My son's friend is having a problem with his Lincoln. It's been hard to start lately, and he has to use starting fluid to get it to fire sometimes. I guess today he did that and it fired up and is now making a popping noise at idle. He hasn't tried to drive it for fear of damaging something. He's not local to me, so I haven't seen the car in person.
My son emailed me a short video of the running car, but it's kind of hard to hear. I'm uploading it to a host so I can post it here, but thought I'd ask for opinions in the meantime.
The car has 150k on it, and my first thought is a timing chain problem, but I don't know this car well enough to know it can't be something like a peripheral component that is specific to this car. So I don't want to jump to serious conclusions.
Anyway, has anyone heard of a symptom like this with this engine specifically?
I'll post the video as soon as I can. Thanks in advance.
klb67
Reader
6/4/14 6:57 p.m.
I have a 4.6 in my 07 Explorer. It eats coils - individual coils on top of each plug. No idea if your engine is the same but I'll toss that out there. Easy R & R once you find out which cylinder.
Sounds like the infamous plug blow out. Look for a dislodged coil pack in the video. Grab a timesert kit.
In reply to Javelin:
I don't think it sounds as rhythmic as that would be. Listen to the video. It sounds to me to be more random than that would be, but like I said it's kind of hard to hear.
I take it back, that video is showing more horrible noises. Sounds like a timing chain guide broke which is extra bad juju...
In reply to Javelin:
Are they interference engines?
It's more expensive to do a timing chain than swap a motor. IIRC, they are interference.
Rare for a timing chain to break but that is not one of the usual sounds for a faulty 4.6
The sounds seem like it could be from the intake, but not being able to hear it up close I am unsure
klb67, the Lincoln Town Cars have the older 2 coil packs and regular plug wires
its not rare for the guides to break or wear thin enough to cause a tooth hop. The R&R on them sucks!
When I was on the Explorer forums years ago (for my 4.6L '03) the timing chain/guide seemed to be an issue.
Those motors were so common that I'd rather swap than replace something like chain and everything that goes with it.
In reply to aussiesmg:
I asked my son to listen at the air inlet and he said it didn't seem to sound any louder there than anywhere else. But he also said the sound seemed to come from the center top of the engine, which would be the intake, so I don't know.
In reply to bravenrace:
I couldn’t watch the video but I would suggest using an automotive stethoscope to find the noise. That is the first thing I grab when I hear something strange.
Okay, I went to look at the car. It's idling like it has a vacuum leak, and the popping sounds like it's coming from under the intake manifold. Does that make sense to anyone? The popping is intermittent, and sounds just like a carb backfiring, but it's not coming out of the intake (nor the exhaust for that matter). What's under the intake manifold on these engines? The car will barely run, seems to run better at higher RPM, ran better when it warmed up, and the check engine light isn't on. It won't drive, it just falls on it's face if you put a load on it. Any ideas? I would suspect a blown intake gasket or cracked intake manifold, except the popping is not consistent.
there's nothing under the manifold.
pull it off and see what's going on.
In reply to belteshazzar:
Are you sure about that? I couldn't see, but it sure looked like there were things under it towards the back.
I'm not the that's going to be working on it, I'm just trying to get an idea of what's going on to help him decide what he should do. I've heard this kind of popping before, but never coming from where this is coming from. I noticed the EGR is in that area, and am wondering if it might have something to do with that.
Where are all the P71 guys? C'mon fellas, help me figure this out.
"Hello...hello..hello, is there anybody out there..."
The manifold can crack but it's rare.
9 times out of 10 a hard start on a 4.6 is a carboned throttle body. It will start okay with a little throttle.
But it sounds like he blew a hose off or something. That assumes he didn't jump a chain, which is common if the engine has been trained to run low on oil.
Hmm, it is low on oil. The thing that I can't figure out is the popping. It seems totally random and intermittent. It sounds like some kind of valve that opens to the exhaust. But it only seems to do it at idle. Give it a little RPM and it stops, but you can't maintain any RPM off idle for more than a couple seconds, and then it returns to idle even if you have your foot on the gas. This is an interference engine, and I don't hear any kind of bad internal sounds, only this popping.
timing retard causing it to pop through the intake at idle from a jumped tooth? im not sure if one tooth is enough to make piston meet valve.
In reply to dropstep:
But the popping isn't coming from the intake. At least not the normal air intake.
One last plea for help. HELP!
Have you tried doing a smoke test on the intake ( inside and outside while it is running)? Also look for a leak in the EGR and AIR if it has them. Unhook their controls and see if that helps. Try to find the source of the sound.
