What could cause a popping noise from the front end when shifting gears or accelerating from 0 mph? (seems to happen more when it's cold)?

Question

Whenever I let the clutch out from 0mph, there are usually 1 or 2 pops just as I get moving. It dosent matter if im going straight or turning, just as my car starts to move there is often a popping / clunking noise. It makes the same noise when shifting into 2nd and sometimes 3nd gear also whenever the momentum of the car shifts forward as I let the clutch out.

It is a front wheel drive 1999 Nissan Maxima

Please throw out any & all suggestions as to what it might be, it will make it easier to inspect components. (No, im not taking it to a shop)

I do a lot of work on my car and have recently replaced a couple things that I thought might be causing the pops, only to have the sound continue after I did the repair. all together in the past 1-2 years I have replaced:

-struts 
-rebuilt the brake calipers, new hardware, new rotors 
-new polyurethane control arm bushings 
-sway bar bushings, end links, & end link bushings 
-power steering rack and tie rods 
-ball joints 
-rear motor mount 
-transmission mount 
-both CV axles

I have no clue what could be causing the noise. I dont know what to look for because I'm not sure what else could be causing it. I've done what I could to inspect what I could but, surely, i missed something.

Thanks for your help

? · Answer

its a header leak/backfire. They pop every time gears are shifted or given a certain amount of gas or letting off the gas. Thats what I determne from the given description.  seeing/hearing it myself I could tell you in a second if its really the case.  With car idilng, With your hand CAREFULLY, feel the air around where the header/exhaust comes from the block, around the gasket.  if you feel any jet of hot air at all, its a header leak.  all it requires is a replacement gasket and it wont even take you half an hour to do it.  If its doing this, its also letting cold air rush inside the leak that can very easily cause something to crack from thermal shock.

I cannot stress CAREFULLY enough because the hot air coming from the leak will burn the **** out of your hand.  hold you hand several inches away and be very cautious.  you're feeling for a stream of hot air coming from the gasket.  If you replace the gasket might as well spring for the aluminum one rather than paper.  and use header bolt lockwashers.  Not lockwashers, header bolt -specific lockwashers.  ... oh, also use anti-seize on those header bolts in case you have to get at the gasket again.  That area gets very hot, last thing you want to deal with is breaking the head off a bolt that's fused.

if that's not the case then I would check the rest of your transmission mounts.  sounds like backfire through the header gasket to me though.

please please please, seriously, don't get a sever burn on your hand.  do with caution!!  the jet will be coming out with a lot of pressure and it is VERY hot, you do not have to get that close to feel it.  if it has header leak, when its not backfiring also just usually sounds like really loud ugly engine/exhaust noise.

Brandon · Answer

U joints or CV shafts, that is where I would look first.

What could cause a popping noise from the front end when shifting gears or accelerating from 0 mph? (seems to happen more when it's cold)?

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