Oil consumption

[V8vortec]

I have a 5.7 in my Tahoe. Just had the engine rebuilt about 12k miles ago. I followed the break in process and did everything I'm told. How much oil is acceptable to burn on a rebuilt engine? It's currently burning about 2 quarts every 2000 miles. I know that's not right and it is still under warranty.

 

[jjester6000]

I have a 5.7 in my Tahoe. Just had the engine rebuilt about 12k miles ago. I followed the break in process and did everything I'm told. How much oil is acceptable to burn on a rebuilt engine? It's currently burning about 2 quarts every 2000 miles. I know that's not right and it is still under warranty.

Man, that's about the same as the 330,000 mile original engine in my '98 Suburban.

Did they bore it out, or did they just do rings and bearings?

If it's former, then I'd definitely have it warrantied. Otherwise that's sort of to be expected when you don't bore it out (I'd throw a quart of Lucas in there at the next oil change in that case).

The only engine I've ever "rebuilt" as this 250 I6 on my '74 GMC, and it was basically just a bearing and valve job.

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It burns a decent amount of oil, but it's good enough for what I use it for. Though it may become my daily driver again at some point, so I'm highly considering investing in a remanufactured short block.

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[CumminsFever]

What were the "break-in" instructions?
Every shop is different.
That is quite a bit of oil to be burning. Especially on a rebuilt engine. Are you absolutely certain it's being burnt? Any chance of a loose fitting or leaking gasket somewhere?
Just tossing out thoughts and ideas before condemning the engine!

 

[Caman96]

My engine w/84k original doesn’t use anything noticeable with every 3k oil change.

 

[termite]

Definitely something wrong there, be it a leak or burning. My 1995 7.4l with 248k miles was losing about a quart in ~1500 miles. Primarily leaking it before some gasket replacements.

Leak check it and pull the plugs for a look. Should be obvious on the plugs at that consumption rate.

 

[rebelyell]

I have a 5.7 in my Tahoe. Just had the engine rebuilt about 12k miles ago. I followed the break in process and did everything I'm told. How much oil is acceptable to burn on a rebuilt engine? It's currently burning about 2 quarts every 2000 miles. I know that's not right and it is still under warranty.

That's Far too much oil use. If your truck had an OE L31, it also had modern thin metric ringpak. Those motors are Notorious for NOT using oil; primarily because of that ringpak, high-precision machining and very effective fuel management.

Lots of 350 rebuilds neither emulate GM's precision machining and/or use of thin metric ringpak ... lotsa rebuilds get the cheapest, relatively inefficient, old-fashioned wide tractor ringpak. Vortec style pistons & rings cost more.

*EDIT it's possible, it happens ... folks get distracted and install the Second rings upside down. That ring typically has a tapered face ... to assist scraping oil from cylinder wall toward crankcase ... when upside-down, it scrapes oil toward the combustion chamber. Alas, ya MUST pull it all apart and visualize it to either confirm or deny that goof.

 

[Sean Buick 76]

Was it a true rebuild with a fresh bore on the block etc or new gaskets and bearings?

 

[Schurkey]

WHAT VEHICLE???

BEFORE you jack-up the folks who "rebuilt" this engine, make sure your intake gaskets aren't leaking on the lifter-valley side, and assure that the PCV system isn't sucking oil because of poor baffling in the valve cover, or a defective PCV valve.

Is there oil in the PCV suction hose?

Is the oil fuel-contaminated because of an injector issue?

Can you poke a borescope down the intake runners to see oil pooled on the intake valve(s)?

Are the spark plugs oil-fouled?

Are there strange black spots on the pavement every time you park?