Blue smoke on start - New motor

[Brando]

My motor blows a thick cloud of smoke the first few seconds on a cold start. It will sometimes do it on a warm start but less frequently. It does not blow smoke every cold start either, but I would say 60% of time it does.
The motor has just been rebuilt with new rings, pistons and rods. The motor blew smoke before and after the rebuild. The valves & seals were not rebuilt.
From the homework I have done all things point to either the valve seals or a bad seal on my turbo. The turbo is a DOM 1.5 XTR.

What is my best approach and determining the root cause and is it something I should be worried about?

[Buzz Skyline]

I'd assume the motor would need to be broken in to get the rings to seat properly. Turbo engines typically leak a bit of oil past the rings when they're cold anyway, and if you have cylinders that have newly been honed, I imagine you would have even more oil leaking past until everything is properly seated and the cross hatching is smoothed out. I'm not sure how to break in an engine that's not in a car that you can drive around a fair bit. You need to run it under load at various RPMs.

Just a guess, but if that's all that's wrong, you can take care of it once the car is on the road. Of course, I'd check the compression just in case.

[D Clary]

I wouldn't worry to much about it if it is just on startup. Could be valve seals if so no big deal It would have to be really bad to cause much trouble. I my experience when the turbo leaks after shut down, the oil collects in the exhaust pipe. The smoke doesn't start immediately at start up but when the pipe heats up after a couple minutes. In any case I don't think a compression test will help you with oil consumption. The compression rings can be fine and the chrome oil rings may not yet be sealing. Give it a chance.

[donshapansky]

In my experience over the past 30 years with all types of engines, such as cars, motorcycles, lawnmowers and aircraft engines (horizontal opposed cylinders) blue smoke on start-up is not going to be seen with worn or unseated wrings. It's the valve guide seals or the lack of and/or worn valve guides that will cause blue smoke on start-up. The other cause can be completely filled crankcases on dry sump engines like older motorcycles, Norton's would leak oil past the oil pump gears from the oil tank to the crank case during long periods of sitting, when started the crankshaft would thrash oil past the rings and cause smoking for few minutes until the crankcase emptied.

[Pearldrummer7]

Compression leakdown test first! Don't panic yet...could be a dozen different things.

[DodgyTim]

I know a mechanic friend who puts 90 psi compressed air in the cyclinder via a fitting that seals in the spark plug hole, then he can remove valve springs and change the valve seals with the head still on the block.
He did it on older style engines, not sure if it would work on the suby

[metalmaker12]

My motor blows a thick cloud of smoke the first few seconds on a cold start. It will sometimes do it on a warm start but less frequently. It does not blow smoke every cold start either, but I would say 60% of time it does.
The motor has just been rebuilt with new rings, pistons and rods. The motor blew smoke before and after the rebuild. The valves & seals were not rebuilt.
From the homework I have done all things point to either the valve seals or a bad seal on my turbo. The turbo is a DOM 1.5 XTR.

What is my best approach and determining the root cause and is it something I should be worried about?

Hopefully your using break in oil bro, rings need to seat and proper break in oil is needed which will make this smoke eventually go away.

[GreenMarine]

Sounds like a really cool way to work on the valves... If it can be done on a Subaru though - in the car, HIGHLY doubt it... Out of the car, don't see why it wouldn't work...

[GoDadGo]

The valve seals are very likely the culprit. You may also have valve guide wear that needs to be addressed too. Good Luck!

[xxguitarist]

The valve seals will be difficult to press into place with the valves in the way. There are tools available to install them. I'd HIGHLY suggest picking one up if you do this work with the heads off.
Also, only good things to say about the EuroExport valve spring compressor, even with our heavy duty beehive springs. They make an adapter to hold the small beehive spring caps.

[Wayne Presley]

You can change, cams, springs, seals and retainers with the motor in the car. I have done it with the Stage 23 spring compressor, looks exactly like the one Andrew listed.

[FFR-ADV]

One of many possible causes:

By any chance did you change the Turbo Oil Feed Line Banjo Bolt? It has a small orifice in the banjo bolt which is there to limit oil flow creating a small stream of oil into the bearing and gravity drains out the bottom. If to much oil flows in (example: wide open banjo bolt) and can't drain out then the oil builds pressure in the turbo bearing and can be pushed into the turbo, mixing with the hot exhaust gas creates huge smoke.

[longislandwrx]

Sounds like a really cool way to work on the valves... If it can be done on a Subaru though - in the car, HIGHLY doubt it... Out of the car, don't see why it wouldn't work...

you'd be surprised what you can do when you loosen the motor mounts.