooling fan, circuit or relay in the discussion!

 

[Schurkey]

This thread is getting fun...