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Truth about gauges

CaFordDude

Charter Member
7,748
464
Cali
I have read a lot of posts about the stock gauges in our trucks, and I would assume the same complaints of most makes of cars.

So to the folks in the know. Seriously how reliable are the gauges in my 06 F350? How accurate are they?
Now I realize that I am not going to get an EXACT oil pressure reading from my guage. Or an EXACT measurement from any of the gauges as the readings just are not broke down into small enough increments.

BUT my MPG seems to be pretty good after having hand calculated a few tanks of gas. When it says EMPTY, that is what it means (Don't ask).

Seems to me there would be some sort of law making the car manufacturers get those gauges pretty damn accurate.

I also realize that if you have modified your vehicle in some way it may be more important to know EXACTLY what your boost is or EXACTLY what your oil pressure is but for the average Joe, or average Aaron as the case may be, with a stock truck do I really need to worry about some sort of aftermarket monitoring system?
 

bowtiehatr

Certified Ford Tech
no you sure dont. for years as far as back as my young self can remember, ford's oil pressure gauge has always shown full pressure around 10 psi even on gassers. the tranny gauge is ok as i think once it goes 20 or 30 degrees hotter than expected, it will climb on the gauge. the engine temp gauge is pretty good but on a 6.0 its either hot or not lol. the gauges are ok for stock, if you know how to stop driving when something doesnt look right ( unlike some of my customers ).
 

Kep4

Jäger
I added Isspro gauges earlier this year for EGT, 0-30 boost psi and 100-240 trans temp.

The boost gauges are within 1 to 2 psi the majority of the time but the Isspro is easier to read with more precise increments.

The Isspro trans temp gauge was interesting. The stock gauge moves to the middle of the temp range before the Isspro even registers 100 degrees. While towing up the Grapevine recently the trans got to 209 degrees for a short time and the stock gauge needle was still in the same position. I don't trust the factory trans temp gauge for that reason.

I believe an EGT gauge is a necessity for those who tow or race their PSD.

That's my .02 and I'm sure you can get change back....
 

blackhat620

You Had to be There
1,687
150
Arizona
Well all through in my $.02 on the Ford Factory "Idiot lights" ( oops i meant gauges).

The factory fuel guage, Tach, Speedometer and Boost gauge are pretty accurate. The Factory water gauge is marginal as FMC damps the response and when it finally starts to move it is already way hot.
As for the Factory Transmission gauge it is marginal at best. The factory Transmission gauge reads in the same spot wether the temperature is 100-220F at 230F it will move to the center of the gauge, at 250F it moves into the Yellow and at 280F it moves into the Red. The Factory Transmission gauge is to little to late.

At 175F the transmission is good for 200K+ miles. For everty 20F rise in temperature of the transmission, the expected life is cut in half. So at 195F it is good for 100K miles, 215F 50K miles, 235F 25K miles. At 250F the seals are damaged in the transmission and must be replaced.
So if 230F is the middle of the Normal range, now you know one of the Reasons FMC says to change the transmission fluid at 30K mile intervals.

Here is a good article on the FMC transmission gauge done by Charles Ledger at Dieselmann's website.
www.intellidog.com/dieselmann/b_smoke13.htm

Basically with an Automatic transmission try and keep the temperature below 200F

As for the Factory Oil pressure gauge, it is an idiot light with a needle. At anything above 5Psi it reads normal and stays there.

Personally in the PSD as a minimum install A/M Transtemp & EGT at the minimum, and if you have the room add Voltage, Fuel pressure, Engine Oil temp, Water temp and Oil pressure in that order.
 

6L PWR

Kansas Chapter member
Boost gauge are pretty accurate.
Until you put a Pro Street 64 Turbo from Long Island Performance Diesel on it. :D

I highly recommend a Water Temp and Tranny Temp for anyone and if you tow, and EGT too. I was surprised at how the stock engine temp and tranny temp worked. They're definetly analog idiot lights.
 

Kep4

Jäger
I've got my three gauges mounted on the pillar. Sounds like a water temp gauge is needed, what are the mounting options for another gauge or two in an 05 Super Duty?
 
I just put these in mine. I can say without a doubt that they are a bit more accurate than the 50 year old factory ones that did not work. :rolling laugh: :rolling laugh: :rolling laugh:

DSCF0625.jpg


Oh....that is not what this thread is about...sorry. :redface:
 

ponyracer

Certified Ford Tech
33
3
When I was a Ford Tech, the Regional dude told us the the speedo is acturate with in + or - 10%. I argued that "so when I get a ticket for being 10% over can you come with me to the court and explain that fact and the fact that the "certified" police speedos may not be "certified" for anything but + or -10% which could become a total of 20% if they were both of at oposite ends of the + or -.

So I dont trust any of the stock gauges except to be "close" and or an average of what they are reading.
 

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