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Discussion Starter · #1 ·
what will happen if i plug the breather hole on my 258 valve cover? right now it is just dumping out oil, so i don't think that it is breathing much in. does any one make a breather with valve built in it?

thanks all
shawn

The cup isn't half full or half empty, it's just twice the size it needs to be!!!
 

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Discussion Starter · #3 ·
i did a search and was reading some of the posts (maybe i should have done that first). so i guess i should get some motor honey and do a compression test.

thanks
shawn

The cup isn't half full or half empty, it's just twice the size it needs to be!!!
 

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I think that you have some sort of PCV problem. The PCV valve is just a calibrated vacuum leak based on displacement. One end of the valve goes to manifold vacuum through a 3/8 hose, and the other end pushes into the valve cover. The other end of the valve cover is the breather, which supplys the air for the PCV valve.

If your engine is worn out, and has excessive blow-by, you can put a larger displacement valve in. I would try one from a 350 Chevy. This should help in overpressurizing the crankcase from excessive blow-by. You will also have to trim your carb.

 

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/wwwthreads_images/icons/crazy.gif Once upon a time on an English-speaking island across the sea, a mota cah engineer designed a sleek V-12 engine for a sleek sports cah named after a large jungle cat. In order to keep the engine uncluttered and more esthetic, he buttoned it up tight with aluminum covers held with chrome acorn nuts. No unsightly breathers for him! Besides, if it HAD a breather, it might leak oil on Lord Cornfed's driveway.....how crude! And so it came to pass that hundreds of these engines were produced and they did find there way under the hood of the sleek sports cah named for the oversized kitty. And so it came to pass that as the engines ran, there was compression leaking by the rings, and that compression did pressurize the crankcase of the engine. The engine did then leak oil out of every seam and every orifice on it. Not only did it soil Lord Cornfed's driveway, but Lady Maximum's driveway; Baron Von Stewball's courtyard; and Count Camshaft's front sidewalk. No matter what they did, the engine leaked oil. Finally, a rude, crude, and socially unacceptable Yankee named Leroy Domore came up with a bold plan. He bought two HELLINGS BREATHERS and comitted the unpardonable sin of drilling a group of holes in each of the two side covers and on those spots he did install two Hellings breathers. The island society circles were abuzz, and speculation was ongoing as to the end result of this corruption of the engineer's perfect design. Would this weaken the engine? Would it leak even MORE oil? Alas.....no one was able to answer the question, so out came the white gloves and away the inspection team went to check the spots in Leroy's driveway. True to form, the big kitty WAS marking the spot where it sat, but nowheres NEAR what was usual for the cah. So, you see, engines WILL have blow-by; and engines MUST have a way of dealing with it. You cannot simply button it up and hope for the best./wwwthreads_images/icons/crazy.gif

CJDave
Quadra-Tracs modified While-U-Wait by the crack moonguy/wwwthreads_images/icons/wink.gif Quadra-Trac Team./wwwthreads_images/icons/tongue.gif/wwwthreads_images/icons/smile.gif
 

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Discussion Starter · #6 ·
cjdave, that was a thrilling tale indeed. thanks

dorfs, i did just buy a new pcv valve b/c i needed a bigger one to fit in the bigger holes in the valve cover. (i just replaced the old plastic one with a new aluminum to try to solve this problem and others) i don't know which application the pcv valve is for, i just bought the one that looked as though it opened the most. and i did check the vacuum going to the pcv valve. it is around 20 at idle then climbs to around 28. i just added some motor honey this morning, so we'll just have to wait and see.....

thanks all
shawn

The cup isn't half full or half empty, it's just twice the size it needs to be!!!
 
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As CJDAVE mentioned, in a rather inspiring fasion I might add, the breather is there to expel excess pressure caused by blow-by, usually of the rings. If you plug that hose to stop the oil leak, your poor little engine will piss oil out of any and every crack, seam and orifice in it. I tried it once without thinking to ask about it and within 5 minutes of my first drive, I had Niagra Falls of hot oil pouring out of and burning all over my engine.


'88 Sahara, 4.2, auto, 4.0 head swap (finally), no trac bars.
 

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Discussion Starter · #8 ·
what if i would make a bigger, longer baffle inside the cover? anyone ever try that?

shawn

The cup isn't half full or half empty, it's just twice the size it needs to be!!!
 

