Rattling engine noise on cold start

BHernandez · Mar 7, 2022

Hello everyone! I'm new to the forum. I have a 98 GT Conv., since new in November of 97. The odometer reads just over 148K. Since new the car has always been a secondary "weekend" cruiser. So, it spends quite a bit of time parked. Lately, on cold starts after sitting a few days or more, it has an abrupt rattling noise for a second or two then goes away. It sounds like a bearing rattle but, as I mentioned, quickly goes away. I've changed the oil and opened up the filter looking for metal pieces, but nothing. The engine is completely stock. Only mods are suspension and sub-frame connectors. The car has been very well maintained. No noticeable performance issues. Anyone else ever have this issue? Any thought or ideas would be helpful.

ttocs · Mar 7, 2022

get a video

BHernandez · Mar 7, 2022

It'll be a few days. Just drove it this morning. It only happens after sitting for several days. If I start it daily, it doesn't happen.

ttocs · Mar 7, 2022

its just hard to diagnose a rattle, it could be anything. I had a friend of mine that for a couple of weeks when we would be out drinking he would mention that he had a rattle that was driving him nuts at exactly 3200 rpms. "Not 3100, not 3250 but at exactly 3200", he told me 3 weeks in a row but by the time we got around to leaving we forgot about it. One day he stopped by my house and I told him to pop the hood and as I reached for the hood prop I found the problem was that the didn't lock the prop rod down and you could see where it had been rattling against the inner fender.

BHernandez · Mar 7, 2022

That's hilarious! I was planning a trip to Orlando this weekend, but I'll use the Accord for that. When I get back, I'm sure I can get a video of the noise.

lwarrior1016 · Mar 7, 2022

That sounds like the typical lash adjuster rattle these things get after some age. My town car does the same thing, I just roll with it. Never skipped a beat.

ttocs · Mar 7, 2022

BHernandez said:
That's hilarious! I was planning a trip to Orlando this weekend, but I'll use the Accord for that. When I get back, I'm sure I can get a video of the noise.

I know the funniest part was my buddy wanted me to look at it because he is not a car dude and anyone that would have just propped the hood up to take a quick look even if they didn't notice the paint rubbed off, would have fixed the problem.

Merlin · Mar 8, 2022

BHernandez said:
Hello everyone! I'm new to the forum. I have a 98 GT Conv., since new in November of 97. The odometer reads just over 148K. Since new the car has always been a secondary "weekend" cruiser. So, it spends quite a bit of time parked. Lately, on cold starts after sitting a few days or more, it has an abrupt rattling noise for a second or two then goes away. It sounds like a bearing rattle but, as I mentioned, quickly goes away. I've changed the oil and opened up the filter looking for metal pieces, but nothing. The engine is completely stock. Only mods are suspension and sub-frame connectors. The car has been very well maintained. No noticeable performance issues. Anyone else ever have this issue? Any thought or ideas would be helpful.

I also have a 98, I have not had this with it. I also Have a 2005 with a 4.0. About two years ago I had thwe same thing on it. I ran it down to a sticking cam chain tensioner. I was told this is common with them.
I added a can of Rislone to the oil and drove it for a day, maybe 75-100 miles. No hot rodding, I changed oil and filter and haven't heard it since. I also add 1/2 quart of ATF at each oil change.
I don't know if this helps you but it did mine.
I have experienced a rattle at start up on other engines but you don't want tohear that, it was the main bearings

RAU03MACH · Mar 8, 2022

Rather have a little rattle here and there
I have an engine knock deep on the ranger
Now I'm in the middle of replacing the engine

badass98svt · Mar 8, 2022

Lash adjuster, timing chain, could be a few things. A vid would definitely help. Also is it coming from the top? The front?

BHernandez · Mar 9, 2022

Can't tell where it's coming from. I'm usually inside the car when it happens and it's gone so quick, there's no real time to hunt it down. The timing chains, tensioners and guides were replaced at 125K along with the balancer and water pump. They even dropped the pan to make sure they got all of the guide pieces out. I'll let it sit a few more days and try to get it on video.

NEURON · Mar 9, 2022

lwarrior1016 said:
That sounds like the typical lash adjuster rattle these things get after some age. My town car does the same thing, I just roll with it. Never skipped a beat.

This.

96blak54 · Mar 9, 2022

Mine did the same, however it did it at idle all the time. I simply removed the muffler. No more rattling

Pallgor · Mar 11, 2022

BHernandez said:
Hello everyone! I'm new to the forum. I have a 98 GT Conv., since new in November of 97. The odometer reads just over 148K. Since new the car has always been a secondary "weekend" cruiser. So, it spends quite a bit of time parked. Lately, on cold starts after sitting a few days or more, it has an abrupt rattling noise for a second or two then goes away. It sounds like a bearing rattle but, as I mentioned, quickly goes away. I've changed the oil and opened up the filter looking for metal pieces, but nothing. The engine is completely stock. Only mods are suspension and sub-frame connectors. The car has been very well maintained. No noticeable performance issues. Anyone else ever have this issue? Any thought or ideas would be helpful.

Maybe a heat shield. They can be ball buster rattles

BHernandez · Mar 24, 2022

BHernandez said:
Can't tell where it's coming from. I'm usually inside the car when it happens and it's gone so quick, there's no real time to hunt it down. The timing chains, tensioners and guides were replaced at 125K along with the balancer and water pump. They even dropped the pan to make sure they got all of the guide pieces out. I'll let it sit a few more days and try to get it on video.

Had to let it sit a few days. Got a short video of cold start after a week of sitting. Very short rattle right at cold start last less than 1 second. The file is 39 seconds and says it's too large to upload here.

BHernandez · Mar 24, 2022

BHernandez said:
Had to let it sit a few days. Got a short video of cold start after a week of sitting. Very short rattle right at cold start last less than 1 second. The file is 39 seconds and says it's too large to upload here.

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BHernandez · Mar 24, 2022

BHernandez said:
https://drive.google.com/file/d/13mucFYZfGZWsQFhd5kBICDCvf7HzGjY5/view?usp=drivesdk[/UR

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BHernandez said:
Had to let it sit a few days. Got a short video of cold start after a week of sitting. Very short rattle right at cold start last less than 1 second. The file is 39 seconds and says it's too large to upload here.

Sounds much more pronounced from inside the car. Makes me think it's coming from the rear of the engine. Maybe torque converter? I don't know.

cobrajeff96 · Apr 26, 2022

To me it makes most logical sense that it would be a chain tensioner, as oil pressure takes a bit of time to work it's way up there. Not to say it could easily be something else though.

SnakeBit! · Apr 26, 2022

get a mechanic's stethoscope (cheap to buy) or a long screwdriver and listen to see where it is coming from. will help alot.

JPuehl · Sep 29, 2022

Was this issue ever diagnosed? I have an '01 Cobra with 4v 4.6 and also have a momentary "rattle" at cold start, but it happens during every cold start not just sitting for a few days. My car has ~70k miles and I plan to auto-cross race it more regularly next year and want to make sure I don't need to replace bearings before I start. Right now I daily drive it without any knocking/rattling sounds after cold start.