GS430 Fluid Leak

abtx · August 18, 2019

Hi fellow Lexus owners. My Lexus broke down yesterday night and I'm waiting till the garage opens on Monday and I've been wondering if anyone here might help me diagnose the issue.

So it's a 2005 (2006 model) with about 110k miles on it, I'm the 3rd owner. Few days ago my heater stopped working. I googled it, got some coolant (or antifreeze), topped it up, drove for about 10 miles tops, everything worked fine.

The next day I take it out for a drive and want to show off to my gf how clever I am and blow some warm air on her cheerful face. The coolant's been topped up, engine warm, and bam. I keep getting cold breeze from the vents. At this point we were approx 2 miles away from home, I keep driving and toying with the A/C but I have a feeling it won't work. Then I notice the engine temp gauge going riiiiight up the red line.

We stop, wait for the car to cool off a bit, pop the hood up, carefully open the fluid cap, fill it in, the fluid goes down. Repeat. It goes down. Repeat...

Long story short I called the AA. They came and by then there was obviously a puddle underneath the car (under front row seats) so I pointed it out: "hey man, I've got a leak here, that's all the bloody coolant I poured in a moment ago". Dude checks it with his glove and he looks at me, then looks at the glove smeared in white creamy fluid and smells it, and says it's probably servo or transmission fluid.

Now I realise it might be a more serious issue and remember that the gearbox was a bit jerky for 2-3 seconds driving smoothly at low speeds when changing from 1st to 2nd, it happened about 5 times during past week and felt as if you'd drive a manual and didn't give it enough clutch/throttle, but it was very very gentle.

Anyhow, the AA guy said we should try the closest garage and will be ok to drive there, he'd escort me. I drove it about a mile to the garage and left it there. Now I got to wait for the garage to open on Monday and give me the verdict (or, most likely, wait for another week before they have time to look at it).

So I wonder what this may be. One detail I left out is that there are traces of some oil in the antifreeze can. The leak under the can might have been all transmission (or servo, but I don't think so as there were no symptoms with steering power, but the transmission), but it as well might be some antifreeze and the fluid. The AA guy shoved a tone of bio-powder or something on the puddle and we drove off so I didn't take a close look. When driving to the garage gear changes were as smooth as ever, engine stayed at the right temp, but as I mentioned it was a short, one mile / 5 minute drive.

So here I am, dear Lexus forum, crowdsourcing some brains out to get a better picture of what kind of trouble I am in for this time and how big of a hole in my pocket it might burn.

Cheers!

PS: gearbox oil has been changed in 2017, under 20k miles ago

The-Acre · August 18, 2019

As you have the same engine as the LS430 I can't help thinking you have the dreaded transmission fluid/coolant mix which can wreck the transmission.

abtx · August 18, 2019

oh boy. hope it's not been wrecked then

The-Acre · August 18, 2019

21 minutes ago, abtx said:

oh boy. hope it's not been wrecked then

I don't want to sound like the harbinger of doom but it seems that most who have had this problem have found the transmission is beyond redemption. I hope I'm wrong! The transmission is cooled by the fluid being pumped through an integrated cooler in the bottom of the radiator, the seals fail due to corrosion/O ring failure which in turn sucks coolant into the transmission.

abtx · August 18, 2019

No worries, it's best to prepare for the most likely consequences. After all, the fluid did get mixed and ATF got spilled, and I read as little as a tablespoon of water in the ATF can damage the box.

Apparently for about 100 quid one can fit a dedicated transmission cooling system. If I only knew...

I think I will see what the garage says, but they'll probably confirm. If that's the case I'll have an auto box specialist have a look at it.

If it's super likely the gearbox is done for I'll need to wage if it's worth replacing. There are boxes on eBay for around 1k plus, but very few. So I guess this can cost about 2k. The car has been very well cared for and I've got a tone of new parts in it including original Lexus fitted shocks couple years ago. It's gonna be a tough call.

The-Acre · August 18, 2019

I fitted a cooler to a previous LS but came to the conclusion a new radiator is easier, plus its another part that should be good for some years.

abtx · August 18, 2019

Yes, I'd defo get a new radiator now. So I'd be looking at a used gearbox + new radiator plus work.

Is it ok to drive the car to the other garage if the gearbox is gonna need replacement anyway (provided I don't overheat the engine, off)?

The-Acre · August 18, 2019

39 minutes ago, abtx said:

Yes, I'd defo get a new radiator now. So I'd be looking at a used gearbox + new radiator plus work.

Is it ok to drive the car to the other garage if the gearbox is gonna need replacement anyway (provided I don't overheat the engine, off)?

