LScowboyLS

Agreed!

when a vehicle starts getting really bad gas mileage all of a sudden and it is temperature related, it is normally due to the engine running too cold, and the thermostat is the common culprit!

Jlacck

Sam, as far as I know, the heat actually blows fine. But at the same time, I haven't had to crank it (haven't turned it past 80 yet), but it seems to warm the cabin enough for my tastes. I definitely don't feel like it lacks for power or anything. However, not sure if its related, but the AC does blow REALLY cold though. I don' t know if this makes it more confusing, but as cold as the AC is, I don't think the heat is "as hot". But that's probably a good thing.

On a related note, I had a look at the coolant level today and I noticed it was RIGHT at the low mark (Not below it, right at it). When I had my oil and transmission fluid changed at the dealer, shouldn't they have filled the reservoir to the correct amount?

johnnyg66

I keep mine at the low mark when cold after it warms it goes to high mark anymore and you run the chance it will leak from the coolant level sensor o ring.

You can add a little more like say to half its up to you.

sam12345

iTrader: (1)

Havent taken any of my cars to the dealer ever. So I would not know

LScowboyLS

the temperature of the A/C being "really cold" has nothing to do with the engine temperature, although it is hard to get cold A/C out of a car that is overheating - although too much refrigerant in the A/C system can cause excessive head pressure which would cause the engine to overheat - but your issue is likely too cold rather than too hot if you are getting bad mileage.

deanshark

Not if you didn't tell them too. If they're not working on that particular system, they don't even look at it. Add a little to it b/c you don't want it getting too low b/c then you'll get air in the system.
You'd think if there wasn't enough coolant that it would warm up faster. You might already have air in the system.

Jlacck

Thats what I'm starting to learn. Sounds like you have to be very specific about what you want done. I just assumed that when I asked for the oil and transmission change, that it included all my fluids and filters. Lesson learned!

I usually don't go to dealers myself. I think their services are way over priced. However, considering that the car was well maintained at the dealer and it seems to run in great shape, I figured for certain important things I would go to do the dealer to handle (besides, I actually love the facility they have here in Denver. Man the amenities make you feel like royalty lol).

Someone mentioned bad gas mileage. I wanted to say this is actually my second lexus, my other was/is a 1994 ls400. I was getting very bad mileage in that particularly lexus until I got the sensor replaced.

In this Lexus, according to the dash read out, I seem to average about 20 mpg. I don' t know how accurate that is due to a possible bad sensor, but it typically fluctuates between 19-21 or 22 mpg with the average being about 20.

LScowboyLS

an LS400 with all systems working correctly should be getting 21-22 mph or so around town and 25-27 on the Interstate

Shmee

iTrader: (3)

That depends on what you paid for. If you paid specifically for an "oil change" then that's what you get, if you paid for an oil service then they(most shops AND dealers) typically do a 20-40pt inspection with a fluids check/top up as needed.
Usually there is minimal difference in price between the two but most people don't pay attention or are biligerent about what they want/think they want when it comes to cars... And then **** as moan about why it costs so much or why they didn't get X, like their buddy did last year, when they paid for Y.

Jlacck

Shmee, it sounds like the dealer did what they were suppose to do. I did get the 20-40pt inspection... here is what I got:

valex

I started having same symptoms on my 1999LS400 - temperature gauge shows low temparature and poor gas mileage.

I replaced coolant temperature sensor about 40K ago, shall I:

1.Get a new one($47 at parts com) this time around anyway?
2.New temperature gauge ($107 at parts com) (you called it gauge sensor - same thing, correct)
3. New thermostat ($17)?

Thank you!

Shmee

iTrader: (3)

After having an aftermarket temp sensor die after just over one year and send my fuel Econ to crap, I bought a new factory temp sensor to replace it.

You do not need a temp gauge, you need a "temp SENDER for gauge" and may be wildly different from what you were quoted... Sounds like they are selling you something like an automated aux temp gauge. It's basically the same thing as the temp sensor and should cost about the same.

valex

Do you have part numbers for the sensor and sender ?
I have changed the coolant temperature sensor before, so I know where it is. What about the sender you are talking about, where is it located?
Thank you,
Val

valex

Anyone cn comment on this sender location as well the part numbers for sender and sensor?

valex

I finally changed my thermostat today. Once I pulled the old one out, it was obvious what the problem was- inner rubber seal completely broken. 1999 LS400 187,000 miles, original thermostat.

Over last couple years I changed oxigen sensors, spark plugs, coolant temperature sensor, trying to improve my gas mileage and it turned out to be such a simple thing as thermostat! Very easy job, easier that an oil change in my opinion, just drain a gallon of coolant to avoid messing up engine and belt.