I have a 2004 F150 Screw Fx4 with the 5.4 Triton, 92,000 miles, very well maintained and need some advice. Two Thursdays ago, I started the truck and it was running very, very rough with little power. It idled rough, it had a hard time accelerating, but eventually accelerated to 15 or 20 mph. I drove it like this for approximately 4-5 miles, in total, just to get it to the mechanic. After a week of checking injectors, plugs, solenoid, cats, mechanic calls a ford tech, they check it over and tell me the timing belt guide (its a plastic piece the timing belt slides along) broke. There's no compression in three of the cyclinders and they are telling me the the valves are damaged (bent). He's now looking into prices for a rebuilt and a used engine. The mechanic says this happens on occasion and he has another 5.4l in the shop with the same issue. Is it likely the valves would be damaged if the timing chain guide broke? Is there something else I should be looking for? I trust the mechanic, he's serviced all my family's cars and is the father of friend. I had plugs replaced at 86,000 with motorcrafts and am religious about changing the oil with Ford spec'd. Any information and advice would be appreciated. Thanks in advance for your time.

 

I forgot to add, only five cylinders have compression. Does anyone have an opinion on this situation?

 

Probably/maybe your tensioner failed. Never heard of anyone have piston valve contact but it could be possible. Sounds real expensive having the dealer fix it. Your gonna need a top half rebuild for sure. Might wanna consider going with a remaned motor. Having the dealer do that will set you back 5-7 grand.

 

i havent heard of that many cases, especially two in the same shop... if it were me id get a second opinion, or ask him what type of compression check he did (leak down, etc..) and two, rebuilding that engine is a better idea imho than buying someelses problem in the form of a remaned motor. there was a thread recently on this. at 92,000 miles seems like a great time to do a rebuild along with some tranny work

 

I'm thinking about a second opinion. I will definitely ask how compression check was completed. A couple folks I spoke to said its rare for damage to valve if there's a tensioner issue. Outside of technique, is there another reason, other than bent valve rods, that would cause there to be no compression? f this damage is confirmed, i will likely rebuild, but am hoping to avoid that bill (estimate $4,000).