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04 1500 Knocking sound fr engine when I start it cold???
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mgabaldon02
New User
Jul 10, 2010, 2:22 AM
Post #1 of 5
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04 1500 Knocking sound fr engine when I start it cold???
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04 chev 1500 truck has a 5.3 V8, Knocking sound starts when the engine is cold. Sounds like its low on oil, but when the engine warms up(2-3 minutes) the knocking sound stops. Recently changed my thermostat, and that's when the noise started. My oil leve Is fine, oil preasure is normal, no engine light. Truck still runs like a champ, no loss Of power, but this cold start knocking is driving me nuts! Truck has 145k, I ran without a therostat For 3 days, but I don't think that should have anything to do with it? Anyone out there can give me a clue I would appreciate it.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 10, 2010, 7:02 AM
Post #2 of 5
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Re: 04 1500 Knocking sound fr engine when I start it cold???
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Some questions and checks, suggestions and warnings *Are you regular with oil changes? How many mile intervals? *Ever overheat? *Ever get too low on oil? * Oil pressure in range right away or slow? * Random noise or more like one cylinder? * Was the noise there before running without thermostat? (see Warning below) * Is a "check engine light on? * if sludge present I suggest very frequent oil changes instead of snake oil tricks to try to solve that or at least help it. New oil has all additives you should need. ~~~~~~~~~~~~~~~ Checks: *Check oil pressure with a mechanical gauge. *Belt(s) can make the noise - wet them first and if temporarily quits once replacement with good quality ones should stop that. *Perhaps take belts off and see if noise quits - just for quick check. If no noise spin pulleys for a bad one. * Cancel cylinders one at a time - if noise disapears withone chase that ONE down. ~~~~~~~~~~~~~~~~ *Warning! Running an engine without a thermostat can be destructive as overheating! This should have alloyheads on iron block but applies to any. What can easily happen is water pump has such a wide hole without one it can't circulate coolant throughout the engine but will satisfy the sender that it's cool/cold but lack of the mixing within via the by-pass and mix cause distant areas to overheat un detected - flow is fast and aggressive with coolant only nearest to water pump when so. Warping of parts and or damage can result. NEVER DO THAT! It also fools vehicle's computer controls and will send mis information for adjustments that can kill converter(s) or more. Expensive problems can easily result. T
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mgabaldon02
New User
Jul 16, 2010, 5:14 PM
Post #3 of 5
(1706 views)
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Re: 04 1500 Knocking sound fr engine when I start it cold???
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Hey Tom thanks for the reply. change my oil without fail every 3500miles oil level has never been below a quart engine has never overheated sounds like loose rocker arms Oil preasure comes up normal quickly, but i haven't checked it with a mechanical gauge. Have not heard the noise, untill I took the T-stat out. I did put a new one and temp is back to normal I examined the oil, it doesnt smell burnt, or look off it's norm color. I did drop a 1qt1/2 and added Lucas oil stabelizer. That stopped the knock. The reason why I thought it would be alright to run w/out a t-stat is my Pop has a 1994 z-71 Gmc and has never had a T-stat, original engine has 410,000 miles with the orginal waterpump! But it's an older truck maybe thats the difference. Thanks for the Help! Mike G
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Loren Champlain Sr
Veteran
/ Moderator
Jul 16, 2010, 5:22 PM
Post #4 of 5
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Re: 04 1500 Knocking sound fr engine when I start it cold???
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mgabaldon; In addition to Tom G's comments, running without a T-stat can cause the engine to run too cool, and therefore overfuel causing internal damage from the oil getting contaminated with fuel. A stethescope should lead to where the noise is coming from. May be too late? Loren SW Washington
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 16, 2010, 6:53 PM
Post #5 of 5
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Re: 04 1500 Knocking sound fr engine when I start it cold???
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Excellent Loren - I'd forgotten that if the sensors are telling the controls it's always cold it would be dumping way too much fuel and be a problem itself. Another reason NOT to run without thermostats, T
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