Rebuilt engine burning oil - zero miles
 

Long story but my Dad had this engine rebuilt about 8 or nine years ago. He passed away and all I know is he said it was a stock rebuild. Got the car together recently and got it running. Can’t drive the car yet so it just idles when I run it. Blue haze starts when it warms up. Took out #1 plug and took these pictures. Spark plug was black. PCV valve is good. Any thoughts on what to do here very much appreciated. Thanks in advance! https://uploads.tapatalk-cdn.com/202...6b46ecb328.jpg
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If you do a hot cranking compression test and all the cylinders are with in 15% then I would at least initially conclude that the rings are sealing ok.

Next up when the exh smoke is Blue is the condition of the valve seals , especially if the blue smoke does not start right off the bat, but until the motor starts to get warm!

1) The seals could have dried up,

2) they could have been installed wrong.

3) they may have busted from being hit by the valve spring retainer due to inadequate clearance, but if the motor uses only a stock Cam of .406 this should not be the case!

4) or like when your same issue was seen from brand new aftermarket heads of a friend of mine that had been assembled with seals for 3/8” stem valves and not the 11/32” stem valves that where used in the heads.
This issue took us quite a while to figure out as we progressed down the list of process of elimination!

Also a true 100% stock rebuild would still be using the stock valve spring retainers and the stock valves which have a second groove below the keeper groove to hold a O ring seal which the stock retainer is designed to hold.

It may be that the heads where not assembled with these seals , or like I posted they have dried up over time and just cracked into fragments.

You need to look to see if during the rebuild the heads had the tops of the valve guides cut for what’s called positive type seals which could seen thru the valves springs, or if like I posted they are still set up fully stock and use just a Valve stem O ring under the keepers.

As Steve points out, there could be a number of things causing this.

I would get it warmed up then perform a leakdown test on it. If one of the rings got installed upside down that will cause it to smoke (but usually under acceleration/load) and the compression numbers would all still be pretty even.

Thank you both! Do a compression test and see what that looks like and report back.


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I had a similar condition once when using aftermarket spring retainers with the stock o-ring seals on the valve. The stock retainers are longer and the bottom and capture the o-ring, the aftermarket retainers caused oil to be sucked down the guide. It would puff blue smoke at idle and clear up when driving. Positive seals on all of the guides fixed the problem.

If the leak down or compression test come out normal, pull the intake and see if there is oil on the top of the valve heads. Sure sign the oil is coming from up top.

Since it's not really been run, other than some idling, since the rebuild, it just may need some more running time to break in and seal up.

With compression rings that are good and just have not bedded in yet you see that as blow by out the breathers because the new oil rings are doing there job.
Blue smoke out the exh like the OP is taking about is not likely from a new motor just needing brake in time.

Already had the compression tester, got a leak down tester today. Gonna do both and see what’s up. Wish I could drive it but need front suspension work, pretty sure it will blow some dense smoke under load. Drove 1 time 15 years ago March the day I drove it home. Was smoking some then too.


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Fresh gasoline involved?

Yes, ethanol free.


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All cylinders were between 145 and 150, leak down test next. Service manual says 120 - 160.


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Compression tester is a new Lang TU-3PB, made in China, for kicks tried my 35 or so year old made in USA Craftsman in cylinder #1 and it read 165. Gonna mess with them see which one is closer to correct


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I wonder if you just need to run the snot out of it for a few hundred miles, to break in the rings?

Hopefully can get it on the road soon but gonna have to drive at night, embarrassing for sure in the daytime.
Definitely do everything suggested here , leak down test very soon, hopefully tomorrow


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if you exhaust every other possibility without success, you could always try the Bon Ami trick.

Regardless of how "good" the PCV valve is, I'd pop it out and completely eliminate the possibility that it could be contributing to the smoke. When we have had a valve that was pulling oil it took about 20 miles and/or 30 minutes to clean up the residual oil in the hose and manifold before the smoke went away.

Rings these days are sent out from the manufacturer after they have been put thru a lapping process and freshly honed cylinder walls with the proper finish for the ring type used 90% of the time fully bed in during the 20 to 30 minute long cam break in session!

That dam Bon Ami / Comet trick some people always throw up and post about needs to be put to bed at this point in time without question!

Its from ancient times when compression ring faces where mainly hard Chrome and ruff finish cylinder walls where needed to bed the two in.

Bon Ami if added to a cylinder will go right to work to chew the Moly face off of your new rings, and even if it did by chance work somewhat it’s extremely uncontrollable and not to mention that it bonds to your spark plugs and makes them unusable!

Call up a tech person at any ring manufacturer and as soon as they hear the words Bon Aim , on your end you will hear a click as they hang up!

Also these days oiling the piss out of your new cylinder walls during assembly will only delay the minor amount of bed in that needs to take place.

All I have ever done for the last 30+ years is to wipe on enough of a ATF film to keep cylinder wall rust at bay and to lube the piston skirts, and I have never had a ring break in issue .

After the leak down test I’ll pull the PCV valve and let it run for a half hour. Would be nice if the answer is something simple for a change.


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I hope that when the motor was assembled the compression rings where installed with the proper side up so that oil is not scraped into the chamber.

I forget what brand ring it was, but there was a batch of compression rings made maybe 10 to 15 years ago that had the dot marking that signifies the top put on the bottom of the ring!
Anyone remember this issue and the brand?

My money is still on something going on with the valve seals or lack there of due to as you have posted that it does not smoke right away.

I doubt only a few know about that, and its not French either.