Time to address rebuilt engine oil consumption

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AJ/FormS said:
So what valve seals are on there now?
I usually put the PCV on the passenger side(but thats no never mind). Pull the PCV hose off completely and check it internally for oil.
I have never seen oily oil migrate up the plug threads, and the firing tips be dry. Wont say it cant happen. Just in 40+ years, Ive never seen it.
You have a good plan.
I cannot understand how the LD test could give such wildly varying results. You can see though, why I hate a lying LD gauge. If your compression test results had been a little lower, coupled with the huge LD, and the oil burning/oil loss, It would have pointed straight to a tear-down. And Who would be the bad-guy, when you couldnt find anything wrong at that time? Phew, that was almost too close for me.
I have another test for you.Plumb a vacuum/fuel-pump gauge onto the dipstick tube. Pull the PCV out of the cover and lay it and its plumbing aside. Then seal all the breathers. Start the engine and watch the gauge while it idles. The gauge should absolutely not show vacuum. In fact it could begin to register pressure.That would be normal.Do not let the pressure rise above 3-4 psi, as it will begin to want to blow out anywhere it can.And if it succeeds, thats just more work for you.Oh this test will prove that the intake is not sucking oily air from the valley.
Ok so carry on....

Oh, and if your results of the compression test do come in that high, you will be in good shape for a bigger cam,should the bug bite.Heh-heh...However, once the pressure goes that high, timing the beast can become a challenge.
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I would do an internal vacuum leak test. Sorta like what he said, but easier and less likely to blow a seal. Leave the PCV hooked up but put your thumb over the breather nipple. At idle you should feel vacuum build. If the idle changes even a little as vacuum builds you have internal vacuum leak(s). Commonly valve guides or bottom of the ports. If vacuum does not build, or pressure builds you have compression leaking past the rings.
 
Were the pins for the intake pulled from the block? The ones that are no the China walls?
 
It is back to the drawing board after my recent tests. I watched the valve train and everything seems to be moving and oiling great. Push rods are stright. I removed the rockers and did a couple different (Hot engine) leak down tests. TDC and BTDC and very little difference. After getting new gauge, I got good results. BTW…The OTC reads ok up until about 60psi then ends up off by 3psi at 100 and I adjusted % for that.

All were under 5%. #1-3%, #3-4%, #5-5%, #7-2%, #2-2%, #4-2%, #6-2%, #8-5%. So it appears valves and rings are ok.

Next I went to the intake and made a pressure plate. Maybe I should have tested vacuum instead but, if it was leaking 10psi would show up. I also used a hose-to-the-ear in the valley and no air escaping.

As of now, I’m not getting into the engine. I’m going to keep a better record of oil usage and smoke when it occurs. I did find a small leak of oil creeping up one intake bolt. Now before you go off, I have been getting light smoke once in a while on startup and on full throttle. See behind gauge left side. I need to seal again. I’ll also make sure there isn’t something else I missed.

I’m using 10-30 with zinc and Autolite 66s. Can either of these contribute to issue? Also, how much oil loss is acceptable between a 3k oil changes? None?

Any other suggestions before I button this back up?
 

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RustyRatRod said:
Just I've been singing all along. This place never changes. Talk till you're blue in the face and no one listens.
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RRR, you're usually helpful. I'm listening and still waiting for your suggestion of how to fix or troubleshoot. Craig
 
my5thmopar said:
RRR, you're usually helpful. I'm listening and still waiting for your suggestion of how to fix or troubleshoot. Craig
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I should have been more clear. I was not talking about you not listenin, but everyone else goin on and on about the rings and such. Only two things will cause those ash deposits and oil is one of them but not from rings. Incorrect fuel mixture is one and oil coming from the valve guides is another.

If it was oil from rings, it would be too much to form ash and you would have a visible, wet, black oily lookin plug. Oil from valve guides is a small enough amount to be burned all off, leaving those type ash deposits behind.

And of course, an incorrect fuel mixture can do the same thing. Pulling a valve cover to inspect the valve seals doesn't take long. Dialing the fuel mixture in just right is a little more in depth, but neither problem is huge to deal with.
 
