e-man

For those of you who have changed your timing belt, did you also change out the "idler sub assemblies" (the 2 rollers that the timing belt rests on)? They are about $70 each, and I don't mind replacing them if they need replacing, but it doesn't sound like it's the kind of part that would wear out.

e

cone_killr

iTrader: (1)

Wondered that myself. I'd like to post a better answer than "go ahead and replace everything while you are there". The same question arises about water pump replacement. The best answer is "it depends".

Do you have AAA?

If you live where the weather is decent (no snow) and keep sand away from the seals, you might leave them alone. It's dirt and lack of lube that kills bearings. If your seals are good and bearings spin free, they may last another 90K.

Presumably, the life of a water pump seal is less than that, but if you service the car yourself and can tear the front apart in a few hours (not that hard really) I feel it's worth the risk. Note that I use Toyota red coolant and distilled water. If the water pump lasts another 50Kmi, it's worth it - just replace it in a day.

If it's your only vehicle or are paying a mechanic, the equation changes. Spend the money now.

gserep1

I'm sure the bearings will last longer, but why risk it? the reason I say that is because the bearings are under a lot of stress by the hydraulic tensioner to keep the belts tight, AND imagine how many times these bearings spin in 90,000 miles at all engine speeds.

I have done the timing belt on 2 GS 400's and I inspected mine at 90,000 miles both times. I was glad I did replace them because the bearings showed evidence of grease leaking out of the seals each time. These bearings cannot be serviced, and if all the grease comes out, it will stop or bind, causing belt slippage and possible loss of cam timing. I did my first one on a 1999 GS4 in 2004, so that was almost 6 years of service time. My second 1999 GS400 was produced in Dec 1998, and I did not change it out until October 2005, which was about 7 years. That is a long time for a bearing that cannot be lubed. I did not want to take these parts to failure, since I DO like to "get on" my car on a regular basis.

By the way, I paid less than $70.00 each at Carson. One is "fixed", and the other swivels above the hydraulic tensioner.

I changed mine right at 90,000 miles. Some folks wait longer, increasing the risk. I guess it is just like the water pump. I agonize buying new pumps when the old ones look so good. To put it in perspective, if I could change the pump without going inside the engine, I would take the chance. I have a 1997 Explorer V8 I bought new, and I have not changed the water pump yet, and I DO change the coolant yearly. It won't do damage to the engine when / if the pump goes out.

That red LEXUS coolant is very slippery, and it will most certainly cause belt slippage if it comes in contact with the belt. If I am trucking along at 70 to 80 miles per, and I get a leak like that, I think I will have valve train damage before I realize what is going on and can get it shut down.

Just not worth the risk to me.

migitymark

Im thinking about preparing to be getting ready to change the timing belt on my 2000 gs4, and my first thought is to just check everything when i change the belt.

I had a 76 dodge aspen as a teenager that had the water pump go out at 230,000 miles and 22 or more years on it. I finally changed it after like 2 weeks of leaking 1/2 gallon of coolant per mile. My mom on the other hand had a 2000 grand cherokee 4.0 that had the water pump go out at 20k and 2 years on it.

For around $120, I'm not planning on changing my water pump unless it has some play in the shaft or something, but I'll probably change the idlers ONLY because new ones will make my noisy engine more quiet. $150 to cut down on noise is alot of money, but like the water pump i'd change them only after inspection.

If the water pump is not leaking now, it wont leak till it pukes coolant out the weep hole when it fails; which wont spray ON the timing belt because thats just stupid engineering, and I saw a water pump with 'revised weep hole location' somewhere. (nice run-on sentence huh) Changing it will only increase the chances of it leaking from the face of the block, where it could get on the timing belt. I don't think it would leak though, unless I do a horrible job of scraping the old gasket off and putting the new one on (whether thats RTV silicone in a tube or an actual gasket).

chuckb

I agree. If you don't plan on being in there again for another 90k, just replace the tensioners too.

FWIW-The bearing on my drive belt tensioner started making noise at 30k miles.

slickgt1

iTrader: (1)

Yup, I replaced mine too. You can barelly hear the engine now. It's awsome. Don't mess with it, and just change them, and forget about it.

e-man

Thanks guys. I agree. For an extra $140, I'll just go ahead and have them replaced.

Hey Slick. How are the HDs treating you? Do you have any further observations? Shoot me a PM when you get a chance.

gserep1

GOOD IDEA! You can't go wrong changing them. If I had a crystal ball I would know just how long they would last, but I don't.

I agree that the dealers have you by the short and curlies, so try to minimize the impact and do it yourself if you can. Or check around for service, because prices vary a LOT from dealer-to-dealer.

You'll FEEL better knowing it was done right, and the extra price you paid for the bearings will not matter as you drive many carefree miles.

And to MIGITYMARK, I'd say to do what you feel on your engine. If you don't believe that the pump can fail without warning, go ahead. It is a gamble you seem willing to take.

