oil pressure wtf

[nickel and dimed]

I was driving home normally tonight and checking my gauges out of habit and found to my horror that my oil pressure gauge had dropped to 0. After about 30 secs of random swear words and wondering when my rod knock was about to begin, the oil pressure went slowly back to normal. Is this just a fluke or is something wrong?

Right now I am running mobil 1 full syn 15w50.

 

[shaeff]

did it happen when you hit the brakes or something? if you're low on oil and hit the brakes, the oil will move away from the pressure sender and show low oil pressure. check your oil to make sure it's not low.

the same thing happens if you're low on oil and go around sharp corners, the gauge will go up and down as the oil goes away from the pressure sender.

-shaeff

 

[mrnickleye]

Quote: the same thing happens if you're low on oil and go around sharp corners, the gauge will go up and down as the oil goes away from the pressure sender.

It goes away from the pressure sender because there is NO pressure.

You should pull the sender wire off and make sure its got a good connector. Then turn the key to 'on' and have someone in the car tell you what the gauge is doing when you ground the wire to the block (on-off a couple of times). Gauge should move slowly to the top and back down. If it does not, the gauge is likely bad. If it does, then sender is likey bad.
I would pull sender out, and hook up an oil pressure testing gauge to get a true reading of the pressure. If its good, and your oil level is correct, then replace the sender.
Senders go bad 10x more than gauges or oil pumps.

 

[IHI-RHC7]

Yeah, the sender is in the oil galery, which is presurized. So the oil does not move away from the sending unit, it moves away from the oil pickup, which results in an empty oil galery, which results in a dead motor.

 

[shaeff]

ah nuts. well, regardless, it's still the same effect! my bad though, dont wanna be spewing out mis-information!

-shaeff

 

[nickel and dimed]

thanks for the advice, I'll check the sender out.

 

[RacerXJ220]

The sender may be going bad too. Mine freaked once, spiked all the way up, then died. The wires may not have good contacts in your case. It's a good idea to run 7 quarts instead of the usual 5.

 

[mrnickleye]

The sender may be going bad too. Mine freaked once, spiked all the way up, then died. The wires may not have good contacts in your case. It's a good idea to run 7 quarts instead of the usual 5.

Its a BAD idea to run more than the correct amount of oil.
Too much oil will put more on the cylinder walls than can be handled by the piston rings, thus causing oil to be burned in the combustion chamber. Oil being burned will cause the inside of the cat converter to be coated, thus ruining it.

 

[IHI-RHC7]

Too much oil also makes the crank whip the oil into a froth, and froth is full of air. Oil full of air is about as useful as no oil at all.

 

[shaeff]

i run one quart over stock specs. many do with no issues.

-shaeff

 

[RacerXJ220]

Regarding the amount of oil, A lot of people use more than 5 quarts. You should. IMO, 7 quarts when you change the filter is a good idea, and I am talking about a stock oil system.

 

[PynkEye]

ya I run 6 with no prob, have had like 7 with also no prob. Most important is to make sure your stock oil dip stick is on the Full line every week..I check it all the time...if its 3/4 full i re full it....anything less than full on stock gauge is not to good

 

[mrnickleye]

Quote: Too much oil also makes the crank whip the oil into a froth, and froth is full of air. Oil full of air is about as useful as no oil at all.

Soooo True...

Well, you all can add as much oil to the crankcase as you 'think' is right for you. But, for me, having lived and breathed cars for 33 years, and an ASE Master Tech for 21 years, I'll stick to what the manufacturer calls for when the vehicle pan is stock. The correct dipstick for that engine will help you keep topped up, even with an 'add-on' oil cooler (which you will need to add approx. 1/2 qt more.

 

[mkiiSupraMan18]

My 82 does the same thing, people always freak out about it, but hey... that'll just make the 7m swap that much more reasonable.... :biglaugh:

I'm sure after 4500 miles it would have done whatever it was gonna do though...
THing is... mine only does it if I keep it at a constant speed for... I dunno... 5-10 mins... then it slowly goes down to 0, hit the gas a little and viola.... shes back in the green... I was gonna get a sender, but.... thats like $40... then I'd have to install it.... F that....