Smoke from exhaust with no load
 

Fresh rebuilt BP, new pistons, rings, valve seals ect... Car drives good, good power but when coming to a stop or just taking off normally in 1st I get a coulple puffs of greyish smoke from the tail pipe. Enough that it is a bit embarrassing. Strange thing is that it only happens sometimes, maybe 50% of the time. I thought maybe I fucked up rebuilding my turbo so I popped off the 16g and dropped in a known good 14b. Still seems to be doing it. Should be noted that I have both valve cover ports going to a VTA catch can, no pcv system. Any thoughts? I have a fair amount of soot coming outta the pipe on a cold start too. Air/fuels look good. Zero oil in charge pipes.

Ok, so it is still using 1qt every 60 miles. Catch can is empty, no oil in charge pipe.

Pulled the plugs today, all have signs of oil burning and ash deposits. I looked down into the cylinders and can see oil on all the piston tops, they are all wet... Car only smokes after decel, coming off idle and spits black outta the exhaust on start up. No smoke when cruising and only light, black haze when really on it. Ill try to do a leak down in the next few days. I had all the valve seals and a few guides done during the rebuild but i used felpro seals. What are your guys thoughts? Strange its all cylinders and pistons are wet... Leads me to believe it could be the valve seals... How could oil get on top of piston when its not running if it was rings.

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Oil on the throttle plate/intercooler would indicate leaking turbo, but decel puts it at valve stems. They are intake /exhaust specific and should "snap" when seated fully.

Ya the throttle butterfly and intercooler are dry so I know it's not the turbo. My machinist installed the valve seals but would assume he did the right. That said anyone can make a mistake. He is one of my best friends, said if I pop the cams out he would come by and install new valve seals again. I just wanna know what it is before i go that far.

I think it has to be stem seals. Decel, extended idle and right after startup are the times that stem seals will let themselves be known.

Ya I think deep down I know you are right. I think it is possible he mixed up the intake/exhaust valve seals. It would be a relief to be honest.

I'm pretty sure that has to be it. Your engine is using 1qt every 60 miles that's pretty significant. If it ends up being seals like you said that's a massive relief.

Just looked on rockauto, intake and exhaust valve seals are interchangable.

Just so weird that its every cylinder. I checked and the seals are interchangeable so he couldnt have mixed it up. I guess the could have been packaged wrong. At this point Im tempted to find a bp4w head.

Were the guides replaced when the head was rebuilt? Worn guides will have the same symptoms as bad seals.

A few of the guides were replaced but not all

I suspect either the remaining guides, or the rings never seated. Its possible to get smoke at startup from worn rings, same for off idle and on decel. My last 944 motor did the exact same thing with rings that were toast, and even it didn't burn oil that fast with track use only (the car basically fogged for mosquitoes every time you decel'd from WOT).

I'm just really hoping you are wrong. I've rebuilt probably a dozen engines and only had problems with the rings one time, that was because I was inexperienced and didn't measure the gaps. There is enough oil on the pistons with the engine off that I can soak it up with a fine tip paint brush. I've never seen valve seals leak that bad, was right after a 30 minute drive staying outta boost.

I did a quick compression test this morning, I didn't have my leakdown tester handy. With engine hot: 160, 160, 165, 167.

Really need the leakdown test, as a bunch of oil in the cylinder can mask compression issues.

Ya, I totally agree. I will say, I would find it strange that all the rings would be bad from a reputable company like arias and I'm getting next to nothing in my catch can. That said, it is totally in the realm on possibility. Leak down test can rule out the rings but it won't tell me if its the stem seals, it can tell if valves are sealing in the head but not if the stems are sealing. Car doesn't have the decel haze you are describing from your other car, I have experienced that before and yes it was rings. Right now I'm considering 2 options, 1) Order new valve seals from Mazda for $200 fucking dollars or 2) Find a bp4w head and just try that. I'm still open to suggestions however and obviously I need to do a leak down before I pull the trigger on either option.

At least it will rule out rings. Doesn't necessarily mean defective rings, could have been too much oil on walls during assembly/break in, wrong hone finish, etc. I'd be pretty surprised if you were losing a quart/60 miles from just seals. If you rule out rings, I'd probably sooner just swap heads.

Ya could be a bad hone finish or something. Part of me wonders if he forgot the valve seals completely, I may just pop the VC off and take a quick peek to see if they are in there. I agree that is an extreme amount of oil loss for valve seals, if you could see how much oil has pooled on the pistons you would be shocked. It pains me that I have so much into this head, my buddy replaced a bunch of valves, guides and resurfaced it then I replaced all the HLA's. I was going back and forth then about replacing the head all together, I really should have.

So I just looked at Kia for valve seals for 97 Sephia. Same part number as Mazda but they are $20 for a set at Kia vs $122 a set at Mazda. Crazy.

If you pull the intake manifold you could shine a light in and see if oil is running down the intake valves.