Old school auto instrument guy here and I have to say, fiiiiiiiiiiiiiiiiiinally someone who knows what they're talking about regarding thermal 5 volt gauges. This video is two years old, so I'm just a little late. Trouble is there aren't too many of us old school repairers left out there. There are just a couple of points I'd like to add to everything you've said. The regulators were very carefully adjusted at factory to be precisely 5 volts not, they should never hit 6 volts. If the regulator hits 6 volts the gauge pointer will "dance", the actual term used at the factor. The tension on the bimetal was adjusted carefully to pulse 60% off, 40 %. 40 % of 12 is 5. If the regulator is tuned correctly it will be a pulsing 5 volt, no more no less. These days when ever I get thermal gauges to repair I always replace the the regulator with a solid state unit. I always advise people NOT to buy a replacement thermal regulator, be it NOS or off ebay. The thermal regulator was the best and easiest technology of the day which worked well until it didn't then it would invariably burn out all your gauges. The thermal gauges themselves were and still are absolutely fine for the job they need to do, the only weak point being the regulator. Also, as a man who loves classic cars, I loathe changing them from original. Often I see a beautiful classic car with a set of new instruments in it, sometimes tastefully done other time done shabbily. I mean, just my humble opinion, classic cars are only original once and every part that was there from factory should remain. Partly though, it may be, as I said, that there are only very few of us of the old school left who still repair the old gauges.
I spent soooo much time getting my temp gauge to work again after replacing the radiator in my 66. This would’ve helped me quickly isolate the problem. Thanks for making such great content!
@@TheGT350Garage Based on all this, I’ll wind up swapping back to a 195 degree thermostat. Before I got the car, someone must’ve swapped it to a 180. The thermostat housing is new, and it evens out at 180 measuring with a laser thermometer at multiple hot spots. I wasn’t going to bother, since it worked, but if it’ll get a cleaner burn, I think that’s well worth it. If you have any affiliate links for the thermostat you recommended, I’m happy to use those. I’ve found some good resources on carb tuning, but would love to hear your take on that, after wrapping up this series and the heater core one. For my build, I’m dealing with some electrical gremlins now, but should be down to just turn signals after replacing the neutral safety switch (which had melted and shorted on the header), and rotted transmission mount. Then I’ll be doing a basic stock steering and suspension maintenance with shocks, springs, bushings, etc. I’ve already done the brakes, starter, radiator, plugs, wires, fluids, etc. Only substantial rust for me is floor pans, so I plan to get it in good driving condition and take it to someone to patch/weld in new ones. I don’t know how to weld or have power in my garage, so that’s more than I can handle, but am trying to do as much of the restoration myself as I can. I appreciate any recommendations on stuff I should make sure to do before shifting focus from basic road safety, to interior, and performance. I’m starting from a 289 2v c4 with power steering and manual everything else.
Great informative video. I'm hoping to buy a 1965 F250 custom cab camper special and have found one. My retirement hobby will be to learn any and all troubleshooting info to keep that truck running on the road for years to come. Cheers and Happy Holidays!
Sounds like an awesome plan. I have videos planned in the near future, work and life have thrown me some curve balls lately, but things are looking up.
i'm trying to get to the bottom of why my temp gauge is reading high (maxed out) on the gauge cluster. it starts off in the center and then by the end of a short drive, it's all the way to the right. However i checked various areas around the engine with IR and things like the radiator were 160 and the engine itself was 180, but that was when it was middle of the gauge. Currently i don't know what it is reaching when the gauge maxes out, but hopefully nothing over 225. I'm thinking maybe it's a bad voltage regulator? If i can check it with the multi-meter, what setting would i use?
To test the Instrument Voltage Regulator you will need to pull the instrument cluster from the dash, you should have battery voltage on one side and 5v on the other testing to the metal cluster ground point for the regulator. Where this can and often does get skewed is at three common locations; the ground connection of the IVR to the instrument cluster, the harness ground from the back of the cluster to the cowl under the dash, or the engine to firewall ground wire in the engine compartment. Each of those three locations can produce high resistance in their connection and cause gauge problems. This unwanted resistance will allow the IVR to produce more than the 5-volts and results in higher readings. You can easily verify this with the fuel gauge as well, if your fuel gauge also reads high, this is the issue. If the fuel gauge reads correctly and only the temp gauge reads high, I would suspect a faulty sender. That can be verified with an ohm meter. It’s a linear sender: 250F = 10 Ohms = Gauge Reads H 100F = 73 Ohms = Gauge Reads C Every 10°F over 100F you add 4.2 ohms, so at 180F you should read right at 39.4 ohms from the terminal post to the sender housing threaded into the intake manifold, also from the red-white wire to the back of the instrument cluster (ground) with the sender connected at the engine.
