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73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: gold84gmc on August 23, 2007, 07:02:14 am
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anyone know why my truck sounds like it is making a steady popping noise coming out of the tailpipe? and every once in a while it backfires (flame) too. im thinking it has something to do with timing? or carb out of adjustment?....it used to have a regular cheap muffler on it and now it has a glasspack..but it used to make the same noise with the muffler. thanks.
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Could be any number of things,the popping and the backfiring may not even be related..but I would guess burnt or sticking valves..
Tim
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ill try to take a video of it later. the truck has like 94,000 miles on it if that helps at all. i would really hate to have to take the engine apart.
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Check your wires, cap & rotor 1st.
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it's possibly running too rich and fuel is collecting in the exhaust and then igniting.
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If it is a sticking valve,
( and someone will be repling saying this is an old wives tale, that it doesn't work, etc. ) an old timer that has forgoten more than i will ever know about cars, & trucks told me to do it.
I have done it and it does work. I took a half quart of transmission fluid, topped it off with gas, got the motor up to temp, took the air filter off, reved it to about 2,000 RPMs and very slowly so as not to make it stall I poured the entire quart of home brew down the carb. At about 3/4 of a quart the valve stopped popping through the exhaust. Never had any more trouble with it, ran that motor in two trucks four about four years. Still ran when I sold the truck and the kid I sold it to ran it for more than a year before he wrapped it around a telephone pole.
Just make sure you do it outdoors as it creates a huge cloud of smoke.
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ooh ic..cuz i know they sell stuff like that except its specially made for that instead of making it urself.....ill have to try that i guess haha...thanks
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Valve lubrication/cleaning at its finest, but what a smoke show it makes. Years ago my father used to do this trick with success, but just straight dextron.
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That's the poor mans top engine cleaner and it does work. Just remember burning ATF is toxic. Don't ever do this anywhere near indoors and be very careful not to hydrolock the engine.
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Yes thats why I said very slowly and do it out doors.
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when you first start the engine it doesnt pop or anything it just sounds normal....but once the engine warms up it starts to pop rapidly. what do you think...spark plug, or what
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Did you check your plug wires cap and rotor like suggested? Always start with the basics
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when you first start the engine it doesnt pop or anything it just sounds normal....but once the engine warms up it starts to pop rapidly. what do you think...spark plug, or what
As the engine heats up the valve starts to stick. Been there done that. Sounds like a sticky valve to me.
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my automotive teacher suggested i slowly pour a small amount of water down the carb as its running. he said hes done it before and that it works better than like carb cleaner or w/e............not sure if i should try that or just use "seafoam" ?
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you're going about it all wrong. If you suspect it's a sticking valve which I doubt it is put a vacuum gauge on it and you'll know for sure.
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well i tried that seafoam stuff, and it seemed to work a lil bit but didnt completely eliminate the popping.
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you're going about it all wrong. If you suspect it's a sticking valve which I doubt it is put a vacuum gauge on it and you'll know for sure.
Some very good advice here. Have you tried it?
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well except i dont have a vacum gauge haha............how would would i go about it anyways? (where to hook it up, wat rpm?)
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http://forum.73-87chevytrucks.com/smforum/index.php?topic=5963.0
If you want I'll email you that powerpoint on vacuum testing. Otherwise go to autozone and pick a gauge up and install it on any manifold vacuum source
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I agree make sure thats the problem first. The only time I have seen water use is if you have carbon knock. A piece of carbon on top of the piston banging into the head.
Same old timer did this once way back when I first started out in the body business. We had a 88 Wrangler that had been flopped on its side. It got deposited into the shop via ramp truck, the fire dept. had cut the battery cables, so we pushed it around the shop until the new cables came in. That just happened to be after it was all fixed and painted. Put the new cables in, fired it up, and wrap wrap wrap, sounded like the motor was gone. Al ( the old timer ) came out listened to it, went back in the mechanic shop, came back out with a spray bottle full of water, reved it up a bit and sprayed a fine mist of water down the intake twice and wala the knock vanished. my boss the body shop manager was in his 40s and had never even seen that.
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vile- yea go ahead an email it ... gamebigboy3@aol.com
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so i replaced the plugs an wires and checked over the ignition system. i did find one wire that basically burned from the exhaust and had an opening in it.....but when i started it, it still had that popping noise...not quite as bad but its still there......and ideas? i am probably going to try that water trick today tho.
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What about the cap & rotor? Did you set the timing? how does the coil look? Did you put a vacuum gauge on it?
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http://forum.73-87chevytrucks.com/smforum/index.php?topic=5963.0
If you want I'll email you that powerpoint on vacuum testing. Otherwise go to autozone and pick a gauge up and install it on any manifold vacuum source
thanks!
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seafoam is a really good engine cleaner. i use it in all my cars throught the brake booster line and it works wonders.
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Where would you attach the vacuum gauge to do this?
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Any manifold vacuum source