90 C1500 engine problem...HELP!!!

Discussion in 'Chevy Truck Forum' started by Robbman, Nov 8, 2005.

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  1. Robbman

    Robbman Member

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    Hey All, 1st timer here and I need some advice. I am having a clanging noise coming from the engine. Was on the interstate and heard a loud clanging, like something rattling around, then smoke poured from under the hood. When I looked, could not tell if it was water or oil. The truck still had power and still starts up but has that clanging noise. Before I look at getting a rebuilt engine, just trying to get some suggestions on other possibilities. By the way, when engine was examined, no sign of a rod through the block or the oil pan. Valve covers are in perfect shape. Someone told me that it could be a broken blade in the water pump flying around...is this possible or is there another suggestion? Thanks for any help you can give me. :confused:
     
  2. chevyguy

    chevyguy Senior Member

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    Remove the belt and start it up briefly, If the noise is gone then it is in the water pump, If not then it is internal. I recommend checking the oil and other fluids first before starting it and making sure nothing is hanging around where it shouldnt b If it was your water pump, then you are probally real low on water. Should be an indicator. Hope this helps. Let me know what you find.
     
  3. Robbman

    Robbman Member

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    Thanks Chevy

    Hey Chevy...appreciate the advice. I will try that this weekend and see what we come up with. I will let you know how I make out.

    Thanks again
     
  4. chevyguy

    chevyguy Senior Member

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    O.K. I am interested to see what you find out.
     
  5. Robbman

    Robbman Member

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    Hey Chevy

    Tried the Water pump thing yesterday. It was not the water pump. Got a loud tapping on the right side of the engine. Took the valve cover off and removed the push rods, alot of carbon build up on them, but they were not bent or broken. Pushin oil through fine. I am now assuming I have a valve knocking. I do not hear the clanging noise anymore and there is no more smoke coming from the engine. Lost no oil. Will a piston knock like that? Is there a way of checking the valves to see if it's them and also which one? And is there a way of checking the Pistons? Appreciate all your help.

    Talk to ya later.
     
  6. Kennyray

    Kennyray Moderator
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    Hook up a timing light. Use it on your lifters with the engine running and the valve covers off. If you have one not moving you will see it that way. Also check your baffles in the valve cover, if clanging is gone with valve cover off a baffle may have broken loose.
     
  7. Robbman

    Robbman Member

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    Hey Number

    Thanks for the info. The noise continues when the valve cover is off. The Valves are moving up and down and the oil is flowing through the rods. I was wondering, what are the chances that the Knock sensor is bad? It is located on the same side as where the knocking is coming from. This is definitely a Knocking sound. The clanging sound is no longer happening.

    Thanks for your help
     
  8. chevyguy

    chevyguy Senior Member

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    Why do i keep thinking this sonds like a wrist pin? Use a long screwdriver as a stethascope (sorta) touch it to different parts on the motor with the engine running and touch your ear to the handle end, It will help you identify where the knocking is coming from. Sound travels better thru a solid than it does thru air so you should be able to identify the source of the knock
     
  9. Robbman

    Robbman Member

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    Hey Chevy

    Okay I tried that and it is the loudest on the right side toward the front of the engine. Even took off the Valve cover and listened to each valve and and they all sounded the same. The Knocking was not coming from there. When I did it on the Intake Manifold, toward the front right, that is where it was the loudest. What is a wrist pin and how do I check that? i also heard that the Knock sensor could be bad or the Timing Chain gears could be messed up. Also someone said something about Spark ignition problem. Is that corrected by changing the plugs and the points?

    Thanks again,
     
  10. chevyguy

    chevyguy Senior Member

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    Its a 1990 it doesnt have points. It is an electronic advance computer controlled high energy ignition. Are you getting any truoble codes (check engine light) A knock sensor will set of the check engine light. If it is coming from the front try to listen at the timing chain cover. If it is a wrist pin the a complete rebuild is in order. Wrist pin is the pin that goes thru the piston
     
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