Smoky 20v 4AGE

[Mr Ed]

So, my 20v 4AGE is quite smoky. Not just a bit on startup but quite a lot right through the whole rev range. Im thinking the problem is the rings, which Im obviously not all that thrilled about. I havent compression tested it yet to confirm things, but I cant think of anything else it would be.

So what options do I have to fix it? Its currently unregistered and definitely wont pass a road worthy as is (not that Id drive it like this anyway).

I havent tried putting thicker oil in it yet but this seemed to work quite well on my housemates MX5 with a similar problem. Opinions/suggestions on this?

Ive had a bit of a look around for a drop-in replacement engine, but obviously this isnt cheap and there are no guarantees I wont just end up with the same problem again.

The other option is to change the rings on my current engine which would probably be best idea, but Ive never done any internal engine work before and dont fancy paying mega-dollars for someone else to do it.

Is changing rings something I should be scared of doing? What special tools would I need? I dont want to get it wrong as this engine will be revved quite high and I want it to be suitable for a daily driver for at least a few months. Would I be crazy to change the rings without doing bearings/etc while Im at it?

Any advice appreciated!

[Bronald McDonald]

Have you checked the PCV valve (and where it goes) for epic blow-by?

It could be really really fucked valve stem seals, 4A's suffer from that a lot. If it's the head, not too hard to replace the stem seals.

As bottom end shenanigans, i'm sure you could use a smallport bottom end. They're everywhere and cheap!

[Mr Ed]

Breather are hooked up to the old intake pipe, which is just hanging off the engine at the moment as Ive put a new intake pipe on.

Can stem seals cause smoke at high revs? Like properly large amounts of smoke? (Should take a vid and post it I guess) Theyre a problem on 2JZ as well but my understanding is they generally only smoke on start up.

Do the small ports have the same pistons/rods as the 20v?

[Bronald McDonald]

Vavle seals can create smoke throughout the rev range, however i'm unaware of how much of a smoke-show you car is putting out.

Remember that valve stem seals prevent oil from meeting the crown, so if they're totally shot, it's going to smoke big time. Also thin oil in a 4A with buggered stem seals = epic smoke.

Smallports have bigger and better rods than the 20V. You should just buy a reco'd / cheap smallport bottom end, rebuilt it and use the 20V head. In the mean time use some thicker oil until you're ready to do the bottom end swap!

[Mr Ed]

Awesome, cheers

Suggestions for oil type?

[oldcorollas]

perhaps you have cracked pistons?
do a leakdown test

[trdee]

smallport bottom end is not suitable unless you swap the pistons around. at which point you may as well just rebuild the 20v bottom end. and i have a sneaking suspicion that AE101 conrods are actually stronger than AE92 conrods, even though the AE92 ones look beefier at first glance, but anyways......

as OC said, a leakdown test will confirm what's fucked. but generally speaking, fucked valve stem seals will be most evident when cold and when the engine is under vacuum

[oldcorollas]

after the engine is at vacuum... ie the 3rd gear decel test...