| Author |
Message |
    
Matt M
| | Posted on Tuesday, March 19, 2002 - 05:13 am: | 
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Can anyone tell me what this noise is ?
http://www.mmaddock.com/engine.wav
recorded from under the front of my Disco v8.
It isn't there when you first start up, but after driving 500 yards it starts. No noise when driving normally, but whilst idling it sounds awful. It just started in the past few 100 miles or so.
I would like an idea of what it is before it goes in for a service and I get ripped off by the dealer replacing unnecessary parts.
Thanks
Matt. |
JMcD
| | Posted on Tuesday, March 19, 2002 - 07:02 am: |
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Wow!! I am unsure about the noise, but am seriously impressed with how you got that recording on the computer!!
I will take a shot, since no-one else has tried yet, It almost sounds to me like it is not firing on all 8 cylinders, my chevy had a bad plug and it sounded just like that.
Does the engine have good power?
Is it running/driving alright? Some more info alomg with that sound bite will help alot, there are some sharp guys here on the mighty D-Web. More info. JMcD |
JMcD
| | Posted on Tuesday, March 19, 2002 - 07:06 am: |
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OK, I just reread your post, probably not a bad plug, did you check the accesories? water pump, alternator,a/c comp,power steering pump? Grab the pulleys and see if they are loose. Just my best guess, but better than nothing. JMcD |
Matt M
| | Posted on Tuesday, March 19, 2002 - 07:19 am: |
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Engine seems to be running fine.
Actually, the recording isn't that representative of the sound - I was a bit dissapointed. A friend did it for me on his MP3 player.
It actually sounds a lot more metalic than that, like a piece of metal rattling against metal.
If you have the ability to turn down the base and the trebble up, that makes it sound a lot more like it actually is. I have an idea it may be a loose exhaust, but can't find any bits loose.
Thanks
Matt. |
Michael Noe (Noee)
| | Posted on Tuesday, March 19, 2002 - 07:40 am: |
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Could it be that piston slapping phenomenon that has been discussed? |
M. K. Watson (Lrover94)
| | Posted on Tuesday, March 19, 2002 - 07:52 am: |
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sounds like an exhaust leak. it disappears as the rev change. i have a similar noise and it changes as the engine speeds up. so i have crawled in and thru and under and found a leak of the exhaust in the area of the forward part of the muffler. well thats the noise my 94 is making and thats the problem i have. good luck
mike w |
Mike J. (Mudd)
| | Posted on Tuesday, March 19, 2002 - 10:38 am: |
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I didn't hear the clip but bad cats are so common and get diagnosed as all sorts of things. My guess: Bad cats! meow. |
Kingfish (Kingfish)
| | Posted on Tuesday, March 19, 2002 - 11:04 am: |
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Sounds like fred sanford's truck! It has to be more than a leaky exhaust. Have you checked timing and other ignition related areas? I gotta learn to record that stuff too. |
Bruce
| | Posted on Tuesday, March 19, 2002 - 12:12 pm: |
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I would recommend checking the fan since it sounds like a cat is caught in the fan shrowd. Has anyone lost their cat lately? If you can't clean-out the body, after awhile it will ripped to parts and eventually fall out. Sure covers-up the smell of oil on exhaust manifold, you just wait... |
jp
| | Posted on Wednesday, March 20, 2002 - 05:45 am: |
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I know it sounds very metallic, but I would bet on an exhaust leak. check the nuts on the flange from manifold to down pipe for obvious looseness, or missing altogether. The noise is very typical of a small leak, and it sort of becomes inaudible when you rev it. Watch out for stripping/breaking the studs - lubricate with antiseize. You may need to replace the gasket if it has been burnt through by the leaking hot gases.
jp |
Tad
| | Posted on Wednesday, March 20, 2002 - 07:04 am: |
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Matt
FWIW I have to agree with the exhaust theory. Since it isn't there when you first start up it has got to have something related to the heat and since the most heat is at the exhaust...
When we had some exhaust work done the fine examples of intelligence at the muffler shop didn't tighten down the conection between the manifold and the y-pipe. I went back to them PO'd thinking that they did something to cause and exhaust leak in the system. Darrell looked at Darrel and said "manifold gasket." "You sure," I said. "Yep, I worked on this myself." I ordered two new gaskets and installed them, old ones looked fine - but who am I to question Darrel -- started the engine and the sound was still there. Further inspection, I found one of the nuts on the manifold stud gone.
Long story to say check you exhaust system.
Have Some Fun!
Tad |
Matt M
| | Posted on Wednesday, March 20, 2002 - 09:42 am: |
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Thanks everyone
I'll give the exhaust a really good checking over.
I was reading all the bills/records from the previous owner recently - one of them was about the exhaust. They had complained of the exhaust blowing around the engine - written on the report was 'Reason : Bolts missing' - I guess this is a common complaint - I never heard of it on any other cars though !
I just had a quick look at the exhaust - doesn't appear to be any obvious bolts missing that I can see, but I didn't go underneath (it's raining quite a bit here at the moment, and I would have had to lay in a puddle - not a good idea in work clothes !!) When the weather improves I'll have a better look.
One thing I did notice, someone has pushed loads of filler around about 4 (2 on each side) of the exhaust ports on the engine block. Presumably the gasket has gone here and they couldn't be bothered to fix it. I guess it is a good idea to get that sorted - can't be much trouble to do can it ?
Matt. |
Alex S. Moore
| | Posted on Wednesday, March 20, 2002 - 10:46 am: |
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Hey Matt, check the catalytic converters. Sounds like one of them is shot and the material is rattling around inside. Had this happen on my 90 rangie. Sure does sound like a conn rod is about to drop, doesn't it!! Hit the cat with a rubber mallet and if you hear anything loose inside its doa. You dont need to get a rover unit, a good muffler shop can install a generic one.
Alex Moore
joplin, Mo. |
Jay Hobbs (Jayxd)
| | Posted on Friday, March 22, 2002 - 12:43 pm: |
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Mine sounds just like that and it is very likely the catalytic converter. My tech gave it a whack for me and it fixed it for a few days. It is an aweful sound, I thought I had a major problem when I took it to him. I'm checking to see if this 80,000 mile warranty thing is valid but I'm not keeping my finger crossed. |
Matt M
| | Posted on Friday, March 22, 2002 - 02:11 pm: |
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I suspect the 'cat' theory is correct, they look a bit knackered - now I've had a good look underneath, one of them looks as though someone's welded a plate to it, to patch it up.
£450 ($700-ish) for 2 new cats (+ Y-piece) any other options available? don't really see the point in changing one without the other, as they're both likely at the end of their life anyway.
Thanks
Matt. |
p m
| | Posted on Friday, March 22, 2002 - 02:15 pm: |
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Matt, if you rule exhaust leak out, -
it sounds like 2 flat valve lifters.
peter |
Mattt M
| | Posted on Saturday, April 13, 2002 - 05:48 pm: |
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Got new cats in today - it's running sweet as now. Don't know if it's my imagination, but it seems to be running smoother too.
I had a shake of the old cats, the baffles were completely loose inside.
Naughty cats !
Matt. |
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