sayow

Video included below.

Maybe I am dreaming but my car idle sounds different than prior to me replacing my timing belt and water pump. Timing checked multiple times, not sure what else could have changed.

The car is very new to me and I am very new to the LS so perhaps its all in my head but I "thought" my car was near silent at idle prior to the work.

Is this a knock?

Please give it a listen and tell me what you think, some of you guys are freaking LS geniuses and I am learning a lot.. so thank you /bow

Finn

Can you pinpoint if the sound comes from valve cover area or from the front?

IMHO it reminds me of what I have on mine. Perhaps the standard 1UZ-FE ticking sound. Valve clearanced checked?

When you changed the timing kit did you also check the fan belt tensioner, idler and fan bracket bearings? Mine are shot causing extra sound and are on the to do-list.

LScowboyLS

take the main serpentine belt back off, and see what you think of the noise (it's fine to run the car like that for at least 15 minutes)

if the knock noise is gone, then the issue is either A/C clutch pulley/bearing, PS pump, drive belt idler, drive belt tensioner, fan pulley bracket, alternator, or the belt itself.

dc893

Doesn't sound like the valve tick in mine. The valve tick is fairly distinct and easy hear where it is coming from. I do hear the knock though.

Not my video but this is more like what a valve tick would sound like.

sayow

The only thing I can think of is that when I was changing the timing belt and water pump I - before I knew better - hand turned the crank counter clockwise about 3-5 degrees after I "over shot" the mark. I know now that I should have just went back around clockwise...

In any event, the car was not started after I did that. After I read (on these forums in fact) that counter clockwise was a no no, even just a few degrees, I went back and turned in clockwise another full rotation until I hit my timing mark.

Surely that could not cause this knock (if we can even call it that). I just drove it 70 miles and it ran beautifully.

My search continues, feedback certainly welcome and appreciated.

aomdedude1

That knock does not sound normal to me personally. My car is having issues at the moment and I need to replace the O2 sensors (just got them in the mail today ) so I cant make a direct comparison to my car, but I'm pretty sure it should not do that.

No one seems to have asked you and you did not make mention of whether or not you have a check engine light on?

Also, what is your idle speed looking like?

Do you still have the same amount of power and throttle response?

Is your CEL on? If it was a bad knock, I'd imagine that the knock sensor might pick it up. Can you feel the engine running any rougher?

As far as checking the timing, as far as I know, the 100% fool proof no questions asked way of doing this is a little difficult. You need to remove the valve cover and hand crank the engine to TDC. Then you take a look at the cam shafts. There will be two "dots" or dimples on the cam shaft gears that line up. (I am not talking about the cam shaft pulleys. I am talking about a gear that synchronizes the two cams. That gear is UNDER the valve cover and ON the shafts)



If the dots on the cams line up, and if crank is at TDC mark, than you should be good.

This applies to the 90-94 ls400 models but may be the same for yours too.

**EDIT: You said no performance issues in the video.. sorry missed that.

sayow

Thanks for the feedback, here are my responses to your questions:

NO CEL and have run a scanner just to make sure. nothing pending either

Engine does not run rough at all, no vibration to speak of

Performance is completely unaffected that I can tell. Ran it 70 miles today, city and highway with great power and acceleration.

Idle at start is high, around 1200-1300 then settles in at around 8-850

The third "check" of my timing, I used a long screwdriver in cylinder 1 to verify TDC at compression stroke so I am very confident this is not a timing issue unless I was completely wrong and it was the exhaust stroke (I cranked a revolution until I hit TDC and "felt" the more forceful stroke).

Just curious, but if i was wrong and hit TDC at exhaust, what would the engine sound like or would it even run?

LScowboyLS

the screwdriver doesn't tell you anything except that you are at the top of a stroke, remove spark plug in cylinder 1 and rotate crank until crank and cam marks line up, then see if cylinder 1 will hold air pressure - it will hold air pressure at TDC (which is top of compression stroke) - but if it had been mistakenly set on exhaust stroke, then the exhaust valves will be open and cylinder #1 will not hold air pressure pumped in (you could use something as simple as a manual tire pump with gauge for this test and an adapter to get you to the right fittings or a compression tester, etc.

did you remove the serpentine belt yet and listen?

aomdedude1

I second doing this. It's very simple and only takes about 15minuites max. It will help you eliminate so many things that could potentially be the issue.

I did it and it helped me figure out that my accessory belt tensioner was shot.
It is completely okay to run the engine for a short period of time without the accessory belt on. Just don't drive around all day like that or your battery will die and you wont have power steering.

As LScowboy said, sticking a screwdriver only tells you that cylinder #1 is at the top of it's stroke. It does not tell you that your engine is in time. All the valves (both intake and exhaust) should be closed as the cylinder #1 approaches TDC in an "in-time" engine. This means it is in the compression stroke. I tested this with my car by placing my thumb over the spark plug hole and hand cranking the engine to TDC. This is tricky and very rudimentary test but at least it will tell you that cylinder # 1 has its valves closed. But I would warn you that this "test" can be very misleading. Your time could just be one tooth off and the test might seem to work but it wont tell you for sure.

Better is to put cylinder number #1 at TDC as LScowboy said and find a way to get air into the cylinder and see if it holds and does not leak out right away. (open valve)

The absolute BEST way is to check that ALL the timing marks align while cylinder # 1 at TDC.

If the marks on the cam pulleys, crank pulley, and camshafts do not line up, turn the engine another few times and see if they eventually line up.
If they do not align properly, your engine is not in time.

rick1987

iTrader: (1)

I don't think it would even run. And it definitely wouldn't run smooth like in the video.

Try taking the belt of as others have stated, but If I had to guess what the noise is in the video I would say it's a slight rod knock.

If you pull the belt and it still makes noise, try changing the oil and add some Lucas to it. I swear by Lucas.

sayow

I am definitely going to remove drive belt I just have not had the time. My main concern or worry is how my car would develop a slight rod knock, if that is indeed what it is.

I will report back after I remove drive belt and diagnose some more.

Yamae

The rod knock can be heard and noticed easily while engine is revving down. Have you tried to compare the sound while revving up and down? The crank bearing knock can be mostly heard while revving up.

I recently have experienced both of them but it was not on my Celsior but on my friend's Subaru Pleo (JDM only car). If you are interested in, I will write more and show you the worn out bearings that I removed from the engine. I initially just replaced rod bearings and the knock at the revving down only disappeared. There still remained the knock at the revving up and I needed to replace crank bearings to stop it.

HKS JZZ30

iTrader: (5)

I had done a timing belt job on a 92 LS400, and it had a similar knock, noticable from the drivers side cam belt cover, and it turns out the small rubber seal/edge on the cam belt cover (the one large piece that says "V8 FOUR CAM 32") was sticking out just enough that it was making very light contact with the cam gear. the cam gear itself had a small tab on the backside of it (if i remember correctly) and thats all it was....

sayow

Now THAT is a very interesting comment. First, I do believe the sound is coming from the driver side valve cover (you can listen to the video as well but it sounds loudest there) and I did remove that cover about 10 different times!

Will look into that and listen with drive belt removed this weekend. As a side note, drove another 120 miles over the new year and it ran like new, very pleased with the car otherwise.

HKS JZZ30

iTrader: (5)

yes please update with how this turns out. the way I figured it out was to remove that plastic cover and start the car up w/o it. noise went away and the cover showed faint signs of where it was contacting the driver side uppermost cam gear.

hopefully you figure out what it is regardless