Oil consumption LS-5
What could cause me to consume 3 qt's of oil in 800 miles of 70 mph driving ? I believe the engine was rebuilt at 57k, it now has 64K. I'm using Valvoline VR1 10w 30. I do't think I'm burning it out the exhaust pipes. However, both pipes have about the same dry soot build up on them. I replaced the oil pan gasket and eliminated that leaking. I may still be getting some small oil leak from some other area, I have to check it out. 3 qt's in 800 miles from a leak is hard to believe.
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Re: Oil consumption LS-5
Chris------
At this rate of oil consumption, if the problem is not due to some sort of gross oil leak, then you must be "smoking" badly.Check the plugs for oil fouling. If oil fouling is observed, then run a cylinder leak-down test or, at least, a compression check.
If the leak-down rate or compression is good, then I'd say there is a problem with either valve guides, valve seals, or the PCV system.
By the way, just because the engine was rebuilt less than 10,000 miles ago does not necessarily mean it was rebuilt properly or that quality parts were used.In Appreciation of John Hinckley -
Re: Oil consumption LS-5
Chris, I experienced a similar oil consumption problem on my '72 LS5 since I owned it. I equated it to about 1 qt/ 200 miles. It was also "rebuilt" by the previous owner, I had no leaks, the car oddly didn't smoke, the PCV system was fine, had the same black soot on the exhaust tips you describe and I did show signs of oil fouling on the plugs but it always ran fine. A compressoin and leakdown test, as Joe reccomends, didn't reveal much so I began to dig. I removed the intake in hopes that the intake gasket was leaking, no luck there but the pic attached shows the oil problem. Turned out the valve guides were spent. I took the heads off (Not fun) had them properly rebuilt with new guides, valves, seals etc... Put it back together and haven't burned a drop of oil since. Good luck!!!
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Re: Oil consumption LS-5
Joe & Tom . . . . thanks for the technical direction. Sure enough, I pulled 2 spark plugs and they were moderately oil fouled. Both had oil all the way up the threads. Next step is to do the tests you recommend. Tom, I'm hoping (though I wish I didn't have the problem at all) that my problem is like yours and contained to the heads. Oh, and while I was under the car it looks like my power steering control valve is leaking . . . . oh boy ! Thanks again for guidance.Comment
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Re: Oil consumption LS-5
As you approach the problem be deliberate and don't over react. Perhaps you'll be lucky and it will be something simple. On another note, the control valve is not a big deal, with basic mechanical skills you can rebuild yours. Corvettes are fun... right???
Just messin' Been there, done that and I don't regret it. Have fun!!Comment
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Re: Oil consumption LS-5
Tom, no better words of wisdom have ever been spoken " be deliberate and don't over react ", which gives me cause to ask you this question. I've had this 71 for about a year and half. My goal is to put it back to how it looked and functioned when it was born. I just got the CEC system (combined emissions control) functioning prior to the 800 mile trip I took. This CEC system was a one year design, your 72 has something similar, I think. When I got the car the system was deliberately disabled by bypassing the CEC solenoid and connecting the carburetor vacuum line directly to the distributor advance. I had to get the CEC solenoid functioning, do some wiring and connect the carb vacuum line to one port of the solenoid and another vacuum line from another solenoid port to the distributor advance. The system is designed to increase vacuum advance when third or fourth gear is selected (at idle rpm's will jump up 200 rpm's when shifting into 3rd or 4th) and this some how reduces emissions (don't ask me how it does it). Anyway, could the now functioning CEC system, in some weird way, be the cause of my oil consumption ? The way I look at it when the carb vacuum line was connected directly to the dist. advance all the time the dist. was getting maximum vacuum all the time. Now it gets it only when the tranny is in 3rd or 4th. Having said all this I think I recall having sooty tailpipes before I fixed the CEC system. What do you think?
Regarding me rebuilding the PS control valve, is there some special procedure to be followed to recommission the system like line bleeding etc ? I see a zerk fitting on the valve, is that for grease or something else ? Thanks.
ChrisComment
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Re: Oil consumption LS-5
Chris
I do not think your reactivating the CEC had any effect on the engines oil consumption. Its function is to port vacuum to the distributor at certain times. First is on initial engine start for approx 15 sec. then 3rd and 4th gears also if if engine temperature exceeds a set value (I do not remember it of the top of head) to bump up engine speed for more air flow thru the radiator. The only thing that has changed is when you have vacuum.
For the control valve you can rebuild it at home as Tom stated. I think there is a section in the Shop Manual for that. If not I am sure there could be instructions in the kits that are sold. Here is a video from youtube http://www.youtube.com/watch?v=bKPPXNvw40M and I sure there are many sites with written instructions. As far as the zerk fitting you should never add grease to it once the valve has been installed this can cause the valve to leak. Do not know why the fitting is there after it was lubed at the factory.
Once you install the valve you must fill the pump and then balance the valve there is an adjustment nut under the end cap. This is to center the valve so equal amounts of fluid move thru the valve assembly so the steering wheel remains centered. Before you start your engine to balance the valve DO NOT HAVE YOUR HANDS ON THE INSIDE OF THE STEERING WHEEL. That is because if the valve is not in balance the wheel will move rapidly to ether direction and can and will cause injury.Comment
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Re: Oil consumption LS-5
Also pay attention to the hose attachment to the valve, it looks backwards but if you don't put it back on this way you are in for a little "fun". Had a customer that decided to replace his own hoses, car ended up being brought to my shop on a roll back because he could not figure what was wrong with it.
Dick WhittingtonComment
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In Appreciation of John HinckleyComment
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Re: Oil consumption LS-5
Joe
I was just letting him know if he does this rebuild what some of the pit falls could be especially the dangerous one. Dickey also hit the other problem to be aware of.Comment
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Re: Oil consumption LS-5
Seems the power steering control valve questions have been answered.
Going back to the oil problem, you can mostly eliminate the PVC system by swabing the PVC hose that connects to the front of the carb. Oily, good news. Dry, bad news. I doubt that the CEC system is the problem, it's only a timing control system and does not have a relationship with the oiling system. Scopes to look down through the intake runners are not too expensive. If you can borrow one you can get to a few of the valves, it's how I first found the puddles on my valves. A frustrating day.Comment
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Re: Oil consumption LS-5
Tom . . . . I swabbed the PCV hose at the carb end. It had s slight amount of oily residue, not actually wet but more like what builds up on front of engine heads from driving. What kind of shape am I in ? Is there any other method to qualify if the PCV system is functioning ? When I do the leak down test where should I be looking for escaping air ?
I would like to thank everyone who has helped me troubleshoot this problem.
ChrisComment
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Re: Oil consumption LS-5
Chris, I would think a PCV system to draw 3 qts. of oil in 800. miles would be a stretch. I would think a camera to peak into the intake as Tom says is my first step( if possible to see with the internal bends of the intake runners), or you can remove intake to get a close-up view of the intake valves, if you have had the car sitting all night the oil will tend to run down the valve guides and can be easily seen. and don't rule out the seals on the valves first as Chevrolet V-8's have been know to be big problems with oil usage over the last 40+ years.Your problem will likely require some research.New England chapter member, 63 Convert. 327/340- Chapter/Regional/national Top Flight, 72 coupe- chapter and regional Top Flight.Comment
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Re: Oil consumption LS-5
Terry,
Thanks for the information. I'll be doing the tests soon.Comment
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