Hi all,

First post here - looking to see if anyone's had experience with this issue or might have suggestions as to what the problem might be:

Currently drive a '10 GX460 and noticing a light rattle/fluttering noise coming from the front end when the engine is cold and RPM's are above 2K. The noise is gone once the engine is warmed up. I've tried to replicate the noise while parked and the car idles/revs fine, so the issue seems to only come up while I'm driving the car. There doesn't appear to be any exhaust leaks or cracks in the header - wondering what else may cause this issue?

Any help would be appreciated!

 

How long does the rattle last? Cold start valve train noise is a sign of carbon building up in the engine a lack of oil flowing to essential parts. Your issue may not be this but this is a common problem. I use MMO (Marvel Mystery oil) religiously to help de-carb the engine and fuel system. The product is a combination of clensers and friction modifiers. Works fantastic and is very safe / cheap. $3.99 at Walmart. I use about 1/2 a quart mixed with whatever your oil you like. For the fuel system about 6 ounces for 20 gallons of gas to to clean the injectors and tank.
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​​​​Lots of good info on the products on BTOG forums as well. Love the stuff.

 

The rattle will persist as long as rpms are above 2K and will go away as soon as the engine starts to warm up. And to reiterate, if the car is stationary and I try to replicate the issue by revving the car while engine is cold, I don't hear anything. The noise seems to only come up when the car is moving/accelerating and rpms go above 2K... I will look into what you suggested though!

 

I wonder if there is something up with your fan clutch?

 

Cold start valve train clatter usually only last for a few seconds. Maybe 15 at most. I don't believe this is your issues. Nonetheless, using MMO still works fantastic for cleaning the engine and injection system. Highly recommend.

From your description sounds like something is loose and expands when it is heated. As Acrad mentioned the fan system is possibility, it might even be suspension related. I know it sounds odd but I have experienced things similar on other vehicles. Possibly that exhaust system. Really need to try to isolate where the sound is coming from.
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That's definitely been the tough part, replicating and then isolating the noise. Interesting you mention the suspension - I had my local mechanic try to look into the this noise while doing some recent work for my rear suspension as it was pretty worn, he couldn't replicate the noise but had mentioned it could possibly be suspension related... On that note, what ended up being the fix for your other vehicles with that problem that was suspension related?

 

Improperly torqued steering rack after replacement. Probably a slightly different noise then you are experiencing but the symptoms were the same. Only made the sound when vehicle was cold and while driving.

 

@gupc Check your exhaust heat shields (thin metal) .... they have a tendency to corrode (in areas that treat the roads for winter) which causes them to rattle at random times/moments in motion.
Easy fix is to remove the heath shield or apply a fender washer to hold it securely in place.
I had this happen to me on both my 4Runners living in PA and it annoyed the crap out of me for months until I could figure out what it was... (sounded like it was coming from the front but it was a heat shield about half way back ... the sound thru the floor made it seem like it was coming from the front.... )

 

Had the car jacked up today and poked around the heat shields, couldn't identify anything loose/corroded. The sound is getting really annoying and I just avoid going above 2K rpm until it's warm to dodge the issue...