Smoke At Startup, Coating Of Internals

[Michael Tyler]

I have a 98 ES300 with a clean engine, no sludge. I get the momentary puff of smoke at startup. My mechanic (whom I trust, family's been with him for 15 years, specializes in Japanese makes) tells me I need a valve job. I've read on here that the smoke is symptomatic of leaky valve stem seals, and that it poses no mechanical danger. My mechanic disagrees, saying that the smoke is going to coat the exhaust system, and if I let it go too long, it's going to require greater repairs because of this.

Is this true? I don't mind the smoke at startup, and I don't want to put down another 1-2K yet for a repair that's not urgent.

[Toysrme]

How he says it'll be a problem. no.

It being a problem, yes.

What's his name's 1mz-fe was completely destroyed from a valve stem seal completely failing to seal. I oughta know. He was nice enough to send me the piston & rod from that engine!

Monitor oil levels & you should have a valve adjustment don't like every 75-90,000 miles anyways. Just nobody ever does it. (Adjusting the valves would be the time to change the valve stem seals. It's still alot more work, but you get half the labor done already so.)

[blk_on_blk]

How is that damage possibly due to a valve stem seal simply failing to seal??? No way! ...maybe a valve retainer failure dropping the valve into the combustion chamber, but that piston is gouged severely, has a hole in it, and the rod is bent. There was something hard that dropped into the cylinder and got the #@$%# knocked out of it as the engine cycled to cause that kind of damage. You can't tell me trickles of oil seeping past a seal caused that. No way. I've had friends run for months and months with nasty leaking valve seals and big O puffs of smoke upon start up with carbon soot forming on the bumper around the exhaust. A severe leaking valve stem seal will not cause catastrauphic damage like that... it will create soot, loss of power, poor emissions, and deposits in the exhaust.

MT, if you've got a slight puff of smoke, it's not a major concern... you've got some time. If you're passing emissions okay, then the problem is mild and just something that you'll probably want to put on your list to repair when you have the time/cash.

[Toysrme]

Because a failed valve stem seal will drain all the oil out while it's running.

In this case, the valve lobes at through the vale shims, and on the offending bvalve that went thrgouh that piston. It ate through the bucket, the valve stem, and finally the retainers. Dropping dothe valve into the cylinder.

There's a differance in a cracked valve stem seal, and a failed valve stem seal. When there's nothing left, the oil simply circulates down into the intake, through the engine all the time.

[tckcumming]

How he says it'll be a problem. no.

It being a problem, yes.

What's his name's 1mz-fe was completely destroyed from a valve stem seal completely failing to seal. I oughta know. He was nice enough to send me the piston & rod from that engine!

Monitor oil levels & you should have a valve adjustment don't like every 75-90,000 miles anyways. Just nobody ever does it. (Adjusting the valves would be the time to change the valve stem seals. It's still alot more work, but you get half the labor done already so.)

Toysrme -

How did a valve seal failure cause that kind of damage? Looks more like LOTS of detonation over a period of time. That piston is trashed but good!

I had an old British car that had leaky valve stem seals. I just ignored it for a long time, until it was burning oil by the quart (that's a litre here in Canada) and running poorly. I pulled off the cylinder head to have a look. The valve stem seals were really bad (a couple of them had disappeared), but that wasn't the worst of it. The valve stems (especially the exhaust valves) were coated with large lumps of black greasy carbon, from the burning oil. No wonder it ran so poorly.

So I'd agree that, if left for a long time, leaky valve seals can cause bigger damage. Not to the exhaust system, but to the exhaust valves and eventually to other parts as well. Once they start to leak, it's all downhill until they're repaired. Only a matter of time.

tck...

edit... didn't read your previous post before I posted this... not trying to "gang up" or anything. A dropped valve explains the damage - holes in piston and all! Leaky seals usually slowly deteriorate over time, you usually have plenty of warning that bad things are starting to happen. A "fix it now or fix it later" kind of thing. Hopefully it's fixed before the valve falls onto the piston!

tck...

[lenore]

The puff of smoke can be a indicator. When the seals go oil goes out the exhaust. This shows on start up because the catalytic converter is not hot enough yet to burn the oil. Eventually the cats will become clogged with oil and may have to be replaced if bad enough. Maybe that is what your mechanic was trying to tell you. The cats get so hot that they will burn evidence of oil leaking pass the seals. however your oil useage will go up.

[blk_on_blk]

Okay, so that's a little different than a simple leaky seal... that's more like "not sealing because it's coming apart". :P A little puff of smoke from a leaky seal isn't major... but if you have really bad valve guides, a cracked valve seat, or more (espeically things coming apart into the engine), then you've got some problems that will probably be progressive. Below is an array of some of the Toyota's valve seals; they're just little rubber caps that sit atop the valve stem in the head... when they leak, it's usually because they just get worn and a little oil seeps down the valve stem. I hear ya if they completely 'go away', then they'll suck up all the oil. If there's just a little puff of smoke, and everything else runs fine, then it's probably just slightly worn seals. If there's a valvetrain clammer under low rpm load, then the problem could extend into worn valve guides. The worse case could be a cracked valve seat, but that's not likely with this engine (unless you're doing something with it you shouldn't).

My Beemer had a ton of miles, leaky valve seals, and worn valve guides... I put a good 10K on before diggin into the engine for a rebuilt... never had much of a problem with anything other than the typical symptomatic signs, but it ran great otherwise. TCK ran his ride for an extended period of time, too, with the end result being the expected sludge build up, but nothing detonating and scattering.

BTW, that's a hella-cool destroyed piston... that valve must have bounced around in there for a while. Recently a friend showed me a bent rod out of his race car... it was twisted in every direction, but hung on... he said it just made a slight knock before he shut it down and took it apart. I couldn't believe it held together.