89 silverado motor rattle when hot


  #1  
Old 01-27-07, 09:28 PM
G
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89 silverado motor rattle when hot

I have a 89 silverado 350 with air cond. when engine is hot it rattles under acceleration from stop and goes away after the rpms get up. it will not rattle in park reving the engine.now my first thought was water pump the tell tale hole on top is dry but underneath 180 degrees from that it is wet. is there 2 holes on a 350 water pump?
 
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Old 01-27-07, 10:20 PM
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By what you have said about the rattle, it is pre-ignition. Is it rattle or ping? Maybe a easy way to check this, let the fuel get down to almost empty and then put in 5 gallons of premium fuel. If the rattle goes away, pre-ignition. You have carbon buildup in the combustion chamber of the cylinders or maybe the wrong spark plugs. I don't know about the top hole in the water pump but if the bottom hole is wet the pump seal is going bad. You will need to replace the water pump in the near future. Take off or loosen the fan belt and see if you can wobble the water pump shaft by grabbing the fan and wobbling it. It should not have any play in the pump shaft. If it does have play replace the pump ASAP.
 

Last edited by Get RRR Done; 01-27-07 at 10:48 PM.
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Old 01-28-07, 05:19 AM
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Water pump leaking = need new pump. I agree that pre-ignition(ping) is probably the noise. Bad pump bearings would make noise all the time. Cause could be as suggested above, run some top engine cleaner thru the tank. Check timing, if off significantly, the problem could be a loose timing chain and/or worn gears.
 
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Old 01-28-07, 05:39 AM
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Is the vehicle overheating????? If so address that issue first. Hot cylinder heads can make an engine ping, but the coolant systen is only one source of the problem...........The other being the EGR system.........If the EGR valve is non-functioning or the ports are clogged, you'll experience a ping similar to what you're describing
 
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Old 01-28-07, 12:44 PM
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There is some black smoke upon start up then it goes away. It has ac delco spark plugs ,MSD coil,MSD 8.5 wires,MSD multi spark 6a box so all that should be good. The engine does not seem to overheat but it is cold here and takes 15-20 minutes to warm up the gauge says it is below 200. The engine uses lots of oil too, burns it but doesn't leak it.I have another engine I am rebuilding but it won't be ready until spring so I just need it to make it through the winter.
 
 

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