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Old 06-14-2022, 06:22 PM
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Default 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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Old 06-14-2022, 06:40 PM
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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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Old 06-14-2022, 07:07 PM
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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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Old 06-14-2022, 07:30 PM
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Also, under wide open throttle there may be no vacuum present at the port.

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Old 06-14-2022, 07:32 PM
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Quote:
Originally Posted by 25stevem View Post
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.
I was thinking about this. Just took an 1800 mile trip in the car and changed the oil before. I did 6 quarts and a zinc additive so I at first thought I over serviced it. But in past experience with a big pan like it has I would think you could go a couple quarts over.

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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Old 06-14-2022, 07:37 PM
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Quote:
Originally Posted by Scott Stoneburg View Post
Also, under wide open throttle there may be no vacuum present at the port.
Would that be abnormal? So maybe I should connect my vacuum guage to the manifold pcv port and rev it to 5000?

Quote:
Originally Posted by Scott Stoneburg View Post
Check the Pcv valve to make sure it is working and at the proper vacuum pressure to open.
I have tried both PCV valves, both new and unrestricted.

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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Old 06-14-2022, 07:53 PM
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What cam are you running and what heads do you have?

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Old 06-14-2022, 09:14 PM
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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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Old 06-14-2022, 09:23 PM
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Quote:
Originally Posted by jugalo View Post
Would that be abnormal? So maybe I should connect my vacuum guage to the manifold pcv port and rev it to 5000?



I have tried both PCV valves, both new and unrestricted.

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.
I think it's common to have little to no manifold vacuum at wide open throttle.

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Old 06-14-2022, 09:48 PM
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Quote:
Originally Posted by 25stevem View Post
What cam are you running and what heads do you have?
Comp cams xe262h
6x heads roller rockers


Quote:
Originally Posted by JLMounce View Post
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.
Interesting. I want to be sure I understand, but I thought If my leak down test showed no issues then my rings are ok. I have been reading about the Mighty Mouse on some of the threads here and will look more into it. That may be the way to go... Or I was even reading about that Wagner PCV with the adjustable vac.

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Old 06-14-2022, 09:53 PM
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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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Old 06-14-2022, 11:25 PM
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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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Old 06-15-2022, 06:25 AM
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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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Old 06-15-2022, 08:03 AM
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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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Old 06-15-2022, 08:54 AM
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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.

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Old 06-15-2022, 09:50 AM
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In the above post, where your pistons new or used previously?

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Old 06-16-2022, 07:43 PM
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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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Old 06-16-2022, 09:34 PM
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Quote:
Originally Posted by jugalo View Post
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.
I’ve never been able to find good Pontiac valve covers with baffles. With a a bit of trimming and forming, I added one of these baffles (I think made for chebbys) to my passenger-side valve cover.

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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Old 06-17-2022, 04:01 PM
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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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Old 06-17-2022, 04:56 PM
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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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