1.6 Capped Oil Return vs Drill & Tap?
 

Hi,

Did a bit of searching and found very little about this (in terms of pros/cons).

The early 1.6 NAs have a Oil Return line in the block behind the alternator next to the Oil Filter.

To avoid the hassle and risk of drilling/tapping the sump, any downside of using that as the oil return? Other than the extra pipes and hassle of connecting it from one side of the engine to the other? Can you allow the return to go up and down... or has the flow always must be downhil (which in itself would be tricky to ensure, unless you made it a hardline from one side to the other).

G

the drain pipe pretty much has to go strait down.

It must not go up at any point or you will get clouds of smoke when you hit boost.

drilling and tapping is not hard or dangerous but the gains are so very worth it.

if you use the drain near the filter you will also end up drilling and tapping.

do it right, do it once, dont look back!

Why the smoke, what is causing that?

Why would it need drilling or tapping? Is it not threaded, or can you not secure a hose onto the existing rubber capped end?

G

the smoke will be caused by oil banking up in the line as it cant escape the turbo fast enough it blows out the turbo seals and youll know exactly when it happens.

you dont drill and tap the inlet at the filter you can just put hose over it and hoseclamp but I guarantee you will change this.

you drill and tap the sump on the turbo side towards the front as shown:
http://miataturbo.wikidot.com/oil-feed-and-return
dont go far back suposedly oil gets flicked by the crank and blocks the hole.

your engine bay will be cleaner you wont have oil return issues.

It certainly can be done- the Greddy kits used this oil drain along with nothing more than a flimsy piece of rubber hose.

But it's far from optimal.

spaztikcamel is on the money here. The oil seals on the turbine shaft can't deal with a huge amount of pressure. So if the oil draining out of the turbo encounters any sort of resistance, there is a tendency for oil to back up into the center housing and cause leakage past the seals. It's not the sort of catastrophic thing that's going to destroy the engine immediately, but it ain't right.

Honestly, drilling the hole in the pan isn't as weird and scary as it might seem. I was a bit trepidatious the first time I did it, and I did in fact scrape the oil pickup tube behind the hole drilling location, but despite the fairly small risk and nervousness, it is a much better solution.

if your turbo is 1ft above the hood level, you can use the drain on the otherside of the motor, otherwise you will burn oil
you want the oil to drain from the turbo as fast as possible, do not want it to puddle anywhere, a level line will not work either, must be down hill 100% of the time

Thanks chaps - all good and informative responses. I'm sure others will appreciate this when they too wonder why they are drilling into the sump and tapping a connection when a perfectly good oil return line already exists... as you can imagine, you kinda wonder why Mazda thought it was ok when they built the 323 GT - they must of found a way to make it work relaibly.

Even so, I see where you are coming from - a simple and better solution is to just tap the sump and get a clean and reliable solution that "just works"

G

aside from being front wheel drive..
they actually use a different oil pan, and the turbo still drains into the pan
so im not sure what the hole on the otherside is actually ment for
https://www.miataturbo.net/attachmen...ine=1337573996

I believe it's a catch can drain for the 323 gtx.

this.

Grant,
Ill lend you the appropriate hardware to drill and tap, and even walk you through it on the phone if need be.

Dann

As already was covered in this thread, DRILL AND TAP THAT BITCH. Seriously. I ran mine like that forever, aside from the HORRIBLE burning oil smell you get after wot pulls, and the fact that popping your hood after boosting hard emits smoke from the turbine yourself, it also looks MUCH cleaner.

I should have done it ages ago. To anyone who reads this thread, learn from other members mistakes. Drill and tap the oil pan, DON'T run band-aids, and DON'T cheap out on parts, or it WILL bite you in the ass. That is my PSA for the day. Thanks.

Finding a 3/8th NPT tap in Australia was a pain in the arse. Found one on ebay eventually. I tried 5 bolt shops in my local area.

I posted mine to Gslender, Id have done the same for you too Jerrah.

Dann