Ls400 Radiator issues ??

Malc1 · March 25

Hi everyone ……. I’ve never read of any radiator issues on the Ls400

Just the oil cooler / gearbox / radiator coolant mix breakdown issues with the Ls430 onwards

Does any of this fragility apply to my Ls400s ?

I ask this Q coz I’m facing this Ls430 style issue on my 2006 Honda Legend at 149k miles from my Thursday’s local breakdown ( RAC Breakdown and Recovery were BRILLIANT ) …….
Steam, I thought exhaust coming from the car in front and fresh tarmac laying smell from the adjacent roadworks , but hot hot oil smell ……. then realised it’s coming from under MY bonnet ….. pulled over into Dobbies carpark ….. good coffee, cafe break for the loooong but welcome RAC wait 👍

She’s in the garage right now but suspects this is the issue above to be sorted

Sadly the Honda forums I’ve found over the years are very very poor on stuff generally ….. they only sold 286 ? of my cars in the UK from 2006 - 2012 when sales started and stopped …… I’ve had this car some 8 trouble free years 👍

So then, does anyone have thoughts on the longevity of the Ls400 radiator ?
is it “ bullet proof “

Thank you

Malc

BigBoomer · March 25

Does the 400 radiator also cool the transmission fluid?
If so, then there is a chance that coolant could get mixed with transmission fluid the same as on the LS430 and your Honda Legend.
If not, then it's just a radiator which will eventually fail but who knows when.
You'll find out when it blows a hole and spews steam everywhere.
Everything wears out eventually, even LS400s 🤣

As for the Honda Legend forums, I assume you are a member of the Acura RL forums in the USA?
I used the US forums when I had my two 1998 Honda Legends.

Malc1 · March 25

Ah thank you for the Acura RL forum USA …… I’ll check it out !

I do know the AWD meant the Honda had to be lifted and Transported ……. thinking maybe there aren’t many AWD ordinary saloons around …… she performs fantastically in snow and ice whatever thankfully

I don’t know the answer to my Ls400 Q at all …… not teccy minded here 😄

Thank you

Malc

Malc1 · March 25

3 hours ago, Malc1 said:

Ah thank you for the Acura RL forum USA …… I’ll check it out !

seems to have stopped posting about 2007 or Am I missing summat ?

4 hours ago, BigBoomer said:

I assume you are a member of the Acura RL forums in the USA?

Malc

BigBoomer · March 26

https://acurazine.com/forums/2g-rl-2005-2012-76/
https://www.acuraworld.com/forums/2nd-gen-rl-2005-2012.113/

No, they are not very active forums but then the 05-12 Honda Legend/Acura RL didn't sell in huge numbers even in the USA.
There is a plethora of stuff to search on though and if you join and post there are still a number of active members who will reply.
I left those forums in 2018 when I got rid of my 98 Legend and bought the LS430.

I test drove a 2007 Legend before I bought my LS and it was considerably smaller inside than my 98 Legend.
More of a 5-Series size than the 7-Series sized 00-05 Legend/LS400/LS430.

Malc1 · March 26

Thank you so much for the Honda links.
Yes quite compact interior compared to the Ls400 BUT she prefers it coz of that …… small boot too and of course the 3.5ltr engine ….. A fine car that sold in tiny numbers

I just can’t drive for long in her, my legs just cannot get quite right …… gf is fine tho’

BUT still no answer to my Ls400 Question 🤔

steve2006 · March 26

The reason why the LS400s never suffered the same fate as the LS430 is because they had separate engine coolant radiators and transmission coolers so they could never mix the 2 fluids.

Cost was a minor factor in the LS400 production whilst it did become an issue in the LS430 onwards which ended up with a combined and therefore cheaper option.

Malc1 · March 26

Thank you Steve ... puts my mind at rest now forever 😇

Malc

Razor61 · March 27

I was always under the impression the LS400 does have a combined radiator and trans oil cooler like the LS430, not seen a separate trans oil cooler on my current 98 or the 95 I had. Will check at the weekend for sure though when doing the oil change. I think the illustration may be for an option of one or it’s fitted for different markets.

Jon Dee · March 27

***** !!! I am having some trouble getting control of this post editor 🤬

However, as I was saying... a quick google indicates that an LS400 is likely to be factory fitted with this style of radiator. Alloy, core, plastic tanks and a transmission cooler inside the bottom tank. I don't know anything about the LS400, but if the pic is correct, then the radiator filler must be located remote from the radiator, and there will be an overflow hose connected to a spigot on the far end of the top tank.

This general arrangement is a bit similar to that used on my 2008 ISF, and on the ISF there is a well known weak point... the overflow hose spigot. The plastic in the spigot where it is covered by the hose breaks down, and it is rare to find any 2008 ISF factory radiator where the overflow hose can be removed without the spigot crumbling and rendering the radiator useless.

Not suggesting that the same issue would apply to the LS400, but it might be worth asking around in LS400 circles to see if it is a known problem.

Cheers...

steve2006 · March 27

It was only a few months ago I got rid of 2 LS400 radiators one from a 1996 the other a 1999 model and I cannot remember any transmission cooler outlets on either.

However I do remember a cooler looking device behind the front crossmember below the power steering cooler pipe on my old 94 Celsior

The picture I posted is for a European spec model not JDM.

Volunteer required to get under their LS400 with camera phone or endoscope 😀

Razor61 · March 27

58 minutes ago, steve2006 said:

Volunteer required to get under their LS400 with camera phone or endoscope

As said earlier, I’ll be checking at the weekend when doing an oil change and will take some pictures as well for evidence either way😄
I thought the exact same thing a few years ago - there is a trans oil cooler listed so it’s separate - then Phil (Ambermarine) clarified that it’s built into the radiator. Can’t remember now but I’m pretty sure I checked on the car anyway.

Malc1 · March 27

…… holding with baited breath ………

Malc

Malc1 · March 27

Remind me …….. what are those parallel copper water pipes I had renewed in front, at the base of the radiator a few years back ?
anything to do with this ?

Malc

steve2006 · March 27

No they’re the power steering cooler 😀

Malc1 · March 27

Thank you Steve

Malc

steve2006 · March 27

You’re most welcome Malc 😀

Rumour has it you put a deposit down on that new Lexus super boat?

Malc1 · April 3

The update on this from our learned Members here is that there is the potential for this same failure in all Ls400 models

However, thankfully, there’s never yet been a report of this ever happening ……, on here anyway …… that I have come across

The Ls400 set-up must surely be built of more robust materials ……. mines on 248k miles and no signs yet …… touch wood

The update on my 2006 Honda Legend is confirming this same problem and my car mechanic guy is trying to source a replacement radiator ….. but challenging …… only 286? Of this model sold in the UK …… then full drain down of the gearbox oil whatever and then hopefully back for another 149k miles of blissful stress free ownership 😄

Malc

Malc1 · April 5

Should there be continuing interest in my rad / oil cooler breakdown issue ………. in the Honda Legend …….after much searching seems likely zero availability of the necessary new specific radiator so it’s to go to a radiator rebuild business ……. as is usual with classic cars ……. I’m thinking there's a few of these still around these days thankfully ……., wonder how busy they are 🤔

Malc