BAD blow by, please help
Postmaster
Joined: Jul 2001
Posts: 4,038
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From: South Kitsap County, WA
It was the psi thing... I am used to seeing vacuum in inches of Hg or a negative psi. You kind of combinded them I guess
I've got you now. You don't have bad blow by if it's solid, something is plugged up. This is weird. Could be PCV, as was mentioned or EGR related. You went to a custom setup, so the EGR should be gone. Sorry for thinking while I'm typing, but I'm convinced you have a restriction in the PCV system.
If you've got a pic of the engine and can point where the smoke is coming from, that'd help me anyway.
-Kerry
I've got you now. You don't have bad blow by if it's solid, something is plugged up. This is weird. Could be PCV, as was mentioned or EGR related. You went to a custom setup, so the EGR should be gone. Sorry for thinking while I'm typing, but I'm convinced you have a restriction in the PCV system.
If you've got a pic of the engine and can point where the smoke is coming from, that'd help me anyway.
-Kerry
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Joined: Mar 2006
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My 83 had major blow by issues when I bought it a few months back......it still ran good except for a miss when accelerating, and rather milky looking oil. I currently have the engine torn down and ready to pull the pistons to inspect the rings for breakage.
I did a compression test before teardown, and came up with 135 psi on two cylinders, 120, 95, and two other cylinders that had 35-50 psi. These results scream broken pistons or rings. I did a wet compression test also where I squirted oil into the plug hole before testing and found that only one cylinder improved. That result tells me that the head also has sealing issues on that cylinder, and probably others.
I have the head in the machine shop getting a 3 angle valve job, new valve stem seals, and a slight re-surface for around $150. I plan on replacing all the piston rings, and doing a quick cylinder hone with a drill mounted 3 stone hone. The factory crosshatching is still very visable, so I won't be doing a bore job with new pistons in an attempt to save a couple hundred bux.
I did a compression test before teardown, and came up with 135 psi on two cylinders, 120, 95, and two other cylinders that had 35-50 psi. These results scream broken pistons or rings. I did a wet compression test also where I squirted oil into the plug hole before testing and found that only one cylinder improved. That result tells me that the head also has sealing issues on that cylinder, and probably others.
I have the head in the machine shop getting a 3 angle valve job, new valve stem seals, and a slight re-surface for around $150. I plan on replacing all the piston rings, and doing a quick cylinder hone with a drill mounted 3 stone hone. The factory crosshatching is still very visable, so I won't be doing a bore job with new pistons in an attempt to save a couple hundred bux.
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Joined: Jun 2003
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From: WA
Originally Posted by ckelly83
I did a compression test before teardown, and came up with 135 psi on two cylinders, 120, 95, and two other cylinders that had 35-50 psi.
Postmaster
Joined: Jul 2001
Posts: 4,038
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From: South Kitsap County, WA
Originally Posted by beeboy
If the two low cylinders are right next to each other, that, in combo with the milky oil, is a sign of a blown head gasket.
Mark - The stock carb set-up used another tube that went to the stock air filter housing from the old filler cap (at least it does on the '82 sitting in my driveway), that would create a vacuum and suck any smoke back into the engine, there's a filter for that to capture oil in the housing. Then I have the PCV to the vacuum manifold hose. The PCV alone may not be large enough to suck all the smoke back into the engine that the old two hose set up was designed to. Then again, if it's got a small clog in the line to the manifold it'll still suck, but not as hard, allowing smoke to go through the breather. If you're using a breather cap/filter assembly that doesn't recirculate back to the intake, that may be a small part of the problem.
Does your valve cover have a baffle at the PCV and filler opening? That'll keep the oil in the valve cover.
If you do have a baffle, the PCV system is working correctly, and the rings are seating and no other piston/cylinder problems... you have a magic engine.
It has just enough power to overcome the rings and smoke...
-Kerry
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Senior User
Joined: May 2005
Posts: 416
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From: Federal Way, WA.
cracked head :(
Originally Posted by doehnter
Park it and rebuild her...
. It blew the head gasket on me a couple weeks ago so i tore it down and sent in the head to get rebuilt, and turns out i had a cracked head. 
I am now waiting on a rebuilt one that i ordered. I hope to get it tomorrow so i can put it back together.
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Post Fiend
Joined: Jul 2004
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From: Northern California
Really excessive blow by can cause "milky oil" due to condensation. A good way to check that though is to see if you are loosing coolant.
Either way, you will be taking the head off anyway, busted pistons, rings or headgasket alike.
Either way, you will be taking the head off anyway, busted pistons, rings or headgasket alike.
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Joined: May 2005
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From: Federal Way, WA.
Originally Posted by ckelly83
As an update on my earlier posts. All of the pistons had broken rings, and 3 of them had the ring landings broken as well. I believe that a head gasket let loose also.
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My motor is all ready to go, reassembled, torqued down and installed. Hopefully an afternoon of reattaching everything will put the truck back on the road looking forward to another 100,000 miles of care free motoring.