JD1

I test drove an LS400 today with a knocking sound when driving. When parked and idling, there is no knock. The owner was honest about it, I couldnt hear it or feel it until I drove it. He had some bearings replaced in the motor, but the problem remains. I had him rev it up in park, and the noise is barely detectable, but I definitely feel it and hear it while driving. It has 150k on it, its a 96. I'm wondering if its a motor mount, I'm just not sure the problem is in the motor. Anybody got any info or ideas?

JD1

I am pretty sure it is not rod knock. If it were, I would hear it when revving in park.

Banshee365

Rear transmission mount pops in my mind, common wear item. the 1UZ-FE is a pretty tough motor and I don't think I've read much at all about guy's tearing deep into one or replacing bearings or anything like that. If the bearings were replaced I'd say it was either ran out of oil or the oil wasn't changed at reasonable intervals.

Don't rule out rod knock yet because it may not knock until it is under a load. My '96 LS had a knock too, which I had never figured out. I changed the oil, which was still relatively fresh, and replaced the filter with a genuine Toyota filter. I now only use Toyota filters and Mobil 1 5W30 and I havn't heard a whisper since. I alway's wandered if the oil filter wasn't flowing correctly. I don't mess around with stuff like that anymore.

JD1

Good to know. Thanks. The guy I'm buying it from does not have the same budget concerns that I do, he just brings it in and says do it. I have a close friend who is a Lexus mechanic, I'll be bringing it to him on Friday. My initial thoughts were to change the oil, and add a bottle of Lucas additive and see what happens between now and friday. I know this motor is one of the best money can buy, and I'm pretty sure it has been well maintained. I'm just fearing bad news after shelling out 4k. I budgeted 5k to spend on a car, so I have about 1500 to put in it if necessary.

sam12345

iTrader: (1)

don't put the lucas additive. Why would you want to dampen the sound before your friend the lexus mechanic sees it? don't you want him to find out what the problem is? How can he find the problem if you hide the problem with a bandaid? it makes no sense or I do not understand what you are trying to say

willhickey

iTrader: (1)

If he replaced the bearings why? Did they plastigage it or feeler gauge? , did they turn the crank? , did they put it oversize bearing? I hope it isnt going to be a problem the moter i mean........ Goodluck with it and try to get the real story out of him on why the bearings were replaced.

Banshee365

Yea don't put any additive in the motor, it will just cover up a potential real problem. The whole bearing replacement thing really weirds me out. Change the oil and use a Toyota filter first. They're pretty cheap. Find out if synthetic oil has been used for the life of the car. I use Mobil 1 5W30. If the knocking continues have the mechanic look at it with the fresh oil change. For someone to have to tear into a 1UZ-FE with that mileage I would deeply be concerned about poor maintenance.

Yotarip

Honestly,
4 grand is alot of cash to put out for a car that has an obvious problem. For that amount of money, you could buy an ls without any questionable problems. Since you have around $5500 to spend, just hold out for something better. $5000 will buy you a great LS400.

If you are bent on buying it, that knocking sound is a strong reason to negotiate the price down to LESS than $2000.

amcdonal86

I agree. I never buy cars that already seem to have problems.

Actually, once this summer, I bought a non-running '94 Mitsubishi Mirage for $300. I put $300 into it to get it running, and then realized that there were a ton of other problems. I sold it immediately for $600.

But there was relatively little risk on a $300. When you're talking about a $4000 car, you better hope that if you try to sell it, nobody else will care about those problems...

JD1

So, I drove it for 20+ miles today. After 4 miles, the noise went away. The car has been sitting for most of the last 6 months. Oil starvation in the heads and top end maybe? He bought himself a new Tundra and his wife the hybrid SUV. I'm pretty sure the guy has never turned a wrench in his life and the dealer gave him a load of crap and charged him quite a bit for virtually nothing. It does make me wonder what Lexus dealers are thinking when a "whatever it needs" customer comes in. So, with that in mind, I think I'm going to get it and take it to my friends at T3 for an inspection, and get some blood and oil on my knuckles this weekend.

JD1

The body is perfect, interior is spotless, interior wear is not too bad for a car with 150k on it. And its black. From what I've seen on the used market, black is the prettiest and the hardest to find for the right price. The only 400's I've seen that could be talked down to $2k are beaten and battered, and I'm not interested in that. If all goes well tomorrow at T3, It'll be mine, and it's only going to be driven daily for the next 6 months. By then, my Volvo 240 wagon will be finished with its refurbishing and turbo swap to become my daily workhorse.

amcdonal86

Yes, black LS400s are pretty uncommon, I think! I wish mine were black. But then again, my last car was black and what a ***** that was to keep clean!!!!!

cjmeyer

My 95 is black and usually has about a 3 minute window of being clean before the dust monster moves in.

JD1

So. I got it. And back to the knocking issue, it's not knocking. It seems to be a slight imbalance around 2000rpm. I didn't have time on Friday and my Lexus mechanic friend had a death in the family, so I'm just going to do the basics. An oil change tomorrow with the oem Toyota filter, as advised, drive it all week. Then plugs and wires, and careful analysis. I'll keep you posted.

sam12345

iTrader: (1)

cjmeyer. Pick up a california duster at walmart. 10 bucks works good. Keep that dust in check