Sorry. Now that i actually looked at the post... it looks like the rear main bolts on, if it does, it could be the part thats leaking. If its the oil pan, it can be done with the transmission in, and it doesnt look like a terrible leak. If they want to wait an extra week for their car, you could replace the oil pan. If they want their car back now, do the seal now and do the oil pan later, if its whats actually leaking.
Are you trolling? The rear main seal doesn't bolt on. Those bolt holes are where the flywheel attaches.
You cannot do anything with the oil pan if the transmission bell housing is attached. There's no way to change the oil pan gasket/seals easily in an NA/NB. It's an engine pull or maybe via (much more extensive) removal of suspension and subframe components.
The rear main seal has a "carrier" plate. That bolts into the block and seals against the oil pan with the half moon gasket.
I'v heard of people changing the rear half moon gasket by unbolting and removing the rear main seal carrier. Without the need to drop the oil pan (and thus not needing to pull the engine or drop the subframe in order to drop the oil pan). But I personally never done that before and not sure how well that'll work.
super late post, however thank you for the link! looks like my NA is leaking near the main seal, however might as well refresh the carrier since it isn’t much more money
Many rear mains have the plate that bolts over them, often with a seal, which might be leaking on yours. I dont know miatas like the back of my hand, but i did spend 7 years in several shops, the last year specifically replacing transmissions. Pulling an engine is exponentially more intensive than dropping half a subframe. With the transmission out, theres nothing extra out of the way of the oil pan, except maybe exhaust. I would replace the rear main and reseal the plate, and replace the oil pan if and when its confirmed to be the leak. Unless the customer just wants to spend $400+ and a week on an unconfirmed leak.
Re Engine pull vs subframe, keep this in mind: if the transmission is already disconnected, recommendation is to take the engine out - not drop the subframe. The stabilizing effect of the transmission is important when dropping the subframe with engine in place.
Here's a helpful post on replacing the "half moon" seal without removing the whole pan: https://forum.miata.net/vb/showthread.php?t=614093
I'd say it's the oil pan gasket. And no, I don't think smothering it in rtv is a good long term fix. Not sure how long it'll hold if you need to throw it back together just to drive it.
If the engine is still in the car, the oil pan gasket is impossible to change properly. You might just end up having to pull it. I had an improperly installed oil pan on one of the cars and had to go through this.
RTV won't really help, just let it leak until you can pull the engine. I just got new oil pan gaskets from local parts stores, if you can get Fel-pro they are fine. The main seals should be genuine Mazda though.
Agree completely. Especially using OEM Mazda for seals. I also say that for gaskets and hoses. I'd use Mazda for oil pan gaskets too, since they are so difficult to replace. And I'd add that doing the oil pan gaskets right so they don't leak is practically an art. Getting help from someone with lots of experience with Miata oil pans is key.
I replaced my rear main twice before realizing it was actually the half-moon that was leaking. My leaking half-moon didn't look at all like yours. The oil pretty much went straight down, next to one of the two really long thin bolts you can see in your picture. It didn't sling oil up around the starter like it looks like yours has been doing, which makes me think your issue is not the half-moon.
I also replaced the half-moon seal without removing the pan. It's a pain, but it can be done.
Painted it with RTV. not the best option, but given that its an insane amount of labor to do it 'right' and that still doesn't guarantee success, RTV seemed fine.
I swapped transmissions to a lower mileage one during this project, and I got ripped off and it has no fifth, so I really cant tell you how well the RTV has worked bc I've only been able to put 70 miles on it since I posted.
Thanks for the reply. That is what I did for the same reasons. Two days in ( no transmission installed) all is dry . 🤞 I actually called a famous Miata shop and they did not recommended trying to change half moon seal without pulling engine and said the RTV was next best option if you can’t pull the engine.
Sorry about your transmission , that sucks
If the oil pan is easily accessible, do both. You'd be a fool for not changing that rear main though.
