my86mj Posted June 20, 2012 Share Posted June 20, 2012 so making a 100 mile round trip and sarge starts jerking and popping like the timing is off. i pull over and its idling like crap and the temp spiked. it cooled down and i started it again. (still on the side of the freeway with a small trailer behind me as well) i make it home and it drives okay runs smooth at anything above 2000 rpm but won't idle for crap. sounds like its on 2 cylinders. i am led to believe that its a burnt valve. i have since run some restore and lucas tune up in a bottle in it. also retimed it. does anyone know of any tricks to fix a burnt valve? i don't want to pull the heads because at that point i will just rip the 2.8 out and throw in something else. Link to comment Share on other sites More sharing options...
Comanche County Posted June 20, 2012 Share Posted June 20, 2012 What do the plugs look like? Link to comment Share on other sites More sharing options...
jimoshel Posted June 20, 2012 Share Posted June 20, 2012 You just don't fix a valve with out pulling the head. Unless you're a really good welder and reach in thru the spark plug hole and build the valve edge back up. :thwak: Link to comment Share on other sites More sharing options...
Comanche County Posted June 20, 2012 Share Posted June 20, 2012 Yeah just pull the heads, its not too hard of a job. If they're looking bad, most likely they'd need a 3 angle job, valve seals and valve guides. The cost of that work would probably run you about 400 bucks. You could just find a 3.4 out of a mid 90's Camaro or Firebird cheaper then getting the heads rebuilt. Then just use the upper intake etc off the 2.8. See the below article. http://www.lunghd.com/Tech_Articles/Pro ... ect_XJ.htm Link to comment Share on other sites More sharing options...
carnuck Posted July 19, 2012 Share Posted July 19, 2012 It could also be carbon in the intake or exhaust valve jamming it open, bent pushrod, broken valve spring, bad plug and a couple other things I can't recall off the top of my head. Ah! Stuck open EGR valve! (that's where carbon chunks sometimes come from) Link to comment Share on other sites More sharing options...
my86mj Posted July 22, 2012 Author Share Posted July 22, 2012 it was bent and burnt valves i pulled the motor apart after i got a new engine and all none of the valves actually were seated Link to comment Share on other sites More sharing options...
Eagle Posted July 22, 2012 Share Posted July 22, 2012 it was bent and burnt valves i pulled the motor apart after i got a new engine and all none of the valves actually were seated That'll do it ... Link to comment Share on other sites More sharing options...
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