Mid rebuild and I have this crazy idea for the coolant seals on the rotor housings. Im thinking about replacing the rubber ones for copper. I know crazy right? I have access to the tools and materials for the construction of them but how well does anyone think they will work? Wouldn't it be basically the same as copper head gaskets in performance piston engines? Any input would be greatly appreciated.

 

the motor is out of a '87 NA fc. Once again ANY input would be greatly helpful . thanks again!

 

WHY? What's wrong with mazda seals. A lot of effort for no gain, no?

 

I think there would be less chance of seal failure over a longer period of time. I'm trying to keep from rebuilding the motor more often then needed. Thank you for your input though.

 

Stockers should last plenty long enough. Seen them go 200K. Just dont get the engine to 240*. Pretty simple.

 

My only concern is that the motor is going to be used for racing and im just concerned about how long the seals will hold under that kind of use and for how many races before another rebuild is needed. Thank you for your comment.

 

As you might suspect, the seals do little to maintain compression or high pressure gasses in the engine.



Neither of the seals would live more than a few seconds exposed to high temperature gasses. The outer (black) seal just keeps the water from falling into the oil pan. So, it need not be very effective to work just fine.



The three piece compression seal is just a bit more effective, in that over time (each heat cycle) combustion gasses leak into the seal groove and force the seal against the outer groove wall where it is compressed and thus pressure on the walls goes up to some number and that added pressure helps seal in the gasses.



So, on very high mileage engines you may find the the inner seal has turned into mush, from cyclic fatigue and may even leak a bit of gas into the water and cause overheating or have a hose blow off, or the end cap of the radiator blows off. Barrs leak won't help you here. But this cyclic failure is a long time coming. Mazda used to provide in gasket sets a "V" shaped strip of metal they called a "seal protector" It was to be installed outboard of the seal along the outside of the seal. So it protected the seal how?



By consuming some volume, and increasing pressure on the seal along the combustion side of the housing. That idea was dropped some years ago, and the seals still hold up very well without them.



The retention of combustion gasses is done by the smooth iron and aluminum surfaces of housing and iron being crushed together at tons per square inch by the case bolts.



Any "O" ring applications book will take you through the process of sealing.



A soft copper that can comform to the imperfections in the seal grooves would work for a while, but must rely on the crush fit from being taller than the seal groove. A bit of silicone and the right size wire would work fine for a while. Just about anything will work for a while.



Many fine "O" ring materials are available on spools of 500 feet, and not all that expensive. Just a drop of silicone at the joint and you are good to go.



However, the three distinct materials used by Mazda are not for looks. You need good static pressure for the life of the engine. Fatigue resitance from cyclic pressure changes, and the wear resistance needed for movement in the groove. So there are three pieces in each seal.



If you race, and have the engine apart every weekend or even every few weekends, then the seal material just about doesn't matter. Anything will work for that long.



Lynn E. Hanover

 

Thank you. Your response has cleared my problem up for me completely. I know what im going to do now. Thank you for the information.

 

Im not sure if he's on this forum, but Peejay on RX7club has had success using high temp 18ga (pretty sure) high temp electrical wire.

 

Go to the low end of torque spec and the engine will tolerate 240F just fine. It won't make much power up there but it will not drink coolant after it cools back down.



This is with stock seals or the cheapskate electric wire seals. The coolant seals are not the weak point in the engine.