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Discussion Starter #1
I2004 TJ 4.0 manual

I just noticed that when I start to move in first gear from a dead stop there is an initial knock under the floorboard (faint but it is there). Then when I shut the engine off there is a couple knocks as the engine cuts off. I noticed it does it as the car has been driving longer, so evertime I take off from a dead stop there an initial knock or two.Its really starting to concern me because it does it evertime now when I take off and when I shut down, kinda faintly does it when I idle into my garage in sync with the drive pattern.

It never did this before I changed my diff, transfer case, tranny and oil fluids. I dont have any leaks and it seems to run fine. My question is what could have caused this and where do I look first. It only has 44,000 miles.
 

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The only thing I can think of related to your fluid changes is, make sure you didn't replace your diff fill plugs in too far. I've read here they can make contact with the gears. Good luck.
 

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I2004 TJ 4.0 manual

I just noticed that when I start to move in first gear from a dead stop there is an initial knock under the floorboard (faint but it is there). Then when I shut the engine off there is a couple knocks as the engine cuts off. I noticed it does it as the car has been driving longer, so evertime I take off from a dead stop there an initial knock or two.Its really starting to concern me because it does it evertime now when I take off and when I shut down, kinda faintly does it when I idle into my garage in sync with the drive pattern.

It never did this before I changed my diff, transfer case, tranny and oil fluids. I dont have any leaks and it seems to run fine. My question is what could have caused this and where do I look first. It only has 44,000 miles.
Might check your spark plugs for connection / tightness. Spill any oil on them?
 

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What about transmission mount? And check to make sure your exhaust pipe is not hitting anywhere when it moves around.
 

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It is your exhaust pipe hitting. Move the mount around on it and it should stop.
 

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Discussion Starter #9
Thanks! I dont think the oil got on any spark plugs and its not engine knock. I will look at the exhaust a little more too (I hope thats all it is).
 

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Discussion Starter #10
One more thing. This clunk I am referring to, I can actually feel it under the floor board. So would the exhaust be the only culprit if I can feel it and hear it?
 

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Either the exhaust or your transmission mount is bad/loose.
 

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Did you remove/loosen the skid plate to change the transfer case fluid (if you actually replaced the transfer case fluid)?

I assume the problem is related to your recent work in some way unless it's coincidental.
 

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Discussion Starter #13
Did you remove/loosen the skid plate to change the transfer case fluid (if you actually replaced the transfer case fluid)?

I assume the problem is related to your recent work in some way unless it's coincidental.
No I did not remove the skid plate I let the transfer case fluid spill onto the plate and out the drain holes in the skid plate.
 
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