Hello all,
Have a 50 Ford F1 w/390 FE. My Dolphin temp gauge shows 210 but with a heat sensor gun it shows 195.
So it’s about 15 degrees off. Is there any adjustment to the gauge itself – I really don’t to change the gauge out but…
I've changed out the temp senor but no help - what about placing a resistor inline..?

Thanks for any help

 

There's several questions that come to mind that need answers before forming any kind of solution.

* Have you asked Dolphin, and what did they say? Imo, this would be first and foremost to know.
* Are you using the correct Dolphin senders to work correctly with your Dolphin gauge, both original and replacement?
* At what points are you taking your IR readings from? Why do you think those are better than the alleged water temp?
* Do you know if your temp gun is accurate?
* What thermostat are you using?
* Have you done any other diagnostics, different gauges, thermometers, etc., to verify results?
* What are the specifics of your cooling system?

 

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Thanks for the response.
I've had an overheating issue for several years in addition to other things... (aka- Our Money Pit)
I replaced the instrutment panel ~ 5 years ago and No - did not contact Dolphin but I "thought" it came with the senor..?
My shop guy used his gun and I'm sure it's correct.
This week we also installed an electric fan for added cooling as apparently 390FE's are known over-heaters..
I believe there's 180 thermo but, can't say that for sure.
Looks like I'll be checking all these things out this winter - while we wait for Spring!!

 

I have played around with gauges a lot. And have transplanted gauges into my original instrument cluster to get rid of the Oil pressure and Gen lights. Once I got to my temperature gauge though, I noticed the same thing you have. The coolant temperature seems 10 to 15 degrees higher than the temperature you will read on a infrared gun shooting the temperature at the sensor location on the intake manifold. Just my theory, and I could be wrong but I chaulk it up to reading a cooler temperature on the engine surface that is dissapating heat because it is exposed to air.
Anyways, my dumb theory aside, if accuracy was your upmost concern I would check your Dolphin temp gauge against a temporary mechanical one. You probably don't want to buy a mechanical temp gauge just for a test, but I have found that they are pretty accurate when I have tested them in a pan of boiling water and against a meat or candy thermometer, and it will answer your question very quickly. Sure, a little bit of a pain to install and remove again. But it could help answer your questions about your normal engine temp and what it should read on an electric gauge.
One final thing. If your Dolphin gauge reads hotter than your mechanical gauge, then like you mentioned earlier , you could add some resistance between the sendor and the gauge. I calibrated a Dorman branded gauge, and its reading very accurately, using a 10 ohm resistor in series with my temp sensor. How do I know? My electric fan switches on at 195 degrees, the Dorman gauge says 195. My thermostat opens at 167 degrees (tested in a pan of hot water) my Dorman temp gauge shows it opening just a hair under 170. Close enough for me.

 

Maybe this is a dumb question but.... for my 50 Ford F1 with a 1967 390 FE - is it better to have a 180 or 195 thermo?
My thinking that a 180 is better but.....
It has always run on the warm side and leaves a little puddle where ever I stop for a bit....
Likes to mark its territory - I guess

 

Have been driving various 390's and many versions of FE and FT engines since 72, don't recall any overheating without good cause.

 

That was my recollection as well. Ford made millions of them for 20 years in all flavors and usages, and they seemed to be just fine. It's easy to blame the engine when one does an incorrect build that fails to provide a cooling system to handle the needs of said engine.

 

If it were me, I'd be looking for a second opinion from a new 'shop guy'. If his idea of fixing a gauge reading is adding an electric fan, I'm guessing something is being overlooked. My 2c.

 

As 52 Merc asked for earlier could you please tell us more about your cooling system?
What type of radiator such aluminum or copper/brass, how many rows, OEM style or universal type, all the correct seals and shrouds installed to keep air from bypassing your radiator? Has your radiator been taken into a shop to see if it needs flushing? Do you have a V-belt or surpentine water pump? All the air out of your cooling system? It might be worth draining out your radiator, pulling out your temp sensor on your intake manifold, then using a large, huge, funnel fill your radiator with coolant again until it starts to belch the air and coolant out of your temp sensor hole, screw temp sensor back in and tighten it down. Then top off your radiator again using the large funnel. Fill your radiator up with coolant just until it starts to creep up the inside of the funnel. Start the engine, let it idle, and watch when the thermostat opens, the coolant will belch up inside the funnel and any air will escape, then the coolant will splash down again inside the funnel. Let the engine run until its up to temp, (you might see more bubbling) then shut it off. Let it all sit for a few hours as more air will escape thru the radiator fill funnel. Come back and top it off and install your radiator cap and take it for a ride to see IF it made a difference. Sometimes when purging air out of a system like this it helps to have the front of the truck up on jack stands, or even just on an slight incline as air likes to rise.
How is your timimg? Have you verified that TDC on your damper is actually at TDC? Sometimes the timing marks are off because the damper has slipped, resulting in the timing being set as retarded, causing the engine to run warmer.
Is distributor advancing correctly?
Your bottom radiator hose is not collapsing is it?
Are you running warmer at idle, then cooling down at steady cruise? Or is it running cooler on low speed, but hotter when you run say 55 MPH?

I have been there before too. Running hot at road speed and I couldn't figure out why. I changed thermostats, temp gauges, water pumps, etc. My problem turned out to be a bad radiator. A radiator a shop supposedly boiled and flow tested. Even though you could be running 210 I would say verify your temp gauge is reading correctly, then take it for a ride on the highway on the open road and see what its running. And work it from there.

Sorry for throwing all this stuff out!

 

Be sure that the cab is grounded to the frame, engine and the battery. A weak ground will make the temperature gauge read higher.

 

I did not see when it runs hot?
Sitting in traffic at idle or running down the high way at 60+ MPH as each points to a different area to look once a known temp reader (gauge) is installed.

BTW if you run a motor to cold, 180 or 190 stat?, you will not boil the condensation out of it and that will cause issues down the road.
They also say you get more ware on the motor too.
Dave ----