Locating oil leaks...doh!

[Wade Nelson]

Doh! Oil from gasket/seal leaks generally flows downward and towards the rear of the car from the site of the leak.

It generally does NOT flow upwards, against gravity, or towards the front of the car, against airflow.

Seems fairly simple, doesn't it?

If you've got a leaking rear seal, transmission rear seal, whatever, the oil can get slung in a circle AROUND that leaking seal, and perhaps drip back down, but it's generally pretty obvious what's going on from the road grime that sticks to the "circle of oil."

Oil almost NEVER appears ABOVE the level of the leak, unless slung.

Case in point, I take a 2000 Grand Cherokee Limited 4x4 in for a pre-purchase inspection. I observe the transfer case is covered in oil and road grime. Top to bottom, front to rear. I even take a picture of it.

They diagnose a leaking "pinion" seal. They replace it.

When they go to top the thing up THEN they find the crack in the side of the case.

And expect me to pay for the repair/replacement despite THEIR mis-diagnosis.

Case #2. Ford F-250, "apparent" leak from rear main seal. Oil dripping from bottom of bell housing.

Working in the shop, I am told "REPLACE THE REAR SEAL".

Carefully observe: I am NOT told to "Diagnose the source of the oil leak and fix it!"

So I pull the tranny. Rear seal, inside of the bell housing is completely dry.

Customer doesn't have enough money to do additional repairs. Shop owner wants me to "mislead or misdirect him" that the rear seal was leaking also and

go ahead and replace it "anyway." (One more reason why I quit wrenching...)

The oil was leaking from a turbo or turbo line ABOVE the bell housing.

There would have been precious little way to spot it, short of knowing where to go fishing with a borescope ahead of time. It was indeed, very nearly invisible both because the oil was so clean AND the transmission blocked viewing the source.

But had the tech / shop owner who "diagnosed" the oil leak looked carefully at the "spray pattern" they probably would have observed oil on the outside of the bell housing, where it was dripping down from the leaking turbo.

What SHOULD have happened in both of these cases? Add some fluorescent dye, go drive the thing 10 miles, come back and put a UV light on it to see where the oil was actually coming from.

Some people have eyes but can't see even if you turn off the lights.

Don't think I'm on a high horse, I include myself in that group as well for numerous violations.

But maybe I can save you from "joining the club..."

Edited February 28, 2013 by Wade Nelson

[Hardway]

The shop owners seems to reflect the way much of corporate society seems to be moving, inpatient and greedy. Properly diagnosing a problem and not just throwing parts at it takes skill, time, and money, the time probably being the more expensive of the 3. I have had the fortune of working with shops that have taken the time to properly diagnose issues when I had them. This is why it is so important for owners to do their due diligence when picking a shop to work on their car, old or new. If you have the misfortune of dealing with a shop you feel has not been fair to you, stand your ground, ask questions, talk to the manager, ask them to work with you, etc. In many cases you have to pay the bill to get your car back. Once you do, talk to some more shops, get a second opinion, ask your friends, etc. Depending on how much you had to shell out to get your car back, talking to an attorney and filing a civil suit may be warranted. However, make sure you are in the right and you have your ducks in a row before doing so.