andyman32

Note : specifically, this is about '98-00 motors... I should have put that in the title...

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Hi all, just a couple of fairly high-level questions.

I have kind of a rattly bad-bearing noise coming out of the front of the engine on cold mornings, in particular, below freezing. It goes away after the engine warms up a bit. I've verified by starting the engine without the s-belt installed that it isn't coming from the harmonic balancer or main bearings - thank goodness for that - but it's very difficult to pinpoint by using a rubber hose or automotive stethoscope. As far as I can tell, it's either the fan bracket bearing or the water pump - something behind the front cover of the engine.

I was surprised to find in the water pump replacement walk-throughs, e.g.:
http://www.lexls.com/tutorials/engine/timingbelt.html
that the timing is belt-driven, not chain-driven. As I don't have maintenance records on this car, I'd assume the belt is original. The car has 78k miles and 14 years of service. I probably ought to refresh the belt if/when I get into removing that fan bracket and/or water pump.

So, here's the feedback I'm looking for -

Is the second-gen 1UZ-FE really belt-driven?
Do you all agree that water pump and timing belt really ought to be addressed while I'm in there?
And, is the process for the later motor, which has VVT, much different than what's shown in that walkthrough? I'd guess not. Anyone know of photographic walkthroughs for a '98-'00 though?

Lastly:
Does the process (timing belt) involve removing any oil channels, seals, anything touching the head gaskets? I did timing components, a bad tensioner, on a car with a timing chain a few years ago and that was really quite involved and pretty fiddly to try and get all the oil seals installed properly.

Thanks for your thoughts!

billydpowe

iTrader: (1)

too many questions to try to answer, do a search on ls400 timing belt/water pump and your questions will be answered for you, many things you need to know.... but they are belt driven and yes you do a pump at the same time. good luck on your journey..

usoff89

iTrader: (2)

I'm not sure about the noise, but I'm pretty sure the harmonic balancer and the main bearings turn even without the S-belt on.... That being said, you might have confirmed that it didn't come from your A/C or power steering. but it COULD still be down in the bottom of the motor. It could be the waterpump going bad, or maybe a bad timing belt tensionor.

As far as replacement. Even with the lower miles, if you have everything apart it would be best to replace the timing belt and waterpump. Someone correct me if I'm wrong (I have a 1st gen), but yes it is all belt driven. I believe once you have the covers off, it's pretty straight forward on replacing the timing belt and pump. Just make sure you get the timing right when putting it back together. I think those motors are "close tolerence", so you could bend a valve if the timing is off.

Hopefully that helped a little.

LScowboyLS

yes!

and a 14 year old timing belt should be replaced NOW, regardless of mileage, due to age-wear

you do realize that your interference engine will implode and do about $5000 in damage if this 14 year old belt breaks, right?

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here is a great video of a first timer doing a timing belt on an LS430, which is the identical job on your '99 LS400

andyman32

Thanks for all of the advice guys!

usoff89 - yes, I should have been clear, the main bearings and harmonic balancer do spin (albeit without the belt tension). But, the noise was not reproduced when the S-belt was off, the engine was whisper-quiet, so the noise had to come from something else.

I am leaning very much toward one of those internal bearings, likely one of the idler pulleys or water pump. I've had water pump bearings go bad several times before on cars this age or less - although never had to replace an "internal" pump like this before!

So it is belt-driven, ah well. Thanks for the video. Is this motor an interference engine? I thought I had read that the 1UZ-FE is non-interference? Dear me, that just doubles the risk of doing the timing belt improperly. Not just a matter of the car not starting... it's a matter of blowing the heads! Well, in any case, this is a project perhaps for April or May. We're going on vacation in a week, for a week. I'll just leave the car up on the ramps for now and plugged in to the trickle charger.

Thanks all!

LScowboyLS

the 1UZ-FE became an interference engine beginning with the 1995 model of LS400

did ya watch that video?

usoff89

iTrader: (2)

Ok, so just so I understand this.... You took the s-belt off, and the noise stopped? And yes like we had stated, you will screw your heads up and possibly more if your timing is off.

fixmiester

You stated that the noise went away when you disconnected the s-belt; therefore, it has nothing to do with the water pump,timing belt, hydraulic tensioner, cam bearings or internal engine components--right? So, it must be something that is driven by the s-belt.

If it turns out to be the fan bearing (which requires about 2/3 the dis assembly of the entire TB/WP replacement job) , then go ahead and do the timing belt/water pump, etc. replacement. BUT, if is one of the other s-belt-driven items, then I suggest that you can get by a while longer on the timing belt, until it is more convenient--but not too long.

I know, there is some risk. But I will say this: very few people on this forum, or the UK forum have seen a timing belt that has actually broken, even after 200K miles. Sometimes they start fraying and making strange noises, which gives you some warning. I replaced my leaking water pump, plus timing belt, tensioners, etc. on my '99 last year at 110K miles, and I could hardly see any signs of wear at all. So, I'm just saying that, unless you push the engine really hard, you do have some time to get to it.