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03-13-2014
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#91 |
Join Date: Jul 2013
Location: Mt.Bethel Pa.
Posts: 73
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Re: 368 LT5 Drinking oil
You need a baffle or something to keep the oil from being sucked into the pvc,ya want to get on the front end of the problem.
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1990 Zr-1 #361 1991 GMC Syclone (built) 1993 GMC Typhoon (stock) 1993 GMC Typhoon (street) 1992 GMC Sonoma GT 1928 Model A pick up |
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03-13-2014
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#92 | |
 
Join Date: Dec 2003
Location: Arcadia,OK
Posts: 3,394
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Re: 368 LT5 Drinking oil
Quote:
The LT5 doesn't have a conventional style of PCV system. The majority of the crankcase vapor comes up through a large baffle with cover and 2 large hoses to an isolated chamber in the injector housings (all under the plenum).There are 2 small holes in the cyl head (or inj hsng if 1990 model) that vapor from the cylinder heads passes through, into the same isolated chamber. The pipes with grommets you see on the outside of the injector housings then connect to the PVC hose at the rear of the plenum. Regarding the pipes from each cam cover to the air horn, in front of the throttle body; Those pipes are for filtered/fresh air purge of the crankcase.
The same principal applies to the cam cover tubes, thus the reason for the cam cover "filters," whose purpose is actually mist extraction. WOT flow would then be from the cam cover to the engine air inlet at the air horn.So, under WOT, low to no engine vacuum conditions, heavily laden oil vapor can reach the plenum by two different paths, PCV system and the cam cover filtered air purge tubes. The amount of oil in the crankcase vapor depends on engine condition and will normally accumulate in the plenum through the PCV system, even under normal driving conditions. Not a perfect condition, but not a serious problem either. It is a condition that can be improved upon, but not entirely eliminated, with the installation of an oil catch can. WOT conditions can still result in oil through the air inlet. The more blow-by the more oil.
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Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 ZR-1, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed. |
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03-13-2014
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#93 |
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Join Date: May 2013
Location: Chicago
Posts: 980
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Re: 368 LT5 Drinking oil
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1993 ZR-1 #211 Yellow On Beige Beast #2 1992 ZR-1 #427 Black On Black *Sold* 1985 L98 Blue On Blue *Sold* |
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03-13-2014
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#94 |
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Join Date: Jul 2013
Location: Mt.Bethel Pa.
Posts: 73
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Re: 368 LT5 Drinking oil
Got ya,BTW Jerry,thanks for the excellent explanation,really helps my understanding how these things work.
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1990 Zr-1 #361 1991 GMC Syclone (built) 1993 GMC Typhoon (stock) 1993 GMC Typhoon (street) 1992 GMC Sonoma GT 1928 Model A pick up Last edited by icarus-54; 03-13-2014 at 08:32 PM. |
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03-13-2014
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#95 |
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Banned
BANNED
Join Date: Oct 2006
Location: MD
Posts: 3,690
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Re: 368 LT5 Drinking oil
Stock 1991 chip?
Do you need one? I can let you borrow it to use. Want me to ship? Cheers David |
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03-13-2014
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#96 | |
Join Date: Mar 2004
Location: Found Member
Posts: 4,346
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Re: 368 LT5 Drinking oil
I'd be Frank U.
Wait a second........go back to the original post. Who built the engine ? The Vette Dr's (Billy Kirchoffer) built the engine ? Quote:
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Frank Urbo. NCM Lifetime member # 982 Registry Founding # 237 |
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03-13-2014
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#97 | |
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Join Date: Aug 2013
Location: NJ
Posts: 117
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Re: 368 LT5 Drinking oil
David to the rescue..I would appreciate that immensely..I'm gonna PM you my addy.. 2 weeks tops and I'll have it back to you with shipping for both ways..I really don't think it's the tune but this will allow me to fully rule that out(hunting idle/rich condition)...
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UPDATE on the oil burning.. I installed the Moroso oil separator inline today and the smoke totally stopped after a good 15 min romping..Upon installation I noticed a fair amount of oil in the PCV tract along with the Map hose and sensor..So don't know for certain but I'm thinking the oil that is making its way to the map is really altering the A/F mixtures being the MAP is being choked on with oil..Thus causing an overly rich condition,fouling of the plugs, and the hunting idle..I'm already happy as I don't have to see that embarrassing smoke cloud behind me when I accelerate..I'll update again soon.. Last edited by Mitsumark; 03-13-2014 at 09:52 PM. |
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03-13-2014
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#98 |
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Join Date: Mar 2004
Location: Found Member
Posts: 4,346
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Re: 368 LT5 Drinking oil
Lets start at the base.......
Do a compression test , preferably a leakdown compression test on the engine first. When was the engine built ? How many race miles have been logged on the engine since becoming a 368 ? Are you checking the oil after the car has been sitting for at least an hour ? VD 368.............
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Frank Urbo. NCM Lifetime member # 982 Registry Founding # 237 |
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03-13-2014
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#99 | |
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Banned
BANNED
Join Date: Oct 2006
Location: MD
Posts: 3,690
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Re: 368 LT5 Drinking oil
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Will ship it tomorrow  David |
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03-17-2014
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#100 |
 
Join Date: Jul 2013
Location: Central Iowa
Posts: 190
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Re: 368 LT5 Drinking oil
One more thing to add to the list of potential sources for the issue: My car was running very rich on one side and after some serious trouble shooting, Marc H figured out it had a decent leak through one of the headers. He welded this up, then completed a tune and it was good to go. On my car, it was running very rich on the side with the leak and a little lean on the other side. I think you would need to be connected to the car's OBD system with a scan tool to read this.
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[CENTER][SIZE=4][COLOR=red]1990 ZR-1 Red / Red[/COLOR][/SIZE][/CENTER] |
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