Oil consumption
Thread Starter
Racer
Joined: Sep 2012
Posts: 420
Likes: 0
Oil consumption
My 74 just had valve seals done and rebuilt carb it was using a lot of oil before Now the start up smoke had gone away but it's still eating oil like crazy I'm talking 1 litre per 500 miles. It doesn't smoke even when I push it where's this oil going ? No leaks from what I see engine has 85000 miles
I'm thinking of using Lucas oil additive ? Has anyone used this and has it worked Any advise on what's going on here
I'm thinking of using Lucas oil additive ? Has anyone used this and has it worked Any advise on what's going on here
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
It could be pulling oil in through the intake gaskets as well.. Usually its pretty noticeable smoke if the gaskets are leaking by..
Really 1 qt for 500 miles isn't THAT bad considering its 40yrs old with 85k.... A lot depends on the RPMs its turning as well.. If its turning 3000+rpms on the freeway for a long cruise, its gonna use some oil..
Really 1 qt for 500 miles isn't THAT bad considering its 40yrs old with 85k.... A lot depends on the RPMs its turning as well.. If its turning 3000+rpms on the freeway for a long cruise, its gonna use some oil..
Drifting
Joined: Jun 2010
Posts: 1,781
Likes: 15
From: Oxford Ohio
That's a bunch of oil to not smoke or leak. 5 to 6 quarts every oil change. Depending how often you change. If you took a trip of much length you'd use half your cargo area to haul oil.
With 85,000 miles on the engine I'd not expect that much oil to be going someplace. Has it been using that much since it was new? Gradually getting worse? What oil are you using? Is the under car oil soaked anyplace?
Take a comprssion test and vacume test just for information purposes.
With 85,000 miles on the engine I'd not expect that much oil to be going someplace. Has it been using that much since it was new? Gradually getting worse? What oil are you using? Is the under car oil soaked anyplace?
Take a comprssion test and vacume test just for information purposes.
Thread Starter
Racer
Joined: Sep 2012
Posts: 420
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I'm using castrol 10 w 40 reg oil ill try the compression test another possible way that I've been thinking is could a gasket or anything start leaking when the engine is runing and hot ? Ill have to take it for a nice drive then quickly check. But it's starting to bother me that's a lot of oil in using
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Advanced
Joined: Jan 2013
Posts: 99
Likes: 3
From: Salem Ohio
Yes if you do a ring job that is major work, not hard but major. You need to determine where the oil is going first. Check under the car for an oil leak and if it's dry then look at your plugs if your burning that kind of oil you will see it on the plug. Depending on rings or valve guides/seals the oil will be different on the plug. If the entire plug is covered with burnt oil then do a compression test. If only half the plug is hit with oil it is more than likely still from your top end. Heads or intake.
Last edited by 1969Corvette; Apr 4, 2013 at 09:05 AM.
Melting Slicks
Joined: Feb 2006
Posts: 3,428
Likes: 5
From: Japan
It could be pulling oil in through the intake gaskets as well.. Usually its pretty noticeable smoke if the gaskets are leaking by..
Really 1 qt for 500 miles isn't THAT bad considering its 40yrs old with 85k.... A lot depends on the RPMs its turning as well.. If its turning 3000+rpms on the freeway for a long cruise, its gonna use some oil..
Really 1 qt for 500 miles isn't THAT bad considering its 40yrs old with 85k.... A lot depends on the RPMs its turning as well.. If its turning 3000+rpms on the freeway for a long cruise, its gonna use some oil..
What he said. At that rate of consumption, it could be a number of things, especially if your valve guides were already worn enough to warrant seal replacement, but I have personally seen up to a quart of oil consumption every 100 miles when it's leaking through the intake manifold-head joint, and VERY little exhaust smoke to show for it. I suspect you have a fairly worn-out motor, but if it IS the rings you'll typically see a big cloud of blue smoke on deceleration. If you're not getting that, I'd be looking at those intake gaskets.
Melting Slicks
Joined: Dec 2009
Posts: 3,235
Likes: 658
From: Thunder Bay
One quart every 500 miles is a LOT of oil in my books. A chevy small block with 85000 miles on it is just broken in. If it has been properly cared for and the heads are fresh, the oil consumption should be barely noticeable. The original 350 out of my Corvette now has over 200000 miles on it and is running in my buddy's truck. He adds less than a quart every 3000 miles. (Yes the heads have been done, but the bottom end is original.) If that much oil is not appearing on the ground, you must be burning it. My guess is leaking intake manifold gasket, but the compression test is good advice.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Do you have a PCV valve in one of the valve covers? Does it have an oil baffle inside that valve cover & under the PCV valve?
