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#1
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Another Crankcase Pressure thread
Well I searched and read dozens on this same subject, but not many folks post remedies or test result follow ups.
My 400 is blowing oil from passenger breather and pushing the dipstick out under really hard acceleration. Pcv valve pulling from top of manifold. I am running Rotella T5 15-40, but I am going to try 30 weight next. I have a fixed orifice PCV valve upon Sniper recommendation. I performed a full compression test, all good. I also did a leak down test with good gauges and all good as well. See picture of my test results. I just decided to replace my oil filler cap with a cheap twist in breather. Have not driven with it yet. One of my concerns is that I have a remote tune scheduled for the stupid Sniper tomorrow. The fellow is VERY reputable and is a pioneer in the EFI world. But he doesnt like pcv valves as they reek havoc with AFR readings. So Im not sure how he is going to advize me on that, I need a good tune AND to keep the oil where it belongs... in the engine! How would ya'll proceed with this troubleshooting? Thanks in advance. Bill
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1980 Trans Am Fiero Bronze 400 w72 Holley Sniper 200-4R Full Dakota Digital 4 Wheel Wilwoods Full PTFB Suspension Pypes Crossflow/X pipe |
#2
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If you have a oil pressure gauge I would drain out the oil and put one less Qt back in, then see if the dip stick gets pushed out while running it hard and keeping a eye on the oil pressure.
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I do stuff for reasons. |
#3
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Check the Pcv valve to make sure it is working and at the proper vacuum pressure to open.
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#4
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Also, under wide open throttle there may be no vacuum present at the port.
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#5
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Quote:
I have read about the dipsticks being long or the tubes being mis positioned as well and I do plan to grind off a 1/4" to test that theory. BTW it is all new stuff from AMEs. Will do oil change Friday and post result.
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1980 Trans Am Fiero Bronze 400 w72 Holley Sniper 200-4R Full Dakota Digital 4 Wheel Wilwoods Full PTFB Suspension Pypes Crossflow/X pipe |
#6
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Quote:
Quote:
I also should have mentioned I have 15hg vacuum at idle which is low. I was hoping my tune will be able to remedy that as I have weak power brakes and have yet to fix that. I have a pretty mild cam.
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1980 Trans Am Fiero Bronze 400 w72 Holley Sniper 200-4R Full Dakota Digital 4 Wheel Wilwoods Full PTFB Suspension Pypes Crossflow/X pipe |
#7
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What cam are you running and what heads do you have?
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I do stuff for reasons. |
#8
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I had the same issue on my 455. The ultimate solution of course is to fix the ring seal issue causing the crank case pressure in the first place. That said I was able to correct the issue while I save for a rebuild.
I went with a Mighty Mouse Solutions draft can and eliminated the pcv completely. The draft can supplies enough positive ventilation for a claimed 800 hp and acts as an air/oil separator at the same time. Think of it as a pcv system that is active at all times. If ventilation needs exceed the can’s capacity it will draft excess. I have mine plumbed with a -8 line coming from an open corner in the factory pcv location. From the can another -8 line plumbs to the rear of the plenum. I additionally have a single open vent on the passenger side head. Since I installed the draft setup, I no longer push oil out of the dipstick tube and I no longer get the smell of blow by gasses in the passenger cabin.
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-Jason 1969 Pontiac Firebird |
#9
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Quote:
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#10
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Comp cams xe262h
6x heads roller rockers Quote:
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1980 Trans Am Fiero Bronze 400 w72 Holley Sniper 200-4R Full Dakota Digital 4 Wheel Wilwoods Full PTFB Suspension Pypes Crossflow/X pipe |
#11
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I would eventually like a nice set of Aluminum valve covers in black that I can put breathers or other accessories on in the aft positions. But it seems none of them have baffles to prevent oil from slinging out. The stock chrome ones I have are limiting. But they have drippers which from I understand are desire-able. Seems there are pros and cons to everything. Im always looking for the perfect set up.
