Front cover o-ring resolve and OMP block-off
 

Hello, I have found quite a few threads that talk about the resolution to the front o-ring issue but the pics do not show up, which is critical I see what they are talking about. Can you point me to either a thread/webpage that covers the best resolve for the o-ring issue and also what all has to be done to correctly delete the OMP. Thanks !

when it comes to the OMP, what series do you have?

and the front cover is covered quite well here:
86-92 Front Cover "O"-Ring

Cool ! It's an '88 FC S4, so I am told. I bought the engine from a person so I didn't see the car.

I went to your link and that helps. I planned on installing the O-ring + teflon square O-ring setup from Mazda Trix, but I'm hearing there is a better solution that involves a copper crush gasket ? I have changed the pressure regulators by adding the 1/8" spacer in the rear and front oil pressure regulators already so I should be getting into the 110 pressure range. Yes the rear regulator is supposed to be non-modify-able, but it can easily be done.

I will be hitting the 8K RPM's routinely and using around 6K+ RPMs most of the time in a sand/dirt rail and I need the engine to last many years thus the persistance to be sure I use the best solution out there to prevent o-ring blowout.

What I ended up doing is have the front side housing machined and a hollow brass dowel pressed into the front side housing that just fits into the front cover. That way the o-ring cannot be pushed out of place and into your front cover and it helps prevent the low pressure drop at high rpm when the oil pressure pushes the front cover away from the front side housing and creates a big leak.

https://cimg6.ibsrv.net/gimg/www.rx7...d3f357a97f.jpg
Make sure that the dowel cannot be pushed into the front side housing and obstruct the oil passage- these types of engine mods can easily cause catastrophic failure if you do them wrong.

im with blue TII, it's a bit involved of an upgrade but it is something i wish mazda did in the first place as the front cover seal has always been a big issue even on stock cars.

an alternate method is to just bypass the front cover altogether, plug the front cover passage and drill and tap out the side brass drift plug underneath the a/c mount on the side of the iron, if you don't have air conditioning. that is about the only reason why mazda made it pass through the front cover was to accommodate the a/c mounting.

Now that is a beautiful fix ! What interference fit did you have... .001" - .0015" ? I have liquid nitrogen or dry ice available to aid in its installation. :nod: :D

I think that solves that one, now I just need to know, besides the addition of a stove pipe in the oil port for the OMP due to no gasket, what else needs done to delete the OMP ?

Brass has coefficient of thermal expansion of like 19 on the C scale and cast iron is more like 11, so I just had a very light interference fit into the cast iron front housing with a step so it can't get pushed in.

When you start adding materials to crack prone areas of the cast iron housings like the turbo oil feed by the top front dowel area I would only use materials that have the same or lower coefficient of expansion to the cast iron (like Stainless Steel or worked Iron/steel).

Good advice on the thermal expansion Blue TII. I will be making this sleeve Today and installing it tonight. The O-ring definitely would not have held up to the added pressure. I'll send pics of the brass tube install when done.

Concerning the OMP Deletion, attached is the pic of the set screw installed in the OMP oil feed line in the cover and I'm thinking since I am replacing the cover gasket with silicone, it will blow out under dead head pressure. What is the best way to do this OMP deletion?

I guess I could turn the engine front side down, tap the block with grease on the tap then vacuum it out then install a set screw. Thoughts?

https://cimg0.ibsrv.net/gimg/www.rx7...dc7e8d48f2.jpg

why would it blow out? i think you are overthinking the OMP block off, that seems suitable as it is.