Where else can blowby come from besides bad ring seal?

My ZZ454 crater smokes quite a lot at idle and other speeds. The smoke is very light gray.

I pulled the manifold and resealed it w/ FelPro 1210s.

There is less than 500 miles on the engine. It is, however, out of warranty, since it sat for a year in the car in the garage protected before first-start.

It did this on first-ever start, R&R the manifold, smoke stops. Fix the header leaks in the reducer area 500 miles later, smoking returns.
It fills the street with smoke, and has blowby.

I'm having a hard time believing it's the rings on a new GM crate engine. It's the blowby that gets to me. I don't know any other way to have it aside from poor ring seal. I have a fair number of years of experience on a lot of engines, but I'm really hoping I can fix this without yanking the mill.

Any thoughts? All would be appreciated. This car has to run; it is hurting my family in ways that are very serious. Having to pull the engine would be a very bad turn of events for us.

Eric

If the exhaust valve guides are bad enough, you can pressurize the crankcase with exhaust gas. This will "look" like blowby, and can overwhelm the PCV system. I would consider this much LESS likely than you having blowby past the rings. It might be a situation on a very high-mileage engine with totally wiped valve guides.

Have you verified the PCV is in working order, and you have some kind of oil baffles to keep lube out of the PCV system?

Are the valve stem seals still in position?

What are your leakdown test results?

The ZZ454 has alum heads with the good seals, so I doubt this is the problem. Going to ask the obvious - these are the stock valve covers with baffles intact?? You sure it's not coming from something else like a bad trans modulator or a brake booster filling with brake fluid from a bad master cylinder?

Eric,if your car is automatic there is a possibility the diaphram in the modulator valve ruptured. This will cause the motor to suck trany fluid into the intake through the vacuum line that goes to the mudulator which will make that grey/white smoke so check that out. I would heat up the motr and get it smoking then uhook the vacuum line from the trany,block it off at the intake ,and the nrun the motor at apporx 1400-1500 rpms to see if it stops smoking after 10-15 mins.

If this is the case replace the modulator and keep in mind you will have a lot of trany oil in your exhaust system that will take some time to burn out .

If this turns out to not be the case coolent leaking into the combustion chambers or intake will make grey/white smoke and have a real sweet smell that will burn your eyes. This can be caused by a cracked block if the car sat durring winter without the correct antifreeze protection,craked head/s or intake,bad head/intake gaskets,etc. Since the motor is out of gaurentee i would try a good quality stop leak in the cooling system. If it works and stops the smoke or greatly reduces it then you know its a problem with the cooling system and you could be lucky and the stopleak could hold for yrs.

But there are tools/kits available to check for exhaust gases in your coolent to determine if its a head gasket and i would also watch for coolent in your oil too.

Let us know how you mak out.

scott

Eric, as Joe mentioned, watch your PCV. The stock GM covers are nice and have a good baffle in there.

How about eliminating the PCV system for a while just to see if thats the problem?

Hi guys,

Thanks for the thoughts. Here are my answers:

The car is a 4-speed, so no vac mod problems.

I ran the engine with the pcv line disconnected from the carb, plugged the vac line on the baseplate, still smokes badly. This is when I noticed the blowby, since the engine was not putting vacuum into the crankase. With the pcv hooked up there is no evidence of blowby, save for during cranking, where some amount of smoke can be seen leaving the breather opposite the pcv.

The car does have the stock valve covers.

The PCV is working ok. Checked it.

Removing the pcv line, which is T'd with the booster hose, meant that the engine was running strictly on its own (no booster/pcv hooked up). That was a great idea about the brake fluid, though.

I don't have a leakdown tool, although I do have compressed air. I ran a compression check, and all the slugs are within ten pounds of each other, 153-161 is the range, with most about 159 or so. All cylinders were checked with the same method at the same time.

When it sat for a year before first-start, it was dry. No water in the engine, and it was inside the car inside a decent garage the entire time. I live in So-Cal, and there were never any seriously cold temps during this time.

>>>

Additiuonal info:

With the intake removed, I noticed that several intake ports in the heads were quite darker than others, same with the intake manifold.

All this time that I've been driving the car, the valve covers were very hot, although the temp guage indicated 150-180, never more. I'm pretty sure the guage (Autometer Sport-Comp) is accurate. When it began smoking again (after 5 months/500 miles), I replaced the Holley that had caused problems with a Mighty Demon 850 (annular boosters) and now when running the valve covers are not nearly as hot, just normal for a running engine. They were almost too hot to touch previously. I figured the engine was running lean, although the plugs were black. It ran with the too hot valve covers (and rad hose and rad top) for the entire 5 months. What kind of damage could this have caused.

What baffles me is that the engine did this when brand new, then quit with a manifold R&R and fixing the carb, now is doing it again after welding up the header leaks. I'm just having a tough time believing that it's the rings. But then there's what appears to be blowby...
It also seems a little strange that all 8 cyls have jet black plugs. All the rings bad at once? On a brand-new motor? Went bad immediately, fixed themselves, then went bad again? I know it doesn't work like that. If the rings were shot from start-up (can happen), it would have continued to smoke. If the rings were installed improperly (2nd ring upside down, for example), It would have stayed smoking. And all 8 installed wrongly? Assembly line terrorists?

There's just go to be another something that I've missed.

