Heres a real doozie... - Ford Forums

drzima · 08-04-2004, 20:57

Get this...

1988 Ford F150 is my truck, it only has 50,000 miles, it is my baby. Garage kept, taken care of. Now right before I purchased the truck from my father, we pulled it out of storage and took it for a drive. It was acting like we had no gas, but one tank was full. Long story short, the in-tank fuel pump was shot and during this little episode of running out of fuel is where my problem arose. I pulled the plugs and the number 1 plug was completely gone. Replaced and all was good except now I have a knock. Still no biggy, part of the plug welded itself to the piston or something, right? Ok so here is what it does: Change the oil, knock goes away (this is not a ping and not a real loud knock, more of a loud ticking) when the oil starts breaking down at 1500 miles you may notice the knock. Now, the knock isnt always there, some days I can drive all over and no knock. The knock does not respond to loads, no matter what I do, I cant change the tone nor make it come or go. Fuel does nothing, and (this is the real kicker) I can have 3000+ on the oil change and goes weeks without hearing this knock! Rpm's either make it go away or just mask it, most noticable at idle. Again, not always. Weather, cold or hot, does not have a play although SOMETIMES when its cold and hasnt been run for awhile, the knock will start out louder. So.... Help...Please!

351w · 08-04-2004, 21:16

with all that said and hearing that the problem is affected by oil changes more than anything else.
it sounds to me like simply a lifter tapping or possibly partially collapsed.
usually when you engine is ideling is when you will hear that type of noise since your oil pressure is the lowest right then and as soon as the rpm's are raised the pressure signifigantly increases as well as the flow.
i have personally witnessed this same ticking noise and found that one roller tip on a complete set of roller rockers was pitted slightly which caused the tick at idle only.