So I have 1973 F250, with a 390 in it. Has been good to me since getting it a few months ago. I finally decided the started needed to be replaced due to some hot start issues (as seen here: https://www.ford-trucks.com/forums/1...ack-go-on.html).

That was pretty straight forward, but I had some trouble getting the headers back on. It sat for 3-4 weeks before I could finish the job. I just got everything back together on Sunday and fired it up and heard a knocking sound. I popped the hood and checked it out and saw/heard this (its kinda loud):

1973 Ford f250 truck making knocking noise - YouTube

On my last post, Stinky7-11 suggested the knocking might be that a lifter bled down.

My question is, what would cause it to smoke like this? I'm not an expert at all but everything seems to be moving correctly up under the valve cover and the noise is for sure coming from this side of the engine. The only work I did was replace the starter, which the new one works beautifully and pull the headers off and put them back on.

What you see in the video is the longest I've run it, I was kind of nervous about running it without the valve cover. But after checking for a bent rod (not sure how it would happen from sitting anyway), I decided I needed to see if there was anything odd happening when it was running. And the only thing the caught my eye was the smoke coming from one of the holes the rod goes in to.

Would really appreciate some help guys!

 

It dont sound like a rod and it dont sound like a lifter to me. If its an automatic it could be a cracked flexplate. Im not firmiliar with 390s but shouldent there be oil flying all over the place with the valve cover off??

 

I'm not an expert, but I actually expected hot oil to be flying everywhere when I started it up...I was surprised! Is it possible to loose oil when its sitting, but not have a leak on ground?

 

Oil has to go somewere. Have you checked the oil since the last startup? On my 300 when I started it with no valve cover I ran it for 30 seconds and I had thrown almost 2 quarts of oil everywere! First thing I would check is if you have any oil pressure.

 

Maybe a lifter issue :33 into the video #4 valve looks sticky, but I'm no expert...BOL

 

That dosen't sound like a lifter! I see what looks like a little oil on the pushrod side but it does seem dry otherwise, valve stem side looks dry. do you have a working oil press gauge? Exhaust leaks can be loud but

 

I wonder if you have the right starter, maybe nose cone is too long and hitting the flywheel or something?

 

holly crap, thats loud. I had 351m that had sat for 6 years and when I got it and put new oil and plugs in it and started it up, it had faint rod knock, but it didn't sound like that. Now, I beat on the truck and bounced in through the woods for a year or two, and by the time I pulled the motor, it was almost that bad, but it wasn't "tatatatatatatat" like a machine gun like that. You could hear the cylinder with the rod knock fire in order with the rest, like put put put KNOCK put put put put. Though actually by that time 2 of the bearings were bad so it was like put knock put KNOCK put put put put. lol.

And yes there should be oil slinging everywhere. I'd agree with the others and make sure you have oil pressure. Whatever is knocking almost sounds like its knocking on every cylinder.

 

If the noise started AFTER you replaced the starter then it could really only be:
An exhaust leak
Wrong starter or possibly a cracked flywheel but doubtful.

Exhaust leaks sound funny on these trucks Did you replace the gasket when you took off the header?

Doughnut gasket?

 

I'll check the oil and oil pressure when I get home from work. Thanks for the suggestions guys.

My co-worker proposed a scary thought. I did have a mysterious disappearing bolt! When I was installing my headers, ya know, its a tight fit and I did drop bought while trying to get the thread started on a few of them. I initially lost 3 bolts and found 2 of them where the 4 header pipes join into one. Looked for an hour and never found it, so I went and bought new ones.

Wouldn't it sound a LOT different if there was a bolt rollin around in a cylinder??

 

Regarding the wrong starter... how would I know? I got it from the local AZ store and verified the part number online to match my truck, but I guess that could be wrong.

I did buy remflex gaskets and got that on there now.


My main concern is not that noise at this point... its the smoke!! It doesn't start smoking unless its running for 30+ seconds. Make me wonder if it is an oil issue

 

Its an exhaust leak.

 

What does an exhaust leak mean? Do I need to tighten the header on a little more? Is the smoke just exhaust smoke?

 

An exhaust leak can have many different variables. Everywhere the exhaust comes together is a possible leak spot. Whether the manifold is true to the head, or the pipes are not clamped together well enough. It sounds like the manifold is leaking in more than one spot.

 

Dropping a bolt in to an engine is never good. It may not just be rolling around in the cylinder it may have done some internal damage. Even it it hasn't,if i thought it was in there i would be pulling that engine apart until i found it and not run it any more until i was satisfied it was not there. Yeah, a lot of work but it may be your last resort and i hope i am wrong.