edit- Today we learned: don't use NPT for oil fittings. It will leak like crazy. Get a mocal sandwich plate and use BSP/AN coupler to run AN ended hoses to the cooler.

 

I think the most important question is, why is your turbo on the same side as the oil filter?

 

That's a picture from a K20 swap I think.

I just noticed the oil plate used AN fittings instead of the shitty leaky NPT ones I have and was wondering where I could find one for a miata. All the ones I've ever found are either NPT or discontinued years ago.

 

So I learned a valuable google lesson tonight.

Search for "miata oil etc etc" find nothing
Search for "20mm x 1.5 oil etc etc" find everything

So basically I'm going to replace all of my external oil things that are leaking with 10AN stuff. Even coating that NPT **** entirely in gasket maker doesn't completely eliminate the leaks.

 

FWIW I've had 10x better luck with NPT not leaking vs AN fittings. That's odd you're having problems with NPT leaking, that's not common at all.

 

Hmm, I'd hate to trade up to even worse leakage.

For low pressure and stuff like water, I think NPT stuff is just fine. My brewing rig is all 1/2 NPT with no issues.

For high pressure oil or fuel, I think it's very much a roll of the dice. For example, my 1/2 NPT oil thermostat doesn't leak, and the oil cooler itself doesn't leak, but I had to redo those connections 2-3 times each and seal the threads with tons of gasket maker to get the leaks to stop. And I'm not entirely sure the oil cooler itself is perfectly sealed. The plate that goes in place of the oil filter still leaks despite probably half a dozen attempts.

I'm afraid that after I upgrade the oil pump I'm going to have 70psi going through those lines all the time... which means I'm going to leave a trail of oil everywhere.

 

How easy are BSP fittings to get hold of in murica?

For an engine that came with bsp and metric threads from factory, adding the NPT thread standard seems needlesly complicating.

 

The real question is why are you screwing with an off-brand oil adapter with NPT threads, instead of just using a Mocal thermostat plate with BSPP fittings and dowty seals (that never ever leak)?

 

I didn't know such a thing existed when I put together my build. To be honest, I didn't know about until you just mentioned it. I think integrating the thermostat into the sandwich plate is a great idea so I probably would have gone this route if I had known about it.

That being said, I've got a mostly non-leaky setup that just needs about 80 bucks in parts (including all the AN hose ends, fittings, etc) to be perfect.

 

Something isnt right about the way you are assembling those npt threads. I use them at work and test 100% of the parts. We get like 1% failure.

 

I thought using thread sealer on NPT was a bad move. Isn't it the flare on the inside that prevents leaks as opposed to the threads themselves?

 

Incorrect, and for us, a paste type sealant works best.

 

Sorry, NPT yes for dope or thread tape -an is apparently not supposed to have anything.

Atleast according to this thread.

I am by no means a professional though. We used AN fittings in the military for our Jets without any thread tape or dope, but we almost always had something leaky. Hell, if those things weren't leaking something was wrong.

 

All I have to say, is if you do go the AN route, buy the highest quality you can afford. The cheap ones are hit an miss junk and leak like crazy. I have a few that all have a different angle cut on the taper, so they'll never seal.

 

I thought this was going to be a post about this:


The 3rd gen Miatas have a known failure point with the cast-aluminum oil plate cracking and then letting go of your oil filter, typically while you're applying some track abuse. It's worse when an oil sandwich plate is used for an external oil cooler because of the additional stress of the hanging lines.

Just ordered one of the pictured units for my NC build to avoid this scenario.