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-   -   oil burning after sbc short block rebuild (http://www.hotrodders.com/forum/oil-burning-after-sbc-short-block-rebuild-221086.html)

stevetankl 06-27-2012 09:49 PM

oil burning after sbc short block rebuild
 
What can be the cause of my sbc 400 burning oil out of the # 5 cylinder???
It was rebuilt as a short block, while using the stock heads. The first crank up it rain perfect. It even drove perfect (city wide). After about 50 miles, I took it on the interstate. It was maybe an 45 min to an hour driver doing 70 mph @2000 rpm's. Made it to my destination with no problems. On the way back, 40 mins in the trip I noticed a change in the sound of the exhaust. Oil pressure still reading fine, water temp also. Pull at the local gas station, and its running like a train. White-ish gray smoke is slightly puffing out of the driver side pipe. Now it feels like its running off 7 cylinders, won't hold a idle in drive, and is hesitating bad. Any help on what can possible be wrong???

BOBCRMAN@aol.com 06-27-2012 11:11 PM

400 decks and heads move around and/or crack a lot. If they were not closely checked for warp and crack on the rebuild. You may have lost a head gasket. Causing coolant and/or oil loss, plug fouling. A scored piston skirt. A broken compression or overlapped expander ring will cause oil use.

Take a plug reading, compression check. Go from there.

stevetankl 06-28-2012 06:51 PM

#5 plug has oil on it. Could it be since the compression jumping back to normal (new moly rings) it could have blown a bad stem seal? Or something in that manor?:confused:

1971BB427 06-28-2012 07:58 PM

Pull the plugs and do a compression test. Probably end up pulling the heads eventually. Did you have the heads magnafluxed and rebuilt, or slap on used heads?

hotrodthug 07-19-2012 05:17 PM

could be blown head gasket,happend too me once

oldbogie 07-20-2012 10:53 AM

Quote:

Originally Posted by stevetankl (Post 1569227)
What can be the cause of my sbc 400 burning oil out of the # 5 cylinder???
It was rebuilt as a short block, while using the stock heads. The first crank up it rain perfect. It even drove perfect (city wide). After about 50 miles, I took it on the interstate. It was maybe an 45 min to an hour driver doing 70 mph @2000 rpm's. Made it to my destination with no problems. On the way back, 40 mins in the trip I noticed a change in the sound of the exhaust. Oil pressure still reading fine, water temp also. Pull at the local gas station, and its running like a train. White-ish gray smoke is slightly puffing out of the driver side pipe. Now it feels like its running off 7 cylinders, won't hold a idle in drive, and is hesitating bad. Any help on what can possible be wrong???

As long as we're guessing, I start my voting with a wiped cam lobe and lifter.

Bogie

JamesDean70mc 07-20-2012 12:29 PM

Don't pull the heads off yet.
 
When you get a chance, do a leak down test. If you don't have a leak down tester, use a compression checker hose and apply air pressure to the cylinder with the valves closed, remove the radiator cap before applying the air pressure. If air is escaping from the open radiator, then you possibly have a cracked or warped head, or a blown head gasket, or a cracked or warped block.
If you have no leaks there, then there is a very good possibility that an intake gasket is not sealing and sucking oil in from the lifter valley. I hope this helps.

James.

jessedenny47 09-12-2012 06:02 PM

Check the rings on 5
 
If it was just rebuilt check compression on #5 if low your rings may have turned where all ring slots are in line and it leaking oil past the rings. jessedenny47

Ruthlessmr 09-16-2012 08:36 AM

400s crack a lot but the guys are right first leak down test it,if it back fires then ya flat cam and lots of metal in the oil


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