Caseyjones

I have been seeking that sweet quiet idle. I saw another LS at the store last week and it was so quiet that I was surprised when it pulled away, literally could not hear it. I want that.

When I bought my 96 it had that hydraulic groan, worse when cold. Quickly diagnosed it as the PS pump, replaced that and thoroughly cleaned the reservoir. Now the ps pump is silent and steering functions perfectly, car much quieter now.

When cold I can still hear a some groan, again it lessens significantly after its at operating temp but can still be heard. I drug out the stethoscope and can not seem to nail it down. I figured transmission pump but it's nice and quiet to the ear. I'm stumped, on cold start its easy to hear but even with the hood up its easier to hear from under the car. I see the trans was serviced awhile back. Fluid is perfect and operation is just as it should be.

Not sure if it's related but there is a tick, sounds like a lifter but it's not. I can barely hear the valve train, this is also easier to hear around the bottom rear of the engine. I did remove the EGR tube as it was cracked in half, I took the lower half off and welded it up into a plug and put it back, leaving the upper half alone. Not sure if this could be a source for these odd sounds. The car runs fantastic otherwise, dead silent inside the vehicle unless I'm next to a building or something with the window down then I can hear both sounds.

I'm looking for any thoughts on what else any of this may be. TIA.

Tony

dicer

1UZFE engines have solid lifters and need periodic adjustment. Groan could be any pump, could be the transmission a pressure relief valve modulating etc. It could also be a bearing did you listen around the front of the engine? Usually they don't get quiet with temperature though.

Caseyjones

I searched a bit before posting and found some threads on valve adjustment but the sound is much less pronounced under the valve covers. I can hear the valve train with the steth but very hard to hear it with the naked ear, I can hear the injectors softly ticking away to. This tick is like back at the rear of the engine, sort of the same area of the groan/whine sound. Both sounds lessen with temperature but neither disappears.

I know an exhaust leak can sound surprisingly like a lifter, that's why I wondered if when plugging the EGR tube if I should have plugged both ends rather than just leave the one coming off of the EGR open.

I also found plenty of threads on the front pump groaning if the filter is even a little plugged up but the service history indicates a trans service a few thousand miles back. With the steth the transmission is very quiet at idle. Im not aware of any other item that can emulate the hydraulic pump sound but I'm probably missing something.

dicer

What kind of trans service? Doesn't always mean the pan was dropped and filter taken care of. Even some times they say work was done and it was not. Especially trans stuff if the trans is working good. It would be easy money for dishonest places. Just look at some of the youtube news items about that sort of thing they caught shops doing or not doing.
There are other pumps on these cars.
Look for DTC 19, and 56 to prove a pump that most may not know about.
And then DTC 51 for the other pump.
Then if you have an air suspension theres a pump for that.

Caseyjones

Thanks for responding, I was not aware of the TRAC system component location and those codes. The sound is definitely from the rear lower, the front of the engine and around the top sounds pretty much like a brand new car. Also the sound speeds up with RPM if I blip the throttle.

I have no trouble lights on and there is no air ride on this vehicle.
I do believe you may be right about transmission, I dont place a lot of faith in the average auto tech. Most of the work was done by Toyota and not a Lexus dealership, not that this makes much difference. Standing beside the vehicle after a cold start it sounds exactly like a sick trans front pump. The only thing that throws me is that its very quiet with the stethoscope, I have heard a bad trans pump with the steth and its damn near enough to make your ears bleed.

I'm going to head outside and put this up on ramps, pull the engine cover and search for the source again.

Caseyjones

Ok, This car saw me coming.

The sounds are more pronounced when cold, so I decided to put it up on the ramps on this below freezing morning and slide under. When started up the sounds were softer, I hurried it onto the ramps with the steth in my ear and listened around with the probe. I also like to unplug the probe and listen through the tube only which is equally valuable for a final diagnosis.

By the time I got under the car it was idling almost like I feel it should. I can hear the light tap throughout everything. I can hear it down low, and through the trans, but very softly and not unlike any of the countless other vehicles I have used this steth on, definately not a knock. When I position the probe over each cyl on the valve cover I can hear each cyl valve train softly and equally with none standing out above the rest. Alt, PS, WP etc all quiet. I can hear no significant groan in the tran, or anywhere else with the probe. With the open hose I think there might be a very small exhaust leak around pass side exhaust, possibly adjacent to where the broken tube was dealt with but this did not start suddenly when I altered the EGR tube, this little mystery tick has been present since the car has been with me. My plan of attack will be to do a filter/service on the trans as I feel that is likely where the hydraulic sound is coming from even though I cant directly hear it there. I can hear the groan in general through the open hose but just cant pin it down to anything.