And a peek at the back of the intake valves(4 & 6 ?) should tell the tale.
So back to the top of the page;what seals are on there now?
EDIT oops . stockers. Missed it two times. Sorry
 
Rusty is right, I can second from experience. The rest is classic over-diagnosing.
 
AJ/FormS said:
And a peek at the back of the intake valves(4 & 6 ?) should tell the tale.
So back to the top of the page;what seals are on there now?
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#17 & 25. The seals were comp cams umbrella but, I replaced them when I thought they were the issue. There is stock OEM type Felpro set in there now. Umbrella on intake and 1/2 umbrella on exhaust.

I'll check #4 and #6 tonight. Thanks again for all the help.
 
Grab the valve springs on those cylinders by the retainer and see if you can rock them back and forth. If you can, make SURE you are actually rocking the valve and not just slipping the spring back and forth. Excessive guide wear can do it, too.
 
All pretty interesting. Has anyone driven behind you to see if there is oil smoke when you decelerate and after idling at a stop for a bit? That is pretty classic oil past the guides, and is a pretty simple check that gets overlooked. You describe smoke at WOT which indicates rings, but perhaps it is happening other times and you can't see it or are not looking for it. Someone driving behind wil see it much better.

Were the pistons used at last rebuild, and were the ring side clearances and end gaps checked closely?
 
Get a inspection camera and run down each of the intake runners from the carb opening and look at the intake valves for excessive oil on the valves/walls.

I have to do this for a 350 as its puffing smoke after sitting for abit and smoking at startup.. few plugs look nasty... Fresh rebuild and I question the valve seals.
 
What is your actual valve guide clearance? If you're not sucking oil in through the ports, this may be worth a look. Also, what is the guide material? Stainless valves and iron guides don't live well together. Thin wall bronze liners are also short lived.

PC style seals will take care of oil consumption resulting from excessive stem-to-guide clearance, but won't help with the shortened seat life.
 
RustyRatRod said:
If it was oil from rings, it would be too much to form ash and you would have a visible, wet, black oily lookin plug. Oil from valve guides is a small enough amount to be burned all off, leaving those type ash deposits behind. /QUOTE] At 1000 miles per quart, the burn rate is so low that it will look OK regardless of the source. IMO, the compression tests and leak down tests don't prove a lot with this case of relatively low consumption: the rings are not being loaded and twisted as they are at WOT when visible oil burning is happening (per the OP's symptoms; none of us have actually seen this!), and minor oil will just make these test numbers look good/better. The stem seals sure are the easiest, is a smart suggestion, and would be where I would start, but just keep all this in mind going forward. One or two compression rings flipped upside down at assembly (wrong ring twist to do the final oil scraping) might do it.
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Inm9stheham…What do you mean relativity low consumption? Are you saying 1 quart every 1k miles is low? I’m using 10-30 with zinc and Autolite 66s. Can either of these contribute to issue? Also, how much oil loss is acceptable between a 3k oil changes? None? SpeedPro cast new with matching rings. Assembly wrong, who knows without a tear down? I set gaps to ring maker’s specs and paid attention to the bevel/dots/twist. I’ll do the ride check after its back together and I have help.

C130 Chief and RRR...New steel guides, but valves reused. No movement with spring on, then I pulled the spring on #4. I didn’t measure any movement but, it does move. I can visually see a very slight gap if I push the valve to one side. So reused valve was too worn and bad news? Shop said they were ok with the new guides. Guides looked new and paperwork says they are. Is this a good test since the valve is not in the down position? I guess I could go to TDC and use the old rope or magnet method. Then I could check the valve in the ½ position. The seals are Victor (not FelPro)and it was fitting tight on the stem and guide.

GAMoparMan... I've thought about an excuse to buy camera.
 
Back in the early 70s, 340s typically burned through 1 qt in 3000miles,routinely. All the ones in my neighborhood did. All were low mileage, to well broken in. We considered it normal. I was just 18ish.
 
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