How common is a warped or cracked intake manifold? These motors have the bow-tie version of the Performer RPM. I can't be entirely positive that the intake is sealed up properly at the gasket area due to the smoking; at least I know I did it the way I have done it for 25 years and used top line gaskets.
When I removed the intake originally to see why it was smoking (first-start/break-in), the center 4 intake bolts were appx 80 ft.lbs (no kidding), and the end bolts were less than spec, two of them finger-tight only. All this as-delivered from GM (Scoggin-Dickey). Reinstalled the manifold, fooled with the carb and BAM!- smoking stopped. Same heavy light grey that is coming out again, now it's heavier, but same color.

If I can't solve this, we will be in a bad way. If we can solve this here, it will be a major deal for my family, not to mention that I will be able to keep my car.
Thanks everybody !

Eric

Jet black plugs show way too rich a fuel calibration.

This rich mixture can cause cylender wash (yes on all 8 clenders at the same time)with too much fuel hindering the ring breakin process glazing the cylenders and then your sunk.

If this happened to you the usual fix is to trear it down,do a quick re-hone not removing much material,install new rings,reassemble motor and go from there.

But you must find & fix your rich fuel mixture issue with the carb 1st. I would check fthe float lvl and for correct power valve or power piston spring (depending on carb type) to match your cams idle vacuum . This is to ensure your carbs power circut does not come in too early like at idle or just off idle at part throttle low load situations.

Could also be too much fuel pressure forcing fuel past the needle & seat in your carb.

Scott

Eric's car has a 4 speed so it's not from a modulator. Isn't white smoke usually from water. Maybe the intake is really warped because of the way it was torqued down when he got it? I dunno.

Eric, just curious, what carb were you running before?

BTW, the 1210's dont have a provision for an exhaust crossover - it may burn through.

Did you pull the plugs and squirt any oil in the cylinders,before letting the engine sit for a year? If you didn't,it's possible you might have scuffed up the rings when you fired it up for the first time.
Been there,done that.

Hi all,

Well, sure looks like rings I guess. Anybody have a recommend for GenVI head gaskets? I don't want to brinnell the aluminum, and I'm not sure what GM put on at the plant. Does FelPro make a rebuild gasket kit for GenVI yet?

Anybody think that bad valve stem seals could cause something like this? Rmember, the problem came back when the vacuum characteristics changed from welding up the holes in the collector area. They were actually numerous. I don't see how the crankcase could be pressurized to creat blowby from stem seals, tho.

Vince, Scott,
I was running a 4779, but it had been modded by a local carb "pro", who gave it back to me with the secondary metering block and 83s mounted in the primary side, ancient shrunken gaskets, and the primary block on the secondary side, also with wasted gaskets. All this from a guy who advertises in the major magazines. He drilled the blocks, and the result was a real fountain of youth.

For this reason, I was afraid that I had washed the rings too, since it smoked so much during break-in.

But it quit smoking and was driving ok (considering the carb) ! That's the part that really puzzles me.

I put on a new 850 Mighty Demon with annulars, and even through the smoke the engine has a totally different idle characteristic. The idle smoothed out a fair amount, and is more steady. Too bad it looks like a WW2 destroyer laying down a smoke screen.

Clint,
I also had not squirted any joy juice in the cyl's during storage, another concern I had when it fired for the first time.

It all adds up ok, except for the fact that it completely quit smoking (not one puff) for such a long time.

Yep, those 1210 stainless pieces are gonna burn thru eventually, unless the crossovers aren't drilled, like the Performer RPM heads, which is what the GMPPD heads are, with better parts.

I'm really really hoping for a miracle that will prevent me from having to yank the motor and hone/ring the cylinders.
It isn't the work... I've done that lots of times.... it's because I'm in the first year of law school, and that means major work overload and no free time at all for an entire year. It's actually against the law for me to work, and it is enforced. Each year they fail the bottom 30% of each class, and that's the end.
The other thing is that I'd sure hate to do all that motor work, and have it turn out to be only a cracked intake, or something that I could have fixed in a weekend. I haven't got the money for decent rings and gaskets anyway.

I couldn't wait to get home tonight and read the replies all you guys posted. Thanks !! I'm a life member here, I just can't post a lot right now due to work.

Hey to Josh (Mac)

Eric

Metering blocks on wrong sides :eek: . Must of run like ass w/83's up front.

I'm pretty sure your heads come w/better seals than my 454HO had. I think you have the PC type seal. Might be worth to look and make sure there on there tight and not damaged.

How do you like the annular carb? I've had my eye on the BG 850 vac sec annular but I'd hate to spend the $$$ and end up going back to my trusty 770 Avenger.

Since you have stated that your smoking stopped after an intake R&R, I would put money on it that it is your intake. If it is a virgin block/heads/intake, they may not be square from the factory.

Or, if the intake is not cast correctly, or warped or not squared, it needs to be milled to fit properly. If there is an uneven spot, then the lack of sealing pressure will, over time, allow oil from the lifter valley seep through, and when that starts, it will ruin the whole intake gasket, and you will find the intake ports of the heads wet with oil, and if you look even more closely, if it is very bad, you may find oil pooling on top of the valves that are closed.

This also happens when you mill the block and heads, and not the intake. Been there, done that. I can even send you pics of the oil pooling so bad on the valves.