Toyota Techs please try to diagnose.
- Thread starter 4RunnERD
- Start date
4RunnERD
New member
Will I got the belt off and started the egine and no noise. Didn't run it long enough for it get warm, put the belt back on and no noise. WTF. Only difference was it was 85 out and the truck was up on ramps all night. So either the temp cut off for the noise is 82 or lower, or having the oil tilted towards the back of the engine helped start up lubrication.
4RunnERD
New member
Left the vehicle over night at the dealer as there was some warranty work that needed to be done. When they started it this moring they said the didn't hear anything. Atleast they didn't charge anything for that. I guess I'll just have to bring it back when I know for sure it will make the noise again. It appears 80 degrees or warmer is the cut off for the noise. May have to wait unitl fall. I'll update later. Thanks for everyone's tips and advice.
Eastcoastrunner
New member
which belt??
4RunnERD
New member
Update.
Alright guys here is the update. The day after I got it back from the dealership for the first time (when they claimed they didn't hear it) I started it up at home and it made the noise for me. I took it back into the dealership and let it sit over night. I met the tech the next morning and started the 4Runner with him sitting in the passenger seat. He heard it this time and they kept the vehicle all of that day and most of the next. They said they thought they might have found the culprit, but weren't 100% sure. In the pic below there are two red circles which highlight plastic clips that hold some fuel lines in place. If you put your hand on these fuel lines when the engine is running you can feel them pulsate as the gas is pumped through them. They said that when they removed the lines from these clips that the noise was diminished so they put sylglide in the clips and on the fuel lines and thought that might solve it, but because the engine was getting warm by that time and the noise seems to go away when it is warm, it was hard for them to say for sure. Took the vehicle home yesterday and I knew the true test would be a cold start up this morning. Went to start it and the noise was still there, but I think they are getting close. It is warm today so the noise went away rather quickly, but I spent some time wiggling and knonking on fuel and brake lines and their mounting brackets in that general area and there are a few places were I can replicate the noise almost exactly by knocking on it with my fist. Just wanted to share this with you in case it inspired any additional insights. The thing that still gets me though is if it is not an internal egine noise, which right now they are claiming it isn't, then why does it all but vanish once the engine is warm? Thanks everyone I'll keep you posted.
Alright guys here is the update. The day after I got it back from the dealership for the first time (when they claimed they didn't hear it) I started it up at home and it made the noise for me. I took it back into the dealership and let it sit over night. I met the tech the next morning and started the 4Runner with him sitting in the passenger seat. He heard it this time and they kept the vehicle all of that day and most of the next. They said they thought they might have found the culprit, but weren't 100% sure. In the pic below there are two red circles which highlight plastic clips that hold some fuel lines in place. If you put your hand on these fuel lines when the engine is running you can feel them pulsate as the gas is pumped through them. They said that when they removed the lines from these clips that the noise was diminished so they put sylglide in the clips and on the fuel lines and thought that might solve it, but because the engine was getting warm by that time and the noise seems to go away when it is warm, it was hard for them to say for sure. Took the vehicle home yesterday and I knew the true test would be a cold start up this morning. Went to start it and the noise was still there, but I think they are getting close. It is warm today so the noise went away rather quickly, but I spent some time wiggling and knonking on fuel and brake lines and their mounting brackets in that general area and there are a few places were I can replicate the noise almost exactly by knocking on it with my fist. Just wanted to share this with you in case it inspired any additional insights. The thing that still gets me though is if it is not an internal egine noise, which right now they are claiming it isn't, then why does it all but vanish once the engine is warm? Thanks everyone I'll keep you posted.
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BlackWorksInc
New member
Oi, you don't make this easy for us do you! LoL
Still wracking my brain trying to figure this one out...
Still wracking my brain trying to figure this one out...
Jeff4runner
New member
Might be the number 3 and/or 4 cat heat shield. From the metallic "slapping" you describe, that sounds like what it is. Try bending it around, get the dirt/rocks out from where it is attached, and bend it away from the frame. Mine did it all the time, until I replaced it with something that doesn't feel like super-duty tin foil.....
4RunnERD
New member
Thanks. Just spent another 45 mins. under the truck wiggiling and shaking everything I could find. Everything is tight. I did knock lose some dirt and rocks and checked the cat shields, but those were fine. Actually it is not really a metallic sound but more of a hollow sounding knock. Like knocking on thick plastic or the iniside of the fender. I even used a screw driver and a broom handle as a sthesiscope (spelling?) and placed it on everything I can reach. Nothing sounds like the hollow knocking I hear on a cold start up. I now have a nice burn and blister on my elbow though from one of the cats.
4RunnERD
New member
I appreciate the extra brain power. I am going to give the original dealership another go at it this week. If they can't get it I have a few other dealerships I can try. It's just a pain in the but with all the back forth and trying to get rides to and from constantly.
progress4m
Member
Wow…I hope they will resolve this for you and if this is what they say it is that tech is good!
Sounds like that are very hard to diagnose… hopefully in your case it would be resolved.