The Ammeter is wired directly through the charging system and does not use the IVR for operation. When an ammeter is factory installed I leave it in the stock form. The factory manual has procedures for diagnosing Ammeter operation. If yours is not working properly but the charging system operates normally, it may be a bad gauge. If you’re looking for something more specific drop another comment.
I have a 1969 mustang mach I with a 351 windsor and it runs a little hot but I have a 180 thermostat so your saying I should put in a 195 ? Please reply . Thank you Tony with the 69
Start with ignition timing. Idle 12-14° BTDC. Mechanical advance should be 20°, resulting in 32-34° BTDC and curve should bring in peak advance 200-500rpm above your normal cruise rpm (usually 2600-3200rpm) which will be below your peak torque. Vacuum advance is critical, connect to manifold vacuum and adjust for advance starting above 6-7in/hg and allow up to 12° of advance. This will help the engine run cooler and maximize power from modern fuel. Beyond that, if the radiator is copper brass or aluminum 3 or 4 row with .500” tubes, or an aluminum 2 row with 1”-1.25” tubes a 20” core, the 195° thermostat will give it more time to cool the coolant, often a 24” core will be ok with a 180° thermostat, small tube 2-row radiators don’t really cut it anymore, especially if they are well used.
I have a mostly stock 65 coupe 289. It's running hot and I'm looking to fix that enough to install an AC. What systems would you recommend to handle that?
The cooling system needs to be in good shape and adequately cooling the engine before adding AC. One thing that causes hotter than ideal operating temperatures is incorrect ignition timing and air fuel ratios. If you’ve watched the cooling system videos to get a handle on the cooling system operation, then I can walk you through how to make the ignition and carburetor adjustments to get operating temps in check.
If it is an electric fan, the fan should come on at about 205°F and turn off at about 185°F, but that depends on where the temperature sensor for the fan is located in the cooling system. I recommend the sensor be placed at the bottom near the radiator outlet hose so that it sees the warmer temperatures from the coolant cycling through the system when the thermostat is open.
Old school auto instrument guy here and I have to say, fiiiiiiiiiiiiiiiiiinally someone who knows what they're talking about regarding thermal 5 volt gauges. This video is two years old, so I'm just a little late.
Trouble is there aren't too many of us old school repairers left out there. There are just a couple of points I'd like to add to everything you've said. The regulators were very carefully adjusted at factory to be precisely 5 volts not, they should never hit 6 volts. If the regulator hits 6 volts the gauge pointer will "dance", the actual term used at the factor. The tension on the bimetal was adjusted carefully to pulse 60% off, 40 %.
40 % of 12 is 5. If the regulator is tuned correctly it will be a pulsing 5 volt, no more no less. These days when ever I get thermal gauges to repair I always replace the the regulator with a solid state unit. I always advise people NOT to buy a replacement thermal regulator, be it NOS or off ebay. The thermal regulator was the best and easiest technology of the day which worked well until it didn't then it would invariably burn out all your gauges.
The thermal gauges themselves were and still are absolutely fine for the job they need to do, the only weak point being the regulator. Also, as a man who loves classic cars, I loathe changing them from original. Often I see a beautiful classic car with a set of new instruments in it, sometimes tastefully done other time done shabbily.
I mean, just my humble opinion, classic cars are only original once and every part that was there from factory should remain.
Partly though, it may be, as I said, that there are only very few of us of the old school left who still repair the old gauges.
I spent soooo much time getting my temp gauge to work again after replacing the radiator in my 66. This would’ve helped me quickly isolate the problem. Thanks for making such great content!
Happy to help.
@@TheGT350Garage Based on all this, I’ll wind up swapping back to a 195 degree thermostat. Before I got the car, someone must’ve swapped it to a 180. The thermostat housing is new, and it evens out at 180 measuring with a laser thermometer at multiple hot spots. I wasn’t going to bother, since it worked, but if it’ll get a cleaner burn, I think that’s well worth it. If you have any affiliate links for the thermostat you recommended, I’m happy to use those.
I’ve found some good resources on carb tuning, but would love to hear your take on that, after wrapping up this series and the heater core one.
For my build, I’m dealing with some electrical gremlins now, but should be down to just turn signals after replacing the neutral safety switch (which had melted and shorted on the header), and rotted transmission mount. Then I’ll be doing a basic stock steering and suspension maintenance with shocks, springs, bushings, etc. I’ve already done the brakes, starter, radiator, plugs, wires, fluids, etc.
Only substantial rust for me is floor pans, so I plan to get it in good driving condition and take it to someone to patch/weld in new ones. I don’t know how to weld or have power in my garage, so that’s more than I can handle, but am trying to do as much of the restoration myself as I can.
I appreciate any recommendations on stuff I should make sure to do before shifting focus from basic road safety, to interior, and performance. I’m starting from a 289 2v c4 with power steering and manual everything else.
