New 331 burning oil

[Hilarius]

Hi all.
A question about a newly made 331 engine in a 1952 burning oil.
The engine was completely overhauled by the small company who have been doing my engines since a long time. All new parts from „Old Parts Source“ by means of a DeLuxe Rebuild Kit were used, from the pistons to the valves, bearings and all. Even the rocker shafts and the rockers were new.
The engine, after putting it back into the frame was started several times and run well as exspected. No smoke clouds out of the back. It has never left the yard, though, and idled for some elongated time about 10 times inside the workshop and out. Never yet did it have to work, yet. Runs on all eight and picks up well from idling, too.
The last time I had it running I saw that some blue smoke came out of the right hand exhaust ( the 1952-60S has two separate exhausts ) after warming up, and when starting the engine, yesterday, the same happened and the left hand exhaust started blowing blue, also.
A compression test cold and hot at starter revolutions showed about 75 psi all around.
Now I am quite at a loss and can't explain where the oil might enter the combustion chamber(s) and for what reason. The engine now shows the known signs of burning oil by expelling slightly blue smoke when idling and when revving her up several times, the smoke turns into a blueish cloud. Impossible to drive like that.
It might be a question of too much oil up there under the rocker covers, even though the shafts were newly manufactured ones as were the rockers.
When I dismanteled the engine before the rebuild, everything inside the rocker covers was bone dry with caked oil, rockers badly scored and run in.  So I took care to get rockers with the right holes in them for the valves as well as for the push rods. The old ones had them too but they were clogged.  At any rate I took the ones that promised the best oil supply and perhaps made a mistake.
What, according to the combined wisdom of this forum is the most likely reason for the above described codition and how to heal it?
Hilarius

[Bobby B]

Without knowing every single circumstance regarding your rebuild and break-in, I would lean towards oil getting past the guides or bad valve guides sucking oil down. What was done to the heads? Were new valves/guides put in? Were the old valves used and the guides knurled? Does it have an "umbrella" type valve stem seals and they were left out by accident? If it's definitely blue smoke, it's obviously oil. When it's THAT much Blue smoke, it's usually getting sucked down and not a small leak. If it's not the rings, it's the valves/guides. Usually a new motor will smoke a bit depending on the ring type, wall finish, and break-in method. I've never gone thru this problem and have had good luck getting rings to seat quickly by coating the cylinder walls with some Marvel Mystery Oil before break-in. It was a little trick passed on from an old school high performance engine builder. Good Luck and keep us posted.....
                                                                                                Bobby

[Hilarius]

Bobby,
I, also, lean towards oil getting through the valve guides, see little other possibilities.
On the other hand the valves were new and the guides, although new ones were handed to the rebuild shop, were not replaced because the technician considered the old guides good enough to show no play with the new valves and he left them in.
I had also bought new valve stem seals but they were rather round not resembling an umbrella, and I don't know if they were actually put on the valve stems. When I got the heads back, I assumed that everything was well done, and I put them on the engine without checking any further.
Same for pistons and rings. They were all new and the shop is reliable as proven by the many engines they had rebuilt for me, and that are still working well.
This post is to collect opinions and recommendations, the majority of which should point in the right direction of the action to be taken. Seems the heads have to come off, at any rate.
More input is highly appreciated.
Hilarius.

[Steve Passmore]

What about contacting the shop that rebuilt it Hilmar and ask their opinion?

[Jay Friedman]

I agree with Bobby and Steve, although my 331 cylinder heads have "round" valve stem seals (rebuilder told me "the same as Chevrolet") with no problem. 

Some other possibilities:

In my opinion 75 psi of compression is a bit low.  It may be because the rings have not seated yet as Bobby mentioned, or it could be because of another piston or ring problem.  For example, were the rings installed with the ring gaps 120 degrees around from each other, which I believe is necessary? 

Something else to check is the rocker arm shafts.  At both ends of each shaft is a notch.  When the complete rocker arm assembly is installed on the cylinder head, the notches on the shafts on both cylinder heads should point toward the middle of the motor.  Otherwise the holes in the shaft won't line up correctly with the holes in the rocker arms.

Good luck.

