LS430 Transmission cooler question

RRKiller · November 18, 2019

Hello Lexus friends,

I'm new here and I'll make a proper introduction later on because I am full of love with the very best brand in the world.

I have read many topics on the tranny cooler problem design flaw but I still have some questions and I cant find the answer. Hoping you gentlemen could help me out.

- Can I get rid of the (future) problem by just mounting a good quality trannycooler like Mocal or another brand?

- If I mount this, do I use the original lines onto the new cooler or is it smarter to get rid of all the lines and renew everything. Every unesseserely connection is a future risk in my opinion.

- Can somebody please show me with a picture what lines I should use to mount on the future tranny cooler.

- Somewhere on this forum I found someone saying that the original cooler is located into the radiator itself. Do I need to shut off those insert lines into the radiator?

- Do I really need to mount a new radiator when I also mounted a new tranny cooler or can I be sure with just a tranny cooler? I want everything to be 100% safe for the future and I think Ill keep this car forever.

- What size cooler would be the best?

- Is it smart to take a thermostatic cooler?

- Do I directly need to fill up the transmission fluid and how can I do that? Or should I fill up the cooler before mounting everything together? Sounds attractive but it's not really precise. Another problem is that there is no dipstick with these type of transmissions.... Very scary.

- Mounting this cooler; Solid or in rubbers?

- Is it correct that the size of the ports should be for 10mm hoses?

After almost 2 years of thinking and googling I thought I should go for it now so thats the reason of this topic.

Many thanks for your help and info!

lex - eleven · November 18, 2019

I don't know the answers to any of your questions but the previous owner of my 430 had one fitted. If it would be of any help at all I could take some pics for you?

Sent from my EML-L29 using Tapatalk

The-Acre · November 18, 2019

The hoses are 10mm and you can mount a cooler directly in front of the AC condenser, there's loads of room and a good solid base for it, it doesn't need rubber mounting. The cooler in the radiator is very small, about 70mm high and a tad shorter than the radiator. The defunct fittings don't need plugging but it's probably good practice. All you need to do it get some decent hose to make the connections. My local motor factor suggested fuel hose which is what I used. On my current car I just replaced the radiator, much easier and reduces the risk of radiator failure. Personally I wouldn't bother with a cooler, just buy a new radiator and be done with it, it should last many years. Fill with fresh Toyota coolant, job done, takes less than an hour and can all be done from the top.

JamesIS220 · November 18, 2019

Don't forget in winter the hot coolant in the rad helps heat up the transmission fluid so needs heating in colder climates. I would buy a replacement rad.

James.

The-Acre · November 19, 2019

6 hours ago, JamesIS220 said:

Don't forget in winter the hot coolant in the rad helps heat up the transmission fluid so needs heating in colder climates. I would buy a replacement rad.

James.

Good point! It's engineered that way for a purpose.

John N · November 28, 2019

Eleven years ago I bought an LS430 and used it to tow a large caravan, and anyone who has used an LS430 to tow something big will know it's wise to fit a transmission cooler. The coil in the bottom of the radiator is just not big enough for towing. I fitted the transmission cooler in line with the coil in the radiator, for extra cooling, and had no problems with the system over the 10 years and 140,000 miles I had the car.

The secret to having no problems with the transmission cooling on an LS430 is to make sure the anti-freeze is up to strength and is less than 5 years old at all times. The anti-freeze contains the corrosion inhibitor that stops the cooling pipe in the radiator rusting through and filling the gearbox with water!

Earlier this year I replaced that car with a lower mileage LS430 (I couldn't think of a better tow car to buy!) and transferred the transmission cooler and tow bar. Then because I didn't know the history of the anti-freeze in the cars' radiator which was starting to corrode, I fitted a new radiator and filled it with new anti-freeze.

If you have bought a 14 year old car and don't know the history of the anti-freeze in the engine, I would advise you to replace both the radiator and anti-freeze.

If you do want a transmission cooler try:-

LEXUS LS430 GS430 SC430 Auto GEARBOX OIL COOLER UPGRADE NEW!!!!

This is the kit supplied by Lexus Spares Direct on eBay.

John N

lex - eleven · November 28, 2019

Looks like my one

Sent from my EML-L29 using Tapatalk

skyway · November 29, 2019

In my humble opinion that oil cooler is a tad on the small size

John N · November 29, 2019

It does look a little smaller than the one I have fitted, but mine was bought 11 years ago from Kenlowe, and it wasn't scientifically sized, it just looked about right to me!

Kenlowe appear to have stopped making them now and the current ones come from China.

If you are concerned give Paul Frost a ring at Lexus Spares Direct, he puts that kits together and sells them. He is very knowledgeable about Lexus. From the feedback ratings he gets on eBay he doesn't appear to be doing anything wrong. His mobile number and E-mail are at the bottom of that eBay advert.

john N

The-Acre · November 29, 2019

I would suggest it's not just internally that corrosion happens. When I replaced the radiator on a previous LS430 the rust outside was really bad on the connection to the radiator because the fittings aren't stainless.

RRKiller · December 11, 2019

Thanks for all your comments and information gentlemen.

This is all very helpful. And @lex - eleven Showing a picture is always interesting to look at. Even for some idea's how to mount the cooler if I will purchase one.

Would you like to share what you have paid for your new radiators?

John N · December 14, 2019

Paid £188.50 earlier this year for one off eBay with a 2 year warranty. I think that's about half the genuine Lexus one costs.

