Rattle in engine bay on warm start-up?
04-17-2006, 01:36 PM
#1
Thread Starter
Rattle in engine bay on warm start-up?
Couldn't find anything on a WARM engine start.
When I've driven the car and it's been parked for less than an hour or so, I go and start it, I heard a rattle for about a half second in the engine bay. Not sure it's valvetrain noise, but it's really weird in that it only does it when the engine is already warm, but hasn't sat too long.
During a cold-start up there is no noise at all. It's really weird.
BTW: Oil level is full, has not burned a drop in the 4,000 I've put so far on this Mobil 1.
When I've driven the car and it's been parked for less than an hour or so, I go and start it, I heard a rattle for about a half second in the engine bay. Not sure it's valvetrain noise, but it's really weird in that it only does it when the engine is already warm, but hasn't sat too long.
During a cold-start up there is no noise at all. It's really weird.
BTW: Oil level is full, has not burned a drop in the 4,000 I've put so far on this Mobil 1.
04-17-2006, 01:53 PM
#3
Thread Starter
Hey Mark! Yeah, it's highly metallic. I seriously doubt it's valvetrain noise, maybe something to do with expansion of the metal in the heat shield and vibration from the engine on start-up that causes the rattle. Even goosing the engine immediately after start-up results in no valvetrain noise. Engine has always been very quiet on start-up irrelevant of the outside temperature.
Maybe at a future meet, I'll let the car sit for a few minutes and have someone start it up while I look in the engine bay to see if I can isolate the noise.
Or just not worry about it. It's less than a half second of rattle under certain conditions.
Maybe at a future meet, I'll let the car sit for a few minutes and have someone start it up while I look in the engine bay to see if I can isolate the noise.
Or just not worry about it. It's less than a half second of rattle under certain conditions.
04-17-2006, 07:02 PM
#4
Registered User
Hmm, weird... How's your oil level? Canadice and I noticed when we did her oil change that there was a rattling sort of sound for a half-second or so immediadely upon initial startup. We theorized that there were air pockets in the oiling system due to the change that were getting flushed.
04-18-2006, 06:18 AM
#5
Thread Starter
Oil level is and has been at the top mark. I changed to synthetic at 3k miles to Mobil 1. That was at 3,000 miles. I'm now at 7,200 miles and have not burned one drop of oil in 4,200 HARD miles on the synthetic. Car really runs great.
I've heard valvetrain noise for a second or so in other cars after changing the oil because the new oil needs to 'push' through the oil filter upon first start-up. That's what I theorize anyway.
I'm not going to worry about it. I'm 95% sure it's something rattling in the engine bay for a half second on a warm start and not valvetrain noise. Even if it were valvetrain noise, a bit of rattle on start-up will not cause any significant damage.
GM certified their '01-'03 smallblock 5.3/6.0L motors to 100k for a lot of people because of piston slap on start-up. GM swore it didn't cause any damage over a long period of time.
I've heard valvetrain noise for a second or so in other cars after changing the oil because the new oil needs to 'push' through the oil filter upon first start-up. That's what I theorize anyway.
I'm not going to worry about it. I'm 95% sure it's something rattling in the engine bay for a half second on a warm start and not valvetrain noise. Even if it were valvetrain noise, a bit of rattle on start-up will not cause any significant damage.
GM certified their '01-'03 smallblock 5.3/6.0L motors to 100k for a lot of people because of piston slap on start-up. GM swore it didn't cause any damage over a long period of time.
04-18-2006, 06:22 AM
#6
Registered User
My guess is that your heat shield has loosened up a bit after the car gets warm, ,so right when you start the car it rattles a bit. IMO you're bein a wee bit paranoid. 
04-18-2006, 07:02 AM
#7
Thread Starter
I totally agree on the paranoid part. It's an old habit worrying about little stuff. Particularly considering this is my first leased car! I should care less as it's under factory warranty the whole time I'll have it.
It's an old habit worrying about little stuff. Particularly considering this is my first leased car! I should care less as it's under factory warranty the whole time I'll have it.
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04-18-2006, 09:40 AM
#9
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I think i had this same thing. Does it sound like the valves are tapping a little? Mine did this when i was using 5w-30. I switched it to 10w-30 and hear no more noise. What grade do you use?
06-04-2006, 06:59 PM
#10
Hi,
I had the same noise when I Used the Fuchs GT1 0-20w on warm start and it was like a minute or so.
I had no problems like this before.I used this oil before when I was NA and no problems.I went comptech FI and put 10-40 motul 300V and my car was burning oil like crazy always and even more with this Motul but no Valvetrain noise but now I went 0-20 and very bad noise is there when hot start... and I doubt its heatshield because it will always buzz in my opinion.I switched to USA Mobil 1 10-30w and no noise but some times on warm start up maybe few seconds.Not more.Now today I was driving highway and went 140mph and when I came back there was loud Clicking noise under the bonnet and it doesn't go away and its different than the start up noise....Damn ...My Mechanic heard it and we will open the Head Cap tomorrow to Inspect it and he Suspects Chain Belt tensioner ..he thinks its hydraulic and its bad..And he assumes its oil related with the 0-20w I used.
I will keep you updated - will write tomorrow what we find out.
Our car likes heavier oil I think and minimum is 40 and I will put Castrol RS 10-60W next. Fi -more heat - thicker oil.
I had the same noise when I Used the Fuchs GT1 0-20w on warm start and it was like a minute or so.
I had no problems like this before.I used this oil before when I was NA and no problems.I went comptech FI and put 10-40 motul 300V and my car was burning oil like crazy always and even more with this Motul but no Valvetrain noise but now I went 0-20 and very bad noise is there when hot start... and I doubt its heatshield because it will always buzz in my opinion.I switched to USA Mobil 1 10-30w and no noise but some times on warm start up maybe few seconds.Not more.Now today I was driving highway and went 140mph and when I came back there was loud Clicking noise under the bonnet and it doesn't go away and its different than the start up noise....Damn ...My Mechanic heard it and we will open the Head Cap tomorrow to Inspect it and he Suspects Chain Belt tensioner ..he thinks its hydraulic and its bad..And he assumes its oil related with the 0-20w I used.
I will keep you updated - will write tomorrow what we find out.
Our car likes heavier oil I think and minimum is 40 and I will put Castrol RS 10-60W next. Fi -more heat - thicker oil.