[V63]

Some suggestions.

Maybe the lubrication?

Oil viscosity issue? Is fuel contaminating the oil? Correct capacity amount of oil. Oil pressure? Oil draining down from heads ok? Any oil additives? Fuel additives? Water contaminating the  oil? Engine temperature?

Maybe remove valve covers and run to observe upper lubrication ?

[35-709]

"The engine, after putting it back into the frame was started several times and run well as exspected. No smoke clouds out of the back. It has never left the yard, though, and idled for some elongated time about 10 times inside the workshop and out. Never yet did it have to work, yet. Runs on all eight and picks up well from idling, too."

One of the worst things you can do to a freshly overhauled engine, it needs to be RUN.  Would not surprise me in the least if you find that your cylinder walls are glazed and will have to be honed and new rings installed. 

[Scot Minesinger]

There is a specific break in procedure for newly re-built (or even repaired) V-8 engine from the 1970's and earlier (maybe 1990's and earlier).  Had a bad intake valve (cylinder # 7) on my 1970 Cadillac 472 and when I took off the head I was not confident in the lifters (engine rebuilt 20k miles ago), and so those were replaced too.  Upon completion, the instructions were to run the engine at 2,200 rpm steady for 30 minutes or I would flatten out the cam.  This engine runs wonderfully since that repair back in 2014.  Any engine/restoration shop should be familiar with this type of procedure in starting a new engine rebuild/substantial repair.  Further, any shop should never rely on the owner to break in the engine properly.

BTW it was really cool to have the 1970 engine all apart, repair head with new intake valve and change lifters, put it back together and it starts like new first crank.  Because of posts like this and many others where a repair is unsatisfactory, I do any repair possible.  When I first bought the car, planned on paying to have all the work done, but that does not work for me.

[Dave Shepherd]

Something is wrong internally with 75psi compression, assuming the throttle was held open and the engine spun over properly.  I would do a leak down test to see where the compression is being lost.

[Bobby B]

  Further, any shop should never rely on the owner to break in the engine properly.

Yes  ..........It's a nerve wracking crapshoot, but rewarding when things go as planned (Miller Time!). I usually substitute a running carb to eliminate that issue, which could send it downhill quickly.
                           Bobby

[Jay Friedman]

Oil draining down from heads ok? Maybe remove valve covers and run to observe upper lubrication ?

I agree with V63 about removing your valve covers to check the oil draining from that area.  There are drain holes at the back of one head and the front of the other (I forget which is which).  If the oil is not draining properly, clean out those holes.

[Caddy Wizard]

75 psi all around indicates a problem.  The compression after a fresh rebuild should be more like 125.  75 is what you would expect from a worn-out engine, so something is off (and on every cylinder).

So yes, a compression leak test is in order.  In that procedure, we would find top dead center on a cylinder (so both valves are completely closed) and screw a special adapter into the spark plug hole and connect it to a source of compressed air.  Then find where it is leaking.  If it is generating bubbles in the coolant, then we have a bad seal at the head gasket or a cracked head.  If it hisses in the crankcase (take the oil breather off to check this), we have bad rings (or pistons that are not properly sized to the bore).  If it hisses in the exhaust pipe, bad exhaust valves (not likely in your case).  If it hisses in the carb, bad intake valves. 

Another thing you can do to check for bad intake valve guides or bad valve stem seals is to remove a valve cover and start the engine.  Squirt oil all over the intake valves right at the valve stem seals while observing the exhaust.  If the blue smoke increases, well, you have your culprit.  If not, you can eliminate that.  Of course, this is messy and best done with three folks (one ready to shut the motor off, one squirting oil, one watching the exhaust.



Good luck.

[Caddy Wizard]

75 psi compression combined with blue cloud strongly indicates a problem at the rings/pistons, not the intake valve guide seals.  If the pistons/rings were good and the intake valve stem seals were bad or missing, the engine might blow smoke but have good compression. 

