Any Advice On An Oil Cooler?

The-Acre · October 8, 2014

I went on line today to order a cooler for my transmission (I see there's another car on eBay with the same failure) but the suppliers don't seem to be able to advise on which size (the number of rows it seems) Can anyone offer any advice as I want to get this done asap.

Thanks

Phil

steve2006 · October 8, 2014

If memory serves me right the transmission cooler is the lower integrated section of the coolant radiator. Would it not be cheaper and easier just to replace this part before it fails rather than an aftermarket fitment?

The-Acre · October 8, 2014

If memory serves me right the transmission cooler is the lower integrated section of the coolant radiator. Would it not be cheaper and easier just to replace this part before it fails rather than an aftermarket fitment?

I didn't realise it was separate from the main radiator. Thanks for the advice, I'll look into that.

Mybikes a cx500 · October 8, 2014

My understanding is the 430 cooler is inside the radiator, and has been known to corrode, thus mixing engine coolant with trans. fluid, and trashing the transmission.

Fitting an external cooler avoids this possibility, sounds like a worthwhile mod to me....

The-Acre · October 9, 2014

My understanding is the 430 cooler is inside the radiator, and has been known to corrode, thus mixing engine coolant with trans. fluid, and trashing the transmission.

Fitting an external cooler avoids this possibility, sounds like a worthwhile mod to me....

That's what I want to avoid, but Steve is suggesting that the bottom part of the radiator is a separate part that can be replaced. The aftermarket coolers are not at all expensive and look fairly easy to do.

Next week I'm having some posh new exhaust tips fitted by a guy who's very familiar with these cars, so I may just ask what he suggests while he's got the car in his garage.

ColinBarber · October 9, 2014

I believe the bottom part of the radiator can be removed and the oil cooler accessed.

There is a benefit to keeping the stock setup, the transmission get up to temperature quicker and cooling can be maintained in traffic as the radiator cooling fans will kick in.

The-Acre · October 9, 2014

I believe the bottom part of the radiator can be removed and the oil cooler accessed.

There is a benefit to keeping the stock setup, the transmission get up to temperature quicker and cooling can be maintained in traffic as the radiator cooling fans will kick in.

Thanks Colin, I'll get them to look at it next week when it goes in for a cosmetic rear end. I'm guessing though that this may mean a Lexus part which could well mean an aftermarket cooler will be a much cheaper option. There is a huge amount of space in front of the radiator and AC condenser, so it should still be cooled by the fan. I've been looking on some American sites to get more info and it seems that many there are using the aftermarket ones on all sorts of vehicles to avoid the same issues.

ColinBarber · October 9, 2014

You are correct it will be cheaper to go aftermarket. It looks like the part (16491-50240 or 16491-54790) is going to be over £300, plus you need to drain and remove the rad, take it apart and probably need a new o-ring seal at £40.

The-Acre · October 9, 2014

You are correct it will be cheaper to go aftermarket. It looks like the part (16491-50240 or 16491-54790) is going to be over £300, plus you need to drain and remove the rad, take it apart and probably need a new o-ring seal at £40.

Do you know if I'm right in saying I can simply remove the hoses from the rad and re route them to a new cooler? Sounds a bit too easy but that seems to be the info I've managed to get.

ColinBarber · October 10, 2014

that is correct, then add a little bit more transmission fluid (Toyota T-IV) to recover any lost fluid and to fill up the new cooler.

steve2006 · October 10, 2014

Here is the exploded diagram of the radiator/transmission cooler, the cooler itself is numbered 16491 on the diagram.

From the diagram it would appear the transmission cooler is mounted inside the engine coolant radiator and is therefore surrounded by engine coolant which acts as an intercooler. It is when the transmission cooler becomes holed that the 2 fluids are allowed to mix with the known subsequent damage.

The setup does however protect the transmission cooler from impact damage so care must be taken to ensure a stand alone cooler is positioned where it is protected against any impact damage and also has adequate airflow. Hopefully the original pipework can be reused or it may need modifying to do so.

Another consideration is how a stand alone cooler will affect the warm up time of the transmission fluid and if it will allow it to get to normal running temperature so the size choice must be carefully considered.

IIRC all Aisin transmissions have a fluid temperature sensor fitted which inhibits the engagement of top gear until the fluid has warmed up to the required temperature, if the fluid never reaches this preset temperature it may cause problems.

The-Acre · October 10, 2014

Thanks for all that info gents. I'm going to get the mechanic to look at it when it goes in next week, then maybe I can decide on an aftermarket cooler or a new Lexus part. Failing that, as I'm getting confused, maybe I should leave it alone and hope it never happens!

Malc · October 11, 2014

then you will be on borrowed time

Malc

The-Acre · October 11, 2014

then you will be on borrowed time

Malc

I am sort of aware of that, although there are many that have covered 250K with no issues. But of course it will always be in the back of my mind. I'll see what's suggested next week when it goes in. I'll report back in case it helps someone else. My guess is that I will go for one of the two options rather than just ignoring it.

colin4989 · January 7, 2015

Phil

How did you get on?

The-Acre · January 7, 2015

Phil

How did you get on?

As of today I haven't! I've had so much conflicting info that I'm not sure what to do. However, I did ask the guy who did some work for me and he said it really is easy to put an aftermarket cooler on. He owns a GS300 and did the same to his as he tows a lot. He said a simple £65 cooler will do, and fitting it is easy. As I've just paid for a new rear height sensor it will have to wait for a while. Bearing in mind the mechanic is Lexus trained and seems to know his stuff, I think it's probably the way to go, there's loads of space to fit one and it means the risk of water damage is gone, so it will be a job to be done soon, unless I need a height sensor on the other side......

colin4989 · January 8, 2015

Phil my Update. Put car into garage. They were aware of the probs with gearbox and coolant mixing with these models

They replaced coolant free and pressurised the system again and gearbox oil (at my request) and checked the car over thoroughly but couldnt find any leaks noting only that the gearbox oil that came out was slightly dirty but not contaminated or burnt. I use the Lexus garage (servicing and warranty etc) a lot and I'm confident that they have been checking it thoroughly.

Got the car mot(£27) at same with no issues woohoo

The-Acre · January 8, 2015

Phil my Update. Put car into garage. They were aware of the probs with gearbox and coolant mixing with these models

They replaced coolant free and pressurised the system again and gearbox oil (at my request) and checked the car over thoroughly but couldnt find any leaks noting only that the gearbox oil that came out was slightly dirty but not contaminated or burnt. I use the Lexus garage (servicing and warranty etc) a lot and I'm confident that they have been checking it thoroughly.

Got the car mot(£27) at same with no issues woohoo

Good news on your part! Most LS430's go through life without the transmission/water problem, and most likely it won't happen to me. It's just that if it is straightforward and inexpensive I think I'll get it done anyway. I may wait until the MOT is due and get it done at the same time.