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The mkiv Supra Owners Club

Oil blow-by


hodge

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Hi guys

A little advice/opinions on this would be great.

I'm getting a little blue smoke when I lift off the throttle then press it again but mainly when the cars cold or when I lift off WOT when the car is warm, (much much less when it's warm).

I assumed the turbo oil seals may have been worn a little causing a small amount of oil to leak past, but when I've gone and stripped the core out of the turbo it all looks perfect. There's no evidence of and oil issues nor play on the shaft, it's still as tight as the day I bought it.

I removed the head to fit new valve springs etc and checked the pistons for and noticeable oil passing past the rings and none to be found. The piston tops were just black with carbon deposit as per normal.

If I thought the turbo required new seals I'd have it sent away for a rebuild but like I said it still looks brand new.

 

I'm starting to wonder if I'm just using oil that's too thin for my setup.

I'm currently using Valvoline VRS racing 5W/50.

 

Any help or opinions would be great.

Thanks

John

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When you close the throttle, there is a big vacuum generated from after the throttle plate, so anything that has the potential to weep/leak will do so, stem seals etc, at WOT the effect is obviously more so, and if the is a PCV system connected, any oil thats sitting in any of the connected pipework, intake etc Will get drawn in and may produce smoke, same goes but differently for the turbo.

 

If you watch a lot of cars on the dyno, you will often see smoke, as a result of this, however the car will be fine the rest of the time, and you will probably never see smoke on the road, if it is the turbo seal you wilgenerallyly see smoke on shutting the throttle and then re opening if its the the compressor seal, and smoke from the exhaut immediatelyly on shutting the throttle if its the exhaust side seal.

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