excessive oil consumption

[71chevylongbed]

i had the motor in my truck rebuilt about 30,000 miles ago and for about the last 6 months or so it has smoked on startup. i changed the oil 2 weeks ago and when i checked it today(600 miles since oil change) it was already down a quart. that seems a bit excessive to me. if it is smoking on startup does that mean that oil is getting past the valves due to worn guides/seals?

[72MARIO]

If you never had that problem to start with it could be rings or getting past the valves due to worn guides/seals.

Did you happen to switch valve covers recently ?

My motor fresh rebuild used oil about a quart every 600-800miles. I went back to the engine builder. He said to remove the PCV and put a breather in the old PCV hole. Problem solved.

The PCV was sucking the oil out of my Edlebrock valve covers baffel and injecting it into the intake.

[crazy longhorn]

Oil smoke on startup in the morn, does indicate loose valve guides/bad seals. That will be common with that quart per 5-600 miles also. The chevys dont have much of a seal from the factory(just a set of O rings under the keepers), & the steel umbrella. If you tear it down to freshen the top, I would insist on bronze liners, or 1/2" cast guides (no knurl job!), & also opt for a set of seals that push on the guides. the positive type seals will require some machine work on the OD of the guide, but will keep you sealed after you do get a little wear on the stems/guides. best of luck, L

[roger0080]

I agree with crazy longhorn.

My when I parked my truck one winter it was roughly 700+ miles per quart.
Come spring when I start it up, puff. Blue smoke ever since. Then is started using a quart every 400-500miles.

When I did the engine swap out of there and took the intake off, I could see the oil just puddled in the head coming down from the valves. Didn't know it could puddle in there.

[53burb]

Originally Posted by 72MARIO

If you never had that problem to start with it could be rings or getting past the valves due to worn guides/seals.

Did you happen to switch valve covers recently ?

My motor fresh rebuild used oil about a quart every 600-800miles. I went back to the engine builder. He said to remove the PCV and put a breather in the old PCV hole. Problem solved.

The PCV was sucking the oil out of my Edlebrock valve covers baffel and injecting it into the intake.

I have the same problem. I know it leaks slightly, but I will try this. I thought it was better to use a PCV valve instead of a breather, but I will definately try this...

[71chevylongbed]

the heads were rebuilt with the rest of the engine with bronze guides. i figured that guides and seals would last longer than 20,000 miles. do i need to worry about it or can i just run it like it is. im planning on getting a new diesel pickup probably in August and then tearing the '71 apart and completly redoing it(wheres the cutoff wheel im thinkin shortbed) so i dont want to invest much more into it since i'll be getting rid of this motor then(i'm drooling over those 502 crate engines) so this motor only needs to run about another 10,000 miles or so. will it make it?

[Green Machine]

You can run with worn guides a long time. You might use 15 quarts of oil then in that 10,000 miles, but still cheaper than getting heads fixed.

I see you have an aluminum intake, might want to try tightening the intake bolts some, sometimes they loosen up and can suck some oil in that way, it's a longshot, but worth a look.

[krue]

I've seen trucks run forever with leaking valve guides. Kind of a Chevy thing, like leaky rear mains.

[roger0080]

Yeah you can drive it for a long time but you will also find a nasty side effect of plugs fouling. Had to do this every 1,000 miles or so. Eventually you know which valve seals are leaking and you only change those plugs. Major drag if you use it as a daily driver. Eventually the cylinders are going to get pretty carboned up. You're always buying plugs-n-oil. Drag. I'd fix it w/only 30K on the rebuild.

[71chevylongbed]

yeah i havent looked at the plugs since i put them in a year ago ago. fouled plugs would probably explain why it is running a little rough at low rpms. it is my only ride right now so i cant afford to have it apart. im planning on getting rid of this motor when i re-redo the truck so as long as is is alright till the end of the summer i think i'll leave it alone. I think i'll check those plugs tomorrow when it is light though