Permanent does not make sense. If a fastener is very stubborn or does not have a good drive, a little heat can be applied from a propane torch.

 

I can build you one that don't leak. Mine is dry, and went in my car in 2017 or 2018. Sees more boost and RPM than most and no leaky.

 

I'm going to agree with pat here, BPs shouldn't leak if built properly. I brake clean the flywheel bolts and wire brush them, apply blue loctite, and they don't leak. Biggest issue I've had with leaks is 6-speed cases leaking. I've resealed a few, but the labor and minor leak aren't generally worth it. That's a foot or two behind the weep hole though.

 

 

On boosted cars, crankcase pressure can help to push oil out of seals. Especially if using a PCV valve instead of venting. PCV closes in boost (if working) and that leaves the breather vent on the hot side that you can't even fit your pinky into.

 

I never said all turbo BP engines leak. Most unfortunately do, they are difficult to seal by design. The high heat and vibration just turns blue loctite into powder. Would definitely recommend using sealer around the through holes in the flywheel. I used silicone, but anaerobic sealer would also work.

 

As an update on mine, the engine builder asked for compression and leak down before the engine was removed from the car
1:140
2:80
3:140
4:140

Number 2 had 80% leak down.

Oil did not improve the numbers, and it sounded like it was venting through the intake side. I don’t think that explains the rear main leak.

The engine is now out and with an engine builder to strip and assess.

I will report back with what is found.

 

Leaking rear radial seal is one of the biggest pains in the rear. I never had problems with them, even though I many times didnt loctite the bolts or used special tools for installing the seals, but I am always careful of:


Before installing the new seal, always inspect the contact area on the crankshaft where the old seal was running. It is usually a very shiny polished 1mm wide strap around the crankshaft. Inspect this shiny ring for any damage or dents or scratches which could harm the radial seal. If damage is directly there, check if you can install the seal a little deeper or less deep to avoid it. You will have to clean the surface well also in this case.

Be careful about area after this shiny surface(towards gearbox), which is usually surface rusty/brown colored and harsh. I think installing the new seal not deep enough(usually 0.5-1mm deeper than cover outside plane), rubber will run on this rusty material and get sanded/destroyed where it contacts.

Also, always make sure that the seal skirt is facing inwards, seen cases where people installed radial seals the arong way around, since they probably felt they fit better this way. Taper on radial seals always faces inwards, use the tool to install or gently work the edge around being careful not to cut or fold the inner contact area.

Last thing I would suggest is not to lubricate the outer(gearbox) side of the seal and crankshaft too much. Dust from clutch will stick to it and also create abrasive acting film. This is the old advice from suspension guys from motocross, the trick is that oiled fork seals wont last long since dust and sand sticks to it and creates the same effects. I always lubricate crank surface with finger sticked into engine oil evenly around and only inside surface of the radial seal, not too much.

Never had issues, hope someone solves those nightmare situations. Good luck have fun!

 

The crank surface the seal rides on was damaged from a past seal removal.

The compression loss was a valve not sealing properly.

The speedy sleeve had been installed too far in and had ground itself to clearance on the main cap.

The engine is back together now, fully rebuilt (rings, bearings, seals, different pistons, and billet main caps). The damaged crank surface was polished out and the seal smoke tested (pass) once the engine was assembled.

Four years on, I hope this is it.

 

I also have a Turboed Miata with a VVT and I am currently on my 3rd Set of OEM Mazda Half Moon Seals, probably 4th rear main and so on. I got the front end completely dry but it’s still seeping through the transmission hole. Went in with a camera and sure as hell it’s oil coming from the engine. Rear main as well as Half Moon seal is the correct one since the VVT has different ones as to a non VVT BP. Went with a OEM Mazda rear main seal also.

im not sure if it could be through the Flywheel bolts, since I have only used red loctite and never gave too much attention to cleaning the bolts. I updated my Catch Can system with 8AN fittings to the valve cover so it’s much bigger diameter than OEM. Tried venting it to atmosphere without the catch can but still seeping.

also running a Boundary Pump and complete build engine. Maybe the crank surface where the rear main sits is not alright. I would like to try to run the engine without the transmission so I can see where exactly it comes from. Loosing my mind here.

are there any updates how it’s holding up?
TheAustralian and Stoffl?

 

how is it holding up?

 

Do you have an update?

 

So yeah assumption that either engine builder or machine shop fucked up was confirmed. Sealing surfaces, crank, oil pump, head / cams - all fucked and scored. Some debris must've remained during the rebuild.
Didn't want that money and / or engine anyways~

 

Wth man. Did you get compensated at least?

 

Lolno, it was built in 2023.

 

Oh yes, this Thread is old

 

Mine is now fine, with no leaks.