4RUNR

It's coming from the front end when the engine is cold in the morning, sounds like metal on metal around 1500-1700rpm. Sounds exactly like a loose skid plate. The rattle goes away after the engine is warm, and strangely does not reappear later in the day, even if the engine has been sitting for 8+ hours.

So I naturally pulled the 2 front skid plates, they were pretty secure on though.

The 2nd plate was rusted through in 2 places! It looked like some sort of plate was welded in the same place where the rust holes are, but obviously that didn't help it any in short 4 years. The weld on and the plate itself were almost dust in those places.

What caused this?

Fink

I have a rattling that comes from the front part of my truck as well...it turns out it is a Radiator hose that is clanking together with another hose...it is RIGHT underneat the very front skid plate...but its there all the time.

If the noise happens only after the rig warms up then it has to be something with the engine/drivetrain.

I dunno what could have caused those holes, leaking batter acid? LoL, I dunno.

Lemme know what you find out.

4RUNR

The rattle is still there, with both skid plates off :pat:

Sounds like something is resonating with the engine.

Lefty

Check out the exhaust manifold heatshield. The heatshield may be rattling against the manifold\headers when cold. I had a '98 Dodge Ram for several years that did the exact same thing.

Steve

Roadrunner

I was getting pretty pissed with a rattling sound on the front end of my 4Runner whenever I went over a bump/dip in the road. I finally figured out what was causing this... the rollers on my winch.

Fink

I agree with the heatshield/manifold thing, I had a buddy of mine put some rubber washers on there to keep it from doing it. No noises anymore!

Let us know man!

4RUNR

It turned out to be the shield on the second cat converter. The shield that (keeps it at operating temperature?) rusted away at one of the bolt points, hence the resonance when cold. I just stuck a little steel wool in there to keep it quiet for now.

Would that shield be not under Toyotas emission components warranty? Or rattles don't count?

MTL_4runner

Heat shields tend to be (from my experience anyway) the most common cause of rattles on older cars or cars that have seen a few winters. When I used to be a mechanic I can't tell you how many rattling shields I zipped off with my air hammer (best tool ever!).

bamachem

rattles, i doubt it, but RUST, i think they would - who knows... maybe the warranty is only for emission and functionality.

4RUNR

Here's where the skid plate rusted clean through in both places! (symmetrical) Under the brackets for the steering rack. It's pretty dry as you can see. Replaced the places where holes were with plastic so it won't happen again. But why did it happen in the first place?