My direct question about the tick... Can the EGR valve emit any sounds that would normally be masked by an intact tube? I do not have emissions checking where I am so I welded up the port in the exhaust side of the tube and re installed it. Maybe some ruckus from the other end of the tube on the EGR side? It just sounds like it's coming from back around that area, its the best I can narrow it down as I find it difficult to see or reach back there from under the hood or under the car.

I'm about ready to stop beating this dead horse and take it into a Lexus dealer but this is a 7 hour drive each way.

I forgot to ad, it runs and drives very smooth, 180k ish mi.

Thanks.

kcHotRodLs

I have these same two issues with my 95 at 180k on the odometer. I had the groaning which, even with the hood up, sounds louder from under the front of the engine. I quickly diagnosed it as PS noise, checked the fluid level and removed the screen at the rack to ck for debris. Discovering clean screen at the rack, I went at the pump and changed out the original for a reman from oreily. 136$. my mistake was having NOT taken the drive belt off to see if the groan remained which was getting progressively worse with time as you revved the engine, even though steering operation remained perfect. Turns out it was the trans filter which had never been serviced as evidenced by the lack of gasket and still factory seal on the pan. I have since serviced the trans and it is dead quiet…. BUT I can now (again) clearly hear the groaning still coming from under the front of the engine.
So after reading here about taking off the acc drive belt to diagnose, I had a duh moment and after recovering from feeling stupid… I shucked the belt and ALL is quiet. I spun tensioner, idler (both changed w timing belt recently), ps pump, fan, all is quiet and none have excessive (wobble) bearing wear. So, I reinstalled belt, cranked it up and scoped it w steth all around (carefully!)
The ONE place where I can clearly hear this groan is behind the alternator below the ps pump when I touch the engine block. I can touch it from the bottom behind the alt and from the top on the pass side behind the ps pump, the alt and pump are dead quiet but when you touch the block grooooooannnnnn… sounds just like power steering pump! still I have to think it’s the aftermarket ps pump (or perhaps cooling fan mount bearing??) And to boot it now overheats when I let it sit at and idle even though it’s cool out.
Come to think of it, I don’t remember the electric fan ever kickin on while I have been struggling w this diagnosis. I love my LS and I hate my LS. Sorry for the rant. Perhaps it will be of some use to you.
Pull the belt and you will have the quiet Lexus we are dreaming of… perhaps that'll help narrow it down.
peace.

fixmiester

Removing the drive belt is the right way to isolate these kinds of noises. Only takes a few minutes. I suspect you may be hearing your alternator, even though you say it is quiet, using the stethoscope: it usually puts out maximum output right after starting (to recharge the battery), then settles down after a few minutes of running - just like you have stated. Could also be partially failing, with one or more of the diodes crapping out. The sounds they make are exactly what you describe. Have it checked at one of the parts stores for free.

Caseyjones

Belt off, was generally quieter but the groan and tick in question were still present. I had my lovely assistant blip the throttle while I moved around under the hood and under the car and the tick sounds very much like an exhaust leak in the front of the exhaust system.

The groan I still cant hear inside the trans but to the naked ear it's definitely coming from that area. I will get the parts coming form Lexus and get that serviced with filter/drain/fill, I'm betting on that being the issue at this point. My earsight aint what it used to be I guess haha.

Probably unrelated, I noticed that if free reving in N there is some roughness coming in over 2000 until around 3000 rpm, cant feel it while driving but pretty clear vibration while parked, still smooth at idle. Also after a throttle blip as the revs return to idle, for just a second I can hear some noise from around the middle of the exhaust system, sounds like someone pouring dirt into a coffee can. This car really needs to be put on a lift, I really cant get to anything with just the ramps. Maybe I have a cat or muffler falling apart from the inside out or a heat shield.

Thanks for the responses and assist. I'll be updating as I find solutions but I welcome any input on any of this in the meantime.

Thanks.