Need help diagnosing car noise

[Java]

I have a 2003 Ford Taurus SES 3.0 SOHC V6 automatic, about 89,000 miles on it. It makes a loud rattling sound, almost a grinding sound that seems to emminate from the engine side of the firewall slightly nearer to the passenger side ONLY while in gear and travelling at about 25 mph +/- and accelerating. You can rev the engine in park or neutral without it happenning. Absolutely no effect on performance in any way. It is loud when the car is cold, gets better as it warms up. I've checked all of the heat shields (fixed a loose one, not change) and have reached all around the engine / transmission from above and below and touched everything with a hammer or a drift and nothing is loose. I'm thinking catatlytic converter??? there are two of them in this model, they are mounted (the engine is sideways, it's FWD with the belt on the pass. side) after the exhaust manifolds but before the pipes connect into a single exhaust. whacking them gives me nothing except a little thrill, I'd expect a rattle... any other way to tell which one it may be? I guess if I can't be sure I'll replace the one with the manifold closest to the firewall first, seems most likely with the noise being sort of more to the pass side, but they are both near each other where the pipe "Y's", not by the manifolds, so it's not a clear call. anything else you can think of? I can't imagine a bad mount or a CV joint or even the A/C (works fine) making quite that sound, but anything is possible... transmission is possible but beyond me to do anything but r/r. :confused:

[Popsgarage]

Would have to listen to that one in person before I'd even guess.

[Brody]

Hey Paul

If you can stop by today or tomorrow, I'll be happy to poke around and see what I can find. Noises that only happen when you are driving are SO fun....Sounds like you are chasing down the usual culprits, too. If the CAT is bad, you will hear it rattle when you get the atavistic thrill whacking it..(something I don't especially want to get into. How you get thrills, judging from a couple of your other posts, well....let's just say.."don't share with me":lmao:)

I have spent a lot of time this last year chasing down mystery rattles/noises on quite a few different rigs, including my own. Can't say that I am great at it, but there is only one running around with a very intermittent rattle now.

I just fixed a rattle on Chris' 4Runner. I had built some skid plates and due to the classy design of the Toyota exhaust, a stylish and well thought piece of cretinish engineering, you have to cut out and relieve the skid plate for where the exhaust crosses under the frame member. On the 2009 Taco in my driveway, if you want to see it. Land Rover had the same cretin design the exhaust on the newer Rovers...Anyway, rattle on start up, intermittent after that. Finally found it. The exhaust was barely hitting the cut out in the skid plate. I cut it out a little more, noise went away. Then it came back, but on the other side. I finally came to the conclusion that the rubber exhaust grommets were worn to the point that they were allowing the exhaust to sag just enough to cause a rattle. I replaced all of them and the entire exhaust system was raised up between 1/2 and 3/4" inch.

Anyway, working on relocating some Jeep coil buckets this afternoon, but should be more or less free tomorrow...

[Java]

Would have to listen to that one in person before I'd even guess.

coward. :lmao:

[Java]

My work schedule lightens up this weekend, I may be able to bring it by tommorow (barring changes). Thanks for the offer, that's cool of you. It's been making this noise for a long time, I'm just considering selling it and want to get it straight first. I may take it to a shop, I hate working on that car, you cant see / reach anything. I thought it had to be the cat, but they usually do rattle when you hit them. I think maybe the mounting position of the cats may prevent them from rattling, they're not horizintal.

Thanks for guessing! Jon is right, you'd really need to hear it.

[Brody]

Just holler on the home phone 303-761-4818 or my cell 303-507-3066. I may have to do some stuff way out east sometime tomorrow, but haven't heard back from the customer yet, so I have no idea what time.....or even if tomorrow is going to work for her..

[Rocket Scientist]

I would suspect the steering rack. Those things are notorius for making noise, worse when cold.

[Java]

Could be... may be a moot point at this stage, we'll see.

[Java]

It was the waterpump... the engine is sideways in the bay, you have about 2" of room to work in so diagnosing it was impossible for me until it started leaking from the weephole. Replacing it took over 6 hours, some of the bolts you can't see and work on at the same time. I didn't actually figured out the noise, it just went away with the new pump. I've never had a waterpump fail w/o leaking right away, and only make bearing noise at about 2000-3000 rpm and only in gear. Cars are weird.

[Squshiee1]

i had the same problem, replaced my water pump and now i can hear my alternator!

[xaza]

Glad to hear you got it fixed. For future reference, if you think you have an exhaust leak you can check by having someone cover the tailpipe (use good thick gloves) it will force the exhaust out the "leak" and you will be able to hear it.