Ls430 Coolant Leak

karmaz · February 20, 2013

Since I bought the car over a year ago, I noticed it there was a very very slight coolant leak, as the level was dipping (over the course of months not weeks), but just topped up with a little water and didn't worry any more.

I got an LPG installation done about 2 months ago, and since then, the leak has accelerated quite a bit and i've had to top up with pre mixed red coolant.

Obviously, this needed further investigation. My suspicion was that it was the waterpump (original pump, at 97k miles, not done with TB at 70k)

I brought it to Toyota, and got a pressure test done, and it held pressure fine. He also said it's not the head gaskets so not to worry about that. He said there was a very tiny leak at the waterpump, but in his experience that was normal enough, and felt they all do that. He filled the coolant to the high line, and told me to come back in a weeks time to reassess.

So today, three days later, the coolant level has dropped by and inch & 1/2 on the reservoir.

I'm trying to figure this one out.

It seems that having the LPG installation (which has been perfect, running great and getting almost same MPG as petrol), has accelerated the leak quite a bit. I don't exactly know how the LPG system runs, but could it be taking coolant?

Any thoughts on this one folks? It's a bit perplexing, and with LPG running hotter than petrol, the cooling system needs to be tip top.

brendangeorge · February 20, 2013

Since I bought the car over a year ago, I noticed it there was a very very slight coolant leak, as the level was dipping (over the course of months not weeks), but just topped up with a little water and didn't worry any more.

I got an LPG installation done about 2 months ago, and since then, the leak has accelerated quite a bit and i've had to top up with pre mixed red coolant.

Obviously, this needed further investigation. My suspicion was that it was the waterpump (original pump, at 97k miles, not done with TB at 70k)

I brought it to Toyota, and got a pressure test done, and it held pressure fine. He also said it's not the head gaskets so not to worry about that. He said there was a very tiny leak at the waterpump, but in his experience that was normal enough, and felt they all do that. He filled the coolant to the high line, and told me to come back in a weeks time to reassess.

So today, three days later, the coolant level has dropped by and inch & 1/2 on the reservoir.

I'm trying to figure this one out.

It seems that having the LPG installation (which has been perfect, running great and getting almost same MPG as petrol), has accelerated the leak quite a bit. I don't exactly know how the LPG system runs, but could it be taking coolant?

Any thoughts on this one folks? It's a bit perplexing, and with LPG running hotter than petrol, the cooling system needs to be tip top.

Hi Mark

No leak is normal so you need to get it fixed asap - I had one caused by a missing hose clip (after some work). If you have a water pump leak then you need to change it. The LPG evaporater needs warm water so it is "T'ed" into the water system and will not use water unless it is leaking. The gear box has an oil cooler and is a source of a possible leak - very nasty. All that said if you have had it checked at a Lexus dealer and they said it is OK except for the pump then it needs changing - it is 2.5 + hours work at a dealer because the RAD has to come out. This can be a problem if the car is old - When I had my 200K cam belt change the rad came out but could not go back in because of corrosion and had to be replaced. I could not find a third party product and the Leuxs gen part was £300. I suspect the dealer does not want to strip it down and possible give you bad news. The cam belt is due at 100K on a 430 but you say yours was done at 74K ? also you have only 94K on the clock so your Rad should be in good shape - mine had probs at 200K.

Good luck but fix that leak.

Bren

Bluesman · February 20, 2013

Since I bought the car over a year ago, I noticed it there was a very very slight coolant leak, as the level was dipping (over the course of months not weeks), but just topped up with a little water and didn't worry any more.

I got an LPG installation done about 2 months ago, and since then, the leak has accelerated quite a bit and i've had to top up with pre mixed red coolant.

Obviously, this needed further investigation. My suspicion was that it was the waterpump (original pump, at 97k miles, not done with TB at 70k)

I brought it to Toyota, and got a pressure test done, and it held pressure fine. He also said it's not the head gaskets so not to worry about that. He said there was a very tiny leak at the waterpump, but in his experience that was normal enough, and felt they all do that. He filled the coolant to the high line, and told me to come back in a weeks time to reassess.

So today, three days later, the coolant level has dropped by and inch & 1/2 on the reservoir.

I'm trying to figure this one out.

It seems that having the LPG installation (which has been perfect, running great and getting almost same MPG as petrol), has accelerated the leak quite a bit. I don't exactly know how the LPG system runs, but could it be taking coolant?

Any thoughts on this one folks? It's a bit perplexing, and with LPG running hotter than petrol, the cooling system needs to be tip top.

Hello Karmaz.

Welcome to this friendly LOC. Sorry you seem, to be having problems with coolant.

I have a MK 4 LS400 which was LPG converted nearly 3 years ago now but have had all my cars converted over the course of 16 years and at no time was coolant leaking a problem.

