Popping noise from engine

[venturenot]

Just finished an 11 hour highway drive and I am getting a popping noise - like a lot of popcorn popping at once, or water boiling. It sounds like it is coming from the engine and only happens when the car is in gear and the brake is on. It does not happen when the car is moving.

I have noticed this noise before, it occurred a week ago after about 500 miles of straight driving when I stopped for gas. About 100 miles later my alternator died. Since then the alternator has been replaced and the car has been running fine on short trips. No sign of any trouble.

Temperature gauge on car does not show any overheating and there is no coolant leak. Turned off AC with no effect on noise. Any ideas?

My car has 200,000 miles, replaced the engine at 163,000.

[merc81]

Wow, that' a tough one. Gets me worried too since I've got a van at 209k with 25k on the engine.
Is there any chance the sound is coming from the serpentine belt? A bad spot on the belt could maybe make such a sound--it wouldn't care about being in drive or park though.

You normally run about 1/4 or so on the temp gauge? Oil looks, smells good? These engines 'ping' alot, sounds like they are pinging the valves at idle speed, but that too sounds the same in park or drive.

You don't say, so I assume the van runs OK, no problems with power or starting? Can you hear the sound from inside, and if so, does it quit after you get moving?
I'm thinking maybe injectors or fuel pressure regulator, but those are WAGs only.
Sorry for all the questions, but your issue is a stumper, and very troubling.
John

[venturenot]

Serpentine belt was replaced with the alternator. I also had the noise with the previous belt that was replaced.

Actually when highway driving the temp gauge is about 1/8. I'm not sure what a pinging sound is like, this is a definite pop. Another description of the sound would be like listening to fireworks from a distance.

Van runs like a champ on the highway, no starting issues great fuel mileage. Oil was changed 3,000 miles ago and still completely full. It does look a little blotchy with dark spots and there is no unusual smell. I started the van today and the popping began after the car had warmed up and I came to a stop. I can hear the sound from the inside of the van, but when I lift the hood I cannot hear it from the outside.

Yes, sounds stops once the van is moving.

This may be a long shot: My mechanic replaced the left lower control arm bushing and when doing so the bracket that secures the bushing broke. This was a last minute job before I left on my trip,and he could not get a replacement bracket. He told me that it would be OK to drive but I might hear some noise. He told me that when I returned he would replace the bracket. I was wondering if the popping noise might be the result of some vibration on the unsecured bushing??

Also, could it be a small leak in the exhaust that I can only hear in the car. Ran the scanner and found no codes. I have been having an issue with fuel trim. The LT fuel trim goes as high as - 22, but never sets a code.

[rodgerturner]

I have the exact same popping noise. I thought it was related to air being in the cooling system as I've had some other issues, namely the head gasket. Guess I'll see shortly if it was related.

[venturenot]

Please let me know. Mine is strange because it only happens after driving for an extended period - like 6 hrs and lasts for the next 24hr. I was driving the car today, there is no noise.and there probably won't be until I head out on my next trip.

[lesterl]

Originally Posted by venturenot

Serpentine belt was replaced with the alternator. I also had the noise with the previous belt that was replaced.

Actually when highway driving the temp gauge is about 1/8. I'm not sure what a pinging sound is like, this is a definite pop. Another description of the sound would be like listening to fireworks from a distance.

Van runs like a champ on the highway, no starting issues great fuel mileage. Oil was changed 3,000 miles ago and still completely full. It does look a little blotchy with dark spots and there is no unusual smell. I started the van today and the popping began after the car had warmed up and I came to a stop. I can hear the sound from the inside of the van, but when I lift the hood I cannot hear it from the outside.

Yes, sounds stops once the van is moving.

This may be a long shot: My mechanic replaced the left lower control arm bushing and when doing so the bracket that secures the bushing broke. This was a last minute job before I left on my trip,and he could not get a replacement bracket. He told me that it would be OK to drive but I might hear some noise. He told me that when I returned he would replace the bracket. I was wondering if the popping noise might be the result of some vibration on the unsecured bushing??

Also, could it be a small leak in the exhaust that I can only hear in the car. Ran the scanner and found no codes. I have been having an issue with fuel trim. The LT fuel trim goes as high as - 22, but never sets a code.

Is that a negative, then it would be cutting back fuel due to excess fuel detected, if it is a positive number, then it would mean that it is running lean and trying to add fuel.....

[venturenot]

Yes, it is a negative. It has been doing that for about the past 8 months and has never set a code. Don't know why the fuel trim is so negative, no other engine problems than the popping noise.

[merc81]

I can hear the sound from the inside of the van, but when I lift the hood I cannot hear it from the outside.

OK, wait. I missed that statement. You can't hear it with your head under the hood? I think that lets out pretty much any thoughts I had about fuel injectors (which are right under the top of the engine) or pulley chirps.

Have you considered that it might be the HVAC system in the cabin making the noise? Try manipulating the system controls next time you hear the noise. Since the engine is out in front of the cabin (not like a rear wheel drive) and sits transverse, virtually no portion of the engine or transmission sits under or around the cabin. If you can't hear a noise with the hood up and your head down near it, but you hear it inside the van, its not engine related--couldn't be.

Toward that end I'm thinking the HVAC doors and related vacuum actuators and lines could be culprits. Those mix doors inside the system get stuck and might sound like popcorn popping to you.

[venturenot]

The problem is: the noise only occcurs after a long trip (11 hours) and maybe for an additional 24hr. When this has happened, it has been late at night and I have been too tired to pop the hood. I have heard the noise on the following day however it is not as extreme and when I have popped the hood I have not been able to hear it. After that period of time it dissappears completely.

I just took it on a 100 mile trip and no noise. I think you are correct about the HVAC. When this noise has happened I have had my AC running the entire trip (11 hrs.). I can't imagine what else it could be. I was originally concerned it might have something to do with the transmission. I have 200,000 miles on the current transmission and am always worried that it will belly- up.

[lesterl]

Whats the timing advance look like? (BTW my Fuel trim runs negative like that also and my Advance is -10 to -30 all the time....)

[bugman742002]

check the blend door or the blower door. it could be a vac leak or a faulty blend door actuator. causing the door to open and close causing the noise you are hearing.

[venturenot]

On my scanner there is a value for Ignition Advance DE, is this the timing advance?

[venturenot]

Ok, got the noise again, without a long trip. I lifted the hood, could hear the popping and sounded like it was coming from the rear of the engine toward the firewall. The noise is much louder in the car but can also be hear with the hood up. Played with HVAC controls and did not stop the popping sound.

[rodgerturner]

Head gasket replaced..popping noise gone in mine. Hope that is not your issue. (gasses in the cooling system)

[venturenot]

Ouch...I do too. Could you hear the popping sound the same as when hood was popped and when sitting in the care. My sound is much louder in the car and with the hood popped it sounds like it is coming from the back of the engine. What other signs did you have of a bad head gasket? Loss of coolant?