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wow i used to have that thud as well...now that u mention it I have not heard in a while, wish I knew what the hell it was to give u some insight if someone chimes in with an answer i would be happy to know what it is.

 

Never heard of this issue? But try checking your starter, see if it's loose. Have someone listen and see where the thud is coming from?

 

Is your defroster or AC already on? If so this is a known issue. At cold start the ac compressor engages with a thud or crashing sound. I learned early on to make sure it is off at start up and to turn it on only after the engine has been run for a minute or so.

 

I've tried to have someone listen for it. No luck. It's too loud outside and the noise thud is a little softer.

I don't have my AC on or my defroster. And it doesn't matter if it's on or not, i still feel and hear that thud sound.

Sounds like something is loose. Something mechanical in nature. I tried checking around in the engine bay for something loose...but nothing.

I'm afraid if I take it in for warranty work they won't find the problem and still charge me for the time. Or blame me and say it's the lift...like last time with another issue.

Any other ideas..? :disappoin

 

I've tried to have someone listen for it. No luck. It's too loud outside and the noise thud is a little softer.

I don't have my AC on or my defroster. And it doesn't matter if it's on or not, i still feel and hear that thud sound.

Sounds like something is loose. Something mechanical in nature. I tried checking around in the engine bay for something loose...but nothing.

I'm afraid if I take it in for warranty work they won't find the problem and still charge me for the time. Or blame me and say it's the lift...like last time with another issue.

Any other ideas..? :disappoin

if it's under warranty, they won't charge for their time..... at least a decent shop wouldn't. if you can re-create the sound, just take her in to your local yota dealer and DON'T LET THEM TELL YOU IT IS NORMAL!!!!!!!!!!!

Anything to do with the lift would happen when you're moving anyway.... it can't be the lift causing the "thud"

It might be the starter head retracting off of the flywheel at ignition...... ie. not aligned properly. it happens every single time you start the 4.0?

 

Thanks eyedoc and everyone else for thier responses.

Yeah, it happens everytime I start the truck. It doesn't matter if it's hot, cold, high elevation or sea level. It's consitent everytime and happens at ignition.

Maybe something's loose. I dunno. I just took a long (well long for hawaii...few hundred miles) road trip and no problems. I'm thinking I'll bring it up at the next service check-up. I'll try and check things again this afternoon. Nothing bad has happened since it started...it's just annoying and it could be bad down the road.

I'll go check the starter stuff...

 

Fixed it...

I decided to take off my intake and revert back to stock. I also unhooked my battery again. It seemed like the first time I disconnected it I didn't do it long enough. I waited a few minutes, but my radio stations were still set.

So I disconnected it again and left it for the duration of my intake swap.
Hooked everything back up, prayed, and started her up. No thud!

I'm thinking my truck computer must have learned some random driving habits. I was driving it hard for a bit. That might have caused it.

I put back my intake, again, and no thud still. Truck runs good.:thumbup: Thankfully it was a simple fix.