The coolant in an LPG system is used as follows http://www.go-lpg.co.uk/Do_I.html

As for water pumps that leak if they do then they are knackered.

You say the water loss has got worse since the LPG conversion then I would first check and tighten all unions that were disturbed when the conversion took place.

My cars are checked from one service to another all without having to top them up.

Good luck and heres to a quick solving of your problem. Mike

Malc · February 20, 2013

On one of my LS400s the coolant level in the reservoir perpetually dropped to an inch below the marker BUT it didn't ever seem to drop further, and when topped up again just dropped to that level again BUT stayed there. Odd I know but you just might not have a problem that's worth worrying about, just maybe keep a beady eye on it.

Malc

brendangeorge · February 20, 2013

On one of my LS400s the coolant level in the reservoir perpetually dropped to an inch below the marker BUT it didn't ever seem to drop further, and when topped up again just dropped to that level again BUT stayed there. Odd I know but you just might not have a problem that's worth worrying about, just maybe keep a beady eye on it.

Malc

Hi Malc

I have the same thing happen on my 430 and a pal does on his 400. If you fill the reserve tank up and then start the engine from cold the water pump pushes water in to the tank and this will run out of the overflow. This means the level in the reseve tank will drop below the low mark when the thermostat opens and stays there. I talked to an old Lexus mechanic about this and he said it is normal (by old I mean has worked on them from day 1) - it seems feasible to me.

Bren

steve2006 · February 20, 2013

Check all the things given in the advice by the guys already and also consider the reservoir pressure cap, there have been cases where these have become weak so allow coolant to seep past the cap seal.

Another common problem with the earlier LS400s was a leaking heater flow control valve mounted on the rear bulkhead but not sure if the designed remained the same on the 430.

ManicMark · February 20, 2013

It is supposedly quite normal for the water level on the 430s to drop below the min when cold my mate & afriend of his was constantly topping up untill told to check the level when at full temp then the level was normal.

steve2006 · February 20, 2013

Just thought, if you have the official red Toyota coolant there is normally a red crusty deposit at the site of any leak so easily spotted.

ipwn · February 20, 2013

Chuck in some dye. Good for tracking down coolant and oil leaks.

Bluesman · February 20, 2013

Chuck in some dye. Good for tracking down coolant and oil leaks.

Brilliant idea. Would never have thought of that one what a great tip. Mike

ipwn · February 21, 2013

;)

steve2006 · February 22, 2013

Which dye would you suggest, I thought L'oreal because a Lexus is worth it!

ipwn · February 22, 2013

Any old eBay uv dye, you only need to put in a tiny bit.

karmaz · February 26, 2013

Thanks for all your help guys, it's really appreciated

DomTurner · February 6, 2023

On 2/20/2013 at 7:40 PM, steve2006 said:

Just thought, if you have the official red Toyota coolant there is normally a red crusty deposit at the site of any leak so easily spotted.

Reviving this topic as I've just checked my coolant as I'm having some heating issues and saw it was very low! Came across this (second image) just above the aux belt. I hadn't noticed this before as I've never taken the plastic intake off but it's very crusty. Not sure if it's the coolant itself or just someone's attempt at fixing a leak but it's worrying ever way. I cannot find anything else that would indicate a leak and the radiator itself looks fairly clean. Any ideas?

As for the low coolant, what is the recommended one to use these days?

steve2006 · February 6, 2023

It looks like coolant clag, there is a gasket between that housing (Front water bridge) and block which is probably the cause ( 2 gaskets, one each side)

4 bolts, remove the thermostat housing and you should be there.

Nothing’s changed re coolant Toyota red pre diluted or concentrate mixed with distilled water.

LDP did have it on offer some time back.

Are you also aware of the need to replace the radiator to avoid the coolant and transmission fluid mixing?

DomTurner · February 6, 2023

3 hours ago, steve2006 said:

It looks like coolant clag, there is a gasket between that housing (Front water bridge) and block which is probably the cause ( 2 gaskets, one each side)

4 bolts, remove the thermostat housing and you should be there.

Nothing’s changed re coolant Toyota red pre diluted or concentrate mixed with distilled water.

LDP did have it on offer some time back.

Are you also aware of the need to replace the radiator to avoid the coolant and transmission fluid mixing?

Thanks for the info and part numbers, for now I will clear up the deposit and fill the coolant back up to a reasonable level and look out for the leak.

I have heard that the radiator should be replaced but wasn't sure if you could get around that with just the transmission cooler bypass kit from LexusPartsDirect (can't find a link atm), or just by replacing the radiator (or both). I am not entirely sure of the correct radiator either as I have heard there are 2.

Malc1 · February 7, 2023

9 hours ago, DomTurner said:

just by replacing the radiator (or both).

at 16 years young, and if it's not yet been changed ..... change the radiator whatever . it's silly not to in order to save a catastrophic write-off of the engine etc

Malc