Clunk sound after startup

[Millerad1651]

So this morning, after driving into work, I restarted the runner. Right after it turned over, I heard and felt a "clunk clunk." That was the first time thats ever happened. I drove down the parking lot and shut it off. I restarted it, and the same "clunk clunk" right after it started. It was in park both times, and the engine was warm, so I don't think its due to being cold. Any ideas? It feels like its under the engine, maybe more on the passenger side. After the noise, it sounds fine and drives fine. Really freaking me out right before a road trip!

 

[DHanz]

I'm not a 4Runner owner but a few Jeeps I owned would clunk their exhaust pipe on the transmission crossmember when the motor mounts and transmission mounts got a little tired and saggy due to age.

I would usually first hear the sound when starting the vehicle. Then as the mounts got a little saggier the pipe would kind of buzz on the crossmember while idling in gear. It would change at different RPMs and whether or not it was in gear or not.

It was just a interference problem and caused no real harm to anything. I usually just gave the pipe a little more clearance to get more miles out of the mounts.

Again, I don't know if this applies or not. You'll probably have to lie on the ground to look and listen while you have a friend starting your T4R for you. Just keep doing it until you locate the source of the noise and take it from there.

 

[Millerad1651]

I dont think it was the exhaust hitting anything. I read in some other forums that it may be the a/c compressor. Apparently if the defrost is on, the clutch kicks in and can make that noise. I usually turn that off before starting, but i was in kind of a hurry. I tried it again while the defrost was off, and it didnt do it. Anyone else have that happen?

 

[DHanz]

I tried it again while the defrost was off, and it didnt do it.

I'm glad to hear that you haven't heard it since.

 

[Baja Runner]

Yeah I was going to say exhaust.... hmmm. .

 

[Millerad1651]

So apparently its not the ac compressor. It has been doing the same clunk, but not every time I start up. I looked under the hood while it was started, but didn't hear or notice anything, but they could hear and feel it in the cab. And now there is a slight vibration under my feet while its sitting still/at idle. Its just started in the last few days. Anyone have this happen, or have any ideas?

 

[sabatorious]

Clunking sound after startup

So apparently its not the ac compressor. It has been doing the same clunk, but not every time I start up. I looked under the hood while it was started, but didn't hear or notice anything, but they could hear and feel it in the cab. And now there is a slight vibration under my feet while its sitting still/at idle. Its just started in the last few days. Anyone have this happen, or have any ideas?

Hi there - were you ever able to figure out what this noise was? I have a 1997 SR5 4Runner with the same sound/feeling that you have described after each startup. Sometimes it happens after a few seconds, sometimes it is after a minute - but always does it, and close to start up. I've noticed that you can't really hear it all that well from outside the vehicle, can more just feel it and hear a slight 'clunk' while in the truck.

Does your transmission drop pretty hard into gear, especially if you don't let the vehicle warm up for 30 seconds to a minute? I've noticed that if I go from Reverse to Drive without hitting neutral for a fraction of a second it really jolts. Perhaps it's all tied to the transmission, I'm not sure what to think. Do you have a similar issue?

By the way, I have about 173k miles on my truck. Recent oil change (although have noticed the slight burning oil smell, and oil drops a bit between changes, but no leakage). All else in good order.

 

[Millerad1651]

It turned out to be the exhaust sitting on the crossmember. Any time the truck started up, it would shake a bit and clunk against the crossmember. It also started happening whenever I hit a bump in the road, which in Indiana is frequently.

I ended up getting new exhaust hangers welded in with a new muffler and its been fine ever since.