Balmy 30 deg in KC, and garage was back to 45 so I tested out the gauge tester. What a handy gadget, and in a rugged case too! Sits nicely in the shock tower brace with ground on the starter solenoid mount. LED (that’s a bright little sucker) flashed on and off about twice each second, so my instrument regulator is working.
Temp gauge was halfway into C band on low, 60% on med, and halfway into red band on high.
Oil gauge was about 10% on low, 60% on med, but 10% over max on high.
I’ve always thought both of these gauges ran a bit on the high side, and now I have proof!
Sounds like it is possible that the IVR output is a little high. If the gas gauge is also high it would tend to confirm that.
Bill, I finally got some time to install the low fuel sender I bought from you last spring. It is reading a bit low, just like the one that was in there. I saw that there is a reproduction electronic voltage regulator that WCCC sells, one is in stock (https://secure.cougarpartscatalog.com/store/p/12544-Voltage-Regulator-Instrument-Panel-Repro-1967-1968-Mercury-Cougar-1967-1968-Ford-Mustang.html?sessionthemeid=26), the other is out (https://secure.cougarpartscatalog.com/store/p/13122-Voltage-Regulator-Electronic-Instrument-Panel-Repro-1967-1968-Mercury-Cougar-/-1967-1968-Ford-Mustang.html?sessionthemeid=26). Which one should I buy to correct my gauge issue?
Any chance that you are the one supplying these and that I could buy them from you along with one of the testers?
If I can carve out some time I will try to do a write up about Instrument Voltage Regulators. Some originals are adjustable. The solid state ones behave a bit differently.
The question is do all of your gauges read a bit low? If not, and we can confirm that, then it is the single low reading gauge that needs adjusted. The gauge tester is what’s needed. And yes I know I owe you one. The first batch sold out before I had a handle on it. I am trying to get the software on the site to allow Canada as a shipping location.
One very important point. The IVR and the gauge are heat activated. It can take a minute or more for the gauges to read right, longer when it’s colder.
I purchased the solid state IVR to have in hand when I pull dash apart next month to install LEDs and have tach / ammeter redone.
I also purchased this handy gauge tester, but on back order. Hopefully the tester will take into account the solid state IVR differences…if any.
Fuel gauge was halfway into red E zone on low, 60% on med, and 10% above F on high. So all gauges do read high, and I will replace or adjust IVR (it’s the original one from late 69) when I have the dash out for heater core. I did notice it took several minutes for gauge readings to stabilize in 45 deg garage.
The tester will show that it is solid state. When it is in the power test position you will get a continuous light from the blue LED. The gauges respond slower when using the solid state version.
Has anyone looked at whether the temp and pressure sensors are linear or do they have a curve to them?
Thanks for the response Bill. I didn’t know that some of the stock IVRs are adjustable, that’s good to know. I don’t really know if my other gauges are reading properly, so that’s a very good reason to buy the gauge tester to check them on both of my 68s. I did leave power on and checked the sender float arm in the low, mid, and high levels for several minutes in each position as I know that they are often slow to respond to a drastic change.
XR7G428 - Do you know what temperature and pressure your resistor values represent on an “ideal” sensor?
It varies. Typically middle temp is 192 degrees. There are at least two oil pressure senders one is maxed at 80 psi and one at 90. They are stamped. Remember, tHe tester tests the gauge not the sender. The gauges are the same internal design, the senders varied by application.
I am seeing 200 ohms at room temp and 30 ohms at 200 degrees from my coolant sensor. Is that in the ballpark? I went through several auto parts store replacements that were way off before finally finding a NOS sensor that seems to work.
That is going to read too low.
…which offsets the high gauge reading due to suspected high IVR. But it sounds like I need to fix both. Do you know of a source for the correct sensor?
I see WCCC has a new repro coolant temp sensor that runs 23-26 ohms at 220 deg. My 351C with heavy duty cooling runs about 220 deg coolant temp on a summer day. Seems about right to have the gauge centered there?
I think what we really need is a sender that is correctly calibrated and tested for our cars. This is just crazy that it should be this hard.
Sounds like I am stuck with what’s available, and the repro wouldn’t be enough different from mine to change it out. Definitely agree it shouldn’t be this difficult, and engine temp is kind of important. Thanks Bill!
Finally! I just got the air shipment of more Gauge Testers. I just finished up with packing and shipping all of those that were on backorder so if you were waiting it is now on it’s way.
In appreciation of the great feedback, all ClassicCougarCommunity.Com members can use COUPON CODE ccc.com and get $5 off
Order here:
https://desertclassicparts.com/product/gauge-tester-gt-ford-1/
Sweet! We have tested more than 200 gauges now. Very happy.