LS400 makes brief rapid clicking noise when engine first starts

jennymurphyjennymurphy Member Posts: 6
edited March 2017 in Lexus
My Lexus LS400 just started making a brief, rapid clicking noise like one of those electric screw drivers that has been set way down so that it won't strip the threads. It only lasts a couple of seconds and sounds like it's coming from near the fan. It only happens when the car has been sitting for at least a couple of days. It never happens once the car is running or on subsequent starts.

Any thoughts as to what it might be? I'd like to get some ideas before I take it in to be looked at.

Thanks, -J


  • ray80ray80 Member Posts: 1,655
    If it is happening before the engine actually starts to turn over (before firing up) I would be thinking issue with battery/charging system, battery would be first to check I think,
  • jennymurphyjennymurphy Member Posts: 6
    I think it happens just as the engine starts to turn over, but I'm not sure. I just went out to see if it would do it right now, but it started up with no clicking. I drove it yesterday, so it had only been sitting for overnight, which is usually not long enough for it to happen. When it happened day before yesterday, we had been gone for a week.

    I've had alternator/battery problems in the past with another car, but this seems like a different sound -- a bit softer. I guess it could be the same thing.

    If it was the battery, wouldn't it happen pretty much all the time?

    I just had it in for the 6 month service about 4-5 weeks ago. They checked the battery at that time and said it was fine.

    I'll try to notice exactly when it happens the next time it does happen.

    Thanks, -J
  • ray80ray80 Member Posts: 1,655
    The clicking makes me think of weak battery (been there many a time), with today's vehicles there is much more things 'active' even when it is shut off (theft protection and others). You mentioned it was more likely to happen after its been sitting, maybe for a few days with this extra stuff slowly draining power. It may also be a parasitic drain , which might be more difficult to track down. How old is the battery?
  • jennymurphyjennymurphy Member Posts: 6
    I replace the battery last in August, 2015, so 18 mo. Maybe I'll have AAA come out and test it. They can also replace the battery if that's it.

  • jennymurphyjennymurphy Member Posts: 6
    It just happened again today. It happens just after the engine starts up or just as the engine starts up. It does not happen before it starts and it is not the same sound as I have heard in the past with a different car that had a weak battery or an alternator problem. The car starts right up without any problem or hesitation and then makes a very soft fairly rapid clicking sound that only lasts 2-3 seconds.
  • thecardoc3thecardoc3 Member Posts: 5,690
    The first question is how long has it been since the oil and filter were changed?

    Beyond this you will need to describe the symptom to a shop and plan to leave the car overnight so that they get to start it and hear the noise and try to get a location on it before it stops happening.
  • jennymurphyjennymurphy Member Posts: 6
    It had its regular 6 month service at the dealer a month ago.

    Overnight is probably not going to do it. When I drive the car at least every 2-3 days, I rarely, if ever, hear it. It's only after it has been sitting for several days.

    Is there some part that needs to be kept oiled and for some reason the oil is draining off after several days?
  • thecardoc3thecardoc3 Member Posts: 5,690
    How long has it been since someone checked the oil?
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    edited March 2017
    Maybe if you stand by the open engine bay while someone else starts the car you'd get a better idea. I was going to guess "timing chain noise" but your engine uses a timing belt.

    You might also listen for some valve lifter noise coming through the valve covers. A weak hydraulic valve lifter can bleed down overnight and would need to pump itself up--resulting in a few seconds of tapping noise.
  • jennymurphyjennymurphy Member Posts: 6
    Good idea. I'll try to remember to try that.
  • CalebaardsmaCalebaardsma Member Posts: 1
    I have a 1998 lexus ls400 that is having the exact same symptoms. Did you ever find the problem?

    My current guess is that the starter is staying on or engaged after the engine starts, resulting in the clicking noise for a couple seconds.

    I am hoping you found the problem so i don't tear into my engine without knowing for sure what the problem is.
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