HOW TO DO AN ADVANCED SEARCH.

Mon Jul 08, 2013 3:56 pm by Admin


For the benefit of 944Hybrids users there are two search functions available for you to use.
The purpose of this sticky is to explain the "Advanced Search" function because it is much more powerful and is the best choice when researching information.

When you log on to the site a list of options is shown in a line at the top of the page. One option is labelled "Search", use this option (NOT the search box lower down on the right).

After you click on the upper search option, a drop down box appears. At the bottom of this box is a radio button marked "Advanced …

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Excessive crankcase pressure

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Excessive crankcase pressure

Post  rooster on Sat Aug 24, 2013 7:28 am

When I run at the track I get oil mist blowing out of the dipstick tube, past the o-ring.  I get a nice mist all over the coils, shock tower and then onto the header.  Track officials don't seem to like the smoke screen I'm laying down to keep the other cars off my ass!Laughing  My PCV setup is what xschop did where the two vent tubes on the passenger valve cover are blocked off and I have the updated PCV from the rear drivers side valve cover running to the intake.  I assume I need to unplug the two passanger side vents and tie it all in to a catch can and than back the the intake - does this sound like the best plan?  

Also, there are some really expensive catch cans and some really cheap ones.  I'd prefer to not spend $130 on a simple can with some fittings and a baffle.  Has anyone had success with the cheaper models on Amazon etc?  Any other tips tricks are welcome.  Thanks guys.  

-Andrew

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Re: Excessive crankcase pressure

Post  money pit 951 on Sat Aug 24, 2013 8:36 am

How old is your engine build? You have to keep in mind that venting is really not the answer for what to do about the problem... The pressure is coming is blow-by past your rings, so I'd guess you're up for a motor freshening up.

But to answer your question, your plan sounds good.  Put as much vented area into a catch can as you can. There's no real need for an expensive catch can unless you want it to look nice.  You need surface area to get the suspended oil out of air, so usually something like a metal wool is used to help catch the oil.
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Re: Excessive crankcase pressure

Post  marc a on Sat Aug 24, 2013 10:01 am

Here is my set up.  Catch can was 50 at Summit Racing. No problems since day one.
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Marc
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Re: Excessive crankcase pressure

Post  rooster on Sat Aug 24, 2013 1:45 pm

@ Money Pit, my motor has approx 70k miles on it. I certainly hope I don't need to refresh it just yet, but perhaps you're right. Thanks for the advice I'll get a catch can ASAP and connect the vents that are currently blocked.

@ Marc, it looks like you opted for the vented type instead of routing the fumes back to the intake correct? Any pros or cons to either method or just personal preference?

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Re: Excessive crankcase pressure

Post  marc a on Sat Aug 24, 2013 3:33 pm

Rooster,

Since it is a track car, I wanted to keep it simple and I did not want to return the "muck" into the engine. YMMV

Marc
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Re: Excessive crankcase pressure

Post  money pit 951 on Sat Aug 24, 2013 11:53 pm

rooster wrote:@ Money Pit, my motor has approx 70k miles on it.  I certainly hope I don't need to refresh it just yet, but perhaps you're right.  Thanks for the advice I'll get a catch can ASAP and connect the vents that are currently blocked.   
Not trying to imply anything, but you might want to do a compression test to see if you have a weak cylinder that's bleeding pressure. The LS1's pistons have a very small ring land and do crack. I just had to rebuild mine when the piston cracked and was venting into the case.

For my vents, I've welded two AN10 bungs to the valve covers and ran them to a can. Plenty of venting area (could have used AN8 I'm sure) to keep the case from being pressurized. Ideally you want a negative pressure in the case but that's not too practical for most of us. Too much positive pressure will create problems with the rings seating and cause more blow-by
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Re: Excessive crankcase pressure

Post  Rich L. on Sun Aug 25, 2013 3:40 pm

I run a dual catch can setup. The "clean" side is from the front of the passenger valve cover to the throttle body. Mine catches nothing. The "dirty" side joins the back of both valve covers and has the PCV before the catch can then goes into the intake. This catches half a quart over the course of a track day.

The later valley cover has an integrated PCV and is supposed to keep oil out of the system. With that later setup you plug the rear valve cover openings. I'd like to update to this eventually.

Rich
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Re: Excessive crankcase pressure

Post  87-944S on Sun Aug 25, 2013 9:16 pm

Rich, what year is your engine?
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Re: Excessive crankcase pressure

Post  Rich L. on Mon Aug 26, 2013 10:39 am

87-944S wrote:Rich, what year is your engine?
I don't know for sure, but think it's from a '99 or '00 f-body.

Rich
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Re: Excessive crankcase pressure

Post  rooster on Mon Aug 26, 2013 10:24 pm

@moneypit, it sounds like you've been down this road and have the receipts to show for it. I'll do a compression test soon just to be sure but my motor has behaved this way for a while now. I guess I'm just hoping I don't need to pull the motor and tear it apart this winter.

@Rich, thanks for the reply and sharing the quantity of oil you collect, that will give me a benchmark at least.

Catch can is ordered I'll see how it does and re-post. Thanks again guys.

Andrew

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Re: Excessive crankcase pressure

Post  docwyte on Tue Aug 27, 2013 10:19 am

I've got the LS6 valley cover venting into a catch can, I'm also venting into the catch can from the LS1 valve cover. Those go into my PCV valve, then into the intake.

I was smoking on decel and it was bad valve stem seals. Compression and leakdowns were good, but there is excessive play in my exhaust valve guides.

I'm probably going to put on a set of ported/rebuilt 243 heads this offseason.

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Re: Excessive crankcase pressure

Post  money pit 951 on Tue Aug 27, 2013 10:59 am

Yes, I've been through this problem before... Excessive crank pressure just isn't normal and is probably an issue you don't want to hear about.  In my case it was a cracked piston which sparked a complete engine rebuild while I was in there....

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Re: Excessive crankcase pressure

Post  money pit 951 on Tue Aug 27, 2013 11:15 am

I got a little off track with the answers, but to answer your initial question here is what I did for venting. I welded in two AN10 bungs to each valve cover which will provide plenty of vent area into the catch can. I got two cheapo AN to barb 90deg fittings so I can quickly remove the covers when needed. The can is vented to the air and not to the intake.
This should be able to vent any generated pressure from the case.

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