Technical New motor break in question???

ITS FIXED!! See last post for details


About 3 months ago I purchased a rebuilt 316 Pontiac motor from a large motor rebuilder in town. They had built it for another customer that never picked it up. It had been on the shelf for a couple of years but they test motors periodicly. This week I finally got it in the car and got it running. It runs fantastic and is super quite and smooth. Bad part is that it smokes pretty bad on both sides and mostly under acceleration. I have only driven it about 30 miles and it seems to be somewhat better with almost no smoke at idle but still puts out a cloud when I take off. I called the builder and explained the issue and he said the rings need to seat and to put a quart of ATF in the gas tank and drive it. This sounds reasonable but I want a second opinion? I got a really good deal on the motor but for the price I offered them they offered no warranty. I do believe they are willing to help out though.

 

Never had a freshly rebuilt engine smoke. I would guess it has ring set from two years sitting, and it may stop. Never heard of the ATF in the oil thing, but Marvel Mystery Oil has worked well to free up rings that were sticky.

 

Not ATF in the oil, In the gas tank.

 

I'd suspect the valve stem seals dried out and got brittle.

 

Thought of that too but it would have to be a bunch of them as it is heavy on both banks.

 

Never heard of putting ATF in the gas tank, would think it might cause situations in the fuel delivery system. Let us know results if you decide to do this.

 

No ATF, anywhere but a transmission.

 

Sounds like your engine guy is passing the buck on you. NO rebuilt engine should smoke like you describe and no snake oil is going to help. He is hoping the high detergents in the ATF clean up the rings, but I bet either the rings are fatiqued from sitting or the valve seals have gotten brittle.

You took a gamble with the no warranty thing and you might have gotten bit.

Don

 

If you guys are trying to make me feel better, its not working!!!

 

You said yourself that the smoke is lessening, so feel better. I wouldn't put any additives of any kind-- additives are used to try and cure old sticky worn out engines.

I'd take it out and drive the snot out of it to get the rings to seat. Just remember to vary the throttle a lot.

I still would focus on valve stem seals. It only takes one bad one to smoke things up and don't forget that most cars have exhaust crossovers in the intake manifolds, so one bank can smoke the other. They also may improve with use as they get heated up and lubricated. They're a bit of a pain to replace, but it goes quick with the right tools.

 

Run a compression test on it, I'd take a look and see if they even installed oil seals on the valves, do you know if it was bored with new pistons?

 

I would drive it,speeding up and slowing down, on the highway. If the rings need to seat that should do it. If not find out what brand of rings they used. They may they have some insite on there product. I'm 65 and have seen lots of remidies to rings not seating, including putting Bonami down the carb to seat the rings. most of the time its driving the car that will seat them. Lots of smoke when taking off is usually the valve stem seals. a compression check dry, and then put oil in the cylinder and recheck, if alot higher then the rings are not seated if everything else in the cylinder is sealing. Good luck

 

Far too many rebuilders use white grease to lube everything, in time it will cake up a bit. If that is what they used, run it for a while..... the ATF in the fuel is similar to adding Marvel to the fuel, helps lube the valve stems and such, really doesn't do much more than that... and it can make it smoke worse, you are burning oil ! Most rebuilders also use cast rings. Nothing wrong with them but they take a few miles to seat, but once they do, you are good to go.

 

Thanks guys, I am going take it out and drive it and see if it helps. I would hate to start over, it really runs great!

 

Greybeard is spot on. Even oil will gum up a bit when it sits for a while. Keep driving it and I bet it gets better.....

 

Don't just drive it....moderate acceleration up to 60 or so then let off and let it coast down ....accelerate....coast down. That will seat the rings. This assumes it's a manual trans.

 

Agree with using a reasonable amount of MMO in the gas for awhile.
Would help to know type of rings, cast, chrome,steel,or moly.
Chrome rings take a bit more time to seat and will smokesometimes till they seat. Drive it some more with a lot of accel&deccel. When you've got 2or 3 hundred miles onm it, come back and let us know what's happening. Just keep a close watch on oil level.

 

Years ago I put an engine out of a junkyard in a Chevy van that I bought because the original motor was shot and burning oil like mad. When I fired up the new motor it smoked like mad and when I went down the road there was a smoke screen behind me.

I called up the junkyard to complain they had sold me a bad motor but after a while the smoke stopped. Then I realized I was burning the accumulated oil out of the old exhaust system that I had reused. Once that burned out everything was fine. (I called the JY and apologized !)

Don

 

In the 50's and 60's Perfect Circle used to put an insert in their ring sets for shops. Their recommendation for breaking in a new ring set prior to releasing the car to the customer was... from a 5 mph rolling start accelerate full throttle to 50 mph. Do this ten times and it is ready for the customer. Dad allowed me to do this on many of his overhauls. I always looked forward to this part of the job.
As has been mentioned, I would run the heck outta this engine and see if the rings will seat.
I believe you will get the smoking down if you do. Good luck.

Ross

 

Don may have it if you old engine was shot and you are still using the old exhaust.

 

Worn valve guides and seals tend to smoke mostly at conditions of high manifold vacuum, like at idle or during deceleration. And you might see a bit of smoke when first starting the engine after it's set a few hours and a bit of oil has drained past an open valve. During acceleration the manifold vacuum drops significantly and doesn't tend to pull as much oil past the intake valve stems and into the combustion chamber.

Give the rings a chance to seat as mentioned above. Are you using a synthetic oil by chance? Some of this fancy new oil does such a good job of lubricating that it can prevent or slow down the break-in process. A detergent additive like Rislone or MMO in the oil might help if the rings are sticking in the pistons. But the ATF in the gasoline doesn't sound right to me. If you think burning motor oil makes smoke, burning ATF will really lay down a smoke screen!

Also... How's this engine set up for crankcase ventilation? Road draft tube? Breathers? PCV plumbing?

 

Old engine didn't smoke it was just worn out no oil pressure. I drove it another 30 miles yesterday and it hasn't changed any. I think valve seals are the problem.

 

How the hell do they check motors periodicly on the shelf ?? I don't think stem seals would dry out and go hard in two years unless they were sitting in direct sunlight. As said above keep driving it and see if things settle down.
When I was building motors, to have one sit for two years was nothing. Good luck and hope it sorts its self out. JW

 

How much is the dipstick level dropping in say, that m30 miles you drove it yesterday. If it has chrome rings you haven't driven it far enough to seat them.
I would keep an eye on oil level and keep driving it awhile constant accel and deccel as much as possible avoid steady speeds.

 

That what I was thinking as well, I had a new never started motor in a car for 10 years and had no problems with it. What they said, is they pressure test them when they are setting and said they did it again just before I picked it up. it sure acts more like seals??

 

I plan on driving it some more and I am running it up to 75 and back to 50 over and over again.

 

just throwing this out there, turbo 350 trans by any chance? vacuum modulator leaking?

 

Nope, still running the original Hydro. I have been super busy and have not had a chance to drive it since my first update.

 

In the old days, for stuck rings & valves, we'd pour a pint of light oil like MMO or ATF through the carb with the engine running. Nowadays you'd get busted for air pollution. But that often worked to free up the rings.

 

I'd bet its chrome rings...Just drive it....The valve seals should be ok...Just drive it....Don't beat on it or baby it...Just drive it...Around town, stop and go, under 60mph...Just drive it..Gotta feel better now?