Oil Guage acting funny

[skeeter72]

First off, i would like to thank you guys for making this an awesome forum. I have learned more in the past couple months looking through yals tech articles and threads than i have in a year of looking on other forums. Anyways, I have a 94 f250 7.3 e40d currently with ~146,000 miles and have had it about a year and half. Since owning it i have replaced the oil cooler and the glow plugs on it, everything has been running fine and sounding fine until today. The oil pressure gauge (stock) has normally been hanging around the "O" and the "R". Then all off a sudden it is starting to twitch and progressively get lower, i checked the oil and it was low, so i put more in, but it is still twitching and hanging around the low to really low mark. It is also moving a lot. I also notice when i accelerate ( i do not accelerate fast maybe up to 1500rpm) the needle will go all the way left and then start twitching its way back to "normal" spot (normal as in how its been acting in the past 5 hours). Is this a sign of problem in the engine or is the gauge is going. Thank You in advance. Cheers.

On a completely different note can any of the Kentucky guys on here recommend where i can find test strips in the lex area.

 

['94IDITurbo7.3]

mine has the SAME exact issue. i don't think it is a prob since the sensor that moves the gauge just needs to see 7psi to move the gauge to "normal", therefore it is not the type of sensor that will move with every fluctuation in pressure. it would still be best to get a real gauge on there though so you can see exact numbers.

i know what my issue is.....when i put my air box on after doing my head gaskets in pinched the oil pressure sensor wire between the air box and the intake snail/hat. i ohmed out the wire and the resistance was to high. it has progressively gotten worse. some time i will cut the bad section of wire out and solder in some new stuff.

BTW, the whole time my gauge goes wacko, my real gauge stays nice and steady showing i have healthy pressure.

 

['94IDITurbo7.3]

if you want to check the wire it is the white with read tracer(stripe) on it. you can find the end of it in the engine harness connector on the drivers side fender.

 

[TWeatherford]

Mine did that, I ditched the stock one and went with a real gauge. It turned out the connection where the wire connects to the sender was loose.

You can get test strips at Napa, just check the expiration date before you buy them. Most of the time they only have expired ones because they sell so few. Most Napas seem to have terrible service in my experience, but the one in Winchester was the best ever when I lived there.

 

[IDIBRONCO]

These factory electric gauges aren't very accurate anyway. I'd put a mechanical gauge in your truck and don't worry about the factory one. The mechanical one gives you accurate pressure readings. Don't worry about low pressure on the mechanical gauge at idle. IIRC, the spec is 10 psi at a hot idle.

 

['94IDITurbo7.3]

if you go with mechanical make sure to get an isolator. i don't think you want to run hot engine oil into the cab.

 

[skeeter72]

Alright so I will assume the gauge is crap. If go looking for a mech gauge what should I look for ie brand, if go through amazon is there specific keywords that should be a red flag, and do they come with isolators or is that something seperate I have to find. Lastly this new sensor would be taped in where on the engine. Thank you guys

 

[skeeter72]

I forgot to mention when u was topping off the oil there was a some vapor coming from the oil fill port. I do not know if it was smoke or condensation with the hot engine environment meeting the cold air.

 

[franklin2]

The oil pressure sensor is in the middle of the engine, way in the back at the firewall. This is going to be a crawl up in the engine compartment deal, it's way back there and hard to see. What i did was go to Ace hardware and and got a pipe nipple to extend the new oil pressure fitting up a little bit to make it easier to mess with.

Some people like the Cadillacs and take the high road on everything, while others are satisfied with there old Ford and get by with the "normal" stuff. I have always used a mechanical oil pressure gauge, and have always run the tube with the oil inside the cab. The only problem I have ever had was the plastic tube getting on the exhaust manifold and melting, and even then it was just some smoke, under the hood. I have never had one leak inside the cab, and they do have kits at the parts stores to use small copper tubing, which may not be a bad idea.

Just saying the isolator is not mandatory, but by all means run one of you think you need it.

 

[79jasper]

The oil pressure sensor is in the middle of the engine, way in the back at the firewall. This is going to be a crawl up in the engine compartment deal, it's way back there and hard to see. What i did was go to Ace hardware and and got a pipe nipple to extend the new oil pressure fitting up a little bit to make it easier to mess with.

Some people like the Cadillacs and take the high road on everything, while others are satisfied with there old Ford and get by with the "normal" stuff. I have always used a mechanical oil pressure gauge, and have always run the tube with the oil inside the cab. The only problem I have ever had was the plastic tube getting on the exhaust manifold and melting, and even then it was just some smoke, under the hood. I have never had one leak inside the cab, and they do have kits at the parts stores to use small copper tubing, which may not be a bad idea.

Just saying the isolator is not mandatory, but by all means run one of you think you need it.

X2 Never had a problem with it. As a kid I don't remember my dad ever having a problem either. My brother has had one on his neon for at least four years and drives the hell out of it, still no problems.
I'm thinking of going to the copper tubing. Or maybe use steel brakeline. I think it'd be cheaper than copper lol
A more expensive and overkill option would be braided stainless line.
Also I just buy whatever's cheapest from autozone or orielly.

 

[RLDSL]

Semi trucks just run aeroquip hose right up into the cab straight to the gauge, no isolator, and those suckers last for millions of miles. The reason they use isolators on race cars is because they are PLANNING on severe crash situations ( kind of goes hand in hand with the roll cage