RX350 Reliability

[tel999]

Hi.

I am looking to purchase a 350 or 400. I have read the water leak horror stories and one question is….do they all leak.

Reliability is everything, so should I concentrate on the 350 or 400. The highbed system is not important to me and I only mention it because there seems to be more 400,s for sale than 350,s.

Have looked at a few MOT results and I often see corrosion mentioned, any thoughts.

Thank you for your help.

[katabrontes]

Hi Terry

My 2006 350 has been superbly reliable and apart from a failed coil on one of the plugs soon after I bought in 2010 it has been trouble free.  It's a lovely car and I would prefer it to the older gen 400.  I did have a small leak into the space under the boot compartment which was caused by a displaced drain tube from the rear  NS drain from the sunroof.  I fixed this by replacing the last 10cm or so of the plastic tube with a length of copper pipe and it hasn't recurred.  I have dithered over replacing it with a newer (2018-20) 450 but, especially since the silly prices they are fetching at the moment I have decided to keep it for another few years.  You could find a good 350 quite cheaply now ( much less than a 400 I suspect) although they are not easy to find.  The eco hysteria is driving the prices of hybrids up but you get quite a lot of petrol for the difference.  A 450 would have cost about £8K more when I bought my 350 and I doubt it has cost me that much extra to run it since.

[Bluemarlin]

Regarding corrosion, it makes sense to  have a good look all over the car to see the extent of it. Fortunately, given the ground clearance of an RX, it's easy to have a good look underneaath with a torch.  Some surface rust is inevitable, but be wary of anything more serious. I'd be most concerned about corrosion on the sills, wheel arches, bottoms of doors, than a little surface corrosion on the subframe, which can be easily treated. It's  also worth  checking the floor of the boot.

Typical areas where leaks occur are the sunroof drains and the roof bar mountings.

I can't really comment on which car would be better, but bear in mind that road tax on the 350 is around twice that of the 400.

[plastic orange]

When I bought an RX 300 for my wife, I found the best one I could find and apart from a slight rust scab on front wing, the body was in good order and interior was immaculate. Underside was ok, and certainly way better than the rust buckets I'd looked at previously.It had done just over 100,000 miles and had just had a cam belt fitted and was in good mechanical order. As I tend to keep cars for a long time, I used about 3 tins of bilt hamber underneath after applying rust treatment where required. In the 5 years we owned it, it was pretty reliable, but after about 4 years all of a sudden the entire floor became soaked. I investigated the problem and it was basically water entering the boot area. Try as I might, this was never resolved, but mitigated by drilling holes in boot floor and making a 'dam' between boot and interior. The water ingress was only discovered as I'd started to use a very hilly route to visit family who had moved house, and obviously, coming down a steep hill - the dam burst lol. Just over 2 years ago we decided that we needed to move the car on as the rust underneath had become really quite bad, plus it was picking up random issues - new front caliper after sitting idle during lockdown was the final issue. Our daughter in law also had an RX 300 with similar miles and condition, and it was rusty underneath too, but seemed to be leak free, but she moved hers on just before us. Would I have another - no. When a car starts to leak and rust becomes rampant it's time to move on. I've checked on the MOT history on the one we sold and it's had extensive welding underneath now, but is still on the road. The person I sold my LS400 to also had an RX 400, and his issues with leaks, rust etc ended in the car being scrapped. Any RX you go to see, make sure you have a really close look underneath and check for damp, plus be aware of the mpg these cars return.

 

Pete

[Bluemarlin]

I think I read somewhere that the older model RX's had leak issues regarding the seams and around the rear light clusters, leading to leaks in the boot. Other things were corroded fuel filler lines.

Initially I was looking at 300's and 400's and read about these isssues so in the end I bit the bullet, doubled my budget, and went for a 450h, without either a sunroof or roof rails. I've also treated and sprayed the underside and wheel wells with Bilt Hamber, and annually give it all a good spray with ACF 50 in the hopes of keeping any rust ay bay.

To improve the chances of finding a relatively rust free car, I'd suggest avoiding any that have come from Scotland and the far north, or coastal regions.

[royoftherovers]

6 minutes ago, Bluemarlin said:

I think I read somewhere that the older model RX's had leak issues regarding the seams and around the rear light clusters, leading to leaks in the boot. Other things were corroded fuel filler lines.

Initially I was looking at 300's and 400's and read about these isssues so in the end I bit the bullet, doubled my budget, and went for a 450h, without either a sunroof or roof rails. I've also treated and sprayed the underside and wheel wells with Bilt Hamber, and annually give it all a good spray with ACF 50 in the hopes of keeping any rust ay bay.

To improve the chances of finding a relatively rust free car, I'd suggest avoiding any that have come from Scotland and the far north, or coastal regions.

Good informative post Bill.

[tel999]

Thank you so much, the information given is fantastic. The only problem is I now have a fear of the RX due to rust issues. I had a problem with my LS430, great car but as soon as surface rust was reported underneath, I couldn’t sell it.

would I be better looking at a 2011/2012 RX450

thanks

[Spottedlaurel]

1 hour ago, tel999 said:

Thank you so much, the information given is fantastic. The only problem is I now have a fear of the RX due to rust issues. I had a problem with my LS430, great car but as soon as surface rust was reported underneath, I couldn’t sell it.

would I be better looking at a 2011/2012 RX450

thanks

If you can afford it, then I'd say yes to going for a 450. Main dealer prices on them seem to be dropping a bit now, I presume the same is the case with independents? As well as the sunroof, as mentioned in Bill's post, also try to avoid air suspension.

[ColinBarber]

2 hours ago, tel999 said:

would I be better looking at a 2011/2012 RX450

To date there has certainly been fewer reports of corrosion and water ingress on the series III 450h compared to the series II 350/400h. The jury is still out as to whether that is just age related or manufacturing improvements, but given these first came out in 2009 I think we are getting to the point where we can say they seem to be holding up better than its predecessor.

[katabrontes]

Another point worth remembering is that the 300/400  have cam belts but the 350/450 have chains which don't require replacement

[plastic orange]

I read a thread here a while ago about a rusty 450 at not many years old that was purchased from a dealer in Scotland. At the first sign of frost up here, the amount of salt thrown on our roads is shocking and sadly Lexus (actually most japanese cars) are poorly protected underneath. I'd recommend proper rustproofing at the first opportunity - preferably when they are new as once it starts it's hard to stop. However in today's pcp throw away society it's the last thing on folk's mind, when a replacement comes along in a short space of time - much like a mobile phone.

 

Pete

[Trefor]

I think the rust issues depend on where the car has lived. Mine had spent it's life in SW London and has no rust underneath. Check the MOT history of any prospective purchases to get some hints on condition. The odd crusty brake line is inevitable at 15+ years old but the MOT tester will note anything too flakey looking on the chassis/components too.

They don't all leak, and I suspect there are a few known weak points to check. If the car has dry carpets/no sign of water under the boot floor (and someone hasn't removed the grommits/drilled holes) then it is probably fine. The sunroof drain blockage issue can afflict any car from any manufacturer.

[ColinBarber]

5 hours ago, Trefor said:

They don't all leak

They will at some point. There aren't enough weld spots and too much reliance on adhesive that cracks with old age on the tailgate section of the body.