Built Motor Smoking Problem
 

Hello everyone, I am writing about an issue I am having with my 94 1.8 engine that I have recently rebuilt (forged pistons and rods, arp hardware, and shimmed oil pump are the highlights). So basically, the engine has around 3000 miles on it since I broke it in and it runs great, however I have this strange smoking problem that I cant seem to diagnose. Basically the car emits a puff of blue smoke every time I give it throttle after letting it idle for more than a few seconds. It doesn't smoke when or cruising or even in boost, only when I am leaving from stoplights/stopsigns and sometimes between shifts. Also noticed that the car is burning a solid amount of oil, as it goes from max fill line on the dipstick to the min line within a few hundred miles...What is strange to me is that I seem to remember the car doing it even before I did the rebuild. Now I know everyone is going to blame the turbo/oil feed/oil drain, but I have even tried running the car with the turbo removed and it still does the exact same thing, so that cant be the problem. Yes I had the block honed, rings gapped (based on CP's recommendations for forced induction applications), valves lapped, the whole 9 yards. It makes 180 psi compression on each cylinder according to my cheap pep boys compression tester (known to produce low numbers for me in the past compared to nicer gauges on the same engines). Running a 2jz pcv valve that leaks no air whatsoever. Like I said, the car used to do this even before the rebuild (though not as bad if I remember right. honestly not sure, I just remember it doing the same thing), and my buddies built 1.8 that I bought the pistons out of did the same thing when he had his car together (Of course I bought new cp rings all the way around to go with the pistons, which were installed so that the gaps do not line up on any of the rings. The pistons only had 1500 miles on them when I bought them, my buddy did a 1jz swap on his car). Also I installed new valve seals (supertech) that I have since replaced a second time just to be sure, yet it still smokes. Ill include a link to a video of me highlighting the problem.

Big concern:
I do remember when I was assembling the engine, right before I put the head on, finding the slightest scratch on one of the cylinder walls (pictured below). I was trying to get the car together for a drifting event that weekend (lol yes you heard me right) and just decided to put it together hoping the scratch wasn't big enough to cause an issue. After all, the machine shop did the cylinder honing and didn't say anything about it. Of course it was probably a poor decision to just run it, but what puzzles me is that I would have thought that if this was the issue that the engine would smoke all the time, instead of just off idle. This thing only smokes right when the throttle is blipped from idle (or between shifts). Not cruising, not in boost. If you have any ideas on tests I could perform, possible culprits, or really anything id appreciate any responses.

Video of the problem:

Picture of the scratch:

https://cimg1.ibsrv.net/gimg/www.mia...8288e84e0e.jpg


Thanks guys

Found it!

Are they really that bad? I tried two different sets of them (replaced the first set after 2700 miles and nothing changed) and it has behaved exactly the same.

Also if you go to 5:05 in this video you can see that it had the same problem even on my original non built engine (watch the puff of smoke when I take off). However I believe I had done supertech seals on it as well so if they are actually that bad maybe thats the problem.

Pretty known quantity at this point that they're trash.

Aidan and I briefly chatted about this at the MRLS MT.net dinner. I've always found it odd that despite all the problems others have with ST seals, I've never had a built motor smoke like that, despite using Supertech seals (until recently - we use Felpro now). My theory is that the Supertech seals are stiffer, and therefore less tolerant to worn-out valve guides than a Felpro or similar seal. Five years ago it was uncommon to see worn-out valve guides in a core. 18 months ago it became so common that it's SOP to change all 16 guides if any are even remotely sloppy when we R&R a head for a longblock.

So OP, I think you have sloppy valve guides. The machinist who R&Red the cylinder head should have caught it. You might be able to solve the problem with some Felpro valve stem seals.

Rover and Acamas both use Supertech seals, neither smokes at all. The difference is that both motors got fresh guides when they were built.

My built motor has supertech seals. But it's been built for i think 5 years now, so maybe i got some older better parts.

How about the scratch in the cylinder? Do you guys tend to agree that if that were the problem it would behave differently than I am seeing?

Your symptoms indicate an issue with valve seals or valve guides

Thats extremely relieving to hear. I really didn't feel like pulling the engine again... Thank all of you guys for the quick responses and helpful information :)

welp... took the second set of supertech seals out and replaced them with felpro seals. the result: still smoking... honestly did seem like it helped, but she still smokes. heres a video of it since the install.

so what, valve guides? oil rings? makes great compression

Valve guides, as sav pointed out, time to pull the head. Or hey - maybe your seals are still bad :dunno:

Might be easier just to source a different head and stick it on. Depends on what your time is worth to you.

Think I'm gonna do a leak down test first, then most likely pull the head. Once it's off the block, will there be any indicators as far as where soot builds up as to where the oil is leaking in? Like would it look different if it were my valve guides as opposed to my piston oil rings? I want to be as scientific as possible, It's been way too long replacing random stuff and hoping it fixes it. Assuming it is the head, maybe I'll try and source someones 1999 head and throw some hardened valve springs in... "might as well while you're in there right?"...