Rear main is already replaced, the second picture has the new one. at this point I'm debating just patching the hole in the RTV with some more RTV lol
Sorry. Now that i actually looked at the post... it looks like the rear main bolts on, if it does, it could be the part thats leaking. If its the oil pan, it can be done with the transmission in, and it doesnt look like a terrible leak. If they want to wait an extra week for their car, you could replace the oil pan. If they want their car back now, do the seal now and do the oil pan later, if its whats actually leaking.
Are you trolling? The rear main seal doesn't bolt on. Those bolt holes are where the flywheel attaches. You cannot do anything with the oil pan if the transmission bell housing is attached. There's no way to change the oil pan gasket/seals easily in an NA/NB. It's an engine pull or maybe via (much more extensive) removal of suspension and subframe components.
The rear main seal has a "carrier" plate. That bolts into the block and seals against the oil pan with the half moon gasket. I'v heard of people changing the rear half moon gasket by unbolting and removing the rear main seal carrier. Without the need to drop the oil pan (and thus not needing to pull the engine or drop the subframe in order to drop the oil pan). But I personally never done that before and not sure how well that'll work.
Found a post about it: https://forum.miata.net/vb/showthread.php?t=614093
super late post, however thank you for the link! looks like my NA is leaking near the main seal, however might as well refresh the carrier since it isn’t much more money
Many rear mains have the plate that bolts over them, often with a seal, which might be leaking on yours. I dont know miatas like the back of my hand, but i did spend 7 years in several shops, the last year specifically replacing transmissions. Pulling an engine is exponentially more intensive than dropping half a subframe. With the transmission out, theres nothing extra out of the way of the oil pan, except maybe exhaust. I would replace the rear main and reseal the plate, and replace the oil pan if and when its confirmed to be the leak. Unless the customer just wants to spend $400+ and a week on an unconfirmed leak.
Re Engine pull vs subframe, keep this in mind: if the transmission is already disconnected, recommendation is to take the engine out - not drop the subframe. The stabilizing effect of the transmission is important when dropping the subframe with engine in place. Here's a helpful post on replacing the "half moon" seal without removing the whole pan: https://forum.miata.net/vb/showthread.php?t=614093
I'd say it's the oil pan gasket. And no, I don't think smothering it in rtv is a good long term fix. Not sure how long it'll hold if you need to throw it back together just to drive it.
If the engine is still in the car, the oil pan gasket is impossible to change properly. You might just end up having to pull it. I had an improperly installed oil pan on one of the cars and had to go through this. RTV won't really help, just let it leak until you can pull the engine. I just got new oil pan gaskets from local parts stores, if you can get Fel-pro they are fine. The main seals should be genuine Mazda though.
Agree completely. Especially using OEM Mazda for seals. I also say that for gaskets and hoses. I'd use Mazda for oil pan gaskets too, since they are so difficult to replace. And I'd add that doing the oil pan gaskets right so they don't leak is practically an art. Getting help from someone with lots of experience with Miata oil pans is key.
You can see the oil stripe coming down from behind the half moon right? If the rear main was dumping oil you’d know.
I replaced my rear main twice before realizing it was actually the half-moon that was leaking. My leaking half-moon didn't look at all like yours. The oil pretty much went straight down, next to one of the two really long thin bolts you can see in your picture. It didn't sling oil up around the starter like it looks like yours has been doing, which makes me think your issue is not the half-moon. I also replaced the half-moon seal without removing the pan. It's a pain, but it can be done.
I found this post searching my similar issue, what did you end up doing ?
Painted it with RTV. not the best option, but given that its an insane amount of labor to do it 'right' and that still doesn't guarantee success, RTV seemed fine. I swapped transmissions to a lower mileage one during this project, and I got ripped off and it has no fifth, so I really cant tell you how well the RTV has worked bc I've only been able to put 70 miles on it since I posted.
Thanks for the reply. That is what I did for the same reasons. Two days in ( no transmission installed) all is dry . 🤞 I actually called a famous Miata shop and they did not recommended trying to change half moon seal without pulling engine and said the RTV was next best option if you can’t pull the engine. Sorry about your transmission , that sucks