I got back from changing the oil, and it looks like there is a small leak in my '03 Ford F150. The truck runs great, no fluid is ever on the ground, but around the rear dif, there is a collection of oil around the seal.
It looks like around the oil cap on an engine at about 100k miles.
So, it’s not a huge leak, more like a blowby thing. Is this critical? Should I replace the gasket immediately or is this a wait forever, not a big deal thing?
Thanks in advance.
If it’s not wet enough to drip, it doesn’t justify a repair. Just make sure that the level is checked occasionally. It should be checked as part of an oil, filter, & lube service.
I know this is a silly question, but how do I check the fluid level in the rear dif?
Pull out the plug and stick in your finger. If your finger doesn’t get wet, add some ninety weight.
That’s reads rather funny, but it’s correct. There should be a threaded plug. I don’t remember if it’s on the front or the rear of the differential on Fords. The plug is located at the level at which the differential should be filled. If you can’t feel the oil with the tip of your little finger, add some.
To expand on that a bit, typically the plug will be on the front half of the differential, probably on the right side, roughly halfway up from the bottom. It has a 3/8" square hole that can be engaged with the end of a 3/8 extension.
The fluid should be checked with the vehicle level. If fluid runs out, let it run until it stops (or nearly so). If it seeps out of the hole, it’s okay. If it doesn’t come out, you can check with the finger method described above, or make a dipstick out a few inches of wire (coat hanger, etc.). Make a 90’ bend about an inch from the end of the wire, stick that inch into the hole and lay the long end of the wire flat against the bottom of the hole threads. Pull it out and see how close the fluid is to the bend. Ideal fluid level is up to the bottom of the plug’s threaded hole, but up to 1/4" low is acceptable.