When I dropped this engine in, I installed a new RMS. Inside of it looked good, I didn't scratch anything. Used the drill a hole and thread a screw in a couple of threads and pull method. Used the flyin miata installer tool to put the RMS in the right distance. Oiled the seal prior to install.

I had a slight leak I was concerned could be contaminating my clutch, since I didn't know if it was RMS, trans, or flywheel. Pinpointed it to the bellhousing weep hole via UV dye (which also proved it is engine oil, not trans oil.)

Being absolutely over this at this point, I paid my mechanic to find the leak (mainly to ensure my brand-new FM level 1 clutch wasn't getting oiled up.) Fortunately, it was not, it was still RMS.

He tracked it to the RMS (pulled trans, looked at dye). He figured I goofed it up or got a RMS that had a crease in it or something, and put in a new one, bolted it back up, and it's all good.

Now I saw some more oil come out.

It's not a lot of oil, and now I'm reasonably sure it's just more RMS leakage and not affecting my clutch. It appears to probably happen primarily when engine is cold and first started, although it's hard to say.

My oil pressure from my 94 OPG is about 60-ish when I first crank it, which rapidly becomes 70-80 if I give it any gas at all. I try to baby it until it warms up enough to not go past 60psi (probably a couple of minutes to hit 120-140F).

So, sorry for the rambling. Here's the question: me and the mechanic have both put in a rear main on this car, and they've both leaked. I'm not sure we're both that derpy.


tl;dr: Is there anything else I could check (PCV issue or anything?) that might cause oil to blow past the RMS besides us just derping it up? Are the pressures I'm seeing too high when I first crank it or anything? According to search, no, but I'm wondering if I'm missing something. Trying to figure out if I should just let this go. At 500 miles in, I put in about a quarter of a quart of oil to top it off, and the leak has slowed down since then. It doesn't drip on the ground, only when I'm driving.

 

I don't think oil pressure has anything to do with it, since it would be crankcase pressure that would push oil out past hte rms.

definitely check pcv system

 

Not all RMSs are created equal. Mazda OEM? I learned the hard way (like you're doing now).

 

Did you put thread sealer on the flywheel bolts? Those holes in the end of the crank are through holes, not blind.
I didn't do this once in my early days and created a leak for myself.

 

What he said. This sucks to learn the hard way.

 

I created myself a RMS leak last time I pulled out the engine for a new HG.. that was 2 years ago. This winter, the engine is getting out for a rebuild... and I must say, a RMS leak is my biggest fear. Share you RMS install hints!

So far :

- Flyin Miata tool
- OEM RMS
- Thread locker on the flywheel bolts

Anything else?

 

That's about it. For a full job you wanna take the pan off, take a softer wire wheel to the gasket surfaces and block, have the oil pan and windage tray jet cleaned at a machine shop, clean everything again, and again, and again. Then lay a nice bead of fresh copper RTV on the block with some fresh seals, the wintage tray, another bead of RTV, and torque the pan to spec.

Step one is technically removing and cleaning the RMS bracket, replacing the seal with a new one, along with copper RTV on both sides, torqued to spec, and then shaving off the excess dried RTV and gasket from the pan surface.

 

Well, I definitely used an OEM seal, not sure about the mechanic. I also used the flyin miata tool when I set it. The flywheel bolts were my big concern, because of fouling the clutch - I did put loctite on them, but didn't realize until I was already done that thread sealant was actually recommended because they need to seal. The mechanic already pulled the trans and verified that the leak is coming from the RMS, not the flywheel bolts, but he re-sealed them anyway.

I'm also seeing an occasional leak out the front, presumably from where I did cam/front crank seals. Those are definitely OEM and I used the flyin miata tools all around.

This is a very small leak and it only happens sometimes. I can't just let the car idle or I won't even see it drip. After my mechanic broke it down and put in the second rear main, he let it idle for a pretty long time to verify no leaks, ran it around the block, etc. Its more like after a hundred or two miles, I might see a spot on the bellhousing. Nothing on the ground. With the front, maybe every 300 miles I'll see a spot on the front of the oil pan below the front crank.

Which makes me really wonder if my PCV is not opening up. I just pulled it yesterday, and when I rattle it, it sounds like it has **** in it. My last engine spun bearings and I pulled a HUGE chunk of metal out, is it possible to have gotten small bits of crap in there that are holding it shut?

I figured I would go replace the PCV valve today either way, they're so cheap.

Thanks for all the input guys, super helpful as always.

 

AFAIK, the rattling noise out of the PCV is normal. But like you said, they are so cheap, worth replacing. Take a look at the 323 GTX PCV Valve, It might be better for your setup.

Thanks Curly for the hints.

 

I mean, yeah, I am aware that the PCV is supposed to rattle, having a valve in it. I meant that it doesn't sound like the new one does, it sounds like it might have crap in it and isn't moving as easily. *shrug* Hard to say, and I didn't want to blow on a PCV with oil all over the engine side, because I'm a princess and gross.

Thanks for the tip, although I thought that was for turbo cars? I'm still N/A.

We'll see if it helps, if not, one of the benefits of paying my mechanic to look into it is that it's his problem if it still leaks.

 

doesn't matter if turbo or n/a, one is supposedly just stronger than the other.