Potential Ls400 Gearbox Failure?

Titch LS · October 30, 2012

Recently, I read about a couple of LS430's (and a Landcruiser) having gearbox failure. The problem was with the ATF oil cooler leaking internally and allowing radiator coolant into the gearbox and contaminating it. 'Drive' was lost and the cars 'failed to proceed', (to quote Rolls-Royce)! Do you think it might be due to the 'wrong' coolant being used over a prolonged period i.e. owners not using Toyota Red? As both the correct coolant and ATF become a bit similar in colour after a few thousand miles, it would be hard to keep an eye on this by checking the ATF dipstick for contamination. Is this problem likely to occur do you think, on our LS400's? (Particularly the Mk4's as they preceded the LS430). I've not come across a case of this yet on the forums. Any comments would be appreciated, thanks.

ROYT · October 30, 2012

I've not heard of it on LS400's, but still may be possible due to similar arrangement.

I stick with Toyota red coolant and hope for the best.

The 430 I heard about escaped with a couple of trans fluid changes, but i think it just luck.

MNP · October 30, 2012

Hi Brian,

I can't comment on the previous owner of my Land Cruiser but when I bought the car it had already got a new radiator but the (green type) of coolant was weak. The gearbox fluid will emulsify with the tiniest bit of water contamination and goes creamy pink, so easy to spot. After 4 years of regular flushing and a few breakdowns the gearbox started making a buzzing noise and soon after failed, to the point that I could very gingerly limp from Wem in Shropshire the 50 miles to Cannock to have the rebuild. He had to buy another donor box to complete the rebuild as mine was in such a state. I needed another radiator too as all the bits from the box clogged up the old one. In summary, easy to spot with regular checks but you are on borrowed time unless caught straight away! Mark.

ambermarine · October 31, 2012

The system is tried and tested and as been used on all the LS configurations since thier launch in 89. there have been a couple of instances reported on the Lexus forums worldwide.

The important issue is to stick to using the toyota red coolant as this is formulated to react non adversly with all the components and materials it comes into contact with,also of significant importance do not dilute with tap water or for that matter any water as the coolant comes premixed and should go in the system without any adulteration.

Parrot of Doom · October 31, 2012

W211 Mercedes E-class's are well known for this. The problem was that certain "valeo" radiators were poorly designed so as to allow engine coolant to leak into the gearbox oil, and vice-versa. There's nothing wrong with with running gearbox oil pipes through the radiator, so long as you do it properly :)

On the Mercs, the solution was to replace the torque converter and radiator only. The gearbox was otherwise undamaged. The problem made itself evident with a pulsing, or thrumming, running through the vehicle.

Bluesman · October 31, 2012

W211 Mercedes E-class's are well known for this. The problem was that certain "valeo" radiators were poorly designed so as to allow engine coolant to leak into the gearbox oil, and vice-versa. There's nothing wrong with with running gearbox oil pipes through the radiator, so long as you do it properly :)

On the Mercs, the solution was to replace the torque converter and radiator only. The gearbox was otherwise undamaged. The problem made itself evident with a pulsing, or thrumming, running through the vehicle.

I had that problem on both Mercs I have owned plus of course numerous other mechanical problems on these well engineered cars.

Mike

Jannie · November 4, 2012

As I work on a lot of LS cars must say that i have changed quite a few radiators as the gearbox oil cooler fails. Fortunately for my customers all of the symptoms was detected early enough and only had gearbox oil in the cooling system and no coolant in the gearbox. In my opinion it would not matter what anti freeze you use if the gearbox oil cooler fails it is not due to corrosion but fails on the joints and seams.

runsgrateasanut · July 28, 2015

Reviving this thread, for some reason I thought early LS400's were immune to this possible problem as I must have assumed the Power steering pipes at front were Gearbox cooler pipes. Doh!

At 21 years, looks like another part I need to replace to feel sure of no catastrophe, especially as I've almost rebuilt this car with new parts!!

Another sleepless night, and 3.00am Rock auto parts scan for Rads, as I had the Autobox pipe literally fall off the Rad on my S Class a couple of years back, fortunately without killing the g/b.

So, check out the six or seven alternatives and read the +/- comments and scratch your head as to what to go for. Denso or Koyo (not sold by Rock) Plastic or Brass or Ali top, then there's the fact that Rock don't show the EU flag against all brands, so is American Rad set up different?

Will check Amayama price.

I keep telling myself all this expense will be worth it in the long run, even if just to keep me in this most friendly of forums!

cruisermark · July 28, 2015

"Another sleepless night, and 3.00am Rock auto parts scan for Rads"

Lol a lexus shouldnt give you sleepless nights

Titch LS · July 28, 2015

Stuart, after 3 and 1/2 years on the LS forums, I've come to the conclusion that the LS400 doesn't suffer from the problem you are concerned about. Definitely seems to affect some LS 430's though, but even then, only very rarely. I can't recall any LS 400 owners on here or on the U.S. sites having a gearbox failure due to coolant entering the gearbox. I think you are fretting too much. Save yourself some money.

