My 97 F150 (w/ 120k miles) began stalling at idle & check engine light came on. Also, I had noticed a noise (tapping) from engine. Technician replaced the original plugs & wires and while cleaning the injectors (engine at 2k rpms) noticed the noise was much worse. He felt it was coming from the timing chain/guides so he pulled the covers and found the tensioners were worn and replaced. Noise is still there (and idle problem). He says the right side tensioner is not under tension and this may be due to inadequate oil pressure from a blocked passage or could be due to excessive wear. Has anyone seen this? He said he had not seen this before and is a little unsure what to do. I don't want to spend a lot of money on the engine since it has 120k miles but oil has been changed regularly and he said what he saw looked clean and sludge free. Note - I may have some of this wrong since I'm not real familiar w/ what he's talking about. Thanks!

Mark

 

I have a '97 F150 4x4 with 4.6L, has 250k miles but was rebuilt 80k ago. I had the same problem and replaced the timing chain tensioner & guides on driver side. Local Ford garage told me it was the first they had seen do this, but come to find out the problem isnt that rare. Cost me around $400 total to fix it with parts & labor but if you do it yourself, will be alot cheaper. I went through everything on that truck before finally isolating the tapping noise to the timing tensioner / guides.....once replaced, it cured the ailments.

 

Sorry for the delay, here's the update on my problem. Turns out the problem was the tuning valve. I'm told this is in the intake and helps midrange power. It's basically an electric motor w/ a vane on it. Motor was bad and vane was flapping and making the tapping/knocking noise. This one really gave my tech a fit. He works at a Ford dealership and said this is only the 2nd valve to come through their parts system.