bswan Posted July 31, 2004 Posted July 31, 2004 I have a 92 LS400 that makes a very loud noise only at speeds of 55mph or higher. It doesn't seem to be engine related as I can put the car in neutral at the higher speed and the noise continues. As soon as I drop below 55mph the noise goes away so I can't isolate it. There's no vibration at all. It seems to run just fine. I can't get it looked at for a few days, I'm wondering if I'm doing further damage to it driving at lower speeds. I've had bad experiences with the Lexus dealership in Sacramento, so I'll wait to take it to a local mechanic. When I do, should I drive it there or have it towed? I love this forum and I sure would appreciate any thoughts on this problem! Thanks!!!
Em91 Posted July 31, 2004 Posted July 31, 2004 We need more information. Can you describe where you think the noise is coming from. Any information will help. :chairshot:
bswan Posted July 31, 2004 Author Posted July 31, 2004 It's a very loud grinding noise. There is no loss of power. It only happens above 55 mph. Could it be something with the drive train? The transmission was replaced last year and it continues to shift fine. If it wasn't for the incredibly loud noise, you wouldn't think anything was wrong. Thanks for responding!!! I need help!
Em91 Posted July 31, 2004 Posted July 31, 2004 Very strange. Grinding could mean tranny but you said that when you shift to neutral the noise is still there. It might be something in the drive line or differential. But, you did not say where you think the noise is coming from. Is it coming from the front,back, left or right. It could be a bad hub bearing but generally that noise would be constant and change with speed. Are you sure the noise is not contant and just more pronounced at 55?
bswan Posted July 31, 2004 Author Posted July 31, 2004 It's definatley coming from somewhere under the hood. But as soon as I pull over to pop the hood, the noise goes away. Just as soon as I drop below 55, the noise stops. It's only at higher speeds. Drive line? Differential? Sounds expensive! Any ideas of $$$ if that is the cause. Going through nasty divorce...running out of thousand dollar bills fast! Actually, I'm out. Thanks
Em91 Posted July 31, 2004 Posted July 31, 2004 Wow that is very odd. I could be anything. I could be something loose under there and making noise. I would get underneath the car and check to see if you see anything loose.
bswan Posted July 31, 2004 Author Posted July 31, 2004 Everything seems to be tight underneath. Thanks for your help, it's very much appreciated!
Em91 Posted August 1, 2004 Posted August 1, 2004 Sorry bswan. I wish I could hear the noise it would be helpful. Well I hope it isn't anything bad. Good luck
flanker271 Posted August 1, 2004 Posted August 1, 2004 The only cause of grinding noise I can think of right now is low power steering fluid. If you turn the wheel left or right while idling, do you hear that same grinding noise?
bswan Posted August 1, 2004 Author Posted August 1, 2004 I just checked the ps fluid. It's fine. It doesn't matter which way I turn the wheel. The noise only starts after 55 mph and stops when I slow below that. Do you think it could be the drivetrain or differential? Thanks for your help.
99lsguy Posted August 2, 2004 Posted August 2, 2004 Have you looked under the hood while someone else hit the accelarator up to 2500-3000+ rpms.........if not, check this out first. I know you've stated it goes away under 55 mph.........I'm just wondering about the rpms.......... NO check engine light on??? Fuel pump is behind rear seat. Diffy is underneath trunk. You say it's under the hood so it's not those........ somethings loose and vibrating
bswan Posted August 2, 2004 Author Posted August 2, 2004 It's too loud to be a loose fitting. It has a grinding sound to it. Like the bearings in a pump are going out. But, it's so loud and seems to be too loud for a pump, besides, what pump would make this noise only at higher speeds and operated perfectly normal below that speed? No check engine light and rpm's do not replicate the problem. ??????????????
99lsguy Posted August 2, 2004 Posted August 2, 2004 Ok....... So sitting in park with RPM's 2-3000 -----and its quiet a a mouse (well, except for normal engine noise), right?? Maybe check the transmission flange where it connects to the propeller shaft... And/or the heat shields nearby, they could be getting "nicked" as at higher speeds they vibrate a little more and getting clipped by the shaft..... Your water pump would be grinding @ rpms if this was the culprit....
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