HELP! Need suggestions as to why I'm USING an inordinate amount of oil in my 67 427/435. I have no visiable leaks, my valve stem seals, although they are the positive locking type, show early signs of leaking and my plugs are a perfect tan color. I figure I'm using a quart every 2 hundred miles. I know that's not right but using that much one would expect to see a trail of blue smoke. I have no trail even when I gete on it.
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Re: Where's the oil going?
This is a long shot but it is a possibility. The diaphragm in the fuel pump could be in the early stage of failure. It may have a small rupture that allows oil to be pulled from the crankcase into the gas supply to the carburetor. Usually, the fuel pump fails very quickly after the diaphragm ruptures. -
Re: Where's the oil going?
do you have a genuine GM PCV valve because i have seen this cause a BIG oil loss problem. i know of one owner that paid a $1000 to overhaul the engine only to find that the oil loss was not fixed. i fixed it with $2.00 GM PCV valve. also aftermarket valve covers without the baffles around the valve will do the same thing.Comment
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Re: Where's the oil going?
Gary-----
You could also be suffering from the problem discussed on the Board several weeks ago in relation to small blocks. Actually, big blocks can suffer from this problem in exactly the same way as small blocks. In a nutshell, I believe that the problem is caused by an "angularity" mismatch between cylinder heads and intake manifold which may be related to the block deck configuration or otherwise. This causes oil to be drawn in from the lifter valley. If you remove your intake manifold and find all of the intake ports in the cylinder heads wet with oil, especially on the bottom half of the port, then I strongly suspect that this is the problem. Unfortunately, and as can be seen in the lengthy previous thread that I referred to, despite herculean efforts, neither myself nor anyone else has figured out a way to correct it (other than replacing the whole engine, of course). The symptoms that you described are the classical symptoms of this problem-----very high oil consumption with no apparent "smoking".
The things that clem suggested are also very possible causes of the problem, too. Certainly, they are the things to check out first. However, if your valve covers are original GM, they will have the necessary oil baffles. You can check for these simply by removing the PCV valve (and air tube on the opposite valve cover which connects the air cleaner to the valve cover). Look down and if you can see a sheet metal "plate" and cannot see the cylinder head inner surface, then you have the proper baffles installed. Checking will only take a minute, or two.
Then, you can check the PCV valve easily. Simply look at the side of it when you pull it out to check for the above-referenced. It should say AC type CV-736 C. If it doesn't say this, you can purchase one of these from any Delco or GM dealer (for GM it's part #6423695).In Appreciation of John HinckleyComment
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Re: Where's the oil going?
Gary,
You might want to check to make sure the drainback holes from under the valve cover area back to your pan are clear and not retaining an unusual amount of oil while in operating conditions.Comment
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Re: Where's the oil going?
Thanks guys for all the ideas. Just returned from a local two day event. Traveled approx. 400 mi. and am embarassed to say I consumed 3 quarts. The guy following me on the road tour said every time I decelerated there was blue smoke, my bumpers confirmend it. Need to check the plugs tonight. Joe, hope your suggestion isn't correct! This engine has been authenticated as original. May have to buy interest in an oil supply house. BTW, recently switched oil brands to Shell Rotella after reading several posts and since then noticed the problem to be worse. Any thoughts as to whether this could possibly be the problem? Thanks again.
GaryComment
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Re: Where's the oil going?
Hi Gary,
Hope your weekend trip was a good one in spite of the oil consumption.
You didn't mention the age of the engine, i.e. miles since last overhaul, etc. Your problem is beginning to sound like the classic "I need a ring job" problem.
The oil smoke from broken or worn oil rings is always much more noticeable under decompression situations, and manifests itself in the blue plume of oil smoke from the exhaust pipes when you "back off". To confirm or refute this idea, I would take a compression check and if there are cylinders that are lower in compression than others, squirt some oil in the spark plug hole then recheck that cylinder. If the compression raises signficantly, (an additional 20psi or so), you, in all likelihood, have a problem with rings or cylinder wall scoring and will need to address it with an overhaul. If it does not raise the cylinder pressure, it doesn't necessarily rule out rings, but may send you in another direction such as valve seals, fuel pump diaphragm, head to intake mismatch etc. that some of the other guys have mentioned.
I'm not sure what kind of pressure you are looking for on a BB when you do the compression check, (I'm a SB kind of guy myself and generally look for 150psi and above), but maybe some of you BB experts out there can help out.
Good luck,
LonnieComment
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