Engine rattles on startup

I get a similar rattle when starting it and also when I'm crusing at like 35 in auto and the car is in 5th, if I give it gas suddendly, but not enough to down shift, it with "rattle" for a second. Someone told me misfire, someone said its normal because its in 5th and you're not going fast enough and someone said the cat shield was loose or some exhaust shield. Haven't checked it out yet though.

I have the same noise, although 02 V8. 40mph ish, coming around on ramps I'll hear the rattle coming off the median before dropping into fourth.

I've never been able to figure out what it is. I hope it's not pinging....I always thought that would be a similar rattle but through the engine compartment. Full tune on the xcal or no tune I have the same sound coming from what seems like exhaust around the cat area (again hard to pinpoint)
 
I get a similar rattle when starting it and also when I'm crusing at like 35 in auto and the car is in 5th, if I give it gas suddendly, but not enough to down shift, it with "rattle" for a second. Someone told me misfire, someone said its normal because its in 5th and you're not going fast enough and someone said the cat shield was loose or some exhaust shield. Haven't checked it out yet though.

if it was a misfire you would probably have a stumble in there too. if you have a stumble included then it it would probably be your coils but could possibly just simply be an improperly calibrated tcc. if you check the drive cycle chart there is a specific action to calibrate the tcc, something like start in d4, accelerate to 45mph, cruise for 15 seconds, throw it into d5, accelerate to 55mph and cruise for 15 seconds. repeat all of that x5. but check the chart to be sure, bc thats off the top of my head and may not be 100% accurate
 
Update on this: The car makes the noise on startup whether I give it a short burst or not. However, I have isolated it to happening when the car has been sitting for a while, and the temp is between about 40 to 60 degrees F. If it's hotter than this or colder than this, it doesn't make the noise. I still need to do the no belt test, but as always my time is not my own for the most part. Seems like the minute I resolve one crisis another one instantly steps up to take its place. Getting old, too. :mad:

As a reminder, the noise only happens when the car is completely cold, only happens at startup, and the longest it's lasted has been 3 seconds, and sounds like a BB in a coffee can. Once the noise has happened on startup I never hear it again until the car has sat long enough to get completely cold. Warm starts as I go through the day, never hear it.
 
...As a reminder, the noise only happens when the car is completely cold, only happens at startup, and the longest it's lasted has been 3 seconds, and sounds like a BB in a coffee can. Once the noise has happened on startup I never hear it again until the car has sat long enough to get completely cold. Warm starts as I go through the day, never hear it.

Here's something to check when you can. Look at the damper pulley to see if it is wobbling when this happens. It may be that the rubber between the inner and outer parts is shrinking when cold. (It's well known that Ford made a bad batch of these.) If so, the sound you here is probably the belt tensioner trying to deal with this. You may be able to quiet it down by replacing the tensioner. Replacing the damper doesn't seem to be very possible anymore. They don't seem to be making it or the one-time-use bolt that mounts it anymore.
 
Bummer. Thanks Joe, I'll take a look. I'll be off work next week for vacation so I'm hoping to have a few minutes to myself to take care of this sort of thing.
 
Ever find out what your issue was? I had the same sound, only I described it to a buddy as my dog running across the harwood floors upstairs. Had a tick tack, rattling sound to it.

Turns out mine was a grooved idler pulley I got from summit to put in place of the origional after removing the hydrolic fan pump so that the belt wasn't riding on a smooth idler. Summit is good for somethings, but generic plastic pulleys with crap bearings is not one of them, but at least I found the issue and resolved it thanks to a junk v6 with the same size pulleys as the v8's.

Removing the belt is your easiest method. 15-20 minutes tops, and I'll bet your issue is one of the idlers or damper, which, like joegr said, will be an issue finding
 
Not yet. Got too busy over my Christmas vacation then the weather turned to crap. Since it only seems to do it on the initial startup when the temp is between 30 and 50, it's not been an issue for a few weeks. I'm hoping to have some time to myself week after next to look into this. This coming week I've got massive overtime to work.
 
Something similar

Oddly enough, my 04 did something similar this morning when my wife started it. In my case, it was very regular and sounded very much like a bad lifter (which this engine doesn't have any). She took another car and I went out to check it later when I was awake. When I restarted it, it did the same thing but stopped doing it this time after two or three seconds. It was too quick for me to localize the sound (and I had my stethoscope ready). I did see that it wasn't anything to do with the belt. I guess I'll have to try it again later. Meanwhile, it apparently needs a new battery. The existing one has been in exactly four years.
 
And as it turns out my 06 needed a battery too. I had to put one in my BMW a few days ago. Something about "when it rains, it pours."
 
And as it turns out my 06 needed a battery too. I had to put one in my BMW a few days ago. Something about "when it rains, it pours."

