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Poor PCV circulation causing oil leaks? by undertakingyou
Started on: 09-29-2013 09:54 PM
Replies: 17 (497 views)
Last post by: undertakingyou on 10-25-2013 10:49 PM
undertakingyou
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Report this Post09-29-2013 09:54 PM Click Here to See the Profile for undertakingyouClick Here to Email undertakingyouSend a Private Message to undertakingyouEdit/Delete MessageReply w/QuoteDirect Link to This Post
87 GT with fresh rebuilt 2.8L. I rebuilt it myself and was very meticulous in all the seals and torque specs as I was building it. But I am getting oil leaks. I say leaks because there is not just one place that I can pinpoint, but it seems like oil is coming out of everywhere! I have heard that if you have poor PCV performance you can get oil leaks just because of built up internal pressure.

Another little piece of backstory. I bought this car off of eBay in March, and it was supposed to run great and be a great daily driver. NOT THE CASE! Which is unfortunate because on the 800 mile drive home from Seattle I thought I wasn't going to make it at a couple of points. It seems that the previous owners were more concerned about having a cool car with a cool radio than a car that functioned great. One of the previous owners installed a cheap, CHEAP, cold air intake system, which takes the intake side of the PCV and changes the tube diameter down from a 1/2 ID to a 1/8 ID. I think this may be the culprit.

So, to the point, two questions:
1) Do you think that my suspicion about the PCV diameter change at the intake could be correct and causing my leaks?
2) I don't have any original intake parts (or I would have installed them!), is there a better intake system replacement that I could buy?

Thanks.
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Marvin McInnis
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Report this Post09-29-2013 10:24 PM Click Here to See the Profile for Marvin McInnisClick Here to visit Marvin McInnis's HomePageSend a Private Message to Marvin McInnisEdit/Delete MessageReply w/QuoteDirect Link to This Post
The most effective thing you can do is return your PCV system to its original condition. The normal PCV airflow in the 2.8 is as follows:

1) Fresh air is taken from the intake system downstream of the air filter.
2) This air enters the crankcase through the fitting in the forward valve cover.
3) Air and other crankcase gases exit the crankcase through the fitting in the rear valve cover, via the PCV valve.
4) Air passes from the PCV valve to the intake plenum, downstream of the throttle body.

Is the PCV valve present and working properly? If there is any doubt, just replace it. It's cheap. Install it correctly.

Are all PCV tubes and hoses in place and leak free? If in doubt, replace them.

The GM/Helm Factory Service Manual addresses testing and troubleshooting the PCV system. Other causes of crankcase pressurization include excessive blowby due to poor piston ring fit, broken rings, or poor sealing.

[This message has been edited by Marvin McInnis (edited 09-29-2013).]

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undertakingyou
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Report this Post09-29-2013 10:44 PM Click Here to See the Profile for undertakingyouClick Here to Email undertakingyouSend a Private Message to undertakingyouEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Marvin McInnis:

1) Fresh air is taken from the intake system downstream of the air filter.
2) This air enters the crankcase through the fitting in the forward valve cover.
3) Air and other crankcase gases exit the crankcase through the fitting in the rear valve cover, via the PCV valve.
4) Air passes from the PCV valve to the intake plenum, downstream of the throttle body.


I didn't realize this was the direction of flow. Great info, thanks.
 
quote
Originally posted by Marvin McInnis:
Is the PCV valve present and working properly? If there is any doubt, just replace it. It's cheap. Install it correctly.

PCV valve and rubber components were replaced when the engine was rebuilt (about 1000 miles of use on them). I can't imagine that there would be an issue there.
 
quote
Originally posted by Marvin McInnis:
Are all PCV tubes and hoses in place and leak free? If in doubt, replace them.

The tubes are all there, and should be leak free. The only real change is the size of the fresh air inlet.

 
quote
Originally posted by Marvin McInnis:
The GM/Helm Factory Service Manual addresses testing and troubleshooting the PCV system. Other causes of crankcase pressurization include excessive blowby due to poor piston ring fit, broken rings, or poor sealing.

Brand new rings and everything. So I don't think that can be the cause the pressurization issues.

From your description it would be easy to test if the reduced diameter was the issue by removing the restriction and run the motor with the PCV intake tube. The only issue here is that I would lose my filtered air going into the crank case.

Thinking aloud: I could do that and just wrap a rag around the end of that tube to act as a filter (against just the big stuff) and then plug the hole in the cold air intake.
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Report this Post09-30-2013 12:11 AM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
Just pull the oil filler cap off while you are running it and see if you have lots of blow by coming out. If you rev it up you will splatter some oil out, but sounds like you have plenty of oil coming out anyway. Just where is most of the oil coming from? If you have pressure issues you will be getting blow by out the fresh air intake tube. Larry

[This message has been edited by trotterlg (edited 09-30-2013).]

