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Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go hereXJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
I'm not sure where to put this but i thought this was the best. Went out to start my 2.5l straight 4 1984 jeep Cherokee. I went to start it and boom! white smoke was everywhere couldn't see 2 feet in front of me. got out and the valve cover was in pieces. What could cause this? no oil? gas with the oil? Its a mechanical fuel pump.
I know on my 85 it builds quite a bit of pressure in there because of ring blow by. If the vent tube at the rear became clogged and the PCV did also, it might be possible to build that much pressure if it doesn't release at the dipstick.
Looks like you did the Webber upgrade on the carb, where does that rear vent tube connect to?
I know on my 85 it builds quite a bit of pressure in there because of ring blow by. If the vent tube at the rear became clogged and the PCV did also, it might be possible to build that much pressure if it doesn't release at the dipstick.
Looks like you did the Webber upgrade on the carb, where does that rear vent tube connect to?
Originally Posted by Bustedback
Crankcase explosion. Fuel vapors collected in the crankcase and ignited.
Both are true.
Likely your mechanical fuel pump leaks.......leaked fuel into the crankcase.
Swap your pump.
Change your oil.
Get a new aluminum VC.
BTW.........that 27 year old POS plastic VC was brittle, likely had multiple cracks in it, was going fall apart anyway.
IOWs it didn't take much to blow it apart.
Yep. I might pull the pump and verify that the diaphragm isn't letting raw fuel unto the crank case. Once you get her squared away, (Oil change?), be sure you have the valve cover venting properly.
I'm a little curious about the actual point of ignition. A spark past both compression rings, and the oil ring as well? Something past an exhaust valve guide. Or maybe a backfire in the intake flashing through the vent tube....I like that last one
Every one was plastic before 90/91.
Yours has be swapped already.
Credit where credit is due JD. It's non oped, and used for "farm work". It's been over 15 years since I changed the head, but today I checked, and indeed, it IS a plastic VC.
(wonder what would have blown if the OP"s wasn't!)
(Oh, and I wouldn't trust that filter to not clog up inside and give CC pressure) How meany RM's have been changed over those?
Last edited by DFlintstone; Apr 24, 2016 at 11:45 PM.
Valve cover exploded!
