Re: 1970 Corvette LS5 454 4 speed consumes a lot of oil from day one
Remove a valve cover, take a good picture of the stem seals and post it.
Remove a valve cover, take a good picture of the stem seals and post it.
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Re: 1970 Corvette LS5 454 4 speed consumes a lot of oil from day one
Here'e 4 files inisde the passemger side head. Cant really see any stem seals beacuse of dual compresion springs. This engine was rebuilt more than 20 years ago by Custom Speed Enterprises, a big name back then. I am sure what ever they did was just factory hardware, nothing special. I do have the original receipt dated May 11, 1991 with itemized details. $853.47 Engine sat never started till 1997.One item I is (16) Seals VP-67 $22.00. 16 other items also. This company no longer exists. Hope this helps. I took and saved these pictures in 2009.White 1970 LS5 390/454Comment
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Re: 1970 Corvette LS5 454 4 speed consumes a lot of oil from day one
Chris------
VP-67 is an old Sealed Power part number for all teflon, positive valve stem seals. These seals require machining of the valve guide upper OD and I presume that was done when the engine was rebuilt. The problem with this installation is that with these valve seals there is very little clearance between the inner valve spring ID and the seal OD. So, it's possible the seals could be damaged during engine operation. I sort of doubt it would occur but it could. In any event, all teflon positive seals are not really the best choice for this engine.In Appreciation of John HinckleyComment
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Re: 1970 Corvette LS5 454 4 speed consumes a lot of oil from day one
Chris------
Yes, you're correct. The PCV system is quite simple. Except for a clogged valve, I don't see how it could fail. That's what I've thought for years, anyway.
However, if you remove your intake manifold (or, inspect the runners with "borescope") and find oil in the intake runners and, possibly, as far back as the plenum, I can't conceive of any way for it to get there except through the PCV system. If your engine is like mine, and I fully expect it will be, you'll find plenty of oil in the intake ports of the manifold.
If you find oil in the intake ports in the heads but not in the manifold ports, that would seem to imply leakage at the lower edge of the intake manifold gasket resulting from the angularity problem I discussed earlier. As I also mentioned earlier, no type of manifold gasket or sealer will correct this. If there is oil in the cylinder head intake ports, that pretty much rules out valve guide or seal problems since there's no way that oil that enters the combustion chamber through the valve guide/seal is going to get into the intake ports. The intake ports in my engine were WET with oil. I think you'll find the same thing.In Appreciation of John HinckleyComment
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Re: 1970 Corvette LS5 454 4 speed consumes a lot of oil from day one
Rich,
I have a video probe with a live screen a the other end. It a very stiff cable to try and fish thru certain areas. Would I try and run thru carb opening in the intake to some valve runner? Never tried putting camera probe in spark plague holeWhite 1970 LS5 390/454Comment
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Re: 1970 Corvette LS5 454 4 speed consumes a lot of oil from day one
Chris, If it's like one of those $100 Harbor Freight units it's not very helpful. I have one, used it once to look in a wall. It' was useless. I wouldn't try that one even if it would fit down the carb, which I doubt would get past the venturis. If it broke off in there that'd be bad.
If your valve seals are what they say they are on your paperwork, and you say it's done this periodically since 20 years ago, I doubt it's those and tend to agree with the consensus.
However I just experienced a 283 first start after it's rebuild 20 years ago and never run until a month ago. It had teflon valve seals installed. It has the puff of blue smoke on delayed restart.(10 minutes to a few hours)
If your block was ever decked, and if the heads were ever decked, if the angular surfaces of the intake to the heads had changed, it may be as mentioned, sucking oil in at the intake ports.
As others have mentioned, we all can speculate to help you try to isolate this oddity but it's tough to do it over the wire. A dissection may be the only way to find out.
But, I'll try one more thought....This may sound odd, but if the block and mating surfaces were decked, and if there is some oil getting sucked in, I'm wondering if it could get the intake ports, not from the lifter galley, but from the intake-to-head bolts. I see in your photo there is no oily stain evidence up under the bolt head flanges, but if it is in fact getting sucked up the threads and into the ports, you'd not see evidence at the intake bolt heads as it'd never reach high enough to weep out in view.
In the head, some are blind holes but several are not. I know several bolts next to some intake ports protrude directly into the oil system. This is all a moot point if there's sealant like Permatex on those bolts.
RichComment
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Re: 1970 Corvette LS5 454 4 speed consumes a lot of oil from day one
I can't understand why you have not pulled the heads by now to find the real problem. All the guessing in the world will not fix it until heads are off and things checked out. Observations all show heads off will lead to discovery of issue. Guides, seals, gaskets etc all tell a story without guess work.Comment
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Re: 1970 Corvette LS5 454 4 speed consumes a lot of oil from day one
Forgive me if this was already posted, but the way we determined if it were the rings or valve guides was to see if it smoked at full throttle . if it did that was rings, then let off the gas at high RPM and let the engine wind down,( causing high vacuum), then give it the gas and see if it puffs oil out the back. With warm oil the high vacuum will suck the oil down the valve guides. That will tell you if the oil is going past the rings or if the guides have a problem.