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look.. all engines have blow by and pressure.. you have excessive blow by.. meaning something is wrong.. most likely the rings are wearing out.. im sure you have plenty of miles on that engine.. and its something that just happens..
your best bet is to run that hose into a container.. and catch the oil.. just make sure you check your oil.. as to not to run it dry.. hell.. i just poured it right back in..
you need to due a compression test.. to see if those rings are bad..

http://www.jeepgod.net

84 CJ-7 401/T-18/D20/D44/D60w/4.10&Detriots/YJ frame & tub/35x16x15 Boggers
survival is instinct, but living takes guts
 

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Gee, Dave /wwwthreads_images/icons/crazy.gif, is that why I love that damm Jag so much too? /wwwthreads_images/icons/wink.gif. I KNEW it had something in common with the Jeep. /wwwthreads_images/icons/laugh.gif

Don't care - the Jag is still the best looking car ever made, I don't care if they tried to plug up the motor /wwwthreads_images/icons/crazy.gif, the electrical system is ridiculous /wwwthreads_images/icons/frown.gif, they carbs go sideways /wwwthreads_images/icons/crazy.gif, the... well, you get the point.


What I did for my old 258 that seeped oil out of that breather big time, was to rig up a 90 degree elbow, through a large diameter heater hose, over to behind the washer fluid reservoir, into a "T", the bottom of which went to a quart size oil jug, the top to a breather. Worked sweet! /wwwthreads_images/icons/smile.gif The oil was carried along the heater hose (make sure it goes downhill all the way) and deposited into the quart oil jug.

I don't think I'd pour it back in the motor, though, it looked pretty nasty when it filled that oil jug. /wwwthreads_images/icons/crazy.gif

You can get all the fittings and stuff right at napa. They fit right into the breather fitting on the back of the motor.

Good luck
Pete
.....and stop putting down the Brit's, Dave. /wwwthreads_images/icons/wink.gif They made a nice looking car. It's the damm Americans who thought you could DRIVE it all the time. /wwwthreads_images/icons/wink.gif Pete

88 YJ - trails/beach trips only!/wwwthreads_images/icons/smile.gif
79 4WD F250-hauler/tower of my toys
70 Jaguar E-type - the best car England ever made. /wwwthreads_images/icons/cool.gif
90 Honda CRX - Daily pavement-pounder. 42 MPG. /wwwthreads_images/icons/cool.gif
 
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Ok I know that the crank case needs to be vented. but is that not what the PCV valve does. As I understand it before PCV valves crank case ventalation was simply through a filter. If the PCV valve is working will it not pull all the oil vapor out of the crank case leaving a slight vacume. Is the PCV valve no longer able to handle the volume of blow by?

I have noticed that many V8's have even very high milage ones only have a PCV valve and have no signs of other vents or valve cover leaks. Am I missing something?

bandhmo

 

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/wwwthreads_images/icons/smile.gif Heh heh.......I just love Pete's perspective on British machinery. Yep......they are a LOT safer than American cars......and that includes motorcycles as well. The reason that they are safer is this: You arise early in your manor house in Southampton, and ring down to the garages to talk to your chauffer "Alf". You tell Alf that today you would like to drive the Aston Martin YOURSELF, and to get it ready. So while you have tea and crumpets for breakfast, Alf rolls the AM out of the garage and into the sun-washed courtyard of the manor. He greases the water pump shaft, rolls under and checks the oil level in the differential, the tranny, the crankcase, and that little thing that nobody really knows WHAT it is. Then Alf adjusts the brakes, and ATTEMPTS to start the engine. Finally, by dinking with the side-draft carbs long enough, he gets the engine started, then spends the next hour synchronizing the carbs. By that time it is late morning, and you have had three more cups of tea, and a not-so-good conversation with your spouse. You storm out of the house, only to discover that you only have 30 minutes left to enjoy driving your car before you have to be back and get changed to go visit Lord and Lady Crumpet. So you see, it's SAFER because the dinking around that you must do gives automobile-based satisfaction in some yet-unexplainable way, without burning expensive fuel and endangering your life on those narrow British roads./wwwthreads_images/icons/crazy.gif /wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/wink.gifHISTORICALLY......the crankcase on most Detroit-built engines was vented via a ROAD DRAFT TUBE, and it was not a bit uncommon to see a car pull up to a stop sign at night and a HUGE cloud of blue smoke drift forward into the headlights. The ARMY was the first to use closed crankcases in WWII in the waterproof Jeeps and trucks. MUCH LATER ON, Detroit closed up the engines and pulled a slight vacuum on them to re-burn the fumes by sucking them into the intake manifold. When engines get real loose, there is more blow-by than the normal PVC system can handle, so extreme measures need to be taken. As DORFS pointed out, the PCV valve is sized for the engine displacement, and the valve itself is vacuum sensitive such that it will meter when the intake manifold vacuum is real high to prevent leaning out at idle. MANY engines....especially indistrial....have catch-and-return oil scavenger setups to separate and get that elusive oil back from the blow-by. /wwwthreads_images/icons/smile.gif

CJDave
Quadra-Tracs modified While-U-Wait by the crack moonguy/wwwthreads_images/icons/wink.gif Quadra-Trac Team./wwwthreads_images/icons/tongue.gif/wwwthreads_images/icons/smile.gif
 
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