blow by
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Tuned
Joined: Jun 2008
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From: sc
blow by
does anyone know how to stop the blow by. i'm trying to stop it untill i can save up for the engine rebuild. so i just want to know is there something that i can do. it comes up thru the oil filler cap tube going to thr carb. 84 302...
Post Fiend
Joined: Jul 2004
Posts: 8,786
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From: Northern California
It depends how bad it is. Is it so bad that it's dripping in the air cleaner? Or is it just some vapor with the cap off?
How is the PCV valve? Even on a healthy engine, if the pcv valve is shot, or disconnected it can cause some blow by at the oil cap. Especially if the engines got some miles on it.
How is the PCV valve? Even on a healthy engine, if the pcv valve is shot, or disconnected it can cause some blow by at the oil cap. Especially if the engines got some miles on it.
Moderator
Joined: Jan 2001
Posts: 56,966
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From: Virginia
If you want to just get through, leave the PCV valve and it's hose hooked up, but take the pipe off the aircleaner on the other valve cover, and hook a old garden or heater hose to it,and run it down along the frame and point it to the ground. This will get the stink and oil residue out from the engine compartment, and works like the old road draft breather tube setups on old cars.
I know we are "going green" here lately, so if you are worried about that, I guess you could rig a old coffee can onto the end of the hose, so it catches most of the oil residue but lets the pressure out.
You would be surprised how long a engine will run like this, especially with the newer electronic ignitions. I have gotten several years out of them. What eventually happens is it burns so much oil, the plugs start fouling and then it's hard to keep it going after that.
I know we are "going green" here lately, so if you are worried about that, I guess you could rig a old coffee can onto the end of the hose, so it catches most of the oil residue but lets the pressure out.
You would be surprised how long a engine will run like this, especially with the newer electronic ignitions. I have gotten several years out of them. What eventually happens is it burns so much oil, the plugs start fouling and then it's hard to keep it going after that.
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Tuned
Joined: Jun 2008
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From: sc
ok! sounds great and i don't want the oil in the drive way either but i might do the coffee can idea. i don't know how many miles are on it but it runs great. like i said i loves gas and i had to change from 87 to 89 octane but the blow by hopefully will be fixed by oct when the rebuild happens. i'll be putting pic of it online later today.
Junior User
Joined: Apr 2009
Posts: 50
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From: Swoyersville
this happens on my engine too but ony when i peg it and drop a gear. Is this normal? i dont have my pcv hooked up either but it did it before i took it off.
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Moderator
Joined: Jan 2001
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From: Virginia
Hook your PCV valve back up as soon as possible. It sucks all that old condensate and stuff out of the engine, and makes the engine last longer. If that gets in the oil, it forms a acid that slowly eats away at the bearings.
I know of no product that will magically rebuild a engine.
Blowby is caused by a faulty PCV system, or a engine that has so much wear, the blowby is too much for the PCV system to handle, and it starts backing up into the breather. The pistons get too sloppy, and the rings and the bore get worn too much to seal anymore. Usually a engine that is worn out will have other signs, like low oil pressure and knocking in the morning during start-up.
I know of no product that will magically rebuild a engine.
Blowby is caused by a faulty PCV system, or a engine that has so much wear, the blowby is too much for the PCV system to handle, and it starts backing up into the breather. The pistons get too sloppy, and the rings and the bore get worn too much to seal anymore. Usually a engine that is worn out will have other signs, like low oil pressure and knocking in the morning during start-up.
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Thread Starter
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Tuned
Joined: Jun 2008
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From: sc
i hear that using a single wt oil will slow it down some along with some cd2. what do you guys think. like i said just a bandaid until i save up the money or after my next deployment!! (
APS going everywhere)
APS going everywhere)
Senior User
Joined: Dec 2008
Posts: 294
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From: East Bernstadt, Ky
Have you inspected the valve cover where the pcv goes. When I took my engine apart to rebuild the slot left open to allow the pcv valve to work was completley blocked off with sludge. If that is the case all of the blow by is going straight to the oil cap. Just a thought.
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Tuned
Joined: Jun 2008
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From: sc
nope i haven't looked there but now i will. that is the only thing wrong with the engine. i just replaced the modulator valve. the tranny guy said that it was the cause of the black oil out thet tailpipe, he also said that it could cause other things to go bad. is this true??
Moderator
Joined: Jan 2001
Posts: 56,966
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From: Virginia
If the modulator valve is bad, it will cause the engine to smoke like a freight train, because the engine vacuum will pull the tranny oil through the valve and into the engine. This is easy to check though. Just pull the modulator vacuum line off and see if it has tranny oil in it.
Postmaster
Joined: Mar 2008
Posts: 3,593
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From: Prairieville, La
I pulled my motor and refreshed it because of blowby. My compression went from 90lbs. per cylinder to 150lbs. The motor ran great had power, just bad blowby. The blowby was just as bad after refreshing. I was about to pull the motor and replace it with another. I decided to check the line from the pcv on the back valve cover going to the back of the carb. It was clogged 3 inches thick with carbon. I cleaned it out and reconnected and said goodbye to the blowby.