I've got a '77 F-250 with a 400 in it. We just bought it back in September and have put about 1,000 miles on it without any issues until recently. Had an oil change done on it when we first picked it up, believe Pennzoil 10W-40 was put in it and has a MileGuard MO8A oil filter on it. Just had to replace the starter on it and threw in a new battery. While I had the hood popped, checked the dip stick to find it on the dry side. Probably put about 2 quarts of Quaker 10W-30 in that I had on hand. Have only fired it up a couple times since. Now we're hearing a pretty noticable rattle for a few seconds when we start it up. Double checked the tightness of the starter, can't get the bolts on any tighter. I'm a newbie to mechanics and would appreciate some feedback.

 

the only thing that comes to mind for me is on my 79, the valves "knock" kinda loud at start-up then quite down...maybe you have some valve knock or a "loose" valve or something like that

 

Same here, especially right after an oil change. On start-up, the top end of the engine is dry and that means its louder. Once the oil starts circulating after a couple seconds, the noise quiets down because oil got to the top now. Try adding some lucas oil oil stabalizer. NOT STOP LEAK, the oil stabilizer stuff.

 

I had a '77 F150 with a 351 M years ago. I had rebuilt the motor, so I know what it was...........basically new, After about 30,000 or so miles it would rattle in the top end at startup. It wouldnt do it every time just occasionally. I seemed to notice that it did it more often when it was parked in my sloped driveway. I beleive that what was happening was I had a hydraulic lifter that would drain out occasionally and cause that valve to rattle. It would go away fairly quickly as the engine started to warm up and the oil began flowing freely. I never did tear into it to repair it since it was such a sporadic problem. It ran that way for quite a few years until I sold it. Never did seem to hurt anything.........However you did not say if yours is a topend rattle or sounds like its in the bottom end so take it for what its worth...........

 

Sadayo, I'm with 78 PEB, sounds like a lifter leaking down.
The oils you are using have changed their formula by removing the zinc for emissions. They are not good for our older engines that don't have roller lifters. You must use a zinc additive or change to something like Shell Rotella T that have high concentrations of zinc or the cam lobes will erode and your engine will lose power. Check on the internet there are lot of articles on this.

 

A couple things on this.

I'm not trying to scare you, I'm just a realist. You just bought it, right? So the previous owner put the last oil in it. You said it's a 400, right?

My 400 I just sold rattled when it got hot. It was a bottom end noise. Usually a rattle is loose mains. A knock is a rod, (or two) and a tap is top end. The previous owner may have put some engine rebuild in a bottle in there to quiet up an engine issue.

Do another oil change and put a bottle of Lucas in there too. If it goes away, start saving for a bearing job. From what I understand, it's common with 400's.

 

10W-40 does not flow very well in cold weather. I don't know where you live, but that could be part of the problem.

 

It sounds like tin cans and from inside the cab seems to be coming from the engine "near the pedals". I'm in Western Washington. I tried to capture the sound in this clip...
YouTube - Truck StartUp

 

I live south of Seattle, and I have 10W-40 in my 351m. I've never had a knock that loud, but have heard something similar specially if I haven’t started the engine up in a while, or if it’s been one of these colder days. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
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That is not the sound I was expecting to hear! Are you sure the fan isn't hitting the shroud or something. To me that sounds like something hitting not a sound from inside the engine. If it has the fixxed fan maybe it's hitting right at start up but then it flexes out with the spinning force and doesn't make contact anymore. IDK just a thought.

 

After it starts you have an exhaust leak....

But WTF is that noise at first? Starter isn't hanging up is it?

Josh

 

Well, seems I've fixed that clanking! I pulled the starter back off, thinking perhaps I might need a shim on it. White grease hud spun out on it, not the best sign. Inspected the flywheel, didn't see any damage, but ran my hand along the teeth and felt a couple burs and did a quick file on those. Brought my "one week old" starter back to the parts store and asked them to bench test it just to humor me. It passed, but they went ahead and swapped me out for another new one to be on the safe side. Installed it, fired it up, and the sound was gone. My guess is that the starter I originally bought was sluggish on pulling away from the flywheel? I'm just thankful it was an easy fix.

I'm not ready to tackle the exhaust leak yet, but understand it's common on the 400's. Part of that project will be replacing the tail pipes and mufflers.

Thanks for all the feedback!

 

I'm a little late to the party here, but yes, no mistaking that noise. The starter was hanging up in the flywheel. I've heard it many times myself.