I am in the process of figuring out how to redo my oil drain on my greddy setup. The PO did a hackjob with the routing and location of the tap. It is a M14x1.25 Tap in the oilpan with a strange gusset. Then some strange silicone hose that goes into somthing which looks like cooper tubing to create a curve routing it to the turbo drain (marked in red) . Here is a pic:
This is the drain thingy which is tapped in the oilpan:

It has a M14x1.25 threading. This may not be the optimal size in diameter for the drain. But i dont want to retap the pan. My plan is to use a m14x1,25 to DASH 8 fitting like this:

Then use an angle like this to route back up to the Turbro:

I want to connect everything with Dash 8 3/4 sshoses. Only Problem is that the Turbo drain adapters only come in DASH10 so i would need to install another reducer that goes from DASH 10 to DASH8.
What are your opinions on this. Do you think i should retap the pan just so i can go Dash 10 all the way?(The car has been running with this drain setup since 1999)
Have i overlooked some cruical things regarding the oil drain?
Love to hear your advice.

 

It’s written -8 and -10, for future reference.

Looks like you have plenty of length, you could put a -8 to -10 union in the middle of the line with 2 straight fittings.

But it that doesn’t fix the problem that it’s tapped with a straight thread that’s only going to seal with the JB weld or whatever you use to seal it, which is not ideal. Personally I’d look for a new pan and fix the drains location, using a tried and true NPT thread

 

Looks like that may have been done when the power steering was still in place? To do this right, you should retap - using a reducer is gonna lead to a bad time.

Have you seen this: Oil Feed and Return - Miata Turbo FAQ

 

The wiki has some good info on oil drains at the bottom. I would reccomend to get rid of that oil drain setup in favor of a full -10 line. It’s not much trouble to retap the pan, you just need to be careful not to touch any part of the oil pickup with your drill bit. Even if it’s been okay for so long, you’ve got it apart - fix it right. More flow back to the pan can only be a good thing.

Oil Feed and Return - Miata Turbo FAQ

 

Yeah i know that a -10 line would be optimal. Also the M14 tap sucks, but since i dont really want to retap the damn pan i may get away with just using the -8 fitting and some copper washer /jb weld for sealing. It held together for 20 years now and drainage did not seem to be a problem considering the condition of the og turbo. I will eventually blow this engine up someday and redo everything the proper way. For now iam considering using the adaptor in the line like curly said.Thanks for the input guys

 

Just resize the hole for 1/2" NPT and retap. It will take you 15-20 min to do it right.

 

You will never get straight threads to seal on the pan unless you file or face a flat surface around the existing threads, and that's a fool's errand IMO. Resize the hole for 1/2" NPT or it will leak forever.

 

This thread seems as good a place as any. Was just reading some stuff in the wiki:


There's no way tapping into the pan at the typical spot is above the oil level—at least at rest. Maybe if all of the oil is being pumped through the engine and it's all up in the head and top of the block?

 

Please note that NPT threads also require a sealant or will leak. Use JB Weld, even with the re-tap to NPT.

 

And make sure you clean the **** out of it with a residue-free solvent before applying the sealer, JB Weld, etc., or the sealer won't bond, and it will start weeping right away. Trying to drain anything into the bottom of a full vessel is not how you want something that relies on gravity to work!

 

I bought a 1/2" NPT Tap. Why would i need to use JB Weld? I thought that NPT would be sufficent? Also, is it okey to pre-drill with 17mm? What is the recommended metric pre drill?

 

I am sorry you were misled, but that is why I posted as I did. ANSI B1.20.1, the standard that defines NPT threads, states:

1.3 Sealing
1.3.1 Where pressure-tight joints are required, it is
intended that taper pipe threads conforming to this
Standard be made up wrench-tight with a sealant.
To prevent galling on certain piping materials such as
stainless steels, the sealant usually contains a lubricant.

(Emphasis mine)

There are more specialized, fully interfering threads called NPTF, but that is not in play here.

I'm not telling you that JB Weld is the only sealant that will suffice, but it is what has been proven for many years now.

EDIT, I am not the one that gave you the NEG-CAT. I'm just here to help where I can.

 

There's also another reason you use JBWeld on the threads (if you're going through the pan wall)... The number of threads engaged is way below what's normally spec'd even as "hand tight" to seal. IIRC the pan wall is .060-.125" thick so at best you'd get 36% of the recommended minimum engagement for that 1/2" NPT thread. It's recommended it be hand tight and sealed with JB Weld to lock the fitting in place, and to seal the thread.

The 1/2NPT thread has barely 1 complete thread with that wall thickness.

 

Okey, i did not know this. I assumed it was self sealing. I kind of messed up the thread anyways. I predrilled with 17mm and the hole was a tad to small. I used the Tap anyways and kind of a respectable thread. My fitting just tightens up as it aproaches the end of its thread. This will for sure never be sealing. I think iam going to JB weld the f out it. Is there any alternative to JB Weld? Maybe some special Loctite? JB Weld is kind of difficult to get around here.And about the neg-cat: I get why people would downvote such a "noob" question but not even the FAQ states that using Sealant is required, which i did read beforhand btw. I just wanted advice how i could redo the mess. And i took every advice which was given here. Thanks guys

 

There is a Loctite formula that is for permanent connections that would work. I can't recall the number. It is even stronger than the JB Weld. It would break the oil pan before releasing if you tried to unscrew it. Maybe that can be found.

 

^ Test

Loctite MetalConcrete 3200psi

 

Also, if i were you, I would use "full flow" hose fittings instead of the standard ones like you have in the picture above. A litle more difficult to find, but much better flow through a 90°