Popping noise from engine


venturenot
10-10-2010, 10:47 PM
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
10-11-2010, 06:53 AM
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
10-11-2010, 05:56 PM
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
10-12-2010, 06:04 AM
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
10-12-2010, 01:32 PM
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
10-12-2010, 08:47 PM
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
10-12-2010, 09:27 PM
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
10-13-2010, 06:37 AM
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
10-13-2010, 06:24 PM
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
10-13-2010, 08:47 PM
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
10-14-2010, 12:34 AM
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
10-17-2010, 08:01 PM
On my scanner there is a value for Ignition Advance DE, is this the timing advance?

venturenot
10-18-2010, 07:04 PM
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
10-18-2010, 07:35 PM
Head gasket replaced..popping noise gone in mine. Hope that is not your issue. (gasses in the cooling system)

venturenot
10-18-2010, 07:39 PM
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?

rodgerturner
10-18-2010, 11:13 PM
Seemed about the same inside as outside to me....maybe a little louder inside. I couldn't really tell if I was loosing coolant b/c it would simply spew out when the cap was off due to all the backpressure. My temp gauge would fluctuate though... going to red, then right back down to cool. I also had a noticable loss of power and horrible gas mileage. Hopefully yours is something simple.

lesterl
10-24-2010, 06:30 PM
You can get your coolant tested for combustion gasses to diagnose a bad head gasket, but is it loosing coolant?

BTW I think your Ignition Advance is what I was asking for, I dont recall exactly how it is worded on my scanner......

venturenot
10-24-2010, 06:43 PM
Funny thing happened: I kept looking at the coolant because I was concerned about the head gasket and I started noticing that a little coolant was missing. The next day I ran the engine and coolant was whipping up the drive belt, it turned out that I had a bad water pump. I would have never even thought of the water pump going bad, because 40,000 miles ago I had the engine replaced and the water pump was supposed to have been replaced with it. If I had not been looking for a head gasket problem, I most likely would have been stranded somewhere with a bad water pump. I wonder if the popping noise could have been from the water pump?

I think that the readings I get on my scanner are a positive 20 to 40. I'll have to double check those numbers, I am not really sure.

merc81
10-27-2010, 06:01 AM
Hmmm..

So you think the coolant was dripping on the belt and hitting the lower firewall area? Pretty weird. I hope this was your problem.
As an fyi, unless some prior arrangement was made, a rebuilt engine will not normally come with the external goodies installed. The whole front cover on the engine would be from your old engine; that includes all sensors and the water pump, alternator, pulleys, etc. The only thing a 'long block' replacement will include is the engine & heads, assembled. The old oil pan, intake manifold, injectors, all that stuff is reused normally.

venturenot
10-27-2010, 01:37 PM
I sure hope it was the water pump. I couldn't handle a major repair especially with so many miles on the van.

When the remanned long block was installed, I had an agreement that he would replace any part that seemed like it needed replacing. The deal was that I would pay for the part at cost with no labor charges. I told him to go ahead and replace the water pump and he charged me for it. If I had it to do again, I would have him replace the alternator as well. The engine now has only 40,000 miles on it, which makes me suspect that he may not have replaced the pump at all.

I had problems with this installer. After the engine was installed I started to have an oil leak which turned out to be the oil pump O ring. The engine was suppose to have a new melling oil pump. He never could explain how a bad O ring go on there, and wonder if even the oil pump was new. Any way, I sure hope I get at least 30,000 more miles out of this van without a major repair.

merc81
10-28-2010, 06:50 AM
I just drove my van through your area this past Sunday. Can't believe how cheap gas was there. We went down to Florida via Columbia and got gas there for $2.55 and on the way back it was $2.53--this while up here it is $2.89.
Anyway, I wouldn't worry about the pump. They are so cheap and easy to install that I see no reason your installer didn't put one in as agreed. It likely just went bad. I put one on just before I replaced my engine and had to install another one recently (about 15k miles later). The oil pump comes new with the rebuild, but as I recall, there is a cheapo O ring that seals the shaft where the distributor used to fit. I changed that O ring out with a viton seal, but I'm betting your installer wouldn't have done that. I just didn't like the way it felt when I put the cap on it.
Do you know who the rebuilder of the engine was?

venturenot
10-29-2010, 06:36 PM
Yes, gas prices are good. I always try to fill up before I leave the state.

