biacs

I know there are concerns with different things but I wanted to build a sticky list for most common /easiest things to check.

2004 LS430 140,000 miles
Car had coolant topped off 3 weeks back. Now the black reservoir is down 6-8 oz.

-No drops on the garage floor
-No noticeable dried puddles under the plastic cowl
-No sweet smell when I start from the exhaust

Is there a checklist etc that I can reference- new cap or does the reservoir hose get old or ?

I assume I need it running on a a rack at a shop to really get a good look, But I'd like to try a few common fixes first.

Thanks all!

Johnhav430

Now I have never given this any thought prior to the LS430, because I never had a car that needed to be topped off except when the head gaskets were faulty (V6). In reading through everything, and also picking up my car used last Oct. and finding no coolant in the reservoir nor radiator (to be seen), and then topping off and then never having a problem ever since.....I wonder if there is something to the radiator cap? It does have a job to do.....I also found '06 is a different cap than '01-'05? More expensive? And I do see pink remnants around my reservoir, but then again, I had a timing belt replacement and it could be from that....otherwise, if nothing else, could it be the water pump which is not seen from the outside....

also I have read the recommendation of 2 kinds of pressure tests....

2KHarrier

The 3UZ-FE engine is notorious for using coolant. Both of my cars (2005 that rarely gets driven and 2001 approaching 170K and driven 155 miles each day) use coolant to an extent. I have to top off the 2001 more frequently than the 2005, but they both need coolant replenished every so often..

That being said, losing 6-8 ounces in 3 weeks is evidence of a more serious problem. The discussion of the radiator cap could be a possibility, as well as the mention above of the water pump leaking. Both those issues would be revealed by evidence of coolant, either on the ground or around the top of the radiator at the cap.
You could replace the cap and get the entire cooling system tested for pressure and with minimal work, access enough of the timing belt cover to see the water pump.

Or, just keep topping it off....

Let us know what you find.

Randy B

If you pull off the front cowl that covers the top of the radiator, you will see a small 3/8 inch hose that goes from the radiator to the overflow. The top clamp was the culprit for me. I would never see coolant on the floor. I was filling the overflow regularly and couldn't figure out what was happening. Turned out to be the hose had swollen at the point of where the clamp went on it. It would leak and blow out under pressure. The faring underneath held the small coolant that didn't blow through from the wind in it and would never drip down in the garage.

Good Luck,
Randy B

rkw77080

Check out this recent discussion regarding the same issues...
https://www.clublexus.com/forums/ls-...ant-issue.html

jpv7774

Hey Randy, I believe my top clamp is the culprit for my leak as well. I see pink residue on top of my over flow tank and near cap base. Did u just replace the clamp with the same part...or use something better? Did u replace hose as well?

can we drive our cars without the radiator cover? It seems to provide air to the air filter area for some reason.

jjb89

I just bought a 2002 LS430 and I'm having the very same problem. The dealership did a timing belt and water pump as a part of my purchase agreement included in the price of the car. It only has 91,200 miles on it. I picked the car up on Friday Feb 23rd fo 2018 and its now the 26th and I noticed my coolant reservoir was totally empty. I filled it all back up and had the levels where they needed to be. They could have been lazy at the dealership and not truly topped everything off but I did notice a slight drop in coolant levels after driving it a while with my heat on. There are no apparent leaks under the hood anywhere at all yet it's going someplace. It has a new radiator cap that I put on it just incase the vapors were escaping and that was my issue. No odd smell from the exhaust upon startup when cold. I've had two previous cars with head gasket issues and this doesn't seem like a head gasket problem, it's not showing any signs of that at all.

The people who have fought with this and actually found an answer aside from a bad clamp or hose, what did you find? Any specific recommendations on what to look at or test?

jpv7774

Hey JB.....I have been tracking my leak for a while. If u look carefully.....do u see pink residue on top of your over flow reservoir....around the cap etc??? You have to remove the radiator cover to see whats going on....its only held on by two plastic grommets.......Once u have that removed use a flashlight and look all over......starting at radiator cap.....follow hoses to over flow cap....looking for residue ......then look straight down the back of the reservoir down to the bottom flange behind your radiator......so u see any pink reside ?????

I replaced my radiator cap.....wasnt it
Over flow hoses and clamps....wasnt it

it appears to be blowing out through my reservoir plastic cap......it may need an O ring that wasnt a stock part......thats my next step. These parts are cheap......so my advice to you is new caps and over flow hoses......let me know if u figure it out.

jjb89

There's no evidence anywhere of pink residue under the radiator cap, around the overflow tank or any hoses connecting the two. The reservoir cap fits very tightly.

I took a shot with the radiator cap because it was only $10. Fittings around the hoses are solid, the hoses are all in excellent shape. I wish I would find a hose or fitting that is in crummy shape! It would give me some peace of mind.

I'm wondering if it isn't escaping through the overflow hose of the reservoir somehow but I also don't see any evidence on the lower plastics under the car covering the bottom of the motor or on the motor in the front looking in from under the hood. So I don't see how that would be possible.

I'll be ding my research and am planning on checking all of my spark plugs to see what they look like here in the very near future as well. I'll keep you posted if I find anything. Thanks for the reply!

biacs

I dont know that you can see the hoses as crumby if they are compromised. Maybe do the cap and reserviour hoses - as just a sanity check - very cheap and its an old car to begin with so certainly not a waste of time.

jpv7774

I am assuming your car was using the OEM pink fluid which the residue is easy to see. I agree with last poster.....replace the over flow cap.....small hoses....and clamps.....its cheap....and I am certain that is where mine is leaking. I have replaced all except cap on over flow.......will get that today. ................The radiator on our cars is the only achilles heel that I am aware of.....could be a leak from the radiator....could have tested by a shop. I dont drive my car much...usually only on the weekends. The car has to get hot for the fluid to overflow into the over flow........so mine is a hard nut to crack....I have to purposely go on a long drive and push it hard to get it to leak.

OG Member

iTrader: (1)

In my experience with multiple Lexus vehicles and based on the details fellow LS members have provided. I'm guessing it could be that your coolant system may not have been 'burped' enough.

Again, my personal experience is that no matter how well I think I may have 'burped' the coolant system - I've always had to go back and top off the coolant levels

Hope it's a simple fix and please let us know what you uncover!

bloomwcjkl

Clarification question.

When the car is cold/air temp, the reservoir might in fact be empty. The coolant expands when the car is fully warmed up, so the reservoir would only be "full" when fully warmed up?

Is this correct? Could people be filling their reservoir when cold and overfilling? This causes the overflow scenario. If the car is cold and the reservoir is full, is that overfilled?

jpv7774

Regarding the burping........this would only apply after a fluid replacement correct????? Like during timing belt / water pump service......What is the proper process of burping the system......or what do we do now after it wasnt burped or let air escape properly....???
I did have my timing belt and water pump service done in the last 10k miles.....so your theory is possible

toddmorr

you can, and I have for brief periods meaning a few days. But its there for a reason, possibly to ensure a more consistent airflow to the intake? which might matter under strong acceleration.
I certainly wouldn't leave it off permanently