So, I've got my motor torn down and the housings/front cover are currently at the blaster getting some baking soda lovin'. Since I cracked the front plate on the dyno several months back, I decided way back when to replace both outer housings and cut a pair of new bridgeports on already un-touched, stock housings. I picked up a pair of S4 turbo front/rear plates (one was given to me by my friend Bob Mulligan; thanks Bob) not too long ago. While I was eyeballing the work I needed to do to remove the plug at the front oil galley to drill/tap for a 1/4"NPT to -6AN adaptor (oil loop line to the front stationary gear for those that aren't familiar with it), I noticed that I'd forgotten that I'd downgraded from the earlier S5 housing to the S4 and that it has the skinner land for the front cover o-ring. In this case, it's designed for the o-ring alone and not the teflon ring/o-ring pair found in the S5's and all later 13B's.



I've been thinking about this for awhile. That front cover o-ring, especially on the older housings, has not only been a sore for me in the past (two, separate 10 hour fun days into tearing the front cover off to replace that o-ring) but also many others. It strikes me as counter-intuitive, at best, to have a silly o-ring as the main seal at the front of a long lubrication path that ultimately depends on that o-ring from not shearing. It's quite easy for it to shear even during assembly if the engine isn't up on a stand (and isn't upright) and is level.



Let's take a peek at the oil galleys in the front iron: There's a vertical galley machined into the iron for the front cover o-ring land and there's a long, lateral galley machined from the oil pump outlet cast, past and through the front cover galley, all the way to the edge of the housing (spark plug side). Oil travels from the pump outlet cast through the lateral galley and up to the front cover o-ring land galley -- hits the plug at the end of the lateral galley and at the bottom of the front cover o-ring land galley. Once it travels through the iron, it goes front-ways into the front cover and splits off in two directions -- one towards the threadding for the front cover oil line (banjo, AN, or whatever) and another down towards the front cover oil pressure control valve (spring-loaded valve).



My idea is a simple one but it's contingent on the actual, practical usefulness of the oil pressure control valve -- I understand it is an over-pressure valve but I'm unsure as to what actual pressure it activates. I'm also unsure as to whether or not it's even necessary in the first place since I would assume the oil pressure regulator located on the rear iron is what actually regulates pressure in the entire system. If it's not practically useful, then why not drill and tap the lateral galley in the oil line for some sort of metric to AN adaptor (for the front cover oil line) then drill, tap, and plug the o-ring land galley?



B

 

the thing i had pictured in my head to sort of fix the problems of the o-ring are hard to explain. disclaimer being that with problems like these i think common sense an not really scientific, so it may be completely horrible thing to try.



but picture alittle cylinder which can slide into the hole on the front cover.



now the bottom "lip" of that cylinder make it flat and fit in to the spot on the front iron (basically the same size as the o-ring)



now slip the o-ring over that cylinder and push it against the lip.



Insert cylinder into front cover.



Install front cover.



theres no real chance of the cylinder falling out and you not noticing it and the o-ring will still seal it perfectly, in my mind at least.



anyone who wants to give that a shot, go ahead i dont build motors often enough to test it.



kevin.

 

OEM oil system in the rotaries is like piston motors in the 60s; horseshit.

I've tried what you're talking about.

 

The "O" ring poping out on a cold start has been killing engines from day one. It gets worse with increased oil pressure, and after the 12A with the front relief set at 100 pounds, and then moved up to 140 pounds.



One could imagine the "O" ring surviving if the relief valve behind it opened on a cold start. But if it is set at 140 pounds, it may not open quickly enough, or the front cover is flexible enough that the stock 140 pound setting is of little value in protecting the "O" ring. The problem is that the front cover is flexible enough that an episode of higher than rear relief oil pressure, will just push the front cover back off the "O" ring junction,

and the "O" ring pops open on one side. The cover reseats with part of the ring trapped in the junction, and sealing is lost, along with most of the oil pressure.



A number of possibilties for a fix come to mind. Many sources suggest leaving out the front cover gasket in order to apply more pressure to that junction. Well, leaving out a .015" thick gasket to gain a pound or two of extra pressure at the junction seems a bit hopeful.



If you want to continue using the front cover outlet for taking pressurized oil out of the engine, may I suggest a all metal replacement for the rubber "O" ring. In aluminum perhaps. About the thickness of the original rubber "O" ring, so when in the spot face in the front iron it will extend above the edge of the hole.



No sealant at all just a flat sided replica of the stock ring. Used with or without the front cover gasket.



It might not be a perfect seal, but perfect is not required. The ring could not fail from the cover moving forward. If there is a fear that the ring might shift and cause a similar problem, a similar piece could be fabricated with a short hat section. Like a ring formed on the end of a short thin walled tube. The tube OD could be a light press fit into the oil gallery in the front cover. Now it cannot shift at all and the preload caused by its extra thickness prevents leaking. This fix would stay in the front cover and could move from engine to engine. Or just make up several and install one in each cover.



If you want to take the oil out of the front iron from the latteral drilling, then you could use a solid aluminum button to close that junction. Same as above but with a .020" hole in the center to provide oil to the OMP, for street use.



There you go. Problem solved, at no charge.



Lynn E. Hanover

 

I have used the Renesis frontcover metal gasket in my 6-port, 100+ psi streetmotor



No o-ring needed, no leaks no problems

 

Why not use a copper "crush washer"? Something should already be available that will fit...

 

Ok -- Is the overpressure valve on the front cover absolutely required? If not, then it's a no-brainer.



B

 

my friends been doing this for a while too. i've been using the rx8 gasket, but i keep the o ring.

 

the newer 13b-rew gaskets are the same also, with the metal o-ring replacement do-hicky.

 

So long as it starts out as thick as the original or dlightly thicker.



Sounds good to me.



Lynn E. Hanover