New stroker engine burning oil

[74stroker]

Photos to go with previous post: plugs pulled on June 1: #4 had lower compression and oil on threads and electrode

 

[74stroker]

I have photos of cylinders 2,4,6, and 8 using horoscope. Cylinders 2 and 8 had good compression (~195 psi) Cylinder 6 was lower (~ 173), and 4 was a little lower (182).

No 6 cylinder photos show melting on top and along edge of piston and small metallic fragments; cylinder wall looks melted in

Cylinder 8:

cylinder 8 plug (above)

Cylinder 4 (below)

 

[74stroker]

last photo above is from no, 6 cylinder (not 4).

more from cylinder 4:

plug from cylinder 4 (above)


cylinder 4 (belwo)

 

[heminut]

I have photos of cylinders 2,4,6, and 8 using horoscope.

Horoscope? I never put any stock in those things!

 

[74stroker]

Boroscope!

 

[Challenger RTA]

Just thinking this through.Question, I don't think this was said. Does the blue smoke clear up after a short period. That would be valve guide problem. continue to smoke rings not sealing or also valve guides. Warped head intake not sealed. Did you do a leak down test? If you did or do,you defiantly can hear the problem. What did the ring look that were replaced? Was the gap checked after they were removed and checked in the cylinder in a few places.

 

[Challenger RTA]

The spark plugs and compression test are the tattle tails where to look. If you don't follow through with leak down and other measurements. Your just shotgunning it zero in on what you know. Are there studs in the main caps? Is this block original the car?

 

[74stroker]

Thanks rta,
have not done leakdown test. Block was factory rebuilt in 1981, 30 over. then 60 over when when rebuilt and stroked from 367 to 415 in 2018.

 

[Challenger RTA]

Are there studs for the main caps?

 

[74stroker]

You have seen pictures posted. Pistons look torched, yes? esp no 6...rings and melted piston photos from last year were posted earlier in thread. Piston photos from second failure were posted today.

 

[Challenger RTA]

Engine Building Fundamentals: Line Boring / Line Honing​

machining processes that may be applied to the main bearing journals in the engine block. These are corrective processes and they're know as line boring and line honing. The actual process that's used will depend on how bad the alignment is initially and hence how much material needs to be removed to correct this. These processes may also be referred to as align boring and align honing but essentially these terms all refer to machining processes used to correct alignment and sizing issues with the main bearing journals or main bearing tunnel as it's also referred to. The alignment of the crankshaft main bearing journals in the engine block is critical to the reliability of the engine particularly with regard to the bearing life itself. It can also affect the frictional losses inside the engine and hence affect the amount of power the engine produces. It's easy to assume that the main bearing journals are all perfectly aligned, concentric and on the correct size. However in reality this main not be the case. OE production tolerances and manufacturing techniques alone may mean that the journal alignment and size isn't perfect. However if you're fitting aftermarket studs to help clamp the main bearing caps to the cylinder block, these may distort the block or the caps and hence affect the journal alignment or size. The other aspect to consider is the alignment of the main bearing journals with regard to the deck surface, sump rails and the cylinders themselves. In an ideal world the crankshaft center line will be perfectly parallel with both the sump rails and the deck surface. And each cylinder would be perpendicular to the crankshaft center line. In many cases, some corrective machining will be required to achieve this sort of alignment. In some cases the factory main bearing caps may have a known weakness when a certain power level is exceeded. And in these engines it's often common practice to replace the factory bearing caps with either billet caps that are much stronger or perhaps swap from factory two bolt caps to four bolt caps which are clamped more firmly into the block. In this case the new caps will need to be machined to achieve the correct size and alignment. The process of correcting journal size and alignment begins by taking the main bearing caps or girdle and removing a small amount of material from the mating faces where they contact the block. Naturally this will end up reducing the size of the main bearing tunnel. And this is essential because it now allows the boring bar to remove excess material and get the alignment and size to whatever is required. Depending how bad the alignment is initially and hence how much material needs to be removed, will affect which process is applied for the machining. If a minor correction is necessary then this may be achieved using a hone, however major corrections will require boring followed by honing to provide the correct surface finish. The higher clamp offered by stronger fasteners, can result in minor distortion of the main bearing tunnel when the fasteners are tightened. Unchecked this will result in tight bearing clearances that can quickly result in serious engine damage.

 

[heminut]

Old time mechanics always said that if it smokes when you're accelerating it's oil getting by the rings, and if it smokes when decelerating is oil getting through the valve guides.

 

[74stroker]

Are there studs for the main caps?

I don’t know. If needed I would expect the builder to have them...

 

[74stroker]

Old time mechanics always said that if it smokes when you're accelerating it's oil getting by the rings, and if it smokes when decelerating is oil getting through the valve guides.

Thanks heminut. I would run this test, but worry I might do more damage to engine. Pretty sure the pistons got too hot because either plugs were too hot N12Y—-should have used N9Y, and fuel cap I had was non-venting, creating vacuum in tank that held fuel back.
I can tell you that it made a heck of a lot of smoke just idling in garage...

 

[74stroker]

Mystery solved (I hope). Builder pulled head and found head gasket was blown on No 6 cylinder. motor pulled oil from galley into cylinder through pcv valve. I used premium gas, never noticed any knocking what would cause pre-detonation and blow gasket. Again, only ~ 250 miles on motor and not pushed since rebuild last fall.
Glad it's not worse--was afraid I melted pistons; thankfully not. But still scratching head on why gasket blew and how to prevent it going forward. Any thoughts/suggestions would be appreciated.

 

[Challenger RTA]

Surface flatness of head and block and between cylinders? Correct torque? Or is this just torture?

 

[pschlosser]

Mystery solved (I hope). Builder pulled head and found head gasket was blown on No 6 cylinder. motor pulled oil from galley into cylinder through pcv valve.

That's good news, indeed. This is an easy fix. It's possible there was a defect in the gasket, or some speck of dirt was in the wrong place when installed prior. I presume the "builder" will confirm the block deck and head are true and flat prior to reassembly. I recommend you ask them to make sure they at least say it was checked.

I've blown a few head gaskets in my driving past. The bulk of them were from poor cooling or over heating. And, of course, hard driving.

 

[74stroker]

Good questions. I will bring them up with builder.

That's good news, indeed. This is an easy fix. It's possible there was a defect in the gasket, or some speck of dirt was in the wrong place when installed prior. I presume the "builder" will confirm the block deck and head are true and flat prior to reassembly. I recommend you ask them to make sure they at least say it was checked.

I've blown a few head gaskets in my driving past. The bulk of them were from poor cooling or over heating. And, of course, hard driving.

Thanks pschosser. I was relieved it was not burned pistons again, though I couldn't see how this would have occurred with such limited and easy driving. The builder and I will be having a talk this week before completing the repairs. I will be sure this is part of the discussion. None of your causes for blown h. gaskets seem to apply here, as the car was not driven hard. Builder suggested it might have misfired (I never heard it knock and ran on premium gas) or that the bolt pattern on the head was wide where the failure occurred.

 

[pschlosser]

Builder suggested it might have misfired (I never heard it knock and ran on premium gas) or that the bolt pattern on the head was wide where the failure occurred.

FYI, I've never heard of a misfire causing a blown head gasket. That seems... reaching, to me. The pressures under a misfire are no more or less than those of normal operation.

 

[74stroker]

Thanks for this insight. I am flying a little blind at this point, but trying to get educated in mopar performance issues. I have a PhD in Geology, but it doesn’t help much in these matters.