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258 help???

452 Views 6 Replies 1 Participant Last post by  **DONOTDELETE**
I've got an 89 YJ with a 258/Clifford intake/ Weber that has been blowing oil out of the valve cover since I bought it a year ago. It has never smoked out of the tail pipe at all. The PCV valve is new (and gets blown out of it's grommet all the time due to the excessive pressure inside the valve cover) and I've installed 2 Mr. Gasket breathers on the cover in an attempt to relieve some of the pressure. Didn't help. The motor now has 160K miles on it- I drive it 60+ miles a day and it runs great (except when I turn left, the engine almost dies- I think this is a problem with the Weber, another problem). I plan to rebuild the 258 sometime in the future and install a 4.0 head/tubular exhaust manifold and Chevy HEI distributor. Is this necessarily worn piston ring blowby? Why is there no exhaust smoke? All ideas are greatly appreciated!

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I would say it's probably blow-by due to wear on the engine. The oil rings are good, so no oil burning, but the compression rings are worn and the compression is leaking past the rings into the crankcase instead of building up in the cylinders as it should. Plan your rebuild in advance and you can save yourself some money. Another idea is get a used engine and rebuild it while you drive on your old one, and you won't be without for very long.

Loose nut behind the wheel
Another right-wing conservative.....
Born and raised in Jeep-Town
Dick has made some very good points. Just a thought that might save you some time.
I have to wonder when the last owner put the weber on if he has the breather hoses on right???
I left the breather hose off the bottom of the carb once and the jeep blew oil all over.
Breather on the valve cover on the back of the engine comes from the air cleaner and the
breather on the front of the valve cover goes to the bottom of the carb to [ported vac.]?????
If you are not moveing the air across the valve cover right you will blow oil.
There better people on this list to explane this than me, GOOD LUCK
Don't tear that 258 up just yet./wwwthreads_images/icons/smile.gif
BTW The weber thing I would guess your float is to high. Just another wild a## guess??????/
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The Clifford covers don't have very good baffles in them for oil control, some of them don't have any baffles! Look in the breather hole, if you can see the rocker arms, there's no baffle! The rockers spray oil directly into the oil breather cap, especially when high speed driving. Even if the baffle is there, it is very minimal at best. My old 6 had this same problem, I cured it by installing a factory plastic cover (updated part) cost approx $110. When you get the 4.0l head, be sure to get the factory aluminum or steel cover it came with. Hope this helps, good luck.

I stopped the blowby by disconnecting the back hose to the air filter housing, and installing a small K&N filter right into the valve cover grommet. The filter is a small cylinder, about 2" diameter by 2" tall, I think the tube is 1/2" to insert right into the valve cover grommet. In the stock plastic cover (with baffles) I've had no blowby for about 100,000 miles. I keep the PCV valve clean with carb cleaner.

I had the same problem with my 86 cj and it was the rings. Getting another engine and starting the rebuild is the best bet.

/wwwthreads_images/icons/smile.gif Looks like time to get the compression gage out. /wwwthreads_images/icons/smile.gif
I would hate to do a rebuild on a whim.
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