Coming from someone who has done a few of these, I can say that you are braver than I am. NUFF SAID

migitymark

to me, its not really a gamble, I just don't think I would mind doing it again when the waterpump fails (my guess around 130). plus I'm planning on switching over to an LS430 before then. l think it would be a lot less difficult a second time if I did have to fix a waterpump, but I haven't actually done it yet; so yall know something I don't know. Is the timing belt change so difficult on these that I wouldn't want to do it again for a waterpump?
Overall the questions governing the waterpump decision are: Do you expect to have the car when you expect the waterpump to fail? and if no: Will the new waterpump 'raise the resale value' of your car when you sell it?

gserep1

That is a two sided question. You cannot change the waterpump without at least moving the timing belt to the side. When the pump comes out, the coolant will gush all out the front and get on the belt if you haven't taken it completely out of the way.

You said that you are going to buy a LS sooner or later. Hopefuly it has less than 90,000 miles on it, because if it doesn't perhaps someone else decided not to change out the waterpump at that time, and you may be faced with a repair around 130,000 miles yourself. Perhaps the pump will go 200,000 or 300,000 miles. It is just WHERE it is located that is a cause for concern.

It is so easy to change the waterpump while the timing belt is out of the way, that it is a no brainer to do it then.

On these cars people look at the miles when they buy them used. If it is close to that 90,000 mile service, it is a big bargaining point if it is not done, and a big plus if it is. Knowledgeable prospective buyers will want to know.

I bought both of my GS400's with less than 90,000 miles on them. I changed the belts and accessories at 90,000 miles on both cars. I drive a lot of miles in a year, so proper mantenance is not a question.

It all boils down to how much you want to gamble with the original parts, and if you are ready to shoulder the responsibilty and expense of fixing your engine if the pump lets go when you least expect it.

Labor is the biggest expense, but if you do your own work like me, it may not matter. I like to work on cars, but not to do extra work I could have avoided in the first place.

Lexus replacement parts are EXPENSIVE. Nothing like old american car parts.

I have never seen a pump go out, but I don't want to be the first. Perhaps someone has more knowledge about this than I do. I believe that you can do a lot of damage if the timing belt slips due to a failed water pump, and others do not. That hot coolant is going someplace when it leaks, and the question is WHERE? Whether the coolant blows up or down, I believe that the belt will somehow get some of it.

IF the pump went bad after your initial timing belt change, I would think you would want to change that belt again. I would, but maybe you wouldn't. The loss of time for the second maintenance action, expense for the new pump and new belt is enough for me to do it while I am looking at it.

The pump comes off so easy.. No sealant (RTV or the like) is needed, as the water pump has a form-fitting O ring around the entire pump mating surface, and the tubes are sealed with small rubber o rings that have to be changed as well. It is a precise fit, with no scraping of gaskets needed.

Just my $.02

400 Degrez

Does anyone have a write up on the timimg belt replacement

cone_killr

iTrader: (1)

NO contest, the pulleys and water pump is 95% easier to replace when you are servicing the timing belt. If my pulleys started being noisy or weep hole started crying the day after a timing belt only change that would really suck. Maybe thats reason enough to change everything at once.

But what is the real risk of leaving well enough alone?

The "just replace it crowd" will never know how long these components will last. The only reason the question is not a "no-brainer" to me is that both the pulleys and water pump fail relatively slowly and give plenty of warning. The pulleys will make noise thousands of miles prior to failure, although you would need to know what to listen for (actually I like a quiet engine also, it's another attractive feature of Lexus refinement).
The weep hole after the seal will keep the timing belt free from exposure to coolant, but you will have to keep your eye out for leakage. If you want to shut your hood and not be concerned, the right answer is to replace the moving parts subject to wearout all at once.

Some of us don't mind the relatively minor risk, however. I'll let yall know how long my bearings and seals last. Keeping my fingers crossed.

gserep1

It is okay with me if it is okay with you. I really wish you good luck. We may all be able to learn something since someone wants to go for the durability test. You may be able to convince Toyota to lengthen the interval between changes, but I doubt that since making money is one thng they like to do.

My water pump looked like brand new when I took it off, but the two bearings had seen better days. The grease was coming from the seals. I questioned the sense of changing it right then, but I had no confidence that it would last another 90,000 miles. I changed my last timing belt in August 2005, and I have 40,000 more miles since then. If the trend continues, I'll need a new belt in 2008.

I hear that someone else in an LS is doing the timing belt durabilty test on their car. I have heard of some diehards driving 200,000 miles on their belt, but that was with the old LS NON-INTERFERENCE engine. 90,000 to 95,000 sounds good to me. Some people don't put miles on as fast as others, and I wonder about belts that have fewer miles, but have a lot of years on them.

Maybe I am wasting money, but until I get more information, I'll stick with the factory recommended schedule.


Thanks for all the replies and opinions. I really enjoy them.

GUNRU-GS4

E, I replaced them when I got my 90k service done recently. I say do it! Car is very quiet and running smooth.

FlavesLex

iTrader: (1)

This is a great thread, good reading all your opinions and advice... Like the last comment GSEREP1 ^^^ made, i'd stick to the factory recommended schedule just to prevent any unwanted surprises. I'm also a strong believer in preventative maintenance, it's just nice to do things when you have the $$ rather than having something break or go bad when the cash isn't available.
My $.02