The-Acre · July 28, 2015

Stuart, after 3 and 1/2 years on the LS forums, I've come to the conclusion that the LS400 doesn't suffer from the problem you are concerned about. Definitely seems to affect some LS 430's though, but even then, only very rarely. I can't recall any LS 400 owners on here or on the U.S. sites having a gearbox failure due to coolant entering the gearbox. I think you are fretting too much. Save yourself some money.

I second that!

Drain the fluid and refill with the correct coolant if you're concerned, but I don't think you should be.

ColinBarber · July 28, 2015

This issue does seem to be mainly related to the LS430 and certain Toyotas (4Runner, Landcruiser and Tacoma). It doesn't appear to be a corrosion issue (there are several accounts where the owners have used official Lexus service centres for the life of the vehicle using the correct fluids) but failure of welds/joints where the pipes join the cooler body - possibly due to long term vibration fatigue.

I'd therefore say the issue is an installation/design issue and/or lower quality components of the LS430 so no reason to suspect your LS400 needs any special treatment.

ROYT · July 28, 2015

There are 'Nissens' radiators on eBay about £90,-----don't know what the quality is.

runsgrateasanut · July 28, 2015

Thanks for input. Anyone who's had one go bad will know what anxiety it brings.

I looked at the Nissen and other brands and reviews, and my own choice would be a Silla at $87 imported - lifetime warranty from what I've read.

Checked whats in the Car and its a Toyota 5009 part 422130 -6460 3n Japan.

I'm not too sure if this is original as I have a problem with my Air intake plastic conduit not fitting precisely over the top. Unless car has an accident history or is out of alignment.

Read some alarming threads on plastic top rads exploding. This one is plastic top.

I hope I don't have to change the Rad as its not a job I'd want to do again. My coolant is red but I put half a cup of distilled water in when I had a 600 mile return journey last June. Bought some Toyota Red when I got home.

Red ATF/Red coolant fluid, not too clever by Toyota. Isnt it yellow somewhere?

Ruud · July 28, 2015

What exactly are the issues with the car?

runsgrateasanut · July 28, 2015

You mean "the latest " of course!!

Slight fluid leak could be ATF or could be Pwr Steering. Not discovered exact location. Had another look under the bonnet and may be wetness on part just below Reservoir. If that is the Control Valve (Idel off Switch according to Scotty Kilmer) I have a bill Jan 14 showing it to have been replaced £99.07. Maybe its the hose/s. Will have to inspect from beneath sometime later in the week. Will need drop the tray I suspect.

Symptoms, selecting reverse at cold not liked by the car and did have an unexpected change down about a week ago, when car hot.

Power steering, slight noise at drive off. Level cold was at bottom of dipstick - should it be half way up the cold mark? did put a dribble in, as have done to the ATF.

Ruud · July 28, 2015

Power steering leaking is a common issue on the early Ls and, if left, can 'fry' the alternator as it is located directly below. There are many topics about this.

Are the ECU capacitors replaced? Bad / leaking caps can cause gearbox issues as well.

Titch LS · July 28, 2015

Good idea to change the ATF every 30,000 miles or so, or at least replace a few litres with the correct fluid around that mileage. My gearbox is as smooth as silk, hot or cold, after 140,000 miles.

Malc · July 29, 2015

... the pas reservoir pipes corrode out and can cause catastrophic loss of pas fluid.

I mentioned this before somewhere when mine did just that mid last year.

One of the few bits of mild steel gubbins on the car and mine only lasted 19 years !

Malc

The-Acre · July 29, 2015

The power steering reservoir leaked on my 93, usually just the O ring between the body and reservoir. Fairly easy job, the new part from Lexus at the time was £2 ( a lot for a rubber ring!)

As Malc says, the cooler pipe at the front corrodes, easily replaced and shaped with copper microbore pipe from a plumbers merchant.

Malc · July 29, 2015

Phil, no I meant ALL the pipework from the pas reservoir, it was that which corroded through, the front cooler pipe, as it happens, was just about OK !!

But it all got replaced.

Malc

runsgrateasanut · July 29, 2015

"Are the ECU capacitors replaced? Bad / leaking caps can cause gearbox issues as well"

Its on the listhaving just purchased a desoldering iron - now added pollen filter change to the list.

Keeping me busy this car!

The-Acre · July 29, 2015

Phil, no I meant ALL the pipework from the pas reservoir, it was that which corroded through, the front cooler pipe, as it happens, was just about OK !!

But it all got replaced.

Malc

I see, still straightforward though, but not if you have sausage fingers! I never did replace mine but I know I was on borrowed time as is looked like brown bubble wrap.

Malc · July 29, 2015

. fairly straightforward I'm told by my indy who did it ....... the OEM replacement mild steel configuration was about a £1mn from Lexus .... flexi hoses and clips did the trick !!!

Malc

The-Acre · July 29, 2015

. fairly straightforward I'm told by my indy who did it ....... the OEM replacement mild steel configuration was about a £1mn from Lexus .... flexi hoses and clips did the trick !!!

Malc

That's the thing, it's possible to improvise, but also even improve on the original set up with certain jobs.