Oil level
Thread Starter
Racer
Joined: Aug 2007
Posts: 414
Likes: 0
From: Quincy MA
Oil level
Going through one quart every 300 miles...very sad...we just had a baby and I don't want to pour a lot of $ into the '74...as I know someday we'll want an old car with a backseat for the lil' guy...anyhow, there are no leaks, must be burning oil...is that usually a headgasket?
Kevin
Kevin
Melting Slicks
Joined: Feb 2006
Posts: 3,428
Likes: 5
From: Japan
That kind of oil usage in a small block Chevy (In MY experience, anyway) is usually traceable to leaking intake manifold gaskets. Do a compression check just to make sure you don't have any major bottom-end issues like severely worn or broken rings OR blown headgasket(s)...if all's OK then I'd advise removing the intale and replacing the gaskets. Clean everything around the intake ports thoroughly then install the new gaskets with a very thin bead of grey hi-temp RTV around the ports on both sides of the gaskets...you might get a pleasant surprise. Leaking intake joints can suck a ton of oil into the combustion chamber...please don't ask me how I know this!
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,112
From: Crossville TN
At least, you can diagnose your problems for no [or very little] money. Did you do any work on the car prior to it using the oil? If not...and you don't know of any "abuse" of the engine that could have caused it...you may want to replace the PCV valve; if it is stuck open, that is a possible cause that can be eliminated by an inexpensive replacement.
Unless your valve seals are just totally shot, I don't think that would use the amount of oil you are losing. If you recently changed valve covers....and the new covers did not have oil-splash baffles below the openings for PCV valve and/or by-pass air hose to air cleaner, the engine will just suck any oil splashed up toward those devices. Also, I would think if you had an intake gasket leak, it would have been doing that since the installation.
Those are some thoughts on your 'issue'. Good luck on the diagnosis. Compression test is a good idea to get a handle on ring/valve issues.
Unless your valve seals are just totally shot, I don't think that would use the amount of oil you are losing. If you recently changed valve covers....and the new covers did not have oil-splash baffles below the openings for PCV valve and/or by-pass air hose to air cleaner, the engine will just suck any oil splashed up toward those devices. Also, I would think if you had an intake gasket leak, it would have been doing that since the installation.
Those are some thoughts on your 'issue'. Good luck on the diagnosis. Compression test is a good idea to get a handle on ring/valve issues.
Melting Slicks
Joined: Aug 2008
Posts: 2,200
Likes: 3
From: Lehigh county Pennsylvania
Burning Brakes
Joined: Nov 2009
Posts: 828
Likes: 103
From: Olney MD
How hard is it to change the intake gasket
Not that I might be having the same problem or anything, but just how hard is it to change tihe intake manifold gasket???
A few bolts, set the manifold aside, a new gasket and some RTV, and you're there... How unrealistic is that scenario???
We're talking LT1 here.
Thanks, and sorry for the hi-jack,
A few bolts, set the manifold aside, a new gasket and some RTV, and you're there... How unrealistic is that scenario???
We're talking LT1 here.
Thanks, and sorry for the hi-jack,
Pro
Joined: May 2011
Posts: 581
Likes: 5
From: BC
Not that I might be having the same problem or anything, but just how hard is it to change tihe intake manifold gasket???
A few bolts, set the manifold aside, a new gasket and some RTV, and you're there... How unrealistic is that scenario???
We're talking LT1 here.
Thanks, and sorry for the hi-jack,
A few bolts, set the manifold aside, a new gasket and some RTV, and you're there... How unrealistic is that scenario???
We're talking LT1 here.
Thanks, and sorry for the hi-jack,
Steve g
Race Director
Joined: May 2005
Posts: 10,674
Likes: 121
From: Millington Illinois
St. Jude Donor '08-'09
If you don't have stock valve covers check to see if your valve covers have baffles in them. I had this issue before and it was using about 1 quart every 300 miles and smoking. It was sucking the fine spray inside the valve cover into the base plate of the carb through the PCV valve. I had uniform looking spark plugs when I checked them and they just looked like it was running rich.
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Melting Slicks
Joined: Feb 2006
Posts: 3,428
Likes: 5
From: Japan
If those valve covers aren't baffled under the PCV outlet either get rid of them or find a way to install some baffles in them. I have personally experienced the sucking-oil-through-the PCV deal and (unlike the sucking-oil-through-the-intake deal) it belched blue smoke out of the pipes like a locomotive each time the throttle was applied. If you're using lots of oil and not getting a LOT of smoke I doubt it's coming up through the PCV hose.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 121
From: Millington Illinois
St. Jude Donor '08-'09
Melting Slicks
Joined: Apr 2004
Posts: 2,008
Likes: 38
From: Space Coast Gator Territory
Remove your distributor cap and mark the rotor pointer orientation, you will need this on reassembly. Tape and number your wires at the plug end for reassembly, before pulling the distributor. Disconnect wires, hoses and linkage and label as necessary. Remove the intake bolts and pry the intake from one end and remove. If you had a bad gasket, you will see burnt oil residue in an intake port where oil was being sucked from the lifter valley. Clean and replace as described in another post.
