So i have some concerns about my 00 lexus ls400 with roughly 104k miles. I noticed when I start the vehicle the idle in park is roughly around 800rpms. but once i put it into reverse or any other drive gear the rpms drop rather low to about 300-500 rpms. I do notice that the tranny does have abnormal upshifts and downshifts ever after the vehicle is warmed up. Another problem Im having is driving long distances in the heat or using the air conditioner. Especially during highway driving. My engine temperature is usually and always a hair under the half way mark. but i noticed that it climbs to a very abnormal rate aswell. What could this be? Im not really car savvy when it comes to lexus. Any help would be much appreciated. thanks in advance.

 

The usual maintenance stuff first: coolant, thermostat, tranny fluid flush then we get into fan clutch and or debris hindering flow through the radiator, etc.

Idle isn't abnormal...when putting it into reverse, mine will drop to ~500 rpms depending on engine/tranny and ambient temps. If the car stalls/dies, there are problems.

 

I've added coolant with water, had my tranny oil drained and filled, and had my valve cover gasket replaced about a month or two ago. But it seems that the problem occured after I did that and my coolant is filled way over the full line for some reason even though when I filled it I filled it just at the full mark. I tested a couple quick high speed punches with my air conditioner on today when I got off work and the temperature gauge started to go up rather fast. It seems like it goes up drastically whenever my air conditioshave on. Ill see if I have to get my thermostat replaced, any write ups on how I can do it myself? I don't have a jack or jack stands but I do have tools. Also u said ur idle is like that aswell. But mine goes that low when I drive or reverse regardless of temperature or running time.

 

It does sound like your thermostat isn't opening enough, if any. Or ya might have a bunch of crud and leaves in front of the radiator preventing air flow through it, it gets a real nasty buildup in there. Here's for removal of t-stat on 90 - 94 but it should be pretty much the same; http://www.lexls.com/tutorials/cooling/thermostat.html

 

Check between the radiator and AC condenser. If the car is driven through leafy environments, stuff manages to get stuck between them. There is a thread in the 2-GS forum showing an accumulation. After that was cleaned/removed, temps were normal.

 

Thanks for the responses guys. Im going to pick up the thermostat and gasket today after work and do the work on it wednesday. i know in that provided link they provided the part numbers but on autozone it doesnt have those.

These are what they have but which one;
http://www.autozone.com/autozone/par...mString=search

And I can use this gasket correct?;
http://www.autozone.com/autozone/par...mString=search

Also in regards to draining the coolant. when i refill the coolant reservior do i fill it up with coolant and water, or just coolant?

 

[Also in regards to draining the coolant. when i refill the coolant reservior do i fill it up with coolant and water, or just coolant?[/QUOTE]


save and reuse if clean or go new with a 50/50 mixture.

put your t/stat in this way.....

 

You need a 180* T-stat. I have a Failsafe T-stat in mine for 2 years now without any trouble. I didn't realize this before but in thier features it says "Patented safeguard against overheating. When overheating occurs, FAIL-SAFE automatically locks in the open position to permit maximum coolant flow" And yes, you do need that gasket to go with it. Do what billy suggested with the coolant.

 

Are you using Toyota red Long Life coolant? Also use only distilled water, not tapwater!

 

Well it turns out I didnt get the thermostat from autozone. I was going to but I rather be safe than sorry. So I went to the toyota dealer and picked up the part number that was provided on that how to write up. Yeah Ill be using the toyota red coolant, I picked up a container of it not too long when I noticed my reservior was under the fill line. Hopefully this fixes my problem. *crosses fingers*

 

Alright I went through all the step until I had to pull out the thermostat. To find out that the one I purchased is slightly smaller. I went back to find out the female who worked there gave me the part number 90916-a3003 not 90916-03084. The gasket was the correct part number. And all she could tell was to goto a lexus dealer to obtain the correct. She didn't seem very informative on anything. Just a computer monkey. So by any chance is there any type of difference in the two??

 

Actually those are all the wrong part #. The link I posted, I said the removal should be the same. The part #s won't be the same b/c they are different generations of the LS400. The OEM part # for your 2000 is 9091603100. But either way, the broad at the parts counter should have given you the right part if you told her what year it was for. The #a3003 is for a 93.

 

So i decided goto the lexus dealer to get the part. Since the girl at the toyota dealer didnt have the faintiest clue that toyota made the ls400. she could even help me out when i told her the type of engine i had. so i finally got the correct part and i finally was able to install it. I should of be taking the freeway today to see if this solved the problem. thanks a bunch for all of your help.

 

The Toyota dealers in my area will not easily oblige a cross reference, instead they say go to your Lexus dealer. My Toyota parts guy will cross reference for me but invariably, they do not stock the Lexus parts because they do not interchange. Carson is one of the few that does sell-stock Lexus parts.

Hope this is all wrapped up and the car is happy again.

 

mike, jason and kerry at westminster are great for getting those pesky "lexus only" parts are are one of the places carson buys their "lexus only" parts from