Without an oil baffle, oil splash from the rocker arms will get flushed over the bottom of the PCV valve; that oil will be sucked up and dumped in with the fuel charge, then burned. If it gets atomized with the fuel and/or there is not a lot at any one time, you probably won't get any blue smoke out the back (or so faint you wouldn't notice it). But, that happening continually for several weeks would easily consume a significant amount of oil.
Without an oil baffle, oil splash from the rocker arms will get flushed over the bottom of the PCV valve; that oil will be sucked up and dumped in with the fuel charge, then burned. If it gets atomized with the fuel and/or there is not a lot at any one time, you probably won't get any blue smoke out the back (or so faint you wouldn't notice it). But, that happening continually for several weeks would easily consume a significant amount of oil.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
The fresh-air vent tube will not be a problem. The airflow in that is from the air cleaner into the valve cover. But, flow at the PCV valve is from the valve cover, thru the PCV valve, and into the carb base.
Melting Slicks
Joined: Jul 2009
Posts: 2,091
Likes: 40
you need to do a SERiOUS investigation of the engine form underneath, put it up on lift where you can really see what the heck is going on.
clean up any wet oil , check the rear area of the the engine , from valve covers down, for wet oil leaks. run it hard down the highway 20 miles, then back on the lift and see what you can find.
seals could be going bad , and probably the oil pan gasket is leaking , I had a vette use 500 mile per qt and it stopped when I took the pan off , replace seals at crank and pan gasket.....to almost nothing , it was just blowing, sloshing out and left small wet trails of oil on different components rearward,car didn't smoke at all , the oil was being lost like crazy.
you can n't tell squat till you can get the car in the air where you can look at every square inch .
an old engine probably has multiple leaks , all which will add up.
cars that my family , owned over my life , 500 miles a quart smoked really bad when the rings were shot.
if the plugs are decent , not oil fouled , then you most likely need the old engine sealed back up. getting to all those seals is not easy to do it right
clean up any wet oil , check the rear area of the the engine , from valve covers down, for wet oil leaks. run it hard down the highway 20 miles, then back on the lift and see what you can find.
seals could be going bad , and probably the oil pan gasket is leaking , I had a vette use 500 mile per qt and it stopped when I took the pan off , replace seals at crank and pan gasket.....to almost nothing , it was just blowing, sloshing out and left small wet trails of oil on different components rearward,car didn't smoke at all , the oil was being lost like crazy.
you can n't tell squat till you can get the car in the air where you can look at every square inch .
an old engine probably has multiple leaks , all which will add up.
cars that my family , owned over my life , 500 miles a quart smoked really bad when the rings were shot.
if the plugs are decent , not oil fouled , then you most likely need the old engine sealed back up. getting to all those seals is not easy to do it right
Last edited by LS4 PILOT; Apr 4, 2013 at 11:37 PM.
Thread Starter
Racer
Joined: Sep 2012
Posts: 420
Likes: 0
Well had the car on 4 jack stands there were some oil spots but nothing big oil pan is new with new gasket the area of concern I think is prob the fuel pump area there was some oil around there and a bit of oil comes from that area when it's parked
Couldn't point the finger exactly where it's coming from but I'm guessing there's only one 2 bolt gasket there right ? Or does it mount to a plate I thought I saw something else does the pump mount to another plate ? Any thoughts ? There's a leak there for sure should I just buy a new pump ?
Couldn't point the finger exactly where it's coming from but I'm guessing there's only one 2 bolt gasket there right ? Or does it mount to a plate I thought I saw something else does the pump mount to another plate ? Any thoughts ? There's a leak there for sure should I just buy a new pump ?
Thread Starter
Racer
Joined: Sep 2012
Posts: 420
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Ok found the mounting plate on corvette central so I guess it mounts to that ill try and tighten the mounting plate bolts before I buy anything see if that helps
Would I have to drain the oil to replace the mounting plate ?
Would I have to drain the oil to replace the mounting plate ?
Advanced
Joined: Jan 2013
Posts: 99
Likes: 3
From: Salem Ohio
Replace the Valve cover gasket on the fuel pump side and I bet when you clean it off and drive it the fuel pump stays dry. The valve cover is also easier and cheaper to replace than the fuel pump. Get the good rubberized valve cover gaskets.
