Hello there, I'm sorry if this topic has been beaten to death, but I couldn't find anything pertaining to my specific scenario through search. I have recently purchased an 83 GSL, one of the ones with the beehive oil cooler. I was blissfully unaware of the dreaded dowel pin oil leak that these cars can develop which my car seems to be suffering from. I believe however that I am experience a leak elsewhere as well. I was looking for a way to mitigate my leak, the previous owner ran 5w-30 synthetic in the car, a friend of mine with an rx7 recommended I run a heavier conventional oil to help slow the leak. So I changed my oil today and switched to 20w-50 mineral oil. My leak which was previously a small dribble after driving the car is now a small puddle under the car. Can anyone explain to me why this would be so? The big problem area seems to be on the passenger side, I am still sort of unfamiliar with the engine bay of these cars so here is a photo of what seems to be the wettest area of the engine, it is right by the exhaust manifold. The bottom left of the photo seems to be the area that is the worst.

 

A dowel pin will normally present itself as puddling on the top of the engine. What you are showing here is the oil metering pump OMP. The gasket can go bad and leak like this. It can also be a bad OMP line or the OMP itself. They can be rebuilt.

 

Agreed. At least check the OMP (Oil Metering Pump) as a source, esp with the cryptic oil drop coming off the pump!
Its a pretty simple device. First/easiest thing to check, as said, is the TWO CLEAR plastic (nylon) lines that run up the front of the motor, from the pump body, to the Left (driver) side of the carb. Make sure these are intact and the rubber connecting "boots" are properly attached. If one of the lines has broken, it (obv) should be replaced. My understanding is that only the LONGER line (??) is still available new from Mazda. I believe others have made this line work in either position.
Second, if lines are OK, is the gasket that goes between the pump body and the front cover, Available from Mazda. Just be sure not to over-torque the 10mm bolts on re-assembly.

Nothing from this photo suggest a dowel leak. This typically is on the TOP driver-side of the engine, near the distributor; showing as a pool of oil on the housing, which the fan usually then sprays down the rear and side of the motor. This is treatable in some circumstances...
but one step at a time! First, the OMP.

Stu Aull
80GS
AZ

 

After checking the oil metering pump and lines as stated above. Clean the area with brake cleaner, and make sure to clean the front cover off well. As Stu stated above, I feel as though the front cover gasket may have hardened, requiring replacement. This is common and I recommend removing the engine to replace the gasket. It can be done in the car but removing it is the best way as there are thrust washers that can be lost upon disassembly or reassembly and its advised that these be replaced with new units and critical that they are put back accordingly and its much easier to do outside of the vehicle.