Rattle/Tinging on acceleration only.

Have a 92 XJ,

Have had this "heat shield" sounding rattle coming from the front end when I moderately accelerate from a dead stop, also have noticed it when on the trail when I am navigating an obstacle and accelerate moderately to get the front end up on it. Does not happen any other time at all. Ive replaced EVERY U-Joint front and rear, including axle shaft joints, I rebuilt the T-Case about a month after noticing it but still have the noise. Thought maybe something in the front axle, but just had the front and rear axles geared and still the noise. Its not the Cat, thats new. Its not the exhaust manifold, thats new.. Motor mounts are new, trans mount was good. Thought maybe the flex plate, bolts were loose, tightened them and put the inspection cover back on and still does it.. I've banged on everything I could think of up front and still cannot find where this is coming from.

Again, it is a metallic tinging that sounds almost identical to a loose heat shield. With windows up and radio off it sounds like its coming from the passenger side mainly. I am stumped, my friends are stumped, girlfriend is stumped.

Trans shifts and drives smoothly, Engine runs great, Transfer case works perfectly.

I have looked through countless forums and threads. So now I am here asking you all haha.

Thanks!

Brake dust shield ?


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I checked those, they are secure.

My mechanical fan did just about the same things. The fan clutch was going bad, and replacing it stopped the noise of the fan touching something when it moved during strong acceleration.

Will check that out today.

Make sure the fan isn't hitting the fan shroud. If the shroud is loose or cracked it'll make some odd sounding noises. Can sound like metal on metal or metal on "thud".

Have you checked your motor mounts?

Motor mounts are good. Going to check fan, fan clutch and shroud on lunch break. Ordered new FC just in case.

So even though everything is secure, the fan is somehow flexing enough when warmed up to hit, under moderate acceleration from a dead stop.

Doing electric fan swap since parts came in this morning haha. Thanks all for the help! I'll let you know if that solves my issue, but I'm preeeeety sure it will.

If you are flexing that much, double check the motor mounts and transmission mount.

old_man said:

If you are flexing that much, double check the motor mounts and transmission mount.

Click to expand...

Yeah, that

old_man said:

If you are flexing that much, double check the motor mounts and transmission mount.

Click to expand...

Right.

The fan is not really "flexing" that much...the whole engine is moving, when it shouldn't. The engine moves, the radiator doesn't...ergo, fan makes contact.

Do the motor mounts (and tranny mounts if there's any question). Even stock ones will make a difference and they're just about the cheapest, good thing you can do for your drive train

Motor Mounts are good. Trans was good when I pulled it last month when I rebuild the transfercase, although I might replace it anyhow.

That fan shroud looks as if it's been repaired a time or two. I'm sure those metal pieces and rivets have been added. It's a very tight fit down there, there was actually a factory service bulletin (I.S. 37E) issued on it back in 87. Service correction involved replacing the fan,shroud, and radiator crossmember depending on the degree of fan contact.

Oh wow lol interesting. Well after hooking up dual Electric fans and a fan control module, I no longer have that issue haha. The cooling isnt kept as low as with the fan clutch set up but it is consistent and stays cool.

Man, that fan shroud look pretty bad. Glad it's OK now.

I'm pretty sure those rivets are not OEM!

pandabear925 said:

So even though everything is secure, the fan is somehow flexing enough when warmed up to hit, under moderate acceleration from a dead stop.

Click to expand...