460 blowing oil
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Senior User
Joined: Nov 2012
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From: Washington
460 blowing oil
Already posted on 460 page. Reposting here for more eyes too see.
I had my mechanic build a 460 for me a year ago. Just got the funds to do final install on my 1977 f250 4x4 with a c6. Motor sounds great. Idles fine. However, running the truck at 50+mph for longer than 5 minutes causes oil to pour out the dipstick tube, Pcv valve, passenger valve cover on the side, and drivers valve cover at the rear. Mechanic says oil pressure is fine and motor temperature is in the safe range.
Here's a list of what was done to the motor during build.
-Block and heads hot tanked/checked for cracks.
-Heads rebuilt/resurfaced(3 burnt valves)
-Block was not bored. Still had cross hatch marks from factory.
-New rings. Same pistons.
-New camshaft
-New timing set
-New 7 qt oil pan
-New standard oil pump
-Edelbrock performer intake
-Intake sealed with gaskets on the sides and silicon on front, rear, and around water jackets.
-Pcv valve on passenger valve cover. No fresh air intake on drivers side valve cover.
Anyone know why this is happening?
I had my mechanic build a 460 for me a year ago. Just got the funds to do final install on my 1977 f250 4x4 with a c6. Motor sounds great. Idles fine. However, running the truck at 50+mph for longer than 5 minutes causes oil to pour out the dipstick tube, Pcv valve, passenger valve cover on the side, and drivers valve cover at the rear. Mechanic says oil pressure is fine and motor temperature is in the safe range.
Here's a list of what was done to the motor during build.
-Block and heads hot tanked/checked for cracks.
-Heads rebuilt/resurfaced(3 burnt valves)
-Block was not bored. Still had cross hatch marks from factory.
-New rings. Same pistons.
-New camshaft
-New timing set
-New 7 qt oil pan
-New standard oil pump
-Edelbrock performer intake
-Intake sealed with gaskets on the sides and silicon on front, rear, and around water jackets.
-Pcv valve on passenger valve cover. No fresh air intake on drivers side valve cover.
Anyone know why this is happening?
Posting Guru
Joined: Feb 2009
Posts: 1,088
Likes: 4
Without knowing more or seeing it in person, I'd say it's probable the rings haven't seated and may be stuck from disuse. An old trick I've heard of to seat rings like that are to get the engine hotter than normal, but not enough to hurt it, by blocking the radiator with some cardboard. I've never tried it myself, so take it for what it's worth.
Elder User
Joined: Mar 2013
Posts: 559
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From: In Hastings Delton area
I'd check PVC system first make sure its working .If PVC system is working I'd run a compression test .Hate to say this but sounds like you got some broken piston rings it only takes one cylinder with broken rings to make your engine start pumping oil in air cleaner and out dipstick tube .I know this from experience From rebuilding a 327 the first engine I rebuilt over 35 yrs ago piston did not tap in easy with hammer handle I forced it should have rechecked ring compressor anyway a week or so later engine was pumping oil into air cleaner .I ended up pulling engine and found one cylinder with broken rings..
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Senior User
Joined: Nov 2012
Posts: 179
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From: Washington
Thank you for the help. Compression check done today. All cylinders are between 115-120. Pcv system checked. Pcv working. I installed a breather. Mechanic says all spark plugs are dry. Now what?
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Senior User
Joined: Sep 2013
Posts: 329
Likes: 4
From: Deer park, Wa.
You might try a leak down test. Valve stem seals? Compression seems a little low.
Good luck with it.
Good luck with it.
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Elder User
Joined: Jun 2012
Posts: 850
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From: Florida
-were the rings installed upside down (or cracked)?
-You have to get air in some way
the top two will cause oil to go where it should not because the fuel/air getting out of the combustion chamber past the rings has to go someplace
the third is what happens when the carb is sucking whatever it can from the valve cover
115-120 sounds real low for a new engine
Elder User
Joined: Mar 2013
Posts: 559
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From: In Hastings Delton area
I have seen compression still be 95 psi and engine having broken compression rings . Other question what was piston ring end gap? specs say .004 to .005 per inch of piston meaning .016 to .020 end gap on piston rings .If ring gap was greater than .030 then that might be contributing to your problem.
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Senior User
Joined: Nov 2012
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From: Washington
General consensus sounds like Mr. Mechanic needs to tear it back down. I don't have the answers to your latest questions but can get them.
-What is a "normal" range of numbers for a compression test on a newly rebuilt, not broke in 460?
-What is a "normal" range of numbers for a compression test on a newly rebuilt, not broke in 460?
Lead Driver
Joined: Dec 2012
Posts: 7,877
Likes: 49
From: Tennessee
Also , were the rings indexed properly ....? ! I had a kid give me a motor after his buddy " rebuilt " it . He ran it 2 days in his mustang and then installed a junkyard engine . All the ring gaps were lined up in a straight row ! It also had 3 bad valves ...
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Senior User
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From: Washington
Update: I talked to a machinist. He said the problem was most likely the synthetic oil I was running. The oil is too slick for the rings to properly seat. So, I drained the oil and changed the filter. Added 7 qts of 30 wt with no detergents. Motor stopped puking oil within 2miles of running it in 2nd (automatic tranny). I ran it another 64 miles at altering rpm levels and speeds. Oil level never altered. I think it's safe to say that the rings finally seated! I can't wait to get the rest of the truck rebuilt. That motor has piles of torque. I still can't believe it. Holy.....cow!
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