And this is a 52 motor, correct?  Not a 54 or 55 motor with the auxiliary vacuum pump on the bottom of the oil pump?  The 54-55 aux vacuum pumps can allow oil to be sucked up from the oil pan directly into the intake manifold and then burned in the combustion chamber, if the check valves are not working or in place in the plumbing.  So on freshly rebuilt 54-55 motor, you could have a perfect motor that nonetheless burns oil because of a fault in the auxiliary vacuum pump circuit. But a 52 motor shouldn't have that system at all...

[Caddy Wizard]

As noted above, the combination of low compression and the blue smoke points toward rings or piston problems.  Tell us, if you remove the oil breather cap and let the engine run, does it puff there more than normal at idle?

[Jeff Rosansky CLC #28373]

You can put a little oil on each cylinder and repeat the compression test. If it is a ring issue the oil will seal it for the test.
Jeff

[Hilarius]

Thanks to everyone who voiced an opinion or contributed in any other way to solve my problem.
Today, I checked the valves, the guides and the seals and they are all OK.
Considering the input of 35-709 that a newly made engine should by no means run for elongated periods of time for the danger of "glazing" is what convinced me the most. I had heard of that before but did not really believe it. In a PM to Steve Passmore I brought it up but he had no opinion about it.
When Art Gardner suggested different ways of checking pistons and rings, today, I did another compression test which, again, showed 75 PSI all around. With a little oil in the bores it went up to about 90 PSI, pointing towards rings.
According to his suggestion, I then made up an adaptor bushing for the spark plug holes to blow compressed air into the cylinders to find out if they held the pressure and hear if there was a hiss in either the carb, the exhaust or the crank case.
Carb and exhaust were OK as was to be expected by the uniform compression results. But there is a definite hiss in the crankcase pointing to the air blowing by the pistons and rings.
Normally the compressed air should slowly leak down inside a good cylinder. In my case the pressure goes down from 80 PSI to zero in a second.
Bottom line: the engine is shot and behaves like a badly worn one.
How could that happen to a newly made engine? This is where the glazing comes in, which in all probability was caused by idling too long instead of "massaging" the engine with high an low loads and high and low revs alternately on the road.
Having read about it on other forums, I now know how glazing occurs, but it would make this story too long to explain. But it is damn convincing.
Seems in the long run I shall have to have the engine re-honed to eliminate the glazing and have new rings installed, meaning it has to come out and go back to the shop.
First, though, I'll take off one head to see what the cylinder walls look like and whether any honing grooves are still visible or glazed over.
I'll keep you posted.
Hilmar.

[/pre]

[35-709]

Hilmar, quite frankly I hope I am wrong as to your oil burning problem and possibly another, simpler cause will turn up as you begin to go back into the engine.  Such a shame to have to go back and do over --- doing something twice I hate to do but have been there before.  Best wishes to you in getting it straightened out and on the road.
Regards.   

[Caddy Wizard]

Sorry to hear your troubles.  Ugh.


In the old days, one would remove the heads, remove the oil pan, unbolt the connecting rods and remove the connecting rods and pistons.  Then you would re-hone those darned cylinder walls and put on new rings and reassemble this new motor.  So it can be done with the engine in the car.  Either way, it is a good bit of work.


If this were my car, I'd probably do it with the engine still in the car.


One final thought -- I'd like to mike (measure with a micrometer) the cylinders and pistons.  It wouldn't surprise me to find a mis-match in the two. 

[Jeff Rosansky CLC #28373]

You may be able to borrow or rent a borescope type camera and look at the walls thru a plug hole. It won't make the fix any better but may allow you to know what you are facing. Art has a good point (he always does). If you have any paperwork for the engine see if everything matches. If this is your fault (for lack of better words, sorry) that's one thing. But if the builder put the wrong stuff in it should be his.
Jeff

[Caddy Wizard]

If you have any paperwork for the engine see if everything matches. If this is your fault (for lack of better words, sorry) that's one thing. But if the builder put the wrong stuff in it should be his.
Jeff

One of the reasons that I suspect mismatched pistons to rings is the uniformity of the compression readings.  I would expect that some cylinders would glaze more than others and there would be some variability in the numbers.  The fact that they all read low and all read the same makes me think that the pistons are too small for the bores or the end gaps of the compression rings are too wide, or something similar.  Some problem is exactly the same across all eight cylinders.  To me, that suggests a parts issue...