Allright, well I have a 78' f250 with the 300 I6. the truck has roughly 140k miles on it. it also has a few performance parts (4 barrel edelbrock, clifford intake, headers). A few weeks ago it devoloped a bad rubing type sound that progresivly got worse. I thought it was the water pump, which I replaced, but the noise only got worse. (the bearing was shot in the waterpump, though) So now, I have no idea where to even start. Iv searched this thread and plan on trying the length of hose up to the ear to isolate where the noise is comeing from, and the trick of removeing the belts to rule out any of the belt driven accesories, but other then that Im lost. I know its nearly impossible to know what the noise is from my discription, but at this point im open for any suggestions at all. I feel like i may be in over my head with this, as iv never really done any internal work on any engines (other then snowmobiles and chainsaws and such) I guess anything with more then 3 cylinders scares me.. as much as I hate to say it, my best bet might be to just take it into a mechanic. I am a pretty hard core do it yourselfer, but my strengths are more in welding/fabrication, not engine work. but im not ready to give in yet, and hopefully you guys can help me out here, from hanging around the site some I can tell there is an incredable wealth of knowledge here.

Thanks for any help in advance,
Tyler.

 

and Another thing to add, I have a suspicion that it may be comeing from under the timeing gear cover, but of coarse thats just a guess, and after my last guess about it being the waterpump, I have little confidence in my diagnoseing skills.. And I should add that the noise is constantly there, weather the truck is at idle or higher rpms, and cold or hot.

 

You say its a rubbing noise...is it a metallic noise? Also does it change pitch when you accelerate the engine or does it stay the same?

 

Yes, does sound metalic to me. Like a bad bearing, and when you give it some throttle it gets faster/more rapid. You cant really hear it over the engine noise from inside the cab, but can hear it clearly from outside the truck, like when you stand in front with the hood open, which is why i think it may be comeing from the timeing gear area. the main belt pully also seems to have a vissable wobble to it, which might mean its the main crank bearing?

 

Take off all the belts and run engine, this will single out if its any of the accessories first. Hope that it stops when the belts are off

 

This is what I was going to suggest.

However, don't run it too long, since without the water pump, the coolant won't circulate. Just long enough to hear if the sound is gone or not. 30 seconds to a minute is fine.

 

Perhaps the harmonic balancer is worn out. That would explain the wobbling pulley.

 

I will run it without the belts tomorrow after work, and report what happens. But incase it is the harmonic balancer, how involved is it to change?

 

If the balancer is shot, it may be wobbling enough to contact the front cover. You should be able to see evidence of that by looking at the balancer and front cover from under the truck.

Pulling the balancer is, iirc, 3 bolts and a puller device. You may have to pull the radiator to get enough room to work. (and to keep from buggering up the radiator, don't ask me how I know about that.....)

If not, then another suspect is the timing set. These engines use a combination of a steel drive gear on the crank and a "plastic" coated gear on the cam. This makes for a nice quiet cam drive. But, the eventually start to fall apart and chunks will appear in the oil. Chunks can get caught in the works, and the metal to metal where the plastic is gone will make noise.

A failing distributor is another possible.

 

The plastic phenolic gears didn't start until about '84, so he should be clear on that.

But as for getting the balancer off, there is just one big bolt on the end (15/16") and then you need a puller to get it off. As said, the radiator usually gets in the way, so it may need to come off.

If you have the radiator and balancer off, it may be a good time to check/replace the water pump, and/or update the gasket on the timing cover if it's leaking oil.

 

Did you ever figure out what the problem was???

 

Yeah, it turned out to be the new waterpump I installed was a lemon. I feel kind of stupid for not catching it, but I'm glad it dint turn out to be something bigger.
If I would have known anyone cared I would have posted that sooner, Haha, thanks for careing

 

Not only do we care, but we all learn by feedback.

 

well this forum keeps impressing me, the incredible wealth of knowledge along with the people who hold the knowledge