Every first start up I get a big puff of blue smoke from the exhaust, but it runs clean the rest of the time. What causes this in an engine?

I notice that I have excessive blow-by, making me think I might have some bad rings. Could that be it?

 

Valve stem seals

 

Cool, so it looks like you gotta take off a spring to replace them, how much of a pain is that?

 

8 outa 10 times its the valve guides themself being worn... sometimes a good set of umbrella seals will get you by for awhile... yeah you gotta take the spring off...be sure you get a tool so you can pump compressed air into the cylinder that way your valves wont drop when u take off the spring... its pretty straight forward.. swap the seals... reassemble and re adjust your valves...

 

many times (not all the time) this problem can be solved by a good cleaning . remove valve covers , clean all sludge build-up on cylinder heads . pay special attention to the drain holes on the lower front & rear of the cylinder heads . they allow the oil to drain back to the crankcase , they can/will get sludged up and slow oil draining back to crankcase . this WILL be a dirty job . regular oil changes and once a year eng. flush could prevent this . new valve seals are also a very good idea . good luck .

 

id say valve seals for sure. over time they wear out just like any other part. there not too hard to replace and you can rent all of the tools needed to do the job at ur local parts store. and if it were me i would put in positive lock seals. intake valves have vacuum on them....

 

I agree about the cleaning, but I have also had all that sludge sealing stuff up! It may start seeping at different locations.

Want to get rid of the puff of smoke? Run synthetic oil - old used car dealer trick. I bought a car and started doing maintenance. Changed the oil to the "dinosaur blend" and I started fogging for mosquitos everytime I started the car. I went back to the used car dealership for the "what gives" and he told me about that. I saw the results in that car and one other that I had.

 

Valve stem seals.

 

Unless the blue smoke really bothers you alot, it's not worth doing anything about it really unless you are going to have head work done anyway, then just let the shop replace the seals. In other words, it's not hurting anything.

I mean yeah you can do it in the driveway - even without air - but all the trouble, why bother really - especially if your doing any head work, motor swap, etc. in the next year or two anyway - just let it ride.

 

I don't believe he said he was going to be doing any head work. And he made a post about it, so it must bother him

 

Unless you're the OP - what difference does it make to you anyway?

No he didn't state that he was going to do headwork, but he didn't state that he wasn't either. And yes he posted about it - whether it's a post about concern over the smoke or being bothered by it only the OP knows, as it hasn't been clarified either way.

I was simply letting him know that it's not a life or death issue - there are many many threads here on TGO about the same issue, and many times folks don't know that it's not anything to worry about - all they know is that they're car is smoking and they don't know why - I was simply putting his mind at ease about it not being an imperative issue to correct.

He could have done a "blue smoke" search and seen a ton of info without posting at all - at least I didn't rag him over that.

We're all so happy that you chimed in with useless non-topic info just to critique my post - Let's waste more of everyone's time as well as server space and debate more whether I should have posted anything, OK?

 

i personally woud use this as motivation to upgrade the heads...just me

 

Heh, I'm doing the entire engine next week. Pullin out the old tbi 305 and dropping in a brand new carbed 355 with some fancy aluminum heads.

Not because of the smoke, just because... well... it's an L03, lol.

 

I have the same blue smoke. I am also shaping up to use this as an excuse to put some nice aftermarket heads on as soon as I have some funds...

 

I have some blue smoke on start-up and after idling for a few moments and accelerating (sitting at a red light). I don't want my car smoking because it's just embarrassing. It just started all of a sudden, too. It actually uses a LOT of oil. I can't see valve stem seals sucking down that much oil. Would one lean more towards the intake gaskets? Removing the oil cap while running to do a generic test of blow-by doesn't result in any air coming out of the valve cover, so it seems that's not a problem.

 

Did you check your PCV valve? It shouldn't pull excessive oil, but something to check and get out of the way.

 

The PCV valve is good.

 

It's most likely valve stem seals.

The guides can consume A LOT of oil.

Could also be the intake gaskets; since across the bottom of every intake port, there's suction vacuum) on one side, and oil (crankcase) on the other.

Might want to just make an afternoon out of it, and change em both.

 

I'll have to do that. Thanks.

 

I was having the same symtoms..

Smoke on start, smoke on idle after sitting, and smoke on acceleration after idling

Replaced my stem seals this weekend, no more smoke, I put positive seals on intake and unbrella seals on exhaust... The old seals Wernt doing anything lol they just turned to dust when I touched them, DO NOT use the shotty autozone rental tool, you'll want to shoot yourself after three valves, get the performance tool brand one( bought mine at oriellys for 19.99$) and it worked 1000000x better


Old vs new

This is the tool that works awesome