Got a rather annoying problem with my KJ.

When I start the car everything sounds normal, but as soon as I put it into D or R I get a horrible rattling sound coming from the engine bay.

The trans fluid is clean red and topped up. The sound fades away a little when the car is at operating temperature. It doesn't seem to impact on the way the car drives either.

Any ideas?

Hi KJ.ei, I'm almost certain that it is the heat shields under the engine that are simply rattling. They just need tightening. It is quite common with all 3rd gens, 3.0 and 3.5......in fact I am trying very hard to locate the exact source of this problem in my 3.5 as well!

Is the noise most obvious around 1200rpm or so? When you startup in the mornings, fast idle will have the engine right smack in the middle of this rev range, thus magnifying the noise.

It is not harmful and there is nothing wrong, it's just really annoying!

I don't get the sound when in neutral. Only when in drive or reverse.

I get this sound too, although only when the engine is cold... It's really quite concerning... :confused:

yeah mine just started doing this too, my first reaction was a loose heat shield or somthing. dont stuffed flex pipes cause the same sound??????

Maybe under acceleration. Mine only does it standing still with the trans in gear.

Mine too has just started doing this. it comes in at 2200 revs and goes by 2400. It really concerns me but car drives no different

Is it a rattle or a groan noise?
Sounds exactly like what i had.
I had this problem in my KJ AWD and had it back to Mitsub under warranty heaps of times. They put new engine pipes on, new cat with all new heat shields. Didnt make any difference at all. I was going to sell the car because it sounded so horrible and mitsub couldnt fix it until i spoke to ANthony from (chel'sTJ) who worked at Mitsub and he knew straight away what it was. Belts. He replaced both the belts (not timing belt but other 2), and problem solved, dead quiet.

Aparently the belts stretch and there is only so far you can adjust them until you need new ones.
Cant believe Mitsub spent huge money replacing pretty much my whole exhaust and it turns out to be just belts.
Shows you how much they talk to eachother when problem solving. NOT.

Could be the belts on mine. I can here one of them slipping occasionally when I have the air-con on.

its like a loud rumble/groan from somewhere internal inside the motor but is the belts.
Can do it at idle bu can also do it as you just put the foot down slightly at round 1200-1500rpm depending on how bad they are.

Rattling noises that are only there when in gear and not under load is due to vibration.
There is something loose in the engine bay, most likely the heat shield. Ever been on an old
bus that does not vibrate when in neutral or when it is going but vibrates like there is no
tomorrow when it is stopped for passengers.

Got my car serviced yesterday by mechanic... Found out the main nut on the tensioner pulley was MISSING :shock: They replaced it and now belt squeal is gone, and so is the rattle on startup when in gear! Hooray :D

Case in point, check your tensioner ;)

Thanks for that Lucifer.

Well it turns out my belt was loose. Took about 20 mins to tighten it up. Groaning/rattling sound is now gone! I just hope I didn't make it too tight.

If anyone else is having the same problem, check your belts.

ok. now the question is, how do i check my belts?
i had my timing belt done recently, so i know its not that,
but i can also hear slipping when the air con is on.
somebody told me it might also be the tensioner.

so all i need to know is how do i check all of this and is it an easy job?

I didn't have a belt tension gauge when I tightened up mine, but it clearly had too much slack compared to the oil pump belt.

If you can hear the belt slipping then I'd say it needs tightening. It's not a hard job, you just have to take the wheel off and the splash guard behind it. I can post a pic from the workshop manual regarding the tensioner if you like.

I've got a workshop manual. might just study it.
I have a torque wrench, i think i can get away with that.

is it worth replacing the other belts, or just tightening them?

Had the same rattle on my Second Gen 2.6 as well, went out and gave it a good check over...

...I left a screwdriver on top of the engine. Nothing major. lol

use a fishing scale... the one with the hook. pull the belt upwards to 10 kg and the belt should move

A/C belt 6-7mm new belt
8-10 old belt

P/S belt 8-9mm new belt
11-14 old belt

Update with my junk... Engine still rattles while in gear, sounds like my old asstron did except quieter. I will try my heat shields tomorrow to see if that fixes the problem.

My groan/squeal on startup (the belt related issue) is still non existant thankfully.