Vibration at idle...

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TommyJ1980

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Hey foks - 1998 K2500 5.7L pickup with 248000 miles. Had it in the shop for some misfiring that was going on, and they said it needs a new intake manifold gasket, which I have and am planning to put in. It had been running smoothly up until a few minutes ago when I noticed a sudden vibration at idle, strong enough to be noticeable while sitting in the cab. I got it home, popped the hood, and went to restart it again, and it started reluctantly, but then ran ok once started. Would you think that fouled plugs could cause a vibration like that? Thanks-
 

TommyJ1980

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So I think I have a couple things going on, first, yes, there was something in the notes about leaking coolant, and the spark plugs develop a brown sort of gunk on them fairly frequently, which causes this misfiring. Secondly, the radiator has a fairly slow leak, but somewhere else has started leaking coolant more quickly in the past week, and thirdly, I hear the wierdest sort of groaning noise, almost like a door opening very slowly, but low pitched, and it sounds like its somewhere forward of the glovebox. From a little bit of research, and putting the picture together, I'm thinking I need obviously the new intake gasket, but also a water pump, and since it seems fairly easy to replace, I'm going to start with those items, as well as a new radiator, which I've had waiting for me in the shop for a couple months now, and a new set of plugs. I very much welcome any other thoughts on this, you guys here on this website have saved my bacon multiple times now. Thank you in advance.
 

SUBURBAN5

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Sounds like you have a plan which is good. Start with all the needed repairs. Intake gaskets are fairly straight forward. The water pump and radiator are easy enough on these. My 2cents are change the hoses as well if there original and anything else since your going to tear into it anyways.... Even the t stat. I just repaired a 99 suburban last week and the guy bought everything for like 600bucks.
 

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DerekTheGreat

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So I think I have a couple things going on, first, yes, there was something in the notes about leaking coolant, and the spark plugs develop a brown sort of gunk on them fairly frequently, which causes this misfiring...

Brown gunk? That wouldn't be caused by coolant getting into your cylinders. Unless it is an extreme amount, a cylinder ingesting coolant tends to look squeaky clean by comparison with another cylinder.
 
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