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undertakingyou
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Report this Post09-30-2013 03:55 AM Click Here to See the Profile for undertakingyouClick Here to Email undertakingyouSend a Private Message to undertakingyouEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by trotterlg:

Just pull the oil filler cap off while you are running it and see if you have lots of blow by coming out. If you rev it up you will splatter some oil out, but sounds like you have plenty of oil coming out anyway. Just where is most of the oil coming from? If you have pressure issues you will be getting blow by out the fresh air intake tube. Larry



Larry, I haven't looked right now, but before I rebuilt the engine (when I had horrible compression) there was oil blowby up the PCV intake tube. I haven't checked that now, but with everything else new I am thinking it has to be this restricted air intake.

I have been looking, and I am thinking of buying something like this: http://www.knfilters.com/se...ct.aspx?prod=62-1560 which could go on the end of that tube, and then I would plug up the hole in the intake (probably with duct tape).

Another thought would be to buy something like this: http://www.westcoastfiero.c...intake_air_tube.html from West Coast Fiero's.
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Report this Post09-30-2013 12:32 PM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
I don't think it is air intake that is your problem, if you are forcing oil out gaskets you have way too much pressure in the crankcase, pull the oil filler cap off and see if you get lots of flow out the hole. Larry
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Marvin McInnis
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Report this Post09-30-2013 01:09 PM Click Here to See the Profile for Marvin McInnisClick Here to visit Marvin McInnis's HomePageSend a Private Message to Marvin McInnisEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by undertakingyou:

Brand new rings and everything. So I don't think that can be the cause the pressurization issues.



Not so fast! Don't rule out that possibility until you've actually measured the crankcase pressure. Rings can be the wrong size or tension. (I've seen that.) They can be installed improperly or fractured on installation. (Done that.) They can fail to seat properly in the first few hours of engine operation. (Done that.)

So far you're only assuming that crankcase pressure is the problem. Another common issue that will leak oil all over the place is the distributor shaft seal in the V6es; I would check that before going any further down the "crankcase pressure" path. The next step would be to actually measure crankcase pressure.

Concerning the modified air intake system: My best recommendation would be to return the air intake to the stock configuration. The OEM design is a true cold-air system, and it is very efficient even with the OEM silencer/water separator in place.


 
quote
Originally posted by trotterlg:

I don't think it is air intake that is your problem, if you are forcing oil out gaskets you have way too much pressure in the crankcase ...



I tend to agree. If anything, a smaller-than-standard vent pipe should result in a slight vacuum in the crankcase if the PCV valve is working correctly.

[This message has been edited by Marvin McInnis (edited 09-30-2013).]

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undertakingyou
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Report this Post09-30-2013 01:38 PM Click Here to See the Profile for undertakingyouClick Here to Email undertakingyouSend a Private Message to undertakingyouEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks for taking the time with me on this. I love asking troubleshooting questions because it helps me think of possibilities that I had not thought of.
 
quote
Originally posted by Marvin McInnis:

Not so fast! Don't rule out that possibility until you've actually measured the crankcase pressure. Rings can be the wrong size or tension. (I've seen that.) They can be installed improperly or broken on installation. (Done that.) They can fail to seat properly in the first few hours of engine operation. (Done that.)

So far you're only assuming that crankcase pressure is the problem. Another common issue that will leak oil all over the place is the distributor shaft seal in the V6es; I would check that before going any further down the "crankcase pressure" path. The next step would be to actually measure crankcase pressure.



Fair enough. I really, REALLY would be shocked if it was rings. I installed them myself. I feeler gauged every ring with the cylinder it was going into prior to install. Not my first motor build. With all that said I have not measured crankcase pressure, and I don't know how. I will do some looking.

As far as the distributor shaft seal once again, that is new (on a new distributor) and is usually accompanied by a puddle of oil at the rear of the block. There is a little pocket there where the oil tends to gather. That spot is bone dry.

 
quote
Originally posted by Marvin McInnis:

I tend to agree. If anything, a smaller-than-standard vent pipe should result in a slight vacuum in the crankcase if the PCV valve is working correctly.



That makes sense to me. I just can't imagine that a brand new PCV valve would have issues like this. There must be some buildup of pressure somewhere. I can do a compression test on all the cylinders to see where I lie there, see if there is an issue that way.

