Miata Turbo Forum - Boost cars, acquire cats. - oil return line under oil level?

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I think the issue may be that the oil coming out the drain is FROTH.

If the return is above the oil level, the froth falls out and spreads over the whole area of the top of the oil to dissipate.

If the oil level is up the drain hose, the froth doesn't break up, and backs up.

Now how bad could backed up froth be... ?

when my p/s fluid gets frothy it pushes out past the fill plug...

Quote:

Originally Posted by DammitBeavis (Post 539887)

2 qts was a guess, I had just put the motor in and forgot that I had dumped some oil in it to check/prime the oil system. Dipstick indicated the oil level was almost exactly inbetween full and the top of the pan, but it was hard to read of course.

Did you have any other symptoms? Aside from the turbo?

Quote:

Out of curiosity, how does it 'blow seals everywhere'? I've hear that before but never witnessed it. Seems like all that would happen is that the crank would maybe froth up the oil a bit if you drove it that way. I know foamy oil sucks for bearings, but why would the seals care?

I'm with you on that - it's one I've heard but never understood. I know people say it can make you burn lots of oil, too. Maybe particulates float on the oil, too? I just don't see where you get a pressure increase - a bubble is no "stronger" than the air inside it and the material's elasticity (or whatever you call it). Oil bubbles seem like they would pop pretty easy. You might get oil on the backside of the oil pressure regulator, but again, it's hard to imagine how this would much matter.

Quote:

Originally Posted by JasonC SBB (Post 539962)

If the return is above the oil level, the froth falls out and spreads over the whole area of the top of the oil to dissipate.

Wow, ok, there's one I didn't think of. All I can say is mine returns high and I don't have issues. :-) That at least seems somewhat reasonable. I'd still like to find a way to test it. It's hard for me to imagine (as mentioned above) what this could do to hurt anything?

Quote:

Now how bad could backed up froth be... ?

heh

Your oil drain has clearly violated all the rules.

I've done much worse, and they always worked.

Part of the key is the height of the turbo above the oil level in the sump.

I think your oil line will work okay.

Corky

Quote:

Originally Posted by JasonC SBB (Post 539962)

In my case I never saw any froth. It started about 20sec after I started it up. First I heard a whizzing sound then saw an oil mist coming out of the compressor outlet (wasn't connected yet). I started it a couple more times but it never ran for more than 30sec because it was making quite a mess. About 10min later I pulled the return hose and realized what happened when oil began pouring out. I don't recall there being any foamy oil though.

As far as the height above the oil level in the sump, I'm running an older FMII kit.

Quote:

Originally Posted by codrus (Post 539548)

Never mind the oil level, how are you going to fit the motor mount on with the oil drain line there? I'm assuming it's going in a Miata?

Mine, for comparison:

http://photos.codrus.com/Cars/Parts/...53_4bikT-L.jpg

--Ian

Do you happen to have pictures of where you tee'd off the oil line for the oil in? I'm about to run a line to a turbo I'm installing and am looking for any info I can get.

iff you have a 1600 there is a feed blocked off on the turbo side if 1800 you have to tee off from the oil pressure sender

take a look on flyin miatas turbo install instructions they will help

Quote:

Originally Posted by sprsta (Post 571728)

iff you have a 1600 there is a feed blocked off on the turbo side if 1800 you have to tee off from the oil pressure sender

take a look on flyin miatas turbo install instructions they will help

http://www.flyinmiata.com/support/in...all_turbos.pdf

Look on page 14.

--Ian

Quote:

Originally Posted by sprsta (Post 571728)

if 1800 you have to tee off from the oil pressure sender

Really? Then I must have one of those uber rare 1800 engines that has an oil port on the exhaust side.

94-95 1.8l have the oil feed on the exhaust side like the 1.6's. The rest of them do not.

Thanks, exactly what I needed to know!