John N

The-Acre · December 14, 2019

On 12/11/2019 at 1:21 PM, RRKiller said:

Thanks for all your comments and information gentlemen.

This is all very helpful. And @lex - eleven Showing a picture is always interesting to look at. Even for some idea's how to mount the cooler if I will purchase one.

Would you like to share what you have paid for your new radiators?

About £120ish, a Koyo from ECP. However, a Koyo isn't a direct fit for a UK LS but is for a Celsior.

skyway · December 14, 2019

Phil does the denso rad not fit the Celsior?

The-Acre · December 14, 2019

2 hours ago, skyway said:

Phil does the denso rad not fit the Celsior?

Not if you buy the UK spec one. You can buy a Denso rad from Rockauto and it'll fit because the US setup is the same as Japan.

skyway · December 14, 2019

I dont suppose you have the link for the one you bought from ecp have you Phil

The-Acre · December 14, 2019

3 hours ago, skyway said:

I dont suppose you have the link for the one you bought from ecp have you Phil

I've just looked and unfortunately they no longer sell them, Rockauto would be your best bet I think.

skyway · December 15, 2019

Thanks Phil

The-Acre · December 15, 2019

4 hours ago, skyway said:

Thanks Phil

Is your Celsior performing well? It must be well over a year now.

RgrWynne · December 16, 2019

On 12/14/2019 at 12:13 AM, John N said:

Paid £188.50 earlier this year for one off Ebay with a 2 year warranty. I think that's about half the genuine Lexus one costs.

John N

RgrWynne · December 16, 2019

2 minutes ago, RgrWynne said:

On 12/14/2019 at 12:13 AM, John N said:

Paid £188.50 earlier this year for one off Ebay with a 2 year warranty. I think that's about half the genuine Lexus one costs.

John N

I paid around £240 for a genuine Lexus radiator that fitted perfectly about 2 years ago, from a main Lexus dealer.

The-Acre · December 16, 2019

1 hour ago, RgrWynne said:

I paid around £240 for a genuine Lexus radiator that fitted perfectly about 2 years ago, from a main Lexus dealer.

Strange don't you think, that there are two different setups for the same car? I often wonder why as both variations do exactly the same thing.

John N · December 16, 2019

When I was looking for a replacement for my first LS430 radiator, I found there were two versions of the radiator available from Lexus.

The spares manager at Lexus didn't know the difference between them!

What I found was that on my radiator there is a connection for a small bleed tube from the top of the radiator to the water reservoir, this make the radiator "self bleeding". If you take the air intake box off the top of the radiator you can see it clearly on the same side as the water reservoir.

On the other version of the radiator this bleed connection is missing. (This is the cheaper version of the 2 radiators available from Lexus, which I bought first, and then had to send back because of the missing connection!)

I think there was a version of the car made with a non-pressurised cooling system, but the version sold in this country used a pressurised system and the self bleeding radiator.

First check the top of your radiator to see if it has a bleed tube connection, and if you buy a replacement on-line check the picture or drawing of the radiator to make sure it comes on the radiator you buy.

John N

The-Acre · December 17, 2019

10 hours ago, John N said:

When I was looking for a replacement for my first LS430 radiator, I found there were two versions of the radiator available from Lexus.

The spares manager at Lexus didn't know the difference between them!

What I found was that on my radiator there is a connection for a small bleed tube from the top of the radiator to the water reservoir, this make the radiator "self bleeding". If you take the air intake box off the top of the radiator you can see it clearly on the same side as the water reservoir.

On the other version of the radiator this bleed connection is missing. (This is the cheaper version of the 2 radiators available from Lexus, which I bought first, and then had to send back because of the missing connection!)

I think there was a version of the car made with a non-pressurised cooling system, but the version sold in this country used a pressurised system and the self bleeding radiator.

First check the top of your radiator to see if it has a bleed tube connection, and if you buy a replacement on-line check the picture or drawing of the radiator to make sure it comes on the radiator you buy.

John N

My system is still pressurised with a standard radiator cap but the coolant reservoir is mounted on the actual radiator which is hard to see so really the air intake has to be removed to check it properly. Not that its dropped over a year.

RRKiller · April 12, 2022

On 12/17/2019 at 12:11 AM, John N said:

When I was looking for a replacement for my first LS430 radiator, I found there were two versions of the radiator available from Lexus.

The spares manager at Lexus didn't know the difference between them!

What I found was that on my radiator there is a connection for a small bleed tube from the top of the radiator to the water reservoir, this make the radiator "self bleeding". If you take the air intake box off the top of the radiator you can see it clearly on the same side as the water reservoir.

On the other version of the radiator this bleed connection is missing. (This is the cheaper version of the 2 radiators available from Lexus, which I bought first, and then had to send back because of the missing connection!)

I think there was a version of the car made with a non-pressurised cooling system, but the version sold in this country used a pressurised system and the self bleeding radiator.

First check the top of your radiator to see if it has a bleed tube connection, and if you buy a replacement on-line check the picture or drawing of the radiator to make sure it comes on the radiator you buy.

John N

I think I have bought that radiator. Mine has the connection on the other side. I need to make the tube a bit longer. My Lexus has the seperate expension tank. In the US they dont have that but thats no problem. The only difference is that little hose and there is also an extra filler cap on my radiator since the models in the us dont have that expension tank where the normal filler cap is located.