rattling under the car before warm up, gear position "d", "r

[vincekim9]

Hi, My 98 XLT has noisy from under the car when put gear position "D" and
"R"....after warm up(5~10minutes later) decreasing slowly....I can not hear from engine room that noisy, probably come from joint position with engine and trans i think...
I put grease around U joint up, still rattling but much better, after week or 2weeks same noisy comming and put grease on again ...
Anyone has been same symptoms before?
Please advice me what's wrong with my X and how to fix it...Thanks!

 

[djjoonie]

my car did the same, it came out to be super rusty cat convertors.

 

[5.0 ANDY]

a few years after we got our 98 XLT some rattling/ vibrating sound started coming from the exaust, one of the tack welds poped off and the guard was vibrating on the CAT converter. we fixed it by putting a long hose clamp on it and that eliminated 100% of the noise.

mabe ur noise is something differnt, but might as well check.

 

[Aussie Explorer]

Yes I would go for the heat shielding on the catalytic converters too.

The Uni Joint on your drive shaft are not grease-able units so the grease is just getting sprayed around the under body and making a mess.

Can’t explain why putting grease on the uni joint quieted it down but as they don’t make a rattling sound even when worn out.

Cheers

 

[vincekim9]

I will check tomorrow on Cat converters...
Hi Aussie X did you fix your X?

cheers

 

[vincekim9]

I checked Cat converters...but it is tight...where does noise come from?
also I can hear chipping noisy between 600~700 rpm from under the car.
noisy gone when put accel over 1,000 rpm.....headache..
I replaced 00m12kit already...really no idea.

 

[foxy]

rattle

Mate what I did was to dump my 2 cats and put 2 hot dogs in place of converted the system to 21/2" with a high flow box then put a 3" cat after that more hp and better torque with a bonus of sounding like it has balls

 

[vincekim9]

Thanks! all, I found it!!! Cat converter Heat shiekld and, Knocking from the
engine....I fill premium fuel up and better feeling during come back home....I think need replace spark plug and wire.
I am sure rattling start after change spark plug(NGK IX Iridium) & wire(aftermarket). I swiched #5 and #6 wire when install. possibly damaged with new wire or plug....
I order "motorcraft dual platinum plug(SP500) & OEM wire.
will reply after replacement!
also i order OBD2 scan too will check o2sensor and Cat...etc

Cheers

 

[Aussie Explorer]

I am running the same Plugs and leads as you, have been running them for the last 20,000k and have had 0 problems.

Cheers.