I wouldn't want to be the one to say yes in case the damage isn't too bad, but from what you say about the two fluids already being mixed it may be beyond that now anyway. Another couple of members had the same issue and spent money on having the transmission checked and flushed, but as far as I recall one was saved and the other wasn't.

abtx · August 18, 2019

Cool, thanks for the advice. I guess I'd be better off taking it to the specialist right away.

If there's a good chance to save it with flushing then I'd probably go for it, depending on the cost..

I had the a/c stop heating on Thursday, so I guess this is when the coolant started to go. I probably did about 20 miles since till the breakdown.

I'll talk to the autobox specialists tomorrow, see what their opinion is.

I'll keep this post updated.

The-Acre · August 18, 2019

3 hours ago, abtx said:

Cool, thanks for the advice. I guess I'd be better off taking it to the specialist right away.

If there's a good chance to save it with flushing then I'd probably go for it, depending on the cost..

I had the a/c stop heating on Thursday, so I guess this is when the coolant started to go. I probably did about 20 miles since till the breakdown.

I'll talk to the autobox specialists tomorrow, see what their opinion is.

I'll keep this post updated.

Yes please, keep us updated as the info may be invaluable. Also it's the first time I can remember reading this regarding a GS so assuming the fluid mix is the problem then it may help as a warning to other GS430 owners to take action.

abtx · August 18, 2019

ofc. I definitely want other owners to beware and take any precautions necessary. I will report back asap.

abtx · August 19, 2019

I talked to the workshop and they will look at it end of the week

abtx · August 22, 2019

I dropped it off to the shop. Below is a pic of the puddle from under the car on the driveway and from the lorry. Another opinions I heard is that this is also typical for blown head gasket. I will see what the auto box garage says and will probably get a second opinion from another garage as well.

abtx · August 26, 2019

I just called the garage, they said it's the gearbox. The garage is an auto box specialist, they want to replace it altogether for about £2000. The gearbox didn't show any symptoms before so I wonder if I can fix the leak and then keep driving it until it does. I'm now gonna take it to another garage now for a second opinion.

The-Acre · August 26, 2019

7 hours ago, abtx said:

I just called the garage, they said it's the gearbox. The garage is an auto box specialist, they want to replace it altogether for about £2000. The gearbox didn't show any symptoms before so I wonder if I can fix the leak and then keep driving it until it does. I'm now gonna take it to another garage now for a second opinion.

If it is the transmission I'm not sure fixing a leak will achieve much as there will be a fair amount of contamination in it. You may just be wasting money. I think I'd be looking for a used unit for a direct replacement, and a new radiator of course, or you could just strip down the radiator connections, clean the parts and replace the o rings, but I don't know of anyone who has done that. The radiator unions screw directly into the cooler, in fact it's all that holds it there. If you did decide to do that be careful to do one side at a time otherwise the cooler will drop and it'll be hard to realign.

abtx · August 27, 2019

What if I replaced the radiator, flushed all fluids, and kept driving the car until there are more noticeable symptoms of the gearbox going bad?

The-Acre · August 27, 2019

1 hour ago, abtx said:

What if I replaced the radiator, flushed all fluids, and kept driving the car until there are more noticeable symptoms of the gearbox going bad?

I can't see it doing any more damage, and who knows, it may just be ok...maybe!

abtx · August 27, 2019

I think I'll try this route first. I don't see the point of changing the gearbox just yet. The other garage will have a look at the car end of the week. Fingers crossed!

The-Acre · August 27, 2019

3 minutes ago, abtx said:

I think I'll try this route first. I don't see the point of changing the gearbox just yet. The other garage will have a look at the car end of the week. Fingers crossed!

I guess it is worth a try, you may be the lucky one. I think a really thorough flush will be necessary though.

abtx · August 27, 2019

6 minutes ago, The-Acre said:

I guess it is worth a try, you may be the lucky one. I think a really thorough flush will be necessary though.

Yes, agree, it only makes sense to clean everything out and hope it will be ok. I guess it really depends how badly the solenoids in the gearbox will have deteriorated over the time, but with new gearbox oil that should slow down any harmful processes inside of the gearbox.

The-Acre · August 27, 2019

21 minutes ago, abtx said:

Yes, agree, it only makes sense to clean everything out and hope it will be ok. I guess it really depends how badly the solenoids in the gearbox will have deteriorated over the time, but with new gearbox oil that should slow down any harmful processes inside of the gearbox.

I hope this works out well for you. I'll be following this with interest.

abtx · September 6, 2019

Quick interim update. I had another mechanic look at the car. They confirmed the antifreeze got into the gearbox, but they think the gearbox can be saved. They're still waiting for the gearbox service parts and new radiator. I hope it works.