exhaust popping

[gold84gmc]

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.

[Leadfoot]

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

[gold84gmc]

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.

[VileZambonie]

Check your wires, cap & rotor 1st.

[dumbucket1]

it's possibly running too rich and fuel is collecting in the exhaust and then igniting.

[Blazin]

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.

[gold84gmc]

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

[78BBSTEPSIDE]

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.

[VileZambonie]

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.

[Blazin]

Yes thats why I said very slowly and do it out doors.

[gold84gmc]

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

[VileZambonie]

Did you check your plug wires cap and rotor like suggested? Always start with the basics

[zieg85]

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. 

[gold84gmc]

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" ?

[VileZambonie]

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.