The engine was remanned by Carolina Machine Engines www.cmengines.com I wouldn't mind too much, except that when the O ring was leaking it dripped down around the transmission pan and my installer kept claiming that that I had a transmission fluid leak. He finally admitted that it was an oil leak but he never did replace the O ring or solve the problem. I 'd leave the car with him and he would wash it down and tell me they fixed the problem. With the help on this board and my mechanic back in PA's knowledge of the bad O ring the problem was solved and my PA mechanic fixed it. The guy that installed the engine was worthless, I truly believe he never replaced the water pump.

Anyway, could the noise be coming from the cat convertor? I got a Po420 code today which points to Cat. I just had the cat along with the downstream O2 sensor replaced about 30,000 miles ago. Also, I came to a stop today and car idle was way high @ about 1100 rpm. It wouldn't come down until I stopped the car. Could that be in anyway related to the CAT code?

lesterl
10-29-2010, 08:31 PM
Could be a bad rear sensor or a bad cat, does it just have one cat or two?

venturenot
10-29-2010, 08:44 PM
Could be a bad rear sensor or a bad cat, does it just have one cat or two?


Cat and rear sensor were replaced just 30,000 mile ago. I bought the parts and took them to a fit shop where the guy welded the cat on for $80.00 and replace the sensor.

Not sure what you mean by "does it just have one cat o rwo"

lesterl
10-29-2010, 09:12 PM
It was a bank1 error code, bank 2 would be the front cat if it had one.....

Doesnt matter if parts are BRAND NEW they can be bad..... I would like to see some live data from the pre and post cat sensors......

Has it been running rich? That could destroy a cat, along with oil/ etc.

venturenot
10-29-2010, 09:21 PM
It's funny, I have been complaining that the long term fuel trim has been running at - 21% for the past 6 months. Now all of the sudden it is back in normal range - 3 - 6 %. Something is definitely screwy. Also all of the sudden the idle is racing after coming to a stop. Could O2 sensor cause that?

What values should I look for on the upstream and downstream sensor?

Up stream sensor does not switch dramatically and usually gets as high as .75

Down stream sensor does not remain very constant and switches around a bit. I thought the the downstream values should remain fairly consistent and not fluctuate too much.

merc81
11-01-2010, 06:48 AM
Hey, 30k miles is anything but new in my book. Anyway, I recently replaced my UP stream O2 sensor. There were no codes, but I had the engine out for a transmission overhaul and I just thought that 200k miles was enough for a sensor and got a new one.

Prior to this, I would get the problem were the rpm would 'hunt' or race at idle from time to time. You could watch the tach just surge from almost a stall up to 2000 rpm and back. It did stall sometimes. The worst problem was it would stall once in a while when driving--when you took you foot off the gas and the rpm would drop it stalled sometimes. Very nasty, that one.

Anyway, the new upstream sensor solved all that. Its not acted that way since the change.
On my odb2 reader, you can watch the graph of both the upstream and downstream sensors. The upstream one cycles back and forth, the downstream is pretty steady with slow changes while driving.

I was under the impression that changing out your water pump solved the noise?

lesterl
11-01-2010, 06:04 PM
It's funny, I have been complaining that the long term fuel trim has been running at - 21% for the past 6 months. Now all of the sudden it is back in normal range - 3 - 6 %. Something is definitely screwy. Also all of the sudden the idle is racing after coming to a stop. Could O2 sensor cause that?

What values should I look for on the upstream and downstream sensor?

Up stream sensor does not switch dramatically and usually gets as high as .75

Down stream sensor does not remain very constant and switches around a bit. I thought the the downstream values should remain fairly consistent and not fluctuate too much.


Vacume leak could cause the racing idle also.

Upstream should switch from about .1 to .9 vdc.
IF the CAT is good Downstream should switch very little at all after warmup.

dewaynep
11-02-2010, 12:27 PM
Just to add to this for others watching this thread: The upstream O2 sensor should switch from rich to lean fairly quickly (.1 to .9 volts) and shouldn't stay rich or lean for more than a second or so. The downstream O2 sensor should stay lean (.3 volts or less) and should NOT follow what the upstream sensor is doing. If the post-cat O2 sensor is following the pre-cat O2 sensor then there is a very good possibility the Cat is bad. Cats can go bad from: over-rich, oil contamination, antifreeze contamination and age.

lesterl
11-02-2010, 06:25 PM
^werd......

jane.simple@ymail.
08-07-2013, 01:38 PM
I had the same problem, and it turned out the belt was bad and the A/C compressor had locked up. It was actually my mom's car, and my boyfriend had told her to replace the belt a few weeks ago, once the belt all but shredded due to her negligence, the A/C compressor locked up.

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