Transmission Problem / Question On 1998 Gs400

[glewis01]

Hello All,

I have been chasing and fixing problems for a clunking sound in my drivetrain for about a year on my 1998 GS400. I have 124000 easy miles on the car.

I checked this site and found that some people were having similar symptoms from bad engine mounts. I had them checked and they were bad so I had them replaced.

While getting the engine mounts replaced the mechanic found that the U-Joints were bad on the driveshaft. Unfortunately you have to have the driveshaft replaced to change the $50 U-Joint....

He also found several bushings that were bad and changed them.

$2600 later :cries: the problem was supposed to be fixed.

Today I was driving up a steep hill and had to come to a stop for a truck that was pulling out. When I lightly applied the throttle the engine reved up but did not move forward for about 1 to 2 seconds and then their was a clunk and the car jolted forward and was working correctly.

It felt like the transmission was completely slipping for the 1 to 2 seconds and then it "caught" and worked correctly.

I think this it the "remaining" problem that is causing the remaining clunk in the drivetrain. It only happens when going from off throttle to light throttle. It happens more often then not when I go up a steep hill.

The transmission does not slip at anyother time or clunk under hard acceleration or at speed when shifting.

Has anyone experienced this type of problem? :(

Is this a transmission problem or one of the transmission sensors or valves? :o

I have had to put about $4000 into the car this year and if it is going to require a transmission rebuild then I am going to have to sell it so I am hoping it is a much simpler fix. :cries:

Any help is GREATLY APPRECIATED!

This forum has been outstanding for helping me to find, resolve and fix problems on this car.

Thanks so much!

Greg

[Lexus_gs400]

Hello All,

I have been chasing and fixing problems for a clunking sound in my drivetrain for about a year on my 1998 GS400.  I have 124000 easy miles on the car.

I checked this site and found that some people were having similar symptoms from bad engine mounts.  I had them checked and they were bad so I had them replaced.

While getting the engine mounts replaced the mechanic found that the U-Joints were bad on the driveshaft.  Unfortunately you have to have the driveshaft replaced to change the $50 U-Joint.... 

He also found several bushings that were bad and changed them.

$2600 later  :cries:  the problem was supposed to be fixed.

Today I was driving up a steep hill and had to come to a stop for a truck that was pulling out.  When I lightly applied the throttle the engine reved up but did not move forward for about 1 to 2 seconds and then their was a clunk and the car jolted forward and was working correctly.

It felt like the transmission was completely slipping for the 1 to 2 seconds and then it "caught" and worked correctly.

I think this it the "remaining" problem that is causing the remaining clunk in the drivetrain.  It only happens when going from off throttle to light throttle.  It happens more often then not when I go up a steep hill.

The transmission does not slip at anyother time or clunk under hard acceleration or at speed when shifting.

Has anyone experienced this type of problem? :(

Is this a transmission problem or one of the transmission sensors or valves? :o

I have had to put about $4000 into the car this year and if it is going to require a transmission rebuild then I am going to have to sell it so I am hoping it is a much simpler fix.  :cries:

Any help is GREATLY APPRECIATED!

This forum has been outstanding for helping me to find, resolve and fix problems on this car.

Thanks so much!

Greg

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I'M ACTAULLY HAVING THE SAME PROBLEM. I'M TAKING MY CAR TO THE SHOP THIS WEEK AND IF I FOUND OUT THE ANSWER I WILL POST BACK TO YOU.

[glewis01]

Hello,

I went into this sites archives to try to find a solution to my problem.

I found threads on resetting your driving habits that are stored in the CPU and decided to give this a try.

I removed the fuses and let it sit for an hour so that it would drain and reset the CPU.

I believe this has solved the problem! I have tried it for about 2 weeks and have not had a reoccurance of the problem (slippage and then hard connecting) even on steep hills where I stop the car and then apply the throttle.

I think that what happened is that either the CPU got confused on the driving habits or it learned them from the earlier owner (I was the 2nd owner and have put 60K miles on it before it got worse) and would slip the transmission for a higher RPM range than what was needed.

As I mentioned in the original thread I did have to replace a lot of parts in the suspension, engine mounts, tie rod ends, etc.

I would recommend checking the front engine mounts, there were a lot of threads on these often going bad as the exhaust is routed by them and the oil inside gets "cooked".

I had them replaced and both of my front ones were bad.

I would recommend trying this as the dealer couldn't find my problem and was thinking of changing the transmission to fix the problem. Fortunatley I found these threads! :)

Thanks!

Greg