I agree with you also, I wish I had the stock air cleaner. It isn't that hard to save, and I wish I had gotten it when I purchased the car.
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Report this Post10-01-2013 10:29 AM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post
When you say everywhere, are you sure it isnt just valvecovers, because they can run down alnd look like everywhere.
I know Felpro makes some awesome blue valvecover gaskets, I used them on my 2.5 liter, but they come with "shim" washers and if you use the wrong washers they dont get tight enough to seal.
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Report this Post10-01-2013 11:09 AM Click Here to See the Profile for rogergarrisonClick Here to Email rogergarrisonSend a Private Message to rogergarrisonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Im with Marvin and Trotter. The factory system IS a cold air intake, other hillbilly rigged stuff is useless. The first thing ricer guys do is put an aftermarket cold air intake on anything to get 50 more hp . Id also test it with the caps off of the covers. Clean the engine well so no oil is on it, then check it often to see where its coming from. Like said already, the 0 ring seal on the distributor shaft is a good source of oil. Ive built my own engines for a long time, and theyve fooled me a few times. Most often it looks like a front or rear main seal is leaking, but its just running down to the lowest point. Put your hoses back to proper sizes like already said too. When you put in your rings, did you scratch up the cylinder bores too with a hone ? Proper break in is important in older style engines. What kind of oil did you break it in with ?
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Report this Post10-01-2013 01:02 PM Click Here to See the Profile for undertakingyouClick Here to Email undertakingyouSend a Private Message to undertakingyouEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
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Originally posted by rogergarrison:When you put in your rings, did you scratch up the cylinder bores too with a hone ? Proper break in is important in older style engines. What kind of oil did you break it in with ?


Your other points are good, and I love the mods that 'ricers' do. Always an intake, flame stickers, and a different exhaust tip. They always look so goofy. But to answer your questions. When the motor was built and new rings installed, the motor had been bored over .25 mm. The oil that I used to break it in. While assembling I used assembly lube from Napa and a 5W30 conventional oil to wipe everything down, including lube the cylinders for ring installation. Then for running a 5W30 fully synthetic from O'Reilly. Changed the oil at 500 miles to clean out the assembly lube, etc.

I wanted to find a stock air cleaner. I will have to peruse eBay again.

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Report this Post10-01-2013 01:43 PM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
I just finished up a 3100 rebuild, I did do a rebore on it, but even at 200 miles there is nearly zero blowby, I just put a 1/4 inch tube in the forward valve cover and vent it into the air cleaner, there is only a tiny amount of air coming out of it. If I pull the oil filler cap you cannot detect anything exhausting from it. Under load there may be more, but it is nothing like what you seem to have. I even have 12 to 1 pistons in it. Larry
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Report this Post10-01-2013 03:54 PM Click Here to See the Profile for rogergarrisonClick Here to Email rogergarrisonSend a Private Message to rogergarrisonEdit/Delete MessageReply w/QuoteDirect Link to This Post
I always been told by mechanics and professional engine builders ( I know some Nascar team builders), to never run synthetic oil in an engine till its well broken in...that being 5,000-10,000 miles. Break in should be done with break in oil designed for it, or at least regular dino oil. Id suspect that might be at least some of the problem...the rings did not seat/ wear in properly.
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Report this Post10-03-2013 10:17 PM Click Here to See the Profile for trotterlgClick Here to Email trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
Ever figure out your problem? Larry
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undertakingyou
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Report this Post10-03-2013 11:09 PM Click Here to See the Profile for undertakingyouClick Here to Email undertakingyouSend a Private Message to undertakingyouEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by trotterlg:

Ever figure out your problem? Larry


Nothing new to report.

I did pull the oil cap and rev it up with my hand over it. I can feel a little air coming out, but barely. I would compare it a an infant breathing out of its nostrils. It is really just BARELY.

I am going to do a compression check on all six cylinders tomorrow or Saturday. If I have anything a out of the ordinary I will assume a ring problem in that cylinder. I really, REALLY hope that everything checks out that way. I just rebuilt this motor and don't want to pull it. The motor doesn't even have 1200 miles on it.

One note, I am thinking that I should change the oil to conventional.
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Marvin McInnis
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Report this Post10-04-2013 09:19 AM Click Here to See the Profile for Marvin McInnisClick Here to visit Marvin McInnis's HomePageSend a Private Message to Marvin McInnisEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by undertakingyou:

I did pull the oil cap and rev it up with my hand over it. I can feel a little air coming out, but barely. I would compare it a an infant breathing out of its nostrils. It is really just BARELY.



That is a strong indication that crankcase pressurization is not the primary problem.
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Report this Post10-04-2013 09:36 AM Click Here to See the Profile for TONY_CSend a Private Message to TONY_CEdit/Delete MessageReply w/QuoteDirect Link to This Post
If you did have severe blow by, you would see excess oil in the air filter. I had a Duke with bad blow by and it would even build enough pressure to push the dipstick part way out of the tube.
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Report this Post10-25-2013 10:49 PM Click Here to See the Profile for undertakingyouClick Here to Email undertakingyouSend a Private Message to undertakingyouEdit/Delete MessageReply w/QuoteDirect Link to This Post
As a follow up on this, I never got around to doing a compression test. I did however have to replace the clutch, and in doing so pulled off all the intake stuff. No oil being pushed up the intake tube, everything good. I did tighten down the accessible valve cover bolts, but I am still getting an oil leak. I am thinking it is either the oil dipstick (I don't recall putting an o-ring in there), the oil pressure sending unit, or the oil filter. I just need to find a decent way to check.

Thanks for all the input.
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