It is hard to say, but I believe I have heard the same (similar) sounds in my truck, but my case I only heard it maybe 5 times total in 3.5 years I owned this truck… In my case it did not last more then a minute or two and I thought it is just resonance of the exhaust … I am fairly knowledgeable when it comes to cars and car’s engines so I knew for sure it was not a piston slap it is not “slapping” metal sounds and it is more hollow and thumping sound and one of the reasons I thought it was a resonance of the exhaust system was that I can only hear that sound inside of the truck but not outside. Also in my case it does not appear to be low temperature related, as I have started my truck many times in low twenties (during my hunting trips) as well as minus fifteen during a week of ski trip last year and I never heard that sounds during those conditions.
Keep us posted and best of luck!
LexusTech1024
New member
Hello everyone, new guy here that works at a Lexus dealership but owns a
4Runner(really don't like the GX470 for my own personal reasons).
Regarding the knocking sound that you hear upon start-up is possibly the fuel
pulsation dampener and/or fuel pump. My 4Runner does this occasionally and we also have a few customers with GX470's with the same concern. Lexus has a countermeasure part for the dampener and if that does not fix the "sound" then we are instructed to replace the fuel pump. All of the repairs that we have done, so far, have resulted in just the dampeners being replaced only because said customer's have not returned with the reoccurring knocking. Sorry guys, no TSIB regarding this concern! And if needed, I'll get the part # for the dampener but I can't guarantee this will fix your sound. Hope this helps with your situation!
progress4m
Member
Thank you! I hope that will help the OP as well, but it definitely made me curios and intrigued me enough to take a look at my fuel dampener and fuel line just to see if it does vibrate\ pulsates on the start up. I am assuming it located near the fuel rail?
4RunnERD
New member
Hello. Thanks for the additional insight. I have been dealing with this since March. I thought the noise might go away in warmer weather, but it has not. I would very much be intereseted in the fuel dampener part number as well as a picture or a desricption as to where this is located on the vehicle. Thanks again.
4RunnERD
New member
Lexustech,
The dealer just called and said they wanted to replace the fuel dampener, which matches what you said. However, not being a mechanic myself, I am struggling to understand why the fuel dampener issue would go away once the engine is warm? Is it made from a material that will expand once warm? Does the fuel heat up and expand enough in the lines and dampener to cause the knocking noise to go away? Any insights would be great. Thanks.
The dealer just called and said they wanted to replace the fuel dampener, which matches what you said. However, not being a mechanic myself, I am struggling to understand why the fuel dampener issue would go away once the engine is warm? Is it made from a material that will expand once warm? Does the fuel heat up and expand enough in the lines and dampener to cause the knocking noise to go away? Any insights would be great. Thanks.
4RunnERD
New member
Update
They replaced the fuel dampener and that didn't get rid of the noise. For anyone else who cares to venture a guess the biggest factors to keep in mind are this, really can't hear it outside the vehicle which is why they don't think it is internal engine or driveline noise, goes away once warm, best way to get it to make the noise on demand is to put a small load on the engine like shiffitng into gear but remaining still with foot on brake. They don't believe it is brake related either.
They replaced the fuel dampener and that didn't get rid of the noise. For anyone else who cares to venture a guess the biggest factors to keep in mind are this, really can't hear it outside the vehicle which is why they don't think it is internal engine or driveline noise, goes away once warm, best way to get it to make the noise on demand is to put a small load on the engine like shiffitng into gear but remaining still with foot on brake. They don't believe it is brake related either.
4RunnERD
New member
Update.
Dealership called back and said they were able to hear the noise really good with a stethoscope the other day and were "100% sure" that the knocking was coming from the fuel lines, but weren't sure why. They checked the fuel presure and everytihng was fine there and they have already tried a new fuel dampener. At this point they have giving me two options.
1. They want to drop the fuel lines as far and as best as they can without dropping the tank and insulated with foam between the fuel lines and the body of the truck (not actually encapsulatuing the whole line).
2. Replace the fuel pump and see if that gets rid of the noise.
Wondering if I should try running a can of seamfoam or something else through the system first as it would be a cheaper first step than the options above.
Dealership called back and said they were able to hear the noise really good with a stethoscope the other day and were "100% sure" that the knocking was coming from the fuel lines, but weren't sure why. They checked the fuel presure and everytihng was fine there and they have already tried a new fuel dampener. At this point they have giving me two options.
1. They want to drop the fuel lines as far and as best as they can without dropping the tank and insulated with foam between the fuel lines and the body of the truck (not actually encapsulatuing the whole line).
2. Replace the fuel pump and see if that gets rid of the noise.
Wondering if I should try running a can of seamfoam or something else through the system first as it would be a cheaper first step than the options above.
galactic_04
New member
Lexus tech did mention the fuel pump too
4RunnERD
New member
I know he did, but if that doesn't fix it for whatever reanson then I am out big money. I wish he would come back online and re-evaluate. I think he's only posted on the forum once.
4RunnERD,
I have 07 v8 Limited and apparentely, I have the same kind of noise at start up and starting driving when engine is cold. I just live with it as I new it was going to be a PITA to diagnose something like this. But it annoys me a lot. I follow this thread very close and really appretiate all your affords to bring the truth up to light.
Please, keep everybody updated on this matter.
I have 07 v8 Limited and apparentely, I have the same kind of noise at start up and starting driving when engine is cold. I just live with it as I new it was going to be a PITA to diagnose something like this. But it annoys me a lot. I follow this thread very close and really appretiate all your affords to bring the truth up to light.
Please, keep everybody updated on this matter.