Great video, thanks for sharing. My temperature gauge is always on the high side. I will check the voltage:)
Great informative video. I'm hoping to buy a 1965 F250 custom cab camper special and have found one. My retirement hobby will be to learn any and all troubleshooting info to keep that truck running on the road for years to come. Cheers and Happy Holidays!
Sounds like an awesome plan. I have videos planned in the near future, work and life have thrown me some curve balls lately, but things are looking up.
IVR part # would be a big help. Much appreciated.
B9MZ-10804-EADJ
Hello and thank you for the very informative video. What is the reading of stock gauge on 6 cylinder 1965 when needle is at the midway? Thanks
Gauge and sender are the same for 6-cylinder and V8. Mid point of the gauge is 190-205 degrees depending on variables like resistance in the circuit.
i'm trying to get to the bottom of why my temp gauge is reading high (maxed out) on the gauge cluster. it starts off in the center and then by the end of a short drive, it's all the way to the right. However i checked various areas around the engine with IR and things like the radiator were 160 and the engine itself was 180, but that was when it was middle of the gauge. Currently i don't know what it is reaching when the gauge maxes out, but hopefully nothing over 225. I'm thinking maybe it's a bad voltage regulator? If i can check it with the multi-meter, what setting would i use?
To test the Instrument Voltage Regulator you will need to pull the instrument cluster from the dash, you should have battery voltage on one side and 5v on the other testing to the metal cluster ground point for the regulator. Where this can and often does get skewed is at three common locations; the ground connection of the IVR to the instrument cluster, the harness ground from the back of the cluster to the cowl under the dash, or the engine to firewall ground wire in the engine compartment. Each of those three locations can produce high resistance in their connection and cause gauge problems. This unwanted resistance will allow the IVR to produce more than the 5-volts and results in higher readings. You can easily verify this with the fuel gauge as well, if your fuel gauge also reads high, this is the issue. If the fuel gauge reads correctly and only the temp gauge reads high, I would suspect a faulty sender. That can be verified with an ohm meter.
It’s a linear sender:
250F = 10 Ohms = Gauge Reads H
100F = 73 Ohms = Gauge Reads C
Every 10°F over 100F you add 4.2 ohms, so at 180F you should read right at 39.4 ohms from the terminal post to the sender housing threaded into the intake manifold, also from the red-white wire to the back of the instrument cluster (ground) with the sender connected at the engine.
I was interested in the AMP gauge, have you covered it?
The Ammeter is wired directly through the charging system and does not use the IVR for operation. When an ammeter is factory installed I leave it in the stock form. The factory manual has procedures for diagnosing Ammeter operation. If yours is not working properly but the charging system operates normally, it may be a bad gauge. If you’re looking for something more specific drop another comment.
Thank you for the excellent content! Question; What is the part # on the 195* Robertshaw Thermostat you are using?
FlowKooler “Robertshaw” 330-195
www.summitracing.com/parts/bra-330-195
Got you bro from Instagram 🔥🔧🇺🇲💪🔴🚗👊
I have a 1969 mustang mach I with a 351 windsor and it runs a little hot but I have a 180 thermostat so your saying I should put in a 195 ? Please reply . Thank you Tony with the 69
Start with ignition timing. Idle 12-14° BTDC. Mechanical advance should be 20°, resulting in 32-34° BTDC and curve should bring in peak advance 200-500rpm above your normal cruise rpm (usually 2600-3200rpm) which will be below your peak torque. Vacuum advance is critical, connect to manifold vacuum and adjust for advance starting above 6-7in/hg and allow up to 12° of advance. This will help the engine run cooler and maximize power from modern fuel. Beyond that, if the radiator is copper brass or aluminum 3 or 4 row with .500” tubes, or an aluminum 2 row with 1”-1.25” tubes a 20” core, the 195° thermostat will give it more time to cool the coolant, often a 24” core will be ok with a 180° thermostat, small tube 2-row radiators don’t really cut it anymore, especially if they are well used.
@@TheGT350Garage per your advise I did this and made a huge difference.
I have a mostly stock 65 coupe 289. It's running hot and I'm looking to fix that enough to install an AC. What systems would you recommend to handle that?
The cooling system needs to be in good shape and adequately cooling the engine before adding AC. One thing that causes hotter than ideal operating temperatures is incorrect ignition timing and air fuel ratios. If you’ve watched the cooling system videos to get a handle on the cooling system operation, then I can walk you through how to make the ignition and carburetor adjustments to get operating temps in check.
If the thermostat should be 195 degrees what should be the radiator fan thermostat? Also 195 degrees? Thank you. Greetings from the Czech Republic.
If it is an electric fan, the fan should come on at about 205°F and turn off at about 185°F, but that depends on where the temperature sensor for the fan is located in the cooling system. I recommend the sensor be placed at the bottom near the radiator outlet hose so that it sees the warmer temperatures from the coolant cycling through the system when the thermostat is open.