It must pour cars for you sheesh. Not just a few LSs but you're part of the dark side...BMW. It's like catching McDonald eating a wendys burger
 
It must pour cars for you sheesh. Not just a few LSs but you're part of the dark side...BMW. It's like catching McDonald eating a wendys burger

My #1 problem with BMW is other BMW owners. It's some sort of cult that I don't fit into. Maybe because I don't drink the blue kool-aid/anti-freeze.
 
My #1 problem with BMW is other BMW owners. It's some sort of cult that I don't fit into. Maybe because I don't drink the blue kool-aid/anti-freeze.

Lmao come on Joegr spill the beans! we did not know you had a BMW?
 
Yep, that's what I have, 2-3 seconds of clatter then it's gone, too fast to localize not that I really can anyway as sound is just a wall to me. I am starting to wonder if it might not be a starter issue, like the solenoid isn't completely disengaging from the flywheel. It does have kind of a tinny quality to it. What do you think? I would also wonder if your weak battery might be an issue here, does a weak battery affect how strongly the solenoid draws back? It's been decades since I've had to deal with a bad starter, not sure if a weak battery might excaberate a weak solenoid issue.

You don't fit in with other BMW drivers? You must not be a prick then. :D
 
I get something very similar to this on my 06. Only at cold start ups. It makes a loud sound that i cannot describe. Once the car drops to idle it goes away. Usually only 40 degrees or colder. Also, I can hear my belt or pulley during this. I usually let the car warm up for a few minutes and the idle/pulley noise goes away. Could these be bad tensioners? I asked a few mechanics and they stated the car has a autotensioner and it cannot be changed? How can this be true?
 
I get something very similar to this on my 06. Only at cold start ups. It makes a loud sound that i cannot describe. Once the car drops to idle it goes away. Usually only 40 degrees or colder. Also, I can hear my belt or pulley during this. I usually let the car warm up for a few minutes and the idle/pulley noise goes away. Could these be bad tensioners? I asked a few mechanics and they stated the car has a autotensioner and it cannot be changed? How can this be true?

Yes, it could be the tensioner. Also check and make sure you don't have a minor coolant leak onto the belt drive.

Yes, it has an auto-tensioner, but it most certainly can be replaced. I've replaced one of mine, and others on here have replaced theirs. You need a new "mechanic."
 
Try This!

Oddly enough, my 04 did something similar this morning when my wife started it. When I restarted it, it did the same thing but stopped doing it this time after two or three seconds. It was too quick for me to localize the sound (and I had my stethoscope ready).

Next time, Joe and Telco, try cranking it cold with the fuel pump fuse removed for six seconds (to build oil pressure.) My guess is that when you replace the fuel pump fuse and start it, VIOLA, it will have no noise.

If that's the case, is this an issue with the main timing chain tensioners bleeding off residual oil pressure and the chain rattling until oil pressure is established?

Does that eliminate the other (myriad) of possibilities?
 
Next time, Joe and Telco, try cranking it cold with the fuel pump fuse removed for six seconds (to build oil pressure.) My guess is that when you replace the fuel pump fuse and start it, VIOLA, it will have no noise.

If that's the case, is this an issue with the main timing chain tensioners bleeding off residual oil pressure and the chain rattling until oil pressure is established?

Does that eliminate the other (myriad) of possibilities?

Sorry, no. Cranking without starting will do the same thing, and I've had the noise after a crank no start. I'm starting to think slow solenoid now.
 
Ive got squeak on cold startup. Think my belt got coolant on it from when i had the leak. Ive recently replaced the idler and tensioner so it should not be those.

Also ive noticed that the LS has a very noisy engine/accessory drive.
 
Update on this: The car makes the noise on startup whether I give it a short burst or not. However, I have isolated it to happening when the car has been sitting for a while, and the temp is between about 40 to 60 degrees F. If it's hotter than this or colder than this, it doesn't make the noise. I still need to do the no belt test, but as always my time is not my own for the most part. Seems like the minute I resolve one crisis another one instantly steps up to take its place. Getting old, too. :mad:

As a reminder, the noise only happens when the car is completely cold, only happens at startup, and the longest it's lasted has been 3 seconds, and sounds like a BB in a coffee can. Once the noise has happened on startup I never hear it again until the car has sat long enough to get completely cold. Warm starts as I go through the day, never hear it.

i had this problem with my old blazer. ended up being the honeycomb broke loose from the steel casing in the converter. give yours a tap when its cold.. if not id say its a shield.
 
Next time, Joe and Telco, try cranking it cold with the fuel pump fuse removed for six seconds (to build oil pressure.) My guess is that when you replace the fuel pump fuse and start it, VIOLA, it will have no noise.

If that's the case, is this an issue with the main timing chain tensioners bleeding off residual oil pressure and the chain rattling until oil pressure is established?

Does that eliminate the other (myriad) of possibilities?

So far, it hasn't done it again for me. When it did do it, it sounded like it was mid engine on the passenger side. It sounded a lot like a rod knock.
 

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