Ok so I need y'alls help in a bad way. I just bought a 85 f150 351w lariat with 66k original miles a couple of weeks ago. I was driving it to go get my tags for it and it all of a sudden starts to make a noise from the front of the engine. My first thought is maybe the fuel pump but that checked out to be good so I put a new timing set in it today thinking that the chain was too loose, I start it up and it up and it's making the exact same noise as before. I did notice when I had it apart that the fuel pump eccentric had quite a bit of slop out but being as this is my first time tearing down an engine that far I don't really know how much slack is supposed to be in the eccentric.. so here's my question what's the chances that the outer ring of the eccentric could be too lose and rattling around?? What are y'alls thoughts as to what it could be? Any help would be appreciated because I'm really starting to get discouraged

 

Timing chain area or Waterpump?

 

timing chain area or that's where it sounds like it's coming. It shouldn't be the water pump because I put a new one on it since I already had everything pulled off.

 

You said you have slop in the eccentric? Do you mean it kind of wiggles around like the eccentric is loose? I have a 302 and not a 351, but should be similar, and when I replaced my timing chain, gears, and water pump, my eccentric didn't have any slop. That might be the sound you're hearing.

Can you take a video of the sound and post it?

 

You should record it and give us a link to the recording whether it be through youtube or etc.

 

Re: The fuel pump. How did you determine it checked out good? If there's nothing else glaringly obvious on the engine, a new fuel pump is a reasonable guess. I'd certainly gamble on that before pulling the timing cover again.

Re: The eccentric ring. Even if too loose, the fuel pump arm should keep some spring pressure on it and theoretically prevent rattling. All bets are off if there's a problem with the pump.

 

Have you temporarily run the engine without the v-belts to make certain it is the engine making the noise?

 

I ran it yesterday for about a minute with all the belts off. Noise is still there

 

I pulled the pump off of the block and let it run with the fuel that was in the fuel bowls of the carb and it was still making the noise. That is how I determined that the fuel pump is not my problem

 

will do this evening when I get off of work

 

yes the outer ring of the eccentric has some slop in it. The inner ring is good and tight.
I'll take a video of it this evening and post it when I get off of work.

 

I'd say that rules out the fuel pump...

Did you leave the hole open on the block while running without the pump? If so, was the noise louder? Wondering if you've got a rod knock.

 

I did leave the hole open but the noise was about the same. I wondered the same thing about rod knock but it gets quieter at higher RPMs and if what I've been told is right, shouldn't rod knock get louder not quieter at higher RPMs?

 

Any rod I heard was not a rattle but more of a larger hammer hitting the block noise.
Even if just starting I have not heard it at idle but would when the RPM went up with no load.
Also the oil PSI would be a little lower than normal.


Now the fuel pump & eccentric. You say the eccentric is lose and if the pump is pushing on it would in not take up the play?


Could the noise be coming from the dist. or oil pump drive as they are up front right?
Dave ----

 

the oil pressure is good at the gauge unless the sending unit is bad.
as for the fuel pump unless the spring is loose it should be holding the eccentric tight.
I have thought about the distributor but I'm not sure how to check it and if it was the oil pump would I see any change in oil pressure?
the other thing I thought of that it could be is something in the valve train like maybe a stuck or sticky lifter or a rocker arm out of adjustment.