Ok, I'm stumped

[wklink]

My GMC 1/2 ton has a 350 4bbl that runs very well but is losing a lot of oil.

I don't get any kind of smoke out of the tailpipe and the truck doesn't have any puddles under her but I lose a quart every 100 miles or so. When I get the oil changed for the first 1 thousand miles the oil stays fine but after that I start losing oil like crazy.

I haven't done a compression check but the truck runs fine, I don't feel any cylinder problems or any issues other than the loss of the oil?

Any ideas where you think it is going and what I need to do is fine. I guess i can get a rebuild done but I was hoping I wouldn't do that. The truck only has 45K on it at this time.

[Prong]

What do the plugs look like?

[77 350 Shorty Wide]

Good Morning, From Yakima, WA

First I would do a quick check of the tail pipe to see if there is any residue from excessive burning oil. Then a compression, leak down check. Checking spark plugs was a good idea they will tell a story as well. If that checks OK, I would then make sure my crankcase ventilation system is working properly. Or in my case I would just go ahead and change the pcv, breather cap and the little filter in the AF housing (if your still running a stock one), also the hoses between each. Maybe even take a look in the cooling system to see if anything maybe showing up there very unlikely but I would check just to make sure. Lastly do a complete visual inspection underneath to see if everything is dry. It sounds like it's a large loss so this isn't likely but then check anyway. I think we've covered all the bases, but let's hear some more if somebody has other ideas.

Good luck & God Bless, Terry

[vtwinsport]

I don't have an answer but I have a similar problem. rebuilt 350 with 2000 miles on it. no leaks, no oil in the coolant and no smoke. odometer is currenly not working so I don',t know how many miles i go before adding but as example; added a quart last friday. I see the dipstick has dropped a bit since then and I have probably put 75 miles on it.
I do have a timing issue I'm working out and my carb seems to be a little lean based on plugs. Might not be a rebuld issue for you given my notes above.
For what its worth.

[truckincurt]

sounds like your burnin oil to me ... if theres no oil runs on the underside of your truck its goin somewhere.... my bet tail pipe

[powerdriver 1958]

If the truck s new enough to have a catalytic converter still on it that will hide an oil burner.valve seals will do that too.

[lester622]

does it have a gm crate motor in it? If so check for valve cover gaskets, for some reason peaple put the crate motors in and do not pull the valve covers to check for gaskets which they do not come with.

Ive bought 2 trucks like this, and that was the problem.