If you have a stock intake, check for oil sludge that can be cleaned at this time. You can pull the tin off the intake underside to clean well before replacing. The rivets will pull out, they are on a twisted spline.
Heel & Toe
Joined: Jan 2019
Posts: 23
Likes: 0
Wow.....I just bought a 69 with a 350 cu engine and also was losing 1 qt oil every 300 miles. I just had the valve cover gaskets and valve stem seals replaced. Since getting it back a week ago I've done 300 miles and it's down almost 1/4 inch on the dip stick. So, hopefully I'll get at least 1,000 miles before needing oil.
Safety Car
Joined: Sep 2012
Posts: 4,688
Likes: 41
From: Palm Harbor, Florida
You have received some good advice here. Unless you see evidence of blue smoke coming out of your exhaust, you won't find heavy burnt oil on your plugs. If you do, more than likely you have a ring problem, but you don't mention blue smoke. I had a similar problem, as others who have posted, and it was the intake gasket. Before removing the intake, be sure your rings and seals are not your problem.
Remove your distributor cap and mark the rotor pointer orientation, you will need this on reassembly. Tape and number your wires at the plug end for reassembly, before pulling the distributor. Disconnect wires, hoses and linkage and label as necessary. Remove the intake bolts and pry the intake from one end and remove. If you had a bad gasket, you will see burnt oil residue in an intake port where oil was being sucked from the lifter valley. Clean and replace as described in another post.
If you have a stock intake, check for oil sludge that can be cleaned at this time. You can pull the tin off the intake underside to clean well before replacing. The rivets will pull out, they are on a twisted spline.
Remove your distributor cap and mark the rotor pointer orientation, you will need this on reassembly. Tape and number your wires at the plug end for reassembly, before pulling the distributor. Disconnect wires, hoses and linkage and label as necessary. Remove the intake bolts and pry the intake from one end and remove. If you had a bad gasket, you will see burnt oil residue in an intake port where oil was being sucked from the lifter valley. Clean and replace as described in another post.
If you have a stock intake, check for oil sludge that can be cleaned at this time. You can pull the tin off the intake underside to clean well before replacing. The rivets will pull out, they are on a twisted spline.
Le Mans Master
Joined: Oct 2007
Posts: 7,398
Likes: 941
From: Tennessee/Rhode Island
Just a heads up that if you are only losing a bit every 300 miles now after valve stem seals and external leak prevention, my next guess would be rings and oil by pass. I would look at an intake gasket last if it was me since that type of leak is rare and once it starts to leak past a bad intake gasket much oil will be sucked into the combustion chamber and you would see blue smoke out the exhaust. You should always do a compression check first before doing anything. The valve seals are very common as they get old to leak. I would definitely look elsewhere before even contemplating an intake oil leak...just me.
How many miles on the motor? Gen 1 SBC start getting tired at 50-60,000 miles and usually will be in need of a rebuild after 100,000 miles, if not maintained with top maintenance. You can get 125,000-150,000 miles from these engines but that was not typical.
BTW-My 78 L-82 when knew was known to eat a 1 Qt of oil every 500-1,000 miles....these engines were build very loose
How many miles on the motor? Gen 1 SBC start getting tired at 50-60,000 miles and usually will be in need of a rebuild after 100,000 miles, if not maintained with top maintenance. You can get 125,000-150,000 miles from these engines but that was not typical.
BTW-My 78 L-82 when knew was known to eat a 1 Qt of oil every 500-1,000 miles....these engines were build very loose
Last edited by jb78L-82; Jan 27, 2019 at 08:10 PM.
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,027
Just a heads up that if you are only losing a bit every 300 miles now after valve stem seals and external leak prevention, my next guess would be rings and oil by pass. I would look at an intake gasket last if it was me since that type of leak is rare and once it starts to leak past a bad intake gasket much oil will be sucked into the combustion chamber and you would see blue smoke out the exhaust. You should always do a compression check first before doing anything. The valve seals are very common as they get old to leak. I would definitely look elsewhere before even contemplating an intake oil leak...just me.
How many miles on the motor? Gen 1 SBC start getting tired at 50-60,000 miles and usually will be in need of a rebuild after 100,000 miles, if not maintained with top maintenance. You can get 125,000-150,000 miles from these engines but that was not typical.
BTW-My 78 L-82 when knew was known to eat a 1 Qt of oil every 500-1,000 miles....these engines were build very loose
How many miles on the motor? Gen 1 SBC start getting tired at 50-60,000 miles and usually will be in need of a rebuild after 100,000 miles, if not maintained with top maintenance. You can get 125,000-150,000 miles from these engines but that was not typical.
BTW-My 78 L-82 when knew was known to eat a 1 Qt of oil every 500-1,000 miles....these engines were build very loose
Le Mans Master
Joined: Oct 2007
Posts: 7,398
Likes: 941
From: Tennessee/Rhode Island