What Truely Makes The Sound Of The 4.0 - JeepForum.com

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post #1 of 9 Old 03-21-2007, 09:36 PM Thread Starter
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What Truely Makes The Sound Of The 4.0

ive always wondered. ive heard a few things of what makes the 4.0 sound as it does after many miles. what really is it that makes the baby diesel sound? ... always wondered and never thought to ask.. hmm

99 XJ Classic, 4.0, AW4, 8.25 Rear
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post #2 of 9 Old 03-21-2007, 10:30 PM
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cracked exhaust manifold...
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post #3 of 9 Old 03-21-2007, 10:37 PM
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Originally Posted by BoHeck
cracked exhaust manifold...

i need to fix mine

its torquey at low RPM, diesels are torquey at all RPM...thats my opinion, then again i don't think it sounds like a baby diesel

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post #4 of 9 Old 03-21-2007, 10:45 PM
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Valve tapping... I6's have done it since day numero uno...


Coming soon: 2000 Jeep Sport (modifications soon after) :-)
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post #5 of 9 Old 03-21-2007, 11:16 PM
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it may have something to do with it being an inline design, and not being tuned for quietness

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post #6 of 9 Old 03-22-2007, 06:33 AM
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The clatter you hear is likely detonation. The 4.0 doesn't have knock sensors, and after enough miles and carbon build up on the valves and pistons, every 4.0 I've heard begins to knock.
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post #7 of 9 Old 03-22-2007, 06:52 AM
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Originally Posted by 1BadJeepX06
Valve tapping... I6's have done it since day numero uno...

Exactly. Inherent issue with straight sixes. This is why the CTD is such an obnoxious diesel - it has the glory of being not only an extraordinarily powerful diesel, but also an I6.

My first car, back in high school, had the old Dodge slant 6. It made an awful racket, but ran beautifully and reliably. We actually nicknamed it the "buzzbuggy".

Oh wait, that had nothing to do with the engine, that's just what we told our parents.
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post #8 of 9 Old 03-22-2007, 07:13 AM
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mostly the injectors, mixed with the leaky manifolds, the valve tapping, rattle of the throwout bearing, fan cl utch cycling on and off..

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post #9 of 9 Old 03-22-2007, 08:26 PM
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lol watever you do, dont disconnect the exhaust fromt the manifold and drive around... unless you wanna sound like your driving a farming tractor around(worst sounding engine i've ever heard in my life including ricers!)
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