jbobst

Fairly new to the forum here... I've been reading a bunch of past threads about DIY stuff.

I bought a 2001 RX two years ago (2wd). It had 119,000 miles on it when we bought it, and it just turned 160,000 miles about a week ago. The last two tanks of gas my wife has put in the car has only yielded about 16.5 mpg, and she started freaking out as she normally would get around 22mpg in the past. After reading some posts on this forum, it sounds like 16.5 mpg isn't all that bad, but since there has been a decrease in the past two weeks, I figured I better start looking into it.

A little more history on the car: When we bought this car, I didn't know anything about the transmission and oil sludge problems. However, the previous owner said he replaced the transmission around 80K miles (I should have inquired more about it at the time of sale, but I didn't). Also, shortly after we bought it, there was a noticeable oil leak, and I found that one of the oil pan bolts was sheared off. I dropped the oil pan and removed the bolt and put a new pan gasket on. I was amazed at how "burned" looking the inside of the oil pan was. I use only synthetic oil on all my vehicles, but I think this particular vehicle was a leased vehicle originally and probably just had conventional oil during the dealership oil changes the first few years of it's life.

Since I have owned this vehicle, I have never had the timing belt changed. Not sure if the previous owner ever did either. I read other posts here and most people say the timing belts are pretty solid, but as I mentioned earlier, the car just turned over 160K miles.

Here are my questions. I figured it's time to do a tune up on the vehicle and replace the spark plugs, oil, air filter, pvc valve and do a few other of the DIY things mentioned on this forum (like the IACV clean out). If I decide to have a dealership or independent mechanic change the timing belt for me, would it save me the hassle to have them also do the spark plugs? Are there other maintenance items they should replace while doing the timing belt?

I am trying to keep the maintenance cost down as much as possible. I'd rather not have to spend the money to replace the timing belt, but not sure if that is something I really should have done or not. I am hoping that just a regular tune up will help with the gas mileage, and I think I can attempt all those tune up items myself (with the help of the DIY thread on this forum).

How would some of you experienced guys handle my current situation with the timing belt and lower gas mileage problem?

thomas1

The timing belt should have been done at around 100k....There is no sticker on the front cover showing a belt change? I changed the waterpump at the same time since you are already in there....stay with your full synthetic....Plugs are good for an easy 125k miles. PCV valve is cheap, do it. Use only the Denso or NGK plugs (iridium) for the plug change.
Cleaning the Maf sensor is easy, and the IACV is good preventative for the vehicle with that many miles. Toyota or an independent can change the timing belt for less than $400

jbobst

Out of curiosity, does the timing belt need to be changed so that you can prevent the old one from simply breaking apart, or does the old belt get stretched out or worn out in such a way that the timing get thrown off on the vehicle, and a new belt "tightens" things up so to speak?

hypervish

There should be a sticker on the timing belt cover saying if it was replaced, and if it was it will list the mileage.

I recently replaced my spark plugs also at 160k and they looked great. Iridium plugs are very good and provide long life. I'd change them, just cause! LoL

You can clean IACV and throttle body if you want, but with things like that I leave them like they are till they need cleaning. Why fix something' that ain't broke... < But both of these things are easy DIY's and can be done in an hour.

PCV valve is about $10, and you can change it out by yourself in 5 minutes or less.

The timing belt is known to be extremely strong, but I would just change it anyways so you can sleep better at night. Changing the belt is cheaper than changing the engine if the belt breaks.

My RX had it's tb belt changed at 90k service. My 97' Accord is still on the original tb, last time I changed out the valve cover seal it still looked good.

thomas1

The timing belt is very strong, however they could possibly break or teeth on the belt can wear...Very undoubtable that it would cause your decrease in mileage...Lexus recommends changing it at 90k miles. The unknown with your vehicle is whether it was changed at 90k? It will not tighten things up....It basically replaced the old style chain in the old engines...

hypervish

BTW: 16.5 mpg in city or highway?

thomas1

here is a utube on the timing belt change:

http://www.youtube.com/watch?v=DI60MOkf168

jbobst

Thanks for the information so far. The 16.5 is mostly city driving. Where as we were getting around 22 just two weeks ago. She has already filled up the RX twice this week!

I was just trying to figure out what could cause the loss in mpg, hence the reason I wanted to try and do all the DIY stuff. However, it could just be her driving habit potentially. No engine light or anything.

I called the local Lexus dealer, and he said nothing can be done, and that someone is probably stealing our gas! I couldn't believe he told me that, and that nothing could be done. He had a bad attitude about it and wasn't even interested in having me come into the dealership for them to check it out. But, I am not sure I would go there anyway, because they charge so much money. This forum has far better information than this service guy!