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1980 Trans Am Fiero Bronze 400 w72 Holley Sniper 200-4R Full Dakota Digital 4 Wheel Wilwoods Full PTFB Suspension Pypes Crossflow/X pipe |
#12
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spendy but i had good results reducing crankcase pressure with the M/E wagner pcv valve. confirmed by comparing crankcase pressure using a manometer at idle and under load.
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The Following User Says Thank You to i82much For This Useful Post: | ||
#13
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Whenever I have had the dip stick pop up it was due to oil control far more then crankcase pressure!
Ask yourself why stock motors in decent shape with 60 psi pumps don’t pop out the stick , yet 60 psi aftermarket pumps with increased volume do!
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I do stuff for reasons. |
#14
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Check them Umbrella Seals for riding off the Guide, and going up n down with the valvestems.
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#15
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I had the same issue. I Used the same OTC pressure gauge to find some very leaky cylinders to. If I moved the piston just slightly in the bore my reading would change quit a bit. I was blowing out the seals on the motor left and right. It was driving me nuts. If I stayed off the gas it was fine. If I got into it I would have oil leaks everywhere and a pool of oil by the distributor. I would have small plums of smoke behind the car from dripping on the exhaust. I blew part of the pan gasket off the back.
I would get the same comments about checking the PCV and valve seals on the head. I pulled the motor in 2017 and then did a bunch of other project work on the car. I plan to see if the cylinders are out of round or if the rings are just bad. Mine is a .060 over 455 and I know the bores can get out of round. I don't know if that is the case here or not. I hope to find out in the next few weeks. |
#16
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In the above post, where your pistons new or used previously?
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I do stuff for reasons. |
#17
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Engine is trying to tell you that it is not happy, are you willing to listen?
a) If you go to WOT and the vacuum drops off, with a good ring seal around the pistons you should have very little additional crankcase pressure. b) A Factory PCV valve actually has several modes of operation: Idle, Light Throttle, Cruise Speed, WOT (PCV rarely affected by carb "Tip-Ins), and "Backfire Mode" where the shuttle closes and keeps flame from entering the oil pan. c) 99% of all of the PCV function being blamed by the owner are related to other worn engine parts. Rings and sloppy pistons in the block being the main causes. Once in a while you have a ring issue from detonation. 1) Have you "pumped the engine"? 2) What actual parts do you have in the engine and age of those parts. Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
The Following User Says Thank You to Tom Vaught For This Useful Post: | ||
#18
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Quote:
https://www.summitracing.com/parts/sdm-pce4801001 I didn’t want mess with something like a rivet showing through or welding aluminum, so I used JB Weld and made sure to do a very solid and thorough job. The flanges of the baffles have a lot of surface area against the inside of the valve covers so you can get a very strong epoxy bond. The baffle works great, and so far it’s holding strong.
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1976 Trans Am Buccaneer Red 468ci, 10.5:1 CR, 87 CC RPM CNC e-heads, HR 282/288, 230/236, 561/.573 lift, Johnson Lifters & HS 1.65 Rockers |
#19
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Depending upon what size the hoels are in your V/C's, Mr. Gasket makes a baffled rubber grommet, that I believe fits 1.25" holes.
IF your vacuum gauge is registering ANY vacuum at full throttle, something isn't right somewhere in your engine.Possibly not a mechanical malfunction, but something to look into... Lack of carb full throttle, huge engine, small carb, restriction somewhere in intake tract. there are more....
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1977 Black Trans Am 180 HP Auto, essentially base model T/A. I'm the original owner, purchased May 7, 1977. Shut it off Shut it off Buddy, I just shut your Prius down... |
#20
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I made baffles also for my Tall Moroso covers from soda can aluminum and did the J B weld thing also.
Worked super ! Where the breathers are on these Moroso covers and a few others a rocker shoots right the hell up in it when you can no longer use the factory baffles.
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I do stuff for reasons. |
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