Here's a stumper.........Buddy has a 93 F-150 4x4 ex-cab 302 E-4OD, runs great no troubles, except for a oil leak. Looks like the rear of oil pan or maybe rear main seal, no leaks above on manifold or valve covers........Here's the stumper, it only leaks when sitting and shut off!.........not when running!..no spray of oil down the underside of truck, all dry. Oil level is at full, not overfilled. Truck has done this for about 2 years according to him. It will leave a 10" diameter puddle of oil on the driveway overnight, and he only has to add maybe a 1/2qt between oil changes even with a leak this big. I am stumped........Ideas?

 

Check the torque of the oil pan bolts. The soft neopreme pan gasket can squeeze out from between the pan gasket surface and the block. The pan bolts are low torque and can loosen up after a period of time.Or the pan gasket can easily be overtorqued and cause leakage when cold. Seems to occur right above the starter and the rear six inches on the driver's side of the pan, on the 5.0, especially.I had about one half inch or more of the gasket squeezed out.

My truck also leaked only when parked and all I had to do was give each oil pan gasket bolts one,two turns or so to loosen the bolts-and then reposition the neopreme gasket into place and then retorque the bolts in the proper sequence and to the correct torque. Do this with the oil in the pan-the weight of the oil helps to pull the pan down and allow the repositioning of the pan gasket.

I did this to my 92 F150 five years ago and it hasnt leaked a drop since.

The 10inch oil spill does seem a bit much though . I suspect that when the engine block,gasket, oil pan heats up-it tends to close the gap and lessens or slows the oil loss during travel and at operating temperature.And if you park on a hill-the oil will tend to leak out more than if the parking spot is on the level.

 

Thanks, Phoneman!........Thats the area we suspect, we parked it nose down last night and the leak was FAR less. We have not put wrenches to it yet, but depending on what the pan gasket looks like we may just replace it completely.......Starting to suspect it may have the wrong oil pan or dipstick on it, the oil level should not be that high in the pan. This truck was a kids "plaything" before my buddy bought it, and has been butchered.

 

Could it be tranny fluid instead?

 

The OP said that he had to add engine oil to replace the oil lost .

 

mine does that too, its the rear main seal... oil collects in the bell housing then leaks out... doesnt leak when on level ground

 

1/2 quart is minor add. That could be burned. Shoot I have 4.6 that goes through an oil changes worth of oil between oil changes and not a drip anywhere. No smoke either.

 

Good point. Almost any vehicle will use 1/2 quarts between changes. Dang-Ford says that a new engine that uses less then 1 quart per 900 miles isnt a problem!

I have a 2001 GT Mustang 4.6 that doesnt use any oil at all! I have actually measured the oil that comes out. One of the few vehicles that I have owned that have never used ANY oil!! Of course-driving like an "old man" may have something to do with it!! (Now if I can only convince the Police of that)

 

"Yes sir Officer, I could not have been speeding since doing so would have burned oil, and as we can see the crankcase is still full"

LOL. Love it!

Back to the topic.

 

Gee-I never thought of that-I have already tried the :"office-my dog ate my speedometer wire/cable and that was why I was doing 110 in a 45 zone ".

 

I am suspecting the RMS now.......It has a re-built trans, they probably screwed it up when installing the trans.

 

If you crawl under when it is dripping, the drip will tell you if it is motor or tranny. Tranny fluid will spread over the ground more easily and look like a lot more than oil will, on the ground.

 

Nope, its definitely motor oil. It appears to be coming from both in front of the inspection plate and behind it. Still cant figure out why it does not leak when running, we cleaned the area off with rags and drove it 20 miles, no leaks........It sits for 45 minutes after driving and now has 4" puddle of oil underneath the rear of motor/ front of trans........drip..........drip...........drip