FloridaML

2006 LS430ML. 112xxx miles.

Seems to run beautifully, with no issues or complaints at present.

I have owned the car for right at a year now.

The reason for this post is that the car has always seemed to drop coolant somehow.

Soon after I got the car, I replaced the radiator and hoses.

I cannot see any coolant leaking from anywhere. My mechanic friend and I have put the car on a lift, put it in the air with the engine running for several minutes and watched. We didn't see anything.

So, my goal with this post is to answer the following questions;

Do other LS430s exhibit the same coolant loss issue?
Does my coolant loss indicate a problem?
If there is a problem, how do I identify the problem and fix it?


So, if you wouldn't mind;

1. Marking with a sharpie, showing the level of the coolant at present.
(there is a window near the radiator that shows the coolant level in the reservoir)
2. Making a note of the date and mileage when you take the picture of the coolant level.
3. Look again in a few days or a couple weeks or whenever you can, and take another picture to compare the coolant level at that time to what it was when you made the sharpie line.
4. Share your findings.

Note: I put draw two lines with the sharpie / marker. One line represents the coolant level when the car is hot, and one when the car is cold.

Note: The few pictures which I have attached are not meant to show the amount of coolant I am losing, they are just to show the method I have been using to document my coolant level.

LeX2K

There appears to be coolant staining on the overflow bottle possibly dripping down from the radiator. Either way this test is no good unless you check the level with the engine at exactly the same temperatures as when you drew those lines.

dwoods801

The 3UZ has a special bolt on top of the throttle body that is the high point in the system, if your just filling the radiator then your leave a major coolant void that is preventing coolant from circulating and your probably over heating it and the coolant is steaming off. Fill the radiator and cap it, then find the large Allen head bolt on top of the throttle body, remove it and fill it til it's full then replace the bolt and you shouldn't have any more problems

FloridaML

Thanks for your response. You have made a potentially important observation.

I neglected to address that in my original post.

The staining is from when the old radiator was leaking.

I replaced the radiator with a new one.

So, the spots and staining you see are all from the old stuff.

The new one does not seem to leak at all.

FloridaML

Thanks very much, I'd like to try that.

Can you direct me to any pictures of where the bolt is that you are talking about?

I am watching a video of how to clean the throttle body, just to see if I can see where the bolt is that you are talking about.

However, I cannot seem to identify the bolt from watching this video.

FloridaML

Thanks very much, I'd like to try that.

Can you direct me to any pictures of where the bolt is that you are talking about?

I am watching a video of how to clean the throttle body, just to see if I can see where the bolt is that you are talking about.

However, I cannot seem to identify the bolt from watching this video.

FloridaML

As far as the temp when I look at the coolant level as compared to my marks;

For the 'cold' reading I check the level in the morning after the car has been sitting 10-12 hours.

For the 'hot' reading I drive at least 5 miles, stop the car, then immediately raise the hood.

But whether or not I check at the exact same temps, the coolant reservoir ends up completely empty, then I have to refill it. So, I certainly seem to be loosing coolant.

dwoods801

I apologise, I described it as a large Allen head bolt, my vehicle has the 1UZ and it has the large Allen bolt, but when I pull up images of the 3UZ, it's clear that they changed this when the redesigned the throttle body. I am certain that the 3UZ has this same feature. It just looks like they have changed it to a flange bolt with an approximately 14mm head. Without having one in front of me, I cannot guarantee that this is the bolt for bleeding the cooling system. But I am like 99% sure. So if someone with access to a 3UZ would confirm it, it would be great. Here are some photos.

It's the bolt in the very center of the photo, and then a few more shots from different angles. I know sometimes it can be hard to pinpoint something from a photo, wovi got carried away with my screenshots.






I pulled one from the 1UZ just for anyone with the older motor and having the same issues

bradland

The bolt you're referring to is a mounting bolt for the upper intake manifold.

911LE

Have you checked underneath the intake manifold for leaks? There are crossover lines under there with gaskets and o-rings that I've seen leak. They are almost impossible to see without removing the intake.

Peacebay

I’ve owned three 430s and have driven them a combined 100k+ miles. Every single one was bone dry in the reservoir when I bought them.

And every single one lost a small amount over the years as I drove them.

The coolant overflow bottle is just a poor design on the 430s, unlike the 400s before them. The cap on top fits poorly, they crack easily, etc.

Basically what I’m saying is, fill it, monitor it, but don’t worry too much about it unless you have an obvious leak or are burnjng coolant (extremely uncommon on UZ engines)

Striker223

Since I did my cam seals a while back my coolant hasn't moved at all over 4 months and 10k miles driven. If it's missing it's going somewhere

Peacebay

The level isn’t going anywhere in 4 months or 10k miles. Check it again at 50k miles, guarantee it has gone down some.

bradland

This single and inexpensive hose, along with the pathetic spring clamps, is def the weak link of the entire cooling system. Replacing the hose and upgrading to actual hose clamps will improve the seal at both ends. You might be surprised what $10 and 10 min of your time will do for the coolant loss nuisance. Lexus part no.- 1637750040

Striker223

It won't lol, there is no reason for it to. I've had the car 30k+ miles and two years now and it's never moved from where I left it unless I serviced something. I fill it hot and purge all air and then check it totally cold.

The level has never moved, if it does there is a leak