Knoking rattling noise 69 GMC Truck

Tiny
WISE651
  • MEMBER
  • 1969 CHEVROLET TRUCK
Ok so when I am doing about 40 mph going up a hill lightly steping on the gas I hear a like knocking, rattling noise coming from the engine and it only does it at this time. And I have had my truck (1969 gmc shortbed) for two years now and I have heard this noise before in the past and it went away and now I belive it is getting progessivly worse. I am thinking it could be my valves. I had my exhaust just replaced as the prior one was not good, it had broken pipes and broken headers and I ran it like that for about a year and a half. So I am thinking I could have a burnt valve. Please tell me what you think.
Monday, March 12th, 2007 AT 8:57 PM

3 Replies

Tiny
MIKE H R
  • MECHANIC
  • 3,094 POSTS
If it was a valve the engine would run rough, have the timing checked, check the plugs and wires. Does it sound like a octane ping.
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Monday, March 12th, 2007 AT 9:20 PM
Tiny
WISE651
  • MEMBER
  • 2 POSTS
No it really doesnt doesnt sound like a ping, but to be honest I am not really sure of what an octane ping would really sound like. And my truck accually runs really good. Its just under a load when I am going up a hill, lightly stepping on the gas pedal, it makes a ratting noise coming from the engine. Its not really a knocking noise. I dont know, its just so wierd becasue I have never heard anying thing like this. And its not a loud noise. When I give it more gas also, the noise goes away.
Today I am going to change the spark plugs and see what happens.
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Tuesday, March 13th, 2007 AT 6:34 PM
Tiny
MIKE H R
  • MECHANIC
  • 3,094 POSTS
Does it get louder when you step on the gas? Is it sound like rattling loudly in the engine or something knocking. If its a rattling then I would have the plugs wires and timing checked. If its a knocking you would hear it when you are not pulling a load, if that was the case you should have the engine checked
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Tuesday, March 13th, 2007 AT 8:18 PM

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