Common Oil Leaks On Rx-7's
   by Mark Schroeder
   mazrx7@onramp.net
   http://www.import-parts.com/parts/

This is Mark's speech about oil leaks on 79-95 Rx-7's.

1979-82:
   Oil pan gasket pretty common, as well as the oil injection tubes. Oil cooler lines usually begin to seep around 100,000, and will either get a little worse, or break. The crush washers on the banjo fitting on the rear housing oil cooler line will also leak. The cheapest, easiest fix is the oil filter stand o-rings, located below the oil filter. Very common, and if they've not been done, likely are leaking now. If the upper front rotor housing is oily, the internal o-rings around the tubular dowels are bad. This is not an easy fix. The engine must be removed in order to repair. The oil coolers are not prone to leak on that year model (see following).

1983-5 12A:
   Ditto the above except instead of the oil filter stand o-rings and oil cooler lines, substitute the oil-to-water oil cooler on top of the engine. Four o-rings in the cooler, all leak eventually, usually around 100,000 miles. This is obviously a concern, but the biggest problem are the two heater hoses that get soaked with oil, weakened, and explode at the most inconvenient time.

   The 'long' heater hose splitting due to oil saturation is the number one killer of engines in all cars made from 1979-1991. If the car is cruising under high load situations, such as highway speeds, and the hose breaks, the coolant will be gone in a matter of a few seconds, and if the car is not immediately turned off, the engine will warp in a VERY few minutes.

1984-5 13B:
   Not prone to oil injection or tubular dowel leaks, although filter stand o-rings and oil cooler & lines commonly leak in the 100,000 mile range. The biggest problem is the oil cooler splitting at the input flange (small crack, parrallel to threads). The only way to properly diagnose is to remove the underpan, clean the area with brake cleaner and compressed air, pressure washer, etc., and with the engine running, see exactly where the leak is.

   This also applies to diagnosing any oil leak properly. Many times oil leaks are confused since fan and moving car tends to swirl oil around.

1986-91:
   Most common leak is the filter stand, oil cooler lines, and the pan gasket. Not prone to injection lines or tubular dowel leaks, though the front pulley 19mm bolt likes to work its way out, causing oil to follow. Look for oil sprayed around fan and on hood. It's a good time to replace the thermo pellet as well, since everything is already apart.

Turbo II:
   Ditto above, but add turbo oil inlets/outlets. Do not usually leak unless not properly replaced if turbo has been removed. Many shops do not replace the 15-20 small gaskets, seals, metal lines and washers that MUST be replaced when removing the turbo for leak free results the first time. Same applies to engine jobs.

1993+:
   No really common leaks as of yet on cars that have not had substantial work. If replaced with Mazda rebuilt, the oil pan and sometimes front cover and other washers, gaskets and seals will leak if not replaced properly.

General & Conclusion:
   Front and rear seal leaks are usually blamed, but actually are very rarely the culprit. The oil filter stand or 83-85 12A oil cooler (or even oil pan gasket) can often appear to be coming from rear seal. Oil leaks in front of engine are often blamed on front seal, usually oil injection pump, lines or front cover if engine has been replaced and gasket not properly installed.

   Oil cooler lines should be replaced in pairs. I can almost guarantee that the one not replaced will leak soon after the other one is replaced, and it's easier to replace them both at the same time anyway.

   Oil leaks can obviously lead to oil starvation, but also attribute to other problems. Leaks saturate rubber, weakening coolant hoses and suspension parts. In addition, oil collecting on exhaust parts, heat shields, etc. can cause underbody/hood fires. That would be in the Bad Thing ® category.

   Hope this helps. It's easier and more cost effective to do it at your convenience than the cars. More rotarys under 130,000 miles die due to oil startvation and overheating than engine mechanical failure (turbo cars excluded). So everyone, pressure wash your engine compartment, find any leaks, and fix them!! Just make sure you have good ignition wires, or your car won't re-start!