Head Problems! Please Help!

undrdcvrs23 said:

I bought a 2004 mustang GT from a guy that said he high rev'd the motor and blew it up after tearing into it I figured out the head gaskets were blown and one of the roller rockers had come out from underneath the cam, Is this a sign of bent valves, or do I replace the rocker and the head gaskets put the heads back on and give it a shot, and is there a simple way to check for bent valves, any help would be appreciated!

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I've heard of rockers slipping out under certain conditions. Hyland mentions this in his book about the 4.6.

Are there any witness marks on the valve or piston to indicate contact occurred?

I would probably take the valve in question out and inspect it for bending (a simple check is to roll the stem on a glass table-top; if it doesn't roll well, it's probably bent...) You could also try pouring some paint-thinner into the ports with the valves closed and check for leakage around the seats into the chamber, another possibly indicator of a bent or damaged valve.

In fact, taking all the valves out gives the chance to inspect them all and to inspect the valve guides, replace the seals and even lap the valves to the seats to enhance their sealing.

Yea, bent valves don't seat properly, so therefore they wont seal, there is a way you can do a pressure test for your cylinder and or head before you go and replacing somthing you don't intend on changing anyway!