I own an 89 f250 4x4 460 192k, accelarrated hard from from a dead stop, motor started running horrible getting a noise simmillar to spark knock or loud pre-ignition ,but not at an idle only under acceleleration and blowing blue smoke,smoke can be seen comming out of the back side of the exaust manifold area,where i have an exhaust leak, (head gasket)??. I still have oil pressure, did compression test , the two rear cyls on the drivers side have 0 compression,others are 155,160 on that side, other side 150,155,145,150.I tried oil in the dead cyls with no change in compression still 0. Next i removed the valve cover, suspecting bent push rods, or broken valve springs, but push rods where straight ,springs good. with the rocker arms off, and the valves closed, i filled the dead cyls with air. Air leaks from one hole to the other, if i put 1 plug in air still leaks by but at a slower rate. I could not here any air cumming out of the throtltle body or the exhaust pipe a slight breeze coming out of the push rod holes. I obviously have a blown head gasket ?? or do you think theres other problems. maybe broken rings or holes in the pistons,(holes in two pistons unlikly i hope)?? maybe valve problem or a cracked head ?? I had recently bumped timming to 12 degrees but had no pinging, i run mid grade gas , has anybody seen a simmillar problem before, i havent. motor was running good no knocks or ticks. motor is tuned up, new plugs, cap, rotor, fuel filtres, 02 sensor, t stat , all a week before . if it is only head gaskets or i rebuild the heads will the bottom end hold up or will it be next to go?? i would really apreciate some input or advice on this, thanks.

 

wecome to FTE, i'm sure that the members here can help you. if you can try posting this in the engines forum just page down and look around , this site has alot to offer

 

its just a head gasket.
when you are putting new ones in, check your valve guides for slop, check your vavles for carbon buildup. if they are looking bad, have the heads done.

 

Welcome. I had a 351W once that blew the gasket in between the cylinders. When one would come up on compression, it would blow it into the other cylinder. It didn't get into the water ports, just the compression seal between the two. I would definately pull the heads.

Jimmy

 

thanks for the insight guys, took it to the shop today , to get the head gaskets done ill let you know how I make out, and how much $$$ it ends up costing. THANK-YOU

 

I was wondering if it was infact a head gasket? I have an 89 F250 with the exact same simptoms. Thanks, John.