Clunk from the front when 4x4 is engaged

[benztech82]

Since I have bought my truck I had this issue with this clunk that takes place only when I'm driving with 4x4 engaged and only with rapid acceleration. I hope it's not the front diff gears or diff bearings. Is there a common issue with transfer case, transmission and or front axle mount bushings? Did anyone experience same issue?

Thanks.

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[TowMeOut]

Hmmm....no good ideas at the moment. However, is it the same regardless of Hi, Lo range and the Diff Lock? Do you get the clunk when you hit the gas then another similar one when you let off quickly? Just trying to figure out if perhaps the front diff mount has come loose....

 

[benztech82]

Hmmm....no good ideas at the moment. However, is it the same regardless of Hi, Lo range and the Diff Lock? Do you get the clunk when you hit the gas then another similar one when you let off quickly? Just trying to figure out if perhaps the front diff mount has come loose....

Thank you for your suggestions. I have to try it with diff lock and 4 low. Clunk is there only when I press gas pedal quickly but not when I let it go. Oh I also tried lubricating all yokes and joints of the prop shaft too. No play there for sure.

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[benztech82]

Tried to switch between 4LO and t-case lock, it didn't make a difference. Makes a clunk under sudden hard acceleration.

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[84ability]

have you greased these fittings? there are 3 in front of t-case and 3 behind it

 

[benztech82]

have you greased these fittings? there are 3 in front of t-case and 3 behind it

Yes, I did it 4 times within 10k and I got rid of the thump on downshift and when I was sitting at the lights but it didn't take care of that clunk from the front on sudden acceleration. It feels like worn engine mounts on a front wheel drive car. Obviously it's not the case with a 4runner. Only when 4x4 is on I get this annoying clunk.

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[Leroux]

Yes, I did it 4 times within 10k and I got rid of the thump on downshift and when I was sitting at the lights but it didn't take care of that clunk from the front on sudden acceleration. It feels like worn engine mounts on a front wheel drive car. Obviously it's not the case with a 4runner. Only when 4x4 is on I get this annoying clunk.

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I have the exact same clunk, only when 4x4 is engaged so it must be on the front end. Did you find out what it was ?

 

[benztech82]

We narrowed it down to the transfer case, something is clunking inside when load is applied, either rolling or stand still. It's been like that since 2018, still clunking today but I just avoid it by accelerating gradually. I honestly think its a chain slap inside.