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Re: another broken valley pan!!
[Re: hornetnut]
#1473814
07/26/13 05:23 PM
07/26/13 05:23 PM
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Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
70Cuda383
Too Many Posts
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Too Many Posts
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
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If there was a dead cylinder, wouldn't it be blowing the pan at any engine speed? He only cracks the pan at WOT
My engine cracked 2 of them, one was a used original so I thought maybe it was already weak, but a week later the brand new one did too.
Only at WOT
I checked my breather (remember, PCV only works when there's manifold vacuum, at WOT it closes, so the only way to evac blowby at WOT is through a breather). And I could barely blow through it by mouth. I pushed open the metal more (it resembled a pop can that was just cracked open) and then removed a big wad of padding. Replaced it with some paper towels to catch any oil vapors and never cracked another pan.
At engine idle, air would suck in at the breather, which is another check the OP could do... Of it was cracking from excessive blow by due to bad rings, hole in a piston, etc, wouldn't it be lightly puffing out of the breather at idle?
**Photobucket sucks**
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Re: another broken valley pan!!
[Re: 70Cuda383]
#1473815
07/27/13 12:59 AM
07/27/13 12:59 AM
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Joined: Jun 2005
Posts: 6,257
gulfport, ms, west mi
rowin4
master
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master
Joined: Jun 2005
Posts: 6,257
gulfport, ms, west mi
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The engine is basically a compressor , the faster you run it the more pressure will build in the crank case . So at wide open throttle if there is a problem there becomes more crank case pressure than the PCV or vents can dissipate. So what is causing the crank case pressure to build up to push the valley cover inside out. Broken rings, hole in the piston, wiped exhaust lobes all would be likely candidates. It might seem to you that it's running OK but your engine has a problem that stuffing in a rag is not the proper fix. 
it's ok to butt heads, just don't do it with a butthead
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Re: another broken valley pan!!
[Re: rowin4]
#1473816
07/27/13 02:04 AM
07/27/13 02:04 AM
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Joined: Feb 2011
Posts: 76
california
hornetnut
OP
member
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OP
member
Joined: Feb 2011
Posts: 76
california
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Quote:
The engine is basically a compressor , the faster you run it the more pressure will build in the crank case . So at wide open throttle if there is a problem there becomes more crank case pressure than the PCV or vents can dissipate. So what is causing the crank case pressure to build up to push the valley cover inside out. Broken rings, hole in the piston, wiped exhaust lobes all would be likely candidates. It might seem to you that it's running OK but your engine has a problem that stuffing in a rag is not the proper fix.
i knew it wasnt the proper fix, but we all do weird things at the track to keep going rounds.. 
ill keep you posted as i get things sorted out... thanks guys
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Re: another broken valley pan!!
[Re: hornetnut]
#1473818
07/27/13 03:12 AM
07/27/13 03:12 AM
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Joined: Dec 2006
Posts: 4,647
aotearoa
rebel
master
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master
Joined: Dec 2006
Posts: 4,647
aotearoa
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Quote:
i knew it wasnt the proper fix, but we all do weird things at the track to keep going rounds..
tell me about it, i cut a daiper into sections & foil taped it over a crack in the pan between rounds. only had to get past the startline without being seen dripping oil. made it all the way to the finals.
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Re: another broken valley pan!!
[Re: 68LAR]
#1473821
07/31/13 01:25 PM
07/31/13 01:25 PM
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Joined: Apr 2005
Posts: 2,128
Salt Lake City
camastomcat
top fuel
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top fuel
Joined: Apr 2005
Posts: 2,128
Salt Lake City
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Quote:
Quote:
The engine is basically a compressor , the faster you run it the more pressure will build in the crank case . So at wide open throttle if there is a problem there becomes more crank case pressure than the PCV or vents can dissipate. So what is causing the crank case pressure to build up to push the valley cover inside out. Broken rings, hole in the piston, wiped exhaust lobes all would be likely candidates. It might seem to you that it's running OK but your engine has a problem that stuffing in a rag is not the proper fix.
Absolutely correct. For some reason, the engine is building too much crankcase pressure. Timing has nothing to do with the problem. I'd bet there is either a broken ring or too much ring end gap. 
Either one of these things would cause excessive smoke and leakdown, I would do a leak down vs. a compression test. What CI? Is it blowing oil out the breathers? Perhaps too much oil causing windage?
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Re: another broken valley pan!!
[Re: hornetnut]
#1473823
07/31/13 03:28 PM
07/31/13 03:28 PM
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Joined: Apr 2005
Posts: 2,128
Salt Lake City
camastomcat
top fuel
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top fuel
Joined: Apr 2005
Posts: 2,128
Salt Lake City
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Quote:
440 ci, eddy heads, .030 overbore, its a truck pan with a windage tray and only put 5 quarts in it.. it does show a lil over the full mark
Does the oil want to come out of the breathers, and does it smoke out the exhaust?
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Re: another broken valley pan!!
[Re: hornetnut]
#1473826
08/01/13 05:21 PM
08/01/13 05:21 PM
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Joined: Apr 2005
Posts: 2,128
Salt Lake City
camastomcat
top fuel
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top fuel
Joined: Apr 2005
Posts: 2,128
Salt Lake City
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Quote:
absolutely no smoke out of the exhaust... i have seen a lil oil dripping from the breather but only at the track
I would try running a tad less oil, maybe a 1/4-1/2 qt. I would prefer you do a leak down, but if you don't have the gauge or can't borrow one,that's your only option. The only other thing I can think of that would cause crankcase pressure other than a worn out engine, worn cam,etc. is too much oil. Are you sure you only have 5 qts? Stupid question....how old is this motor? If there is any way you can leak it down, do it.
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Re: another broken valley pan!!
[Re: camastomcat]
#1473827
08/02/13 02:06 AM
08/02/13 02:06 AM
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Joined: Jan 2003
Posts: 2,932
Finalnd, Perkele
jyrki
master
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master
Joined: Jan 2003
Posts: 2,932
Finalnd, Perkele
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Is there only a crack but the shape hasn't changed? Because when you really have excessive crankcase pressure, the bathtub will balloon "upside down" before cracking. If not, then I believe you've got somekind of harmonics that crack the pan. I believe that's the reason why factory also used a "sandwich" between the intake and valley pan, to avoid cracking caused by harmonics.
Plynouth VIP '67 TT IC EFI
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I could be thinking way wrong 
