Burning Oil?

[JTautomotive]

hey everyone, i have a 1980 K10 with a 350/SM465. The 350 has a recentish rebuild about 25000 miles. Oil is changed every 3000 miles and when i was pulling in my drive way last night it had a slight knocking sound, so this morning i checked the oil, there was none on the dipstick. added about 4 quarts of oil to it. the knocking stopped, there are no visible oil leaks that i can tell, what can cause this much oil consumption?

[Zane M]

Does it smoke on startup? That would be an indication of bad valve guide seals.
Does it smoke while driving?

[JTautomotive]

There is an inital puff of white smoke when it cranks but then it stops, following condensation from the tailpipe. It does not smoke while driving

[Firebirdjones]

If it has cat converters, you likely wouldn't see alot (if much at all) of smoke out the tailpipe since converters tend to burn most of it off.

If it is indeed burning it, it could be a number of things. Worn guides, or in your case of a fairly new engine, gulled up valve guides from improper valve guide clearance settings or no lube during assembly (dry startup).

Could be a poor intake seal sucking oil from the lifter valley. Or possibly sucking oil from the PCV valve (bad valve or lack of baffling).

Sounds like you'll have to start investigating which cylinder or cylinders and pinpoint the issue. 4 qts low before the next 3,000 mile oil change is a ton.

[JTautomotive]

Originally Posted by Firebirdjones

If it has cat converters, you likely wouldn't see alot (if much at all) of smoke out the tailpipe since converters tend to burn most of it off.

If it is indeed burning it, it could be a number of things. Worn guides, or in your case of a fairly new engine, gulled up valve guides from improper valve guide clearance settings or no lube during assembly (dry startup).

Could be a poor intake seal sucking oil from the lifter valley. Or possibly sucking oil from the PCV valve (bad valve or lack of baffling).

Sounds like you'll have to start investigating which cylinder or cylinders and pinpoint the issue. 4 qts low before the next 3,000 mile oil change is a ton.

There are no cat converters, it is duals from header back, how would i check if my pcv is baffled? and what is the best way to pinpoint the cylinders? start pulling plugs and check them?

[Firebirdjones]

Checking for PCV baffle under the valve cover. If they are factory covers I'd say you're okay, but alot of your aftermarket covers don't have baffling,,,or don't have sufficient baffling. Since I'm not sure whether you have factory valve covers or not, I thought I'd mention it.

Quick way to check if this is even the problem, just pull the PCV hose and see if it's wet with oil inside. I will even use a Q-tip and reach up inside to swab it around. If it comes out clean,,,,you're golden That would eliminate this possibility.

Yes I would start pulling plugs and see if you can pinpoint the offending cylinder/cylinders.

[JTautomotive]

Originally Posted by Firebirdjones

Checking for PCV baffle under the valve cover. If they are factory covers I'd say you're okay, but alot of your aftermarket covers don't have baffling,,,or don't have sufficient baffling. Since I'm not sure whether you have factory valve covers or not, I thought I'd mention it.

Quick way to check if this is even the problem, just pull the PCV hose and see if it's wet with oil inside. I will even use a Q-tip and reach up inside to swab it around. If it comes out clean,,,,you're golden That would eliminate this possibility.

Yes I would start pulling plugs and see if you can pinpoint the offending cylinder/cylinders.

im running aftermarket edelbrock elite valve covers. so if theres no oil in pcv im good? or if there is? sorry i got confused.

[Firebirdjones]

Originally Posted by JTautomotive

im running aftermarket edelbrock elite valve covers. so if theres no oil in pcv im good? or if there is? sorry i got confused.

If there isn't any oil in the PCV system, your fine. I'd swab the inside of the hose first before you go pulling off valve covers. If it's dry, then the oil is coming from somewhere else.

[JTautomotive]

Originally Posted by Firebirdjones

If there isn't any oil in the PCV system, your fine. I'd swab the inside of the hose first before you go pulling off valve covers. If it's dry, then the oil is coming from somewhere else.

Ill have to wait till i get home to swab the hose, but i pulled the pcv for a visual inspection and there was oil on the outside of the housing

[JTautomotive]

today i found that a had some loose intake manifold bolts, im guessing this is my problem, the gasket isnt sealing and the oil is passing through

[Firebirdjones]

Cross your fingers and hope that snugging them down will reseal it.

[JTautomotive]

should i torque them down or just snug them?

[Firebirdjones]

I believe in most cases, 30 ft lbs. is enough, but you could just give them a good tug for now if you wish, starting from the center out, and drive it for a while and see if your oil usage changes, slows down, or goes away completely.

If it slows down but is still using some, then you may have found the issue, and it may just require removing the intake for another gasket.

[bnoon]

Originally Posted by JTautomotive

should i torque them down or just snug them?

You should probably loosen and retighten ALL of the bolts to try to get it to pull down even. You risk poorly sealed gaskets or even cracking the intake manifold if it's tweaked down awkwardly. Personally, I'd be so curious that I'd have to pull the intake off and look for oil tracks leading past the gaskets to know for sure if it was leaking into the intake ports.

[Firebirdjones]

Originally Posted by bnoon

Personally, I'd be so curious that I'd have to pull the intake off and look for oil tracks leading past the gaskets to know for sure if it was leaking into the intake ports.

Yep, me too.

[Tonio327]

Hey just came across this I broke a bolt for the valve cover tighten it down today I'm like screwed I don't have the tools to back it out and it's leaking a quart a min when running will have to have it towed to a shop and have the screw backed out I'm kinda scared its leaking somewhere eles also never seen that much oil come out at one time but I never broke a bolt in the valve eather smh
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[85Bowtie]

There's no reason to crank on valve cover bolts to the point of breaking them off. Just to them from the center out evenly and get them snug....and use a 1/4 ratched set.

The intake doesn't "normally" get torqued anyway....what's really important is that you tighten it in the proper pattern and evenly. Same thing, start with the inside and work your way out, but criss cross while you do it.