Parked truck on saturday, went to start on friday, it would just clunk when turned it over, it finally started and is knocking really bad. What would it be when one minute its fine and the next its not. Checked oil just before that and had brown gunk on cap, sometimes just condensation.
Knocking kinda sounds from top end but not sure. Any suggestions??




1997 Ford F-150
4.2L, 4x2, Extended Cab, Short Box

 

i think the early 4.2s had some bad problems with the head gaskets.... i think the head gaskets would blow and then it would spit a rod out....from hydrolic locking... sorta sounds like what happend here... if it was me....and i was going to try to see if the bottem end of the engine is fine...... i would drain all the water and anti freeze out and drain the oil and get all the fluids out of the engine get some cheap oil and oil filter and pour back in it crank it up.... (do not add anything to the cooling)... see if you still have the bad knocking.... re check the oil and make there theres not an abundance of water in it.... if oil looks ok and you have no knocking still..... you could get by with just putting headgaskets.... but you would also need to have your heads checked... if your noise is just on the top end its prolly just the lifters loosing there prime from the water..... but they would chatter and rattle.... a knock is a piston or rod....

 

bobkyle is correct - the '97-'98 models had problems with intake manifold gaskets and hydrolocking - your symptoms of brown gunk on the oil cap indicate that coolant and oil are mixing - you are most likely looking at putting in a used engine in place of this one or doing a rebuild. In a pinch it's not difficult to install a used 3.8 from a windstar or mustang as well

 

I might be able to get a used 4.6L out of a Crown Vic., is that interchangable?

Can I do the rebuild without taking motor out?
Not going through coolant at all,
I did a head gasket change on a 2000 Grand Am and had to fill with water every day... It wasn't too bad to do the rebuild, but little easier when lower to the ground.
It cost me $300 to do the Grand Am myself.

 

yeah the crown vic engine should be interchangeable - you will have to drop in the computer from the donor car as well - someone else will have to confirm that it will bolt up to the tranny but I'm almost positive that it will

 

I concur, you got a broken/bent rod.