nautskye Posted March 2, 2008 Share Posted March 2, 2008 Hello everyone, There is a noise that seems to be coming from my engine bay in my '91 LS400. I can't really think of any other way to describe it other than calling it the noise of a hard drive doing reading/writing. It's intermittent and I can't hear it if I am not sitting in the car with the doors closed. Any Ideas? Thanks! Quote Link to comment Share on other sites More sharing options...
TA in KC Posted March 3, 2008 Share Posted March 3, 2008 Hello everyone,There is a noise that seems to be coming from my engine bay in my '91 LS400. I can't really think of any other way to describe it other than calling it the noise of a hard drive doing reading/writing. It's intermittent and I can't hear it if I am not sitting in the car with the doors closed. Any Ideas? Thanks! I own an Apple computer sales/support company and know exactly the noise you are talking about. Probably the "valve tap" or injectors ticking like some people talk about. Some say it is just normal valvetrain noise for these cars. My LS does it as do all others I have seen. Mine has 140K, my friend's has 300K, makes the same noise and probably has for a while. If it was an indication of a serious problem, I'm sure it would have happened by now with that kind of mileage. Quote Link to comment Share on other sites More sharing options...
chilkoot Posted March 3, 2008 Share Posted March 3, 2008 are you referring to a hard "chunking" sound like hail or something more like an intermittent puff of air? I have the latter, I'm hoping it's my PCV valve. I can hear it mostly through the wheel well. Quote Link to comment Share on other sites More sharing options...
nautskye Posted March 3, 2008 Author Share Posted March 3, 2008 are you referring to a hard "chunking" sound like hail or something more like an intermittent puff of air? I have the latter, I'm hoping it's my PCV valve. I can hear it mostly through the wheel well. Mine is more like the latter too. It goes off/on for a second or two when I cold start the car. I don't know if it continues when I drive because of the road noise. I can't tie it to anything I.E. turning on/off A/C or turning the steering wheel- reving the engine etc... Can you hear it in the cabin at all? Quote Link to comment Share on other sites More sharing options...
TommyBoy72 Posted March 3, 2008 Share Posted March 3, 2008 Sounds like you guys are describing the air ride compressor venting. Its located near the passenger front wheel well. Quote Link to comment Share on other sites More sharing options...
glenmore Posted March 4, 2008 Share Posted March 4, 2008 I get the same sound and it is exactly as how you describe it, like a hard drive. But my sound would be just once or twice and then stop, always at startup. I suspect it is the air dams that control the mix of air from the outside that are electronically controlled. For instance if I have the heater on, hot air will come but after turning off the heater, the hot air still comes. To get it back to no hot air, I have to flip on the AC for 30 seconds and the flaps move to shut off the hot air. At least that is what I THINK is happening. No air suspension in my car. glenmore 1990 LS400 1991 300CE 2000 C280 Quote Link to comment Share on other sites More sharing options...
2rotor Posted March 4, 2008 Share Posted March 4, 2008 PS pump churning the fluid perhaps? Quote Link to comment Share on other sites More sharing options...
dpellet Posted March 4, 2008 Share Posted March 4, 2008 Does the vehicle(s) have trac control/Anti Lock by any chance? On start up the it's either the trac pump or anti lock system that run momentarily, it makes a similar sound. Hope this helps! US Model 91 Ls400. Quote Link to comment Share on other sites More sharing options...
nautskye Posted March 5, 2008 Author Share Posted March 5, 2008 It may be PS pump but shouldnt I not have any noise coming from that? I mean that makes me think I have air in the system??? Quote Link to comment Share on other sites More sharing options...
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