Oil Pressure Drop

Derphound01

Derphound01

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Tennessee
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Chameleon 1995 Thunderbird LX 4.6
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Drove my 4.6 today and noticed every time I came to a stop with the nose of the car pointed downhill, the oil pressure gauge dropped to zero and the Check Gauges light came on. It did the same on a hard panic stop as well. Once the car stopped, the gauge went back to the normal range and the light went off.

Oil level is fine and it was changed within the last 2000 miles. There's no signs of leaks or significant burnoff. Any thoughts.
 
How sure are you that the oil level is fine? Cause that is a classic symptom of low oil. On a downhill or hard braking, the oil sloshes away from the pickup causing it to suck air and the pressure drops. If the oil really is full, then I would put a real gauge on it to see what it is actually doing. The factory gauge is just an idiot light made to look like a gauge. With the factory setup, if you have 7psi or more of oil pressure, the gauge goes to somewhere in the middle, and if you have less than 7psi, it goes to zero.
 
There's a tech article on how to convert the oil pressure indicator in the cluster into a real gauge. Really easy, if you haven't already done it.

HOW TO CONVERT YOUR OIL PRESSURE GAUGE

Most MN12s have an oil pressure gauge on their clusters, but it's not an actual pressure gauge because the pressure sensor is just a switch and not a sender. The gauge moves to somewhere near the center of the range as long as there's at least 6-7 PSI. Increased or decreased oil pressure will...
forum.birdcats.com forum.birdcats.com
 
I checked it after the drive and it was in the full range on the stick. It was in the bottom half of the range though, so that's probably it.

Appreciate the article, as well.
 
Stock pan and pickup, as far as you know?
 
Just topped it off and drove it again. Took about 1qt to get from the bottom of the range to the top. All well now and no more lights.
 
I had to take Lazarus to the vet today, and on the way home, I was going to hit mcdonalds, and while I was in the drivethru line, I saw the check gages light come on, the oil pressure was dropping to almost nothing, and it's knocking like a bitch. I'm going toget the red one driving, and pull it before it windows the block. :)
With the rod knocking loudly, there's pretty much no chance on the crank being usable, wouldn't y'all?
 
much as I enjoy the oil gauge dance around with rpm and temperature with the sender mod as a pseudo low oil indicator the factory switch is just as adequate
 
Lazarus has been converted. It has to drop bad to turn on the light. It was dropping to almost zero. :) I've removed another can of gas out of the red Cougar, There shouldn't be another can.
 
You'r right matt, varying is pretty normal, but dropping to where the light comes on is bad.
 
Grog6 said:
I had to take Lazarus to the vet today, and on the way home, I was going to hit mcdonalds, and while I was in the drivethru line, I saw the check gages light come on, the oil pressure was dropping to almost nothing, and it's knocking like a bitch. I'm going toget the red one driving, and pull it before it windows the block. :)
With the rod knocking loudly, there's pretty much no chance on the crank being usable, wouldn't y'all?
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You'd have to mic it to be sure. Likely not useable, tho
 
I'm expecting it to window the block if I drive it again. I have dry days of 90 degrees for the next few days, so I'll go out to work on the red car early tomorrow, and see If I can finish with the old gas extraction. I think that, the radiator, The trans cooler lines are all that's left I've got to find my prp dongle by Monday, lol
 
Grog6 said:
I'm expecting it to window the block if I drive it again. I have dry days of 90 degrees for the next few days, so I'll go out to work on the red car early tomorrow, and see If I can finish with the old gas extraction. I think that, the radiator, The trans cooler lines are all that's left I've got to find my prp dongle by Monday, lol
Click to expand...

Honestly unless you're revving the piss out of it constantly, a modular will live with a rod knock longer than a lot of other engines before windows are made and connecting rods become souvenirs. It's just offputting hearing it.
 
Agreed; it sounds fucking bad at 2500 rpm. 3k sounds like it's coming apart, lol
 
Derphound01 said:
Just topped it off and drove it again. Took about 1qt to get from the bottom of the range to the top. All well now and no more lights.
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I worked with a mechanic years ago, he told me that the range between full and low is a standard on all dipsticks; 1 quart. Not sure if that is always true but so far it has been for me
 
On most cars that is the case. Bottom of the hash marks 1qt below capacity and top of the hash marks capacity.

On some Japanese cars, bottom of the dipstick hash means it's empty. A Honda friend of mine bought my old Jetta wagon recently for a cheap daily driver. He called me in a panic because it had been 4500 miles since his last change and the oil level was just barely a smidge above the bottom mark. He thought it had been run dry.
 
I've put maybe 20? But the noise get's more insistant every time I drive it
 
I went to harbor freight yesterday, as well as the vet. I'm hoping Kaatu is just pissed at me, he didn't come home last night. He's not one to miss a meal.
 
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