98 Ls Start Up Grinding Noise

[Jarebear]

Hi everyone,

My Ls is starting to make some nasty noises on start up. It doesn't happen everytime, but once in a while, on the last crank when the engine actually starts, I can hear a nasty grinding noise. It goes away immediately and the car drives smooth. Maybe a bad starter?

[steve2006]

It could be the starter failing to disengage cleanly with the flywheel gear but a big job to strip down and physically check.

[z_johnq]

Could you make sure your water pump running OK? It sounds quite unusual for a start to behave like that.

[landar]

My money would also be on the starter. It does sound like the pinion gear is not disengaging quickly enough and the flexplate is briefly spinning the starter motor. It could be the "Bendix-type" mechanism getting sticky or perhaps your solenoid contacts have worn enough to sometimes cause a temporary welding together of the contacts thereby keeping the starter engaged slightly longer than necessary.

I do not think it is something for immediate concern but begin saving your pennies for starter replacement. The starter repair itself is not all that expensive but there is a lot of labor involved getting to the starter. If you also begin to experience a single 'click' (no start) once in a while when you turn the key, you will know for certain that your starter is EOL.

[z_johnq]

OK. But replacing starter is really really a PITA. I did it on my 1991 400. I did not replace the whole motor, just the points, which cost me about $35 bought from web. Usually the motor can last very long time so it's better to keep it.

The starter is located in the engine bay. You will have to remove intake manifold and lots of something else to reach it. You probably need 14 mm flexible head wrench, don't even think about ratchet. The Japanese probably try to make it last forever to place it at the location like that but it's not good enough to last forever. Some guys took pics how they did it and posted them on the web. Good to check them out. They will certainly be helpful.

[Goleden Jennings]

I had a noise like that and it ended being the alternator rotor.

[Ancdmd]

My '02 LS430 did that for several years. I did replace the alternator a while ago since it developed a bearing whine, and come to think of it, it's been a long time since I've heard that grinding noise. I guess the alternator could have been the source of the grinding noise.

[Jarebear]

Ok, sure it could be the alternator, but if it is, why does it only make the sound on start up. I would think if it were the alternator rotor I would here it at other times when I drive, I even revved the car in my drive way to simulate a cold start and I heard nothing. Shouldn't that narrow it down to the starter since the sound is only heard when the starter is engaged?

[SRK]

The easy thing is to drop the serpentine belt off and start the engine briefly. If the noise doesn't happen, check the alternator and water pump. If it does, it's the starter.

[Ancdmd]

Ok, sure it could be the alternator, but if it is, why does it only make the sound on start up. I would think if it were the alternator rotor I would here it at other times when I drive, I even revved the car in my drive way to simulate a cold start and I heard nothing. Shouldn't that narrow it down to the starter since the sound is only heard when the starter is engaged?

Not necessarily. When the starter is engaged, it is turning the motor and accessories at a very low relative speed. When the motor first fires up, all the rotating mass in the engine and in the accessories suddenly accelerates to a higher rpm (the idle rpm). It may be that something in the alternator makes the noise as its rotation is suddenly accelerated from cranking speed to idle speed or higher. But also keep in mind that this doesnt mean it should make the noise every time you stab the gas pedal either. I'm not real familiar with alternator anatomy but since I haven't heard this grinding noise in my car since I've had the alternator replaced, it would make me lean to it being the alternator.

[landar]

The easy thing is to drop the serpentine belt off and start the engine briefly. If the noise doesn't happen, check the alternator and water pump. If it does, it's the starter.

That's a good idea. Since the water pump is not driven by the serp. belt, did you mean power steering pump or ac compressor?

[SRK]

That's a good idea. Since the water pump is not driven by the serp. belt, did you mean power steering pump or ac compressor?

I keep forgetting about the water pump drive on these engines, but yes all items driven by the serpentine belt can be eliminated as a cause of the noise by dropping the belt off for a short time.

[Jarebear]

Thanks SRK for the cunning idea. I tried it out. Well this is weird. I must be the most unlucky guy with diagnosing this problem. Every time I've tried this experiment with the serp belt (I've tried it twice so far) the noise won't replicate itself with the belt on or off. Seems that when I take the belt off the noise goes away, and when I put it back on it doesn't come back either. But then the next morning it came back. So maybe retensioning the belt on my alternator temporarily fixes the noise on the rotor bearing? IDK, I'm gonna try it tommorow morning. It usually always makes the grinding noise at first crank in the morning (three mornings in a row so far). I'll update on the progress later.

[SRK]

So with the belt off did you rotate the various pulleys by hand to feel for any roughness? You may find the culprit that way.

Alternatively serpentine belts, when old, will make noise when first warmed up in the morning, especially if they get damp. That may not be a problem in Louisiana.

If the noise is intermittent it's not as worrisome for sure.

Good luck with it!

[Jarebear]

Well we can rule out any of my accessories. This morning I pulled off the serp. belt to see if it would make the noise at first crank. Jackpot! Made the noise, and a funny smell too this time. My money is on the starter. Should I just not drive it around till I fix it, I'm afraid I'll ruin my ring gear.

[SRK]

If the starter pinion remained engaged you would hear it quite distinctly. It can happen when the starter contacts weld together, and as we all know these starters will damage the contacts. My Dodge Dakota 5.2 welded it's starter ( a reduction gear Nippondenso starter, smaller version of the Lexus model) and the noise was very loud. Also when I shut the engine off the starter continued cranking the engine. That's what you would hear.

It's still possible that the noise you have is the water pump or one of the idler/tensioner pulleys. That would be more likely. The smell could be antifreeze collecting on the belt - a sickly sweet burned smell to my nose.

[Jarebear]

The smell was more like.....burnt...electric or mechanical crap. Yea I've smelled antifreeze, that sweet smell, didn't smell like that at all. And by the way, what the heck is gear reduction anyways.

[SRK]

Many starters today are not direct drive - they use a second gear to reduce the speed of the motor shaft to the starter pinion gear shaft. That allows for a smaller lighter starter, and retains the torque of the old style. Old Chrysler starters were reduction gear, which is why people always imitated them cranking as "chewy chewy chewy" LOL.

[Jarebear]

By the way, so I understand that removing this starter is a pretty big undertaking, I know I'll need to replace the intake manifold and plenum gaskets. Are there any other gaskets I should worry about replacing when doing this job? I heard something about a water bypass gasket.

[SRK]

Don't even think about replacing the starter until you've diagnosed the problem as the starter - for certain.

[Jarebear]

How should I go about diagnosing the water pump or idler pulleys?

[Ancdmd]

Last time I heard this exact noise in my car was over a year ago and mine still starts and runs fine. As stated above I'd confirm the diagnosis before replacing the starter.

[landar]

Jarebear, you might want to crawl underneath your car and take a peak at your flexplate(aka: flywheel) ring gear to see if it looks ok or is worn down in some spot. There is a plate with 2 bolts on the bottom of the bellhousing. Remove that plate and have a look. You will have to rotate the crankshaft by hand (clockwise only) with a socket wrench (22mm IIRC) to monitor the entire ring.

[Jarebear]

Man I wish I had a pic where that plate is on my transmission, I was looking earlier but I couldn't find it. I'll keep looking.

[landar]

Man I wish I had a pic where that plate is on my transmission, I was looking earlier but I couldn't find it. I'll keep looking.

Here is a pic of the access hole on my '98 with the cover removed (there is an allen key in the flywheel). You can see the ring gear teeth. Just two small bolts in the cover. Its at the bottom front of your transmission (between engine and transmission...what is referred to as the 'bellhousing').