I have a horrible grinding, scraping noise coming from the engine. It's a 76 F150 with a rebuilt 390. It's only been in for about 5 years and only has a few thousand miles on it. It was built with a brand new Melling oil pump and has been running perfectly.

I was driving along and all of a sudden it started making this horrible scraping/grinding noise. It's the sound I would picture if an engine had no oil in it - like metal against metal. You can barely open the hood without ear plugs it's so loud. I finished the drive home (about 5 minutes) and parked it. I took the valve cover off and the distributor and ran the pump with a drill for a while. No oil is coming out anywhere on the head. I pulled the filter and oil pumps out of the filter boss when I turn the pump. t's been a while since I've changed the oil and it's pretty black, but there is still plenty of oil in it.

I don't know what else to test, but I don't want to drive it for fear of seizing it. I tried to search, but haven't found anything. If you can think of any suggestions of things to try, I would greatly appreciate it. Thank you for your help.

 

Drain the oil pan and see if there are any metal filings in the oil. Certainly does not sound good.
I don't know if you have an automatic or a stick shift, but if you have an auto check to see if you have a broken flex plate. That will make a hell of a racket, kind of like what you discribe.

 

I would remove the belts to the motor, one at a time, run the engine for JUST a second, check for the noise, then shut it off. When you run out of belts to remove, and it is still making noise, you at least have ruled out the accessories as the culprit. Also look for anything that might have come loose, and is making contact with something it should not have. I also agree with what fastfarmer says.

 

I would go with fastfarmer if it is an auto, cracked flewplates sound hella awful bad...
I would crawl underneath and start there...

 

Thank you guys for the advice. It is an auto, so I'll start there. Would it still start, run and drive fine even with a cracked flexplate? Also, isn't oil supposed to be circulating inside the valve cover with the engine running? I don't know why I'm stuck on the oil thing - probably because I put a ton of time into the engine and I'd be peeved if it died. I'll post what I find out from taking the tranny off.

 

OK. I removed the converter access cover and examined the flexplate, which looks perfect. I checked all the converter bolts and they're tight. The starter gear looks good and the teeth on the ring gear look pretty good. I didn't pull the trans, 'cause I don't want to have to unless that's the very last option (I have headers, so I'd have to practically pull the whole engine to get the trans out). I drained the oil and there were no metal shards in it, though it was pretty black. Any other ideas?

 

I will start this by saying "using common sense" climb under the ol girl, and have someone start it up, and listen and watch everything and see if you can pin-point from the underside where it is coming from. No metal or stuff in the oil leads me to go back to the flywheel/flexplate, maybe check your tranny fluid also, see what it looks/smells like. That much noise, you will be able to find it..

 

honestly i dont think there should be that much oil circulating up there, some yes but not that much, it should be mildly soaked in oil. like a light coating.

 

any issue with engine performance?
I have heard some serious noise from a failed water pump............

 

Well I put the distributor back in, re-set the timing (wife cranking it over while I used the timing light), and now I can't even get the thing to run - won't even turn over. I don't know if it's the ignition box (again) or what.

Anyone want to buy a '76 half ton that had a perfectly running 390 two weeks ago? . . .

 

well check the basics, are you getting fuel? getting a good spark? i mean those 2 things most likely cause the most trouble. and there easy to check too.

 

Are you sure the distributor isn't 180 degrees out?

 

Did you try disconnecting any of the belts like I suggested?

To solve your current riddle, did you mark anything before you yanked the dizzy? Disable the ignition system. Transpose a mark EXACTLY where #1 is on the cap to the base of the distributor. #1 should be pointed at about the 2 o'clock position if your vacuum advance is pointed directly at the radiator. Pull the number 1 spark plug, rotate the engine till the compression blows your finger off of the hole, check to see where the rotor is pointing at. If it is anywhere else than #1, yank the distributor and try again. (you could cheat and move your wires) If that checks out, have a helper crank the engine (once you un-disable the ignition) while you move the distributor through its full sweep. If your timing is one tooth off, it might fire. OR you could just set the timing while cranking the motor over. By the way, are you getting spark?

 

I didn't get a chance to disconnect the belts, as I yanked the distributor before you posted your suggestion, but it really didn't sound like the noise was coming from the front, but once I get it running again, I'll give it a shot. The belts were badly worn, so that'll be the next step. I marked the dizzy & the block to get it lined up right, but when I set it down, I accidentally moved the gear, so it screwed everything up. I should've set it at TDC before I pulled it, but hindsight is a wonderful thing. . .

If the timing light fires, that means I'm getting spark, right? I haven't watched the plug for an arc with it cranking yet, but I will if I need to. The timing light is firing and it's indicating the right timing - 12 degrees BTDC. It still could be firing on the exhaust stroke and not the compression, so I'll confirm that next to make sure I'm on the right stroke. I have a Mallory Unilite distributor and Hyfire CD box and have replaced the eye a couple times already - those things are touchy. I forgot about the "rules" and cranked it with a battery charger attached, so that might have blown it again. Again, though, if the timing light is firing, doesn't that mean I'm getting spark?

Thank you all for your help - I really appreciate all of the suggestions (and keep 'em coming).

 

I rekon if the light is working, you are getting spark. If you are lazy, you can move the wires 180* and it'l run. The schmuck who does a wire change without doing it one at a time will be in for a rude surprise 5 years from now...