AandSC

2000 LS400, 41,000 miles, TB/WP never replaced.

I've decided not to gamble any more on the original, 16 year old TB/WP and have ordered the following parts:

TB
WP
Serpentine Belt
Spark Plugs
Tensioner
Idler and tensioner bearings
Upper and Lower Radiator Hoses
Thermostat
Will flush radiator and cooling system
Will clean the throttle body and IAC

Anything else you guys would recommend replacing or cleaning while I have the front of the engine apart? I recently replaced the PCV and grommet and will be doing the transmission drain and fill with every 5,000 mile oil change. Also have recent air and cabin filters.

Stroock639

technically there is no IAC valve it's all just done with the throttle body valve. also on top of the throttle body at the front there's a metal plate held in by 2 phillips screws, underneath it are a bunch of air passageways that can get dirty but if you're not noticing any sort of lower than usual idle it's probably ok

sheila814

i have a 93 sc400 with 156,000 miles and moved the car from CT to Orlando, FL area. I've heard that cars don't like changing climates. However, The timing belt has been change 2 times and the last time there was nothing wrong with it as the mechanic showed me the belt when he replaced it (it is good to ask for the parts they remove, even just to make sure they actually replaced them - there are a ton of crooks out there). The serpentine belt really didn't need replacing as well, just 2 weeks ago, but i had to put in a new p/s pump and alternator since the foolish design of mounting the weep hole from the leaking pump over the alternator windings took that out as well. The tensioner is original and had tons of leverage still on it (there are lines on it and on the mount that let you know if the spring mechanism is fatigued. The idler pulley's bearings were worn by the sounds of them. Autozone charged $72 for the big one! i had to take about an 1/16" of an inch off it with a grinder cuz it was to wide and rubbed against the housing and also needed to put a shim on the front. the maker put the bearing slightly off the required depth.

If i were you I'd save my money for the necessary repairs that will ultimately come with mileage and age.The car is well made but the rubber and plastic components are going to disintegrate in due time. The o-rings and seals are going to start leaking from the p/s components, the a/c, the hydraulic fan, etc. those are hard to get at and cost a ton of labor $$ unless you do it yourself. The Engine Control Module's capacitors may start leaking, which will lead to all kinds of codes that you will spend time and money to track down (probably replacing sensors that are perfectly fine) before you discover you need a new
ECM for a couple of hundred dollars. The needles on your dash will die and bug the hell out of you cuz you can't see how fast your going, etc and that is another couple of hundred dollars even if you remove the dash cluster yourself (which appears to be a major pain in the ***).

Be patient and save up for the big stuff. Just my 2 cents worth.

dicer

And if your not a mechanic don't try to learn on that project, its better to spend a bit more to have it done than to have to replace the engine.

AandSC

I've been turning wrenches for many years. The last timing belts I replaced were on my Ducati 1198. Doesn't get much more complicated than that.

Sheila814, appreciate your thoughts. I'm aware of all the potential issues you've listed. The parts to do all this work myself is around $400 and given that the 2000 motors are interference motors I would rather not risk a failure. Will also give me a 100,000 miles before I have to worry about another TB. All those other items I can tackle when they happen. I will give the PS system a good look over while I have the front of the car apart. In fact, now that I think about it I'll go ahead and flush the power steering fluid also.

Stroock, appreciate the info on the IAC. I'll clean those air passages while I'm doing the other work.

dicer

Sorry no way of knowing things like that on here. Not many cyl's on the duck.

AandSC

Dicer, this is true. One fourth the cylinders but twice as many timing belts means twice as many possibilities of screwing up.

UNCJD

41K miles? I'm drooling.
I am a chairborne commando who once had a buddy's Blazer on the back of a tow truck after an oil change that went bad. How does an oil change go bad? That's OT. And a long story.
But my point in bringing it up at all is this: I changed my TB, WP, PS pump & alternator. It's time, tools, patience and education. There are some fantastic tutorials out there, and you CAN do this. It's a total pain and took me several weekends. But even a blind squirrel finds a nut...given enough time.
I have a '95, also interference. Your 2000 may be different, I don't know. But we all changed spark plugs for the first time at some point, right? If you can spare the time and can handle the near-heart attack when you crank it for the first time, it's a mad ego boost.

sheila814

i was going to change the transmission fluid and filter (if there is one) just for maintenance. my "trusted" mechanic warned me against it. he said he has seen alot of people have problems with their trans after doing it. he said there was a problem with overheating and other issues. his advice to me was if the fluid is still red (not burned from heat) leave it alone. this made since because after using seafoam on my motorcycle i had more idling problems than i was trying to get rid of. it was obvious the idle valve was clog from sitting to long, but i didn't want to remove all the parts to take the bowl off the carb just for that. well when i finally had to do it to sell the bike i found all the "stuff" in the carb that the seafoam loosened and flush to through the carb. this showed me that if i did something like this to my transmission thinking i would clean it up i would loosen up all the coatings and they would probably get stuck in the hydraulic channels of the trans.

dicer

I'm kinda gutsy with transmissions, I believe that doing a normal change of fluid especially on these LS400's that only drain about 2 quarts is a good thing, because there are additives in the fluid that need periodic replacement. Not changing the fluid would be like saying don't add any if its low. I have done this 2 quart drain and fill on some very high mileage cars with fluid that was many years old. Its a gallon on a Subaru and did one of them with at least 15 year old fluid, with zero problems.

AandSC

Dicer's method is what I am planning. 2 quarts every oil change. With the lower miles on mine I think that method will serve me well.

dicer

That is what I do on the LS.

brybo86

in addition to your list i would also recommend you change the crank seal and fuel injector seals/grommets (cheap from napa)

timmy0tool

iTrader: (7)

if it were my car i would actually just drive it until the regular scheduled maintenance of 90k. sure things age but the timing belt is internal not exposed to the elements. i would base it all on the condition of the serp belt, which is outside. if the serp belt is ok, then what more the TB. my $0.02 but i know you decided to just replace anyway.

the peace of mind is a great plus, including all the new knowledge gained and confidence in yourself to do such a job. best to you sir!

AandSC

Timmy, I was going to wait until closer to 90K miles but I don't want to gamble with this. The serpentine belt looks okay, but not good enough to make me comfortable enough. Given that I intend to keep this car for a long time and the fairly low cost since I can DIY it just makes sense to me to go ahead and update all the maintenance. This should give me peace of mind for another 90K miles. Thanks also for words of encouragement Doing the timing belts on my Ducati (2 belts for 2 cylinders) gives me a good understanding of the process and confidence that I can tackle this.

Brybo, thanks for the additional recommendations. I will be researching those today. I have a little bit of time since I am planning to wait until closer to 45K miles when my next oil changes is due.