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Discussion Starter · #1 ·
I have a 99 7.3 with a manual transmission. When I'm taking off at low speeds I get a rambling/vibrating/rubbing type noise that seems to be coming from the bell housing or maybe far back in the motor. Only happens in 1st, 2nd, and Reverse (so far that's where I've gotten it to replicate the noise). Has 175k on it so I'm thinking it might be the flywheel or clutch but don't want to go through 6 or 7 hours of labor to find out I'm wrong lol. I'll be pretty specific here. It only happens at low speed. Of I depress the clutch it goes away but there's a pretty loud knock. If I let the clutch out slowly at about 1000 to 1200 rpm, no noise or it's really short. If I let off the gas it goes away. It only really happens if I take off slowly or creep around(I have to do that sometimes, I work construction) and only while slightly keeping the rpms up if I go WOT it jumps but doesn't pop no noise no weird behavior so I'm thinking it has to be the clutch or flywheel. I might be a retard though I don't usually play with manuals lol.
 

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What you're hearing is gear rollover noise, which is pretty common for the ZF-6 tranny. If your clutch disk snubber springs are giving up, it does get worse. But it's hard to tell how bad it is from your description.
The engine rotational vibration gets thru the clutch to the transmission, vibrating the gears together where they mesh.
The older 94-97 powerstrokes used a two piece (dual mass) flywheel with damper springs in it, but in 99, Ford changed to a single mass flywheel with damper springs in the clutch disk instead.
 

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Mine has done it from new.. If I was sure a new or different clutch would make the noise go away I would gladly spend the time and money to change it over.. Slight slipping of the clutch on take off will stop the noise, but just idling off or idling around such as in a car park you are stuck with it and it's quite unpleasant !
 

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Mine got a little better after a fluid change and a little better again after a clutch change. But still there and still pretty loud.
 

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Discussion Starter · #5 ·
*Bump* First of all
So I've come to terms with the noise and that it's probably there to stay. From my research it seems like all these answers are right. Fluid clutch, etc. to come. But before I start tossing coins in the pit I have another symptom of two. A slight leak coming off of the transmission drain plug....well maybe. I have the apparently infamous valley leak that I've slimmed down to the HPOP line going to the passenger side heads. It usually drips from the rear main seal area obviously and as far back as the pinch weld on the front of the transmission. This fluid is hard to pinpoint cause of course it gets dirty on the bottom of a 3/4 ton truck but it seems to have a lighter consistency than motor oil. Its a little less viscous as well. Also today I noticed a little bit of lurching in first and second gear when taking off. Before I have to hear it I know how to drive a stick lol. I've been driving them for a while. It happens between 50 and 75 percent clutch out. I'm thinking they might be separate. A clutch and then a loose drain plug. But is there some issue I could be overlooking here? I have to get this thing fixed I'm in pretty deep lol. I can do it I just want to have a good idea of everything I need to buy first.
 

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Hmmmm. The lurch sound like it could be clutch or pressure plate going.
Iv'e never had an oil leak with my ZF. But I have had the O rings on the HPOP go 3 times. Twice while under warranty and then again just out of warranty. Seems a bit strange they went 3 times in just over 5 years and haven't had to do them again since I replaced them myself the third time..... nearly 8 years ago. ( Still no leaks when i changed out HPOP for the Adrenaline )
Anyway. Make sure you clean the whole lot up real well, especially in the valley and then check for the leak. Not saying it's not the ZF :)
 
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