Lexs400

I had the water pump replaced on my 90 LS. now the engine vibrates at around 1500 rpm. and the vibration goes away after the rpm needle moves above 2000.
it vibrates even if i put the car in park and press the gas pedal to put the rpm needle between 1500 and 2000 leading me to take the trans. out of the picture.
my question is, can a faulty water pump cause vibration in the engine that's felt all across the body of the car ? if not then during the installation of the water pump is the engine lifted from it's mounts ? could it be the the engine was not put back properly on the mounts causing such vibration ?
any ideas / help will be appreciated.

SeattleGS400

iTrader: (1)

To get the water pump replaced, you have to take off the timing belt. It seems like when the timing belt was replaced and it was off a teeth or two on the camshafts. Further, your idler pulleys might be damaged. Also, the engine does not need to be lifted off the mounts to replace the water pump, so it's probably not that. How has the power in the engine since the water pump replacement?

Check w/ VVT-i (in the maintenance forum), as he's Lex tech, and can probably help you out with this. . .

VVT-i

Like SeattleGS stated, you don't need to mess with engine mount to do the water pump on the LS. You may need to check the cooling fan pulley and make sure that all the nuts are tight( if this problem just happened after the water pump was replaced). Let us know of the result.

Lexs400

I took the car back to the dealer. they said they checked everything and they "don't know" what to do. they do acknowledge the vibration but are playing dumb. that makes me really mad. They refuse to admitt that the vibration has started after the water pump and timing belt replacement.
I even asked them whether they checked the nuts and bolts when they were putting it all back together for proper torque etc. and they said they've done all that correctly the first time.
I'm lost. the car is terrible this way with the constart vibration everytime the rpm hits 1500 and then again when it hits around 3000.
with the vibration coming with different rpm settings and then going away i'm certain that this has something to do with the speed of some pulley or a rod when it reaches a certain speed. had it been otherwise then the vibration should've been constant no matter how much i had pressed on the pedal.
the service guy said it could be the torque converter. but to me that doesnt make any sense. this is happening even when the car is in park. is the transmission really operating at that time ? service guy told me it is even when i have the car in park or neutral. is that correct ?

Lexs400

allright , I took it to a private mech. and his analysis is the following:
either the camshaft balancer, or the MAS/ vacuum leak somewhere along the lines.
does that sound right ? cound one of the two possiblities be causeing the problem ?
thanks.

JPI Racing

Is the check engine light "on"? If it miss a tooth your check engine will be on. Check to see if they have the a/c compressor tight.
JPi

Lexs400

Jpi,
it's funny you asked, because I've seen the check engine light flicker twice so far. though it doesnt stay on. does the check engine light have to stay on all the time or would it somewhoe automatically go off as well ?

Lexs400

does anyone know a good private lexus mech. in the central NJ area. I'm sick and tired of the dealer rip offs ! For once I'd like to take my lexus to the shop and get it fixed right for the money I pay.
any inputs would be appreciated.

JPI Racing

I think I know a good lexus independent shop overthere. Please pm me.
JPI

PERRYinLA

But you really should not have to resort to that. A Lexus dealership, of all places, should stand behind its work.

Perhaps a diplomatically-worded letter sent first to the dealership GM, and later on, if necessary, Lexus HQ.

It would help if you had some way to prove the engine was running smoothly before you visited the dealership.

2KGS400

This happened on my 90 LS400 too. I just started it one day and it was there. Since then I've had the timing belt and water pump replaced along with various other regular maintenance and it has not gone away. I was also told it was a vaccum leak, the shop I was working with couldn't figure out where it was.
After a couple more frustrating attempts to pinpoint the problem I just learned to live with it.

2KGS400

This happened on my 90 LS400 too. I just started it one day and it was there. Since then I've had the timing belt and water pump replaced along with various other regular maintenance and it has not gone away. I was also told it was a vaccum leak, the shop I was working with couldn't figure out where it was.
After a couple more frustrating attempts to pinpoint the problem I just learned to live with it.

Lexs400

interesting.
the shop that you were working with, are they the lexus dealer or independent shop. did you ever take a trip to the dealer for this problem ?
how many miles on the car if i may ask ?

2KGS400

The first shop I went to specializes in imports and does really good work but do not know the ins and outs of RWD Lexus all that well. I also took it to Exact Performance here in KC, a shop owned by a Lexus enthusiast, who in many ways is more competent than the local dealer. He said that with some man hours and $$ he could probably figure it out, but that living with it probably made more sense.
The car had about 130k give or take when it started, 151k now.

Lexs400

interestingly enough mine's a 90LS with 135K as well. could this be a factory problem that we're experiencing ? I'm curious what other owners with the same year/mileage car's experience has been.