Question:

 

I bought an old 1979 Toyota Tercel and it has some kind of leak. My mechanic has told me it was an oil leak, maybe from the oil pan. He changed the oil pan gasket but it only stopped for a week or so. They have changed almost every seal but I still have this leak leaving spots on the driveway. I have spent more than I like to think about already. What do you think this leak could be?

 

Answer:

 

The shop should warranty their work. As far as the leak disappearing for a while after the oil pan gasket, that's probably from the mechanic cleaning down the engine when he was done with the work. It will then take some time for a small leak to work its way back down to the bottom of the engine. Either that, or there's more than one leak.

 

Leaks can be a real nightmare if not handled properly. Often a mechanic will put the car up on the lift and see an oil pan soaked with oil, automatically condemning the gasket or worse, a rear main seal. Then they sell the required job for a couple hundred dollars, and everybody's happy, until the customer comes back the next week with that same leak.

 

Just because a part of the engine is covered with fluid, does not mean that is what's leaking. The origination point may be higher up or further forward on the engine. The oil finds a hidden path leading to the part that's wet.

 

The best way to check an oil, transmission fluid, or coolant leak is with a black light. This method requires adding a fluorescent dye to the suspect component's fluid and then putting a few miles on the vehicle in order to get the dye out of the origination point of the leak. Then you can shine the light on the engine looking for the bright green area, and follow the glowing trail to where it begins.

 

I can't tell you exactly where the leak is coming from, but this is the best way to find out. And hopefully you're not seeing transmission fluid while the mechanic is resealing the engine.

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