DomComment
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Re: 1970 Corvette LS5 454 4 speed consumes a lot of oil from day one
Gene,
Myself, I like to learn as much as diagnostically possible before I take things apart. I feel once it's apart there's no way to reproduce the particular condition.
Remember this from a few years ago? Between coolant volcanoes, analyzing spark plugs, combustion gases in coolant tests, cylinder leakdown tests at both top and bottom of cylinders, viewing and reading pistons, and other hair pulling adventures, I then pulled the heads.
All of my tests confirmed what each cylinder was up to when I discovered the problem.
Rich
(OMG I just got a anxiety attack reminiscing that one)Comment
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Re: 1970 Corvette LS5 454 4 speed consumes a lot of oil from day one
Cylinder walls glazed, rings never seated.Comment
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Re: 1970 Corvette LS5 454 4 speed consumes a lot of oil from day one
Edward------
Yes, that can happen. However, if one finds wet oil in the intake ports and the manifold as I've described, there's no way that any sort of piston ring problem could be the root cause. The vast majority of the time when one encounters one of these "oil burners" (especially the 300 miles per quart type), oil wet intake ports and manifold will be found.In Appreciation of John HinckleyComment
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Re: 1970 Corvette LS5 454 4 speed consumes a lot of oil from day one
Wow, didn't think it would be this complicated. I don't want to jump right in with no ideas and pull the heads.
Right now I have allot of easy time on my hands, because I cannot physically do any
work yet due to just having a tumor removed from my spinal cord last week. I really want to be involved with the repair. Physical repair will have to be delayed till summer. Right nowhave time for correspondence and gathering ideas.Thank you all so far for all ethe great input. I just have to work on feeling bettter and pain management. Bending forward over an engine right now would kill me!White 1970 LS5 390/454Comment
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Re: 1970 Corvette LS5 454 4 speed consumes a lot of oil from day one
It's not complicated. The oil can only get into the cylinder from two places, past the rings or past the intake valve. Step one, find out which it is. As was pointed out above, oil coming past the rings does so under various load conditions, oil coming in through the guides, or anywhere in the intake side, pulls the greatest amount at high vacuum.
I live in the mountains, so this is really easy to determine here. Drive the car down the hill letting the engine slow the car. Stop at the light at the bottom and when you take off, look for a cloud of smoke. On a long hill under that high vacuum you can pull enough oil that there's no missing it.
If you've determined it's valves, pull the springs and check the guides. Guides okay, change the seals, guides bad, pull the heads. No need to diagnose anything any further.
If it's not coming past the valves, pull the engine. No need to diagnose any further.
According to Hasting rings, over 75% of the issues with rings failing to seat is cylinder walls insufficiently cleaned after honing. Could have been someone had a bad day. Whatever it is on the block side, it requires the engine to be pulled and stripped. The problem will become evident when you do that.
SteveComment
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Re: 1970 Corvette LS5 454 4 speed consumes a lot of oil from day one
Steve------
There are more than 2 ways for oil to enter the cylinders. As I've mentioned above, it can enter via being drawn in from the lifter valley at a leak at the lower intake manifold gasket. It can also enter via the PCV system. If one finds significant oil in the ports in the heads and/or intake manifold ports, then the source of the oil is from one of these two sources and not leakage past the rings or leakage past the valve guides/seals.
In the majority of cases of very high oil consumption, especially in the 200-300 miles per quart, one will often find the intake ports absolutely wet with oil.In Appreciation of John HinckleyComment
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Re: 1970 Corvette LS5 454 4 speed consumes a lot of oil from day one
Joe,
Whether it comes from a pcv valve or a leaking intake, it still has to pass the intake valve, which is what I described as one of the two ways for oil to enter the combustion chamber. Through the top or through the bottom.
No disrespect intended. We are all products of our own experiences. In mine, however, oil coming from a leaking lower edge intake gasket would be a real rarity. In 40 some years of doing this professionally, I have never personally encountered it. I don't deny it's a possibility, however the accompanying vacuum leak would produce a driveability problem much more obvious and troubling than the oil consumption. If it can pull a quart of oil splashing around in the valley in 300 miles, imagine how much air it would pull. And when I consider the amount of crush in those composite intake gaskets that GM used (as opposed to steel shim gaskets used by others), the amount of difference in the angles would have to be great enough that it would be visually evident when viewing the mating areas from the exterior front.
As to a PCV possibility, again, something I've never seen and have difficulty envisioning how liquid oil would get to the end of the PCV valve. I have seen the cyl head drains plug up (not on a Chevrolet built engine), but even in that case the issue becomes oil consumption through the guides because the seal's design is to shed oil, not seal it. So again, it first manifests itself as a guide/seal issue with the head flooded rather than a pcv issue.
So if we start first with the 99.99 percent of the time, it's cyl walls and valve guides. And I've seen enough valve guides taken out in very short order from dry assembly and wrong push rod lengths for the cam being used that I'm never very quick to rule out those things. And dirty cyl walls a common enough occurrence that the ring manufacturers include a notice in their packaging.
As an aside, the only time I've seen wet runners is super and turbo charged engines, leaking from their respective seals.
SteveComment
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