90 Turbo

iTrader: (3)

So I have a 90 with 134k 1.6 and an older 2554. It has been turboed for 30k but it did not have the oil restrictor. I added one 5k ago and it has not impoved oil usage. So the car now uses oil about 1/2-3/4 a tank. It does not leave a lot of oil on the floor and it smokes on cold day right after it starts and a little black smoke at full throttle but really thats about it. It does leave a black mark around the exhaust and when i pulled the cat it had been turned black with oil.

So here is the 100 dollar question. Is it the turbo or the valve seals. I have a 04 1.8 swap planned but have not got all the parts yet. I need a new turbo for the new 1.8 so I am thinking of buying a 2560 and throwing it on the 1.6 while I get the rest of the parts together for the swap.

So will swapping the turbo fix most of my oil usage?

90 Turbo

iTrader: (3)

Oh and is the 2560 a good choice for a non built 1.8 vvt 04 engine.

Braineack

iTrader: (62)

find out where it's going first.

if it's your rings, obviously changing the turbo wont help.

hustler

iTrader: (6)

Turbo rings or piston rings?

You can cold-start the car, let it idle up to temp, then turn it off, remove the turbo, and see if there is crusty-oil burnt flakiness in the manifold and possibly the turbine, or if it's all behind the heat-sheild. This will tell you if it's from the engine or the turbonator.

Braineack

iTrader: (62)

Or check the intake piping, the compressor blades, and charge piping for oil first most.

that will help pinpoint if it's coming from the crankcase due to blow-by, or the turbo from over-oiling.

90 Turbo

iTrader: (3)

The cold side is almost oil free and I dont rember the turbo manifold being oily when I changed the turbo gasket but I did not honestly check. Dhoo i should have checked dam.

thirdgen

iTrader: (26)

https://www.miataturbo.net/engine-performance-56/compression-leakdown-results-what-now-64069/
Do what I did in this thread and report back with the numbers on both compression and leakdown.
That thread should be made a sticky...BTW

90 Turbo

iTrader: (3)

I have done a compression test and it was 179 185 185 170 but it was right after it had been running so if I had oil ring failure it would have already had oil in the piston. Although I have never noticed oil on my spark plug.