Hey guys, I just put together and dropped my new VVT engine into my NB2 Miata, 2002. I put in a rebuilt long block with rods, pistons, BE oil pump, and completely refreshed head.

I've broken the motor in and after 100 miles I just have oil everywhere. It's on the subframe. It's on the passenger control arm. It was all over the inside of the passenger front wheel. Just everywhere. I have two visible leaks:

1. Oil coming out of the bellhousing weep hole at the bottom. This oil is very dark, possibly contaminated with the dirt inside the bellhousing.
2. Oil coming down the side between the bellhousing and oil pan. It drains down to the bottom of the bellhousing/oil pan mating area, where it drips. Tracing the leak, it appears to come up from the top.

I thought maybe I had forgotten the copper washers on the lower VVT banjo bolt, but I pulled the bolt put and there were indeed two washers. Putting that back together was a real pain in the butt.

Looking at this, I've got a few possible causes:

1. Rear main seal: The motor has a brand-new rear main seal on it, but it's possible that this is "new old stock", meaning although it's new, it's been sitting for so long that the rubber has dried out and no longer provides a seal.

2. Rear oil pan half-circle seal: Same deal. Possible that this is just an unused but old seal.

I would also like to note that the half-circle seal was sorta installed incorrectly. The seal has these two small "flaps" on the edges that are meant to be captured underneath the MBSP. When I put the MBSP on, I suppose the flaps sorta moved out of the way and were no longer captured. I figured this wouldn't really be a problem as there is RTV in that area and it's relatively small.

3. Improper RTV application: I applied the RTV the way I've sorta always done it, and the way I've seen my mechanic friends do it, which is to apply a bead, spread it evenly along the flange, wait 5-10 min, then mate with the part. Bolt it down hand-tight, wait an hour, then torque it to spec. I've done this before with success. Is it possible the oil pan could be leaking in the rear from this?

Please let me know your thoughts on what I may have done wrong and what might be the best way to correct it. I'm considering removing the engine again to redo the oil pan gasket.

 

Spray the whole thing down and pay attention to where the oil is coming from after it is clean.

 

Sure doesn’t sound like a valve cover leak. The kind of leak you describe would be easier for me to fix by pulling the motor and tranny to reseal it on a stand. I personally wouldn’t even spend very much time diagnosing it. Just pull and re-do the pan and rear main seal is what I would do.

 

Oil gallery plug or rms

 

The plugs were removed and the interior cleaned out, so this could be a possibility.

I'm gonna make extra sure it's not the valve cover gasket, if not I'll just get started with pulling the engine.

Just really sucks because I just finished dropping it in.

 

Check the dipstick o-ring. Seriously, there are several places it could leak back there that don't require an engine pull.

 

I replaced that o-ring, it's also leaking from the side opposite the o-ring. I wish it were that easy.

 

I feel your pain. My big lesson was trying to do a “quick” replacement of the front crank seal that was puking oil. As I put the ATI back on, the stupid key pushed thru and I didn’t know it. Timing belt back on and turned the belt twice with a wrench. The stupid key had pushed through the seal at an angle and ruined a brand new BE pump. Cried for a few minutes and then started unhooking everything to pull the whole dang motor and tranny again. I’ve done the pan replacement by dropping the front subframe too and consider that strategy to equally suck plus it isn’t easy to get a good pan seal with oil continuously seeping down on you.

 

So I took sixshooter's recommendation and took a look at the oil galley plug. I cleaned them up with brake cleaner, started the engine and waited for it to warm up, then put a blue shop paper towel on it. Sure enough, it came back wet.

But not very wet, not wet enough to suggest the amount of leak there is. Then I noticed that the VVT pipe near the head is wet. Dry it off, gets wet again. I blast the whole thing with brake cleaner and observe the upper banjo bolt, specifically near the washers. Sure enough, it's leaking on the inside washer. Give it an extra tight torquing, still leaking.

Pulled off the banjo bolt and both washers. The inside washer is the same ID and OD as the outside washer, so I don't know why it would be leaking. It doesn't have any obvious deformities either. It's just somehow compromised and leaking.

So the good news is that I don't have to pull out the engine to fix this, however it's still possible I may have a bad rear main seal because there's oil coming out of the bellhousing weep hole.

 

I run this stuff in my car and generally like it. Definitely makes diagnosing oil leaks a lot easier.

 

Did you remember to put sealant on the flywheel bolts?

 

Use a good fluorescent leak detection kit. Once found, change your oil and filter.

 

I put on blue threadlocker, is that all I need? I've never heard of needing to seal the flywheel bolts. Aren't the holes drilled and tapped directly into a solid part of the crankshaft? Why would oil pass through there?

 

The Flywheel bolt holes are through holes on the crank

Per the Factory Service Manual:

 

WHELP, I SURE HOPE LOCTITE DOES THE JOB

Anyway, turns out it's not engine oil leaking from the weep hole, it's gear oil. I probably installed the input shaft seal incorrectly. Yay.

Whatever, I'll wait for the transmission to grenade and swap to a six-speed.

 

Loctite is typically used for this.

 

This sure sounds exactly like what I had. (except I didn't have as much as you). That Banjo bolt for the VVT oil is a pain to get correct. I used the glowing oil additive to positively identify it. New copper washers, flat/clean surfaces and torque it down as much as you dare.

The weep hole on the bottom of the tranny can be very sneaky. Because it is a low/rearward point behind the engine, the oil tends to flow back from the engine (near the oil plug) and then drip down and around that hole. So be wary of the actual source, you may not have a leak at all.

On the other hand, tranny fluid stinks to high heaven. So if the smell from the hole is stinky, you've got a crappy fluid coming from your tranny.

 

Loctite 263 seems ideal, and 272 seems ok. Do you have any other suggestion?

 

If you are leaking that much gear oil, your clutch is going to be trashed very shortly if it isn't already. Fix it before driving it.

 

We used the Red 271, or 272: and the bolts came out fine when we changed the flywheel later.

But, honestly, a 243 or other blue should be fine.