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HybridZ

Bad Motor Knock


kam

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My straight 6 started to knock when I took the car out off storage. Iput new gas and a battery in it and it started after a few cranks. Gave it some gas and it started to knock at 3,000 r.p.m. and would stop at 5,000. What would do that to my motor? It ran great befor and it was only stored for 4 months. I don't want to put a nother motor in because this one hardly has 4,000 miles on it. Is there a way to fix it with out a rebuild?

 

thanks

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Does it knock at idle? I'd recommend getting a stethoscope with a metal tine on the end of it (can get at a tool store or auto parts store for cheap) - or you can use a long screwdriver and put your ear down on the end of it - with the motor running, and try to determine if the knock is coming from down low in the bottom end or up top in the head.

 

I'm hoping you verified you had oil pressure when you ran it up to 5K -

 

I had a Chevy 400 SB in one of my old Z's that had a bad wrist pin in the #5 cylinder that would knock at a certain rpm range - and only after it was warmed up. Not saying this is your problem, but it was mine.

 

I'd also pull the valve cover and see if you can see anything awry. I have had a situation with an old motor in my DD that would knock like a bastage upon startup once every blue moon. Sounded like a rocker out of adjustment, but it usually went away after 2 minutes of running, so I could never track the gremlin down.

 

Hope others chime in - that's just my personal experience with getting "knocked up".

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It runs great at idle. Only at 3 to 5,000 r.p.m. The knock sounds like its on the bottom end cylinder #1 or #2. I pulled the valve cover and it looked good, but I drained the oil and there was metal shavings and I think it's piston skirt aluminum chunks. So I think my motor is junk. I ran great befor storage, but why would it start now?

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Shavings = bad. Reason = ?? Rebuild = Most likely to definitely

 

My thought on the reason. If it only has 4K on it b4 you parked it, most likely and this is a guess, it wasn't put back together correctly or one of the new parts completely failed.

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I got a motor from a rolled 280 with cam, header and a 250 hp shot of nitrous kit on it. The guy I got it from never used it. Will this motor hold up to that much spray or would I just have to pull it out the first time I try to spray.

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I got a motor from a rolled 280 with cam, header and a 250 hp shot of nitrous kit on it. The guy I got it from never used it. Will this motor hold up to that much spray or would I just have to pull it out the first time I try to spray.

 

It depends. If you get a good long spray on it, it will probably leave the engine bay for you (in pieces). Otherwise, you will have to pull it yourself.

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