Water leak in RX450h

RodfromCov · November 19, 2019

Has anyone had experience of water coming into the a)engine bay or b)the boot area underneath the spare wheel?

My car is an 09 RX 45Oh.

I foolishly drove through a flooded road, about a foot deep and my electrics died a couple of days later. Lexus are telling me my problems are due to

water coming in through the windscreen seal (which got to the junction box) AND via the body panel seals at the back (which collected under the spare wheel). Too much of a coincidence? Any ideas?

ChrisM · November 19, 2019

I have water ingress in my boot, collects in the lowest parts of the floor so around Battery and right rear corner, but haven't driven through deep water.

So looks like body panel seals.

Any one know the best way of fixing them ??

Herbie · November 19, 2019

Borrow or hire a smoke machine and put it inside the car, then see where the smoke emerges from.

Grey RX · February 19, 2021

On 11/19/2019 at 4:42 PM, ChrisM said:

I have water ingress in my boot, collects in the lowest parts of the floor so around battery and right rear corner, but haven't driven through deep water.

So looks like body panel seals.

Any one know the best way of fixing them ??

Did you ever get to the bottom of this? I have water definitely coming in the rear left corner (right in the corner) and running down to the Battery recess. Tried re-seating the light cluster but it hasn't made any difference. I don't think it is leaking high up in the car but rather low down since running water from the light cluster down results in water appearing inside. Just can't see where from so I'm wondering if I need to remove the bumper next.

RodfromCov · February 20, 2021

GreyRX - My car was in and out of my local dealer for weeks before they discovered that the car had been in an accident that caused a fine crack (expertly concealed) in the rear offside corner. I kind of lost trust in the car and got nervous every time it rained so I got rid of it. Shame because mechanically it was great. My fourth and last Lexus unfortunately.

Grey RX · February 20, 2021

3 hours ago, RodfromCov said:

GreyRX - My car was in and out of my local dealer for weeks before they discovered that the car had been in an accident that caused a fine crack (expertly concealed) in the rear offside corner. I kind of lost trust in the car and got nervous every time it rained so I got rid of it. Shame because mechanically it was great. My fourth and last Lexus unfortunately.

Thanks for that info Rod. Sorry to hear it put you off Lexus. I'm trying not to blame the car since I am also trying to fix a similar leak in my son's Astra at the same time.

I've stripped out the interior and discovered where the water is eventually appearing inside the car and it's definitely coming in from around the bumper level rather than higher up. I've partially removed the bumper but now my wife has summoned me to go for a walk so will leave until tomorrow. I really hope it's not a seam problem as yours and is just a leaking grommet or something. I've also no idea how long it has been going on since I have never removed the Battery in 5 years but when I did recently there was about an inch of water in the Battery well. The water seems to seep in very slowly so could have been literally years. I only know of 2 accidents the car has had, both on the rear nearside door - nothing affect the rear wing.

ColinBarber · February 20, 2021

23 hours ago, RodfromCov said:

I kind of lost trust in the car and got nervous every time it rained so I got rid of it. Shame because mechanically it was great. My fourth and last Lexus unfortunately.

I can understand you lost faith in the car but not sure how that is down to Lexus - hardly the manufacturer's fault if an accident had caused the issue.

Grey RX · March 5, 2021

In case it is helpful to anyone else I think I have fixed the water ingress problem. Removing the plastic trim which runs down the back of the C (?) pillar reveals 4 white plastic erm clips that the trim piece clips to. The lowest of these just above the rear bumper was leaking water straight into the boot. I sealed all of the clips just to be sure. The upper clips were actually loose but strangely the lower one wasn’t but it certainly leaked.

LeakyRX · October 29, 2022

@Grey RX I have this issue too, can I please ask how you removed the C Pillar plastic trim? dont want to break any thing of the trim edges. Is it just the matter of prising away the panel?

Thanks

LeakyRX450H

Grey RX · December 9, 2022

On 10/29/2022 at 11:21 AM, LeakyRX said:

@Grey RX I have this issue too, can I please ask how you removed the C Pillar plastic trim? dont want to break any thing of the trim edges. Is it just the matter of prising away the panel?

Thanks

LeakyRX450H

Sorry, just seen your post. The trim panel comes off sideways at the top and bottom fixings (towards the outside of the car) and upwards on the middle two. It's also fixed with sticky tape stuff down the outside edge. I'll add some photographs of the rear of the trim panel since I have never put it back. Ideally I need to replace the white clips but have given up trying to find the part number for them.

Grey RX · December 9, 2022

Grey RX · December 9, 2022

The top 2 pictures are the lower and centre clips. The bottom picture is the top fastening clip. I think the technique was to slide the top and bottom fixings towards the outside of the car to release and then slide the whole lot up to deal with the 2 centre ones, You have to handle the sticky stuff too of course.

Still have some leaks mind, but not nearly as bad. Also think there is a leak at the front since the windscreen is usually very wet on the inside, even when the boot is dry, Can't face investigating that at the moment.

RodfromCov · November 4, 2023

And here we are 4 years away from the brand and I'm looking for another RX450h! i like the look of the F-Sport but still wary of the water leak issues on the RX.

Frank the Hornet · November 5, 2023

Rod,

In my 7th year of ownership GEN3 2012 RX 450H FSPORT no water ingress issues at all " what's not to like ? "

I have never kept a car so long !

N18RKS · February 10

On 12/9/2022 at 2:38 PM, Grey RX said:

Sorry, just seen your post. The trim panel comes off sideways at the top and bottom fixings (towards the outside of the car) and upwards on the middle two. It's also fixed with sticky tape stuff down the outside edge. I'll add some photographs of the rear of the trim panel since I have never put it back. Ideally I need to replace the white clips but have given up trying to find the part number for them.

Hi, part no for the clips I pretty sure is 90467-09204- search eBay

N18RKS · February 10

Hi, part no for the clips I pretty sure is 90467-09204- search eBay

Johntechx · February 25

Hey guys, I have this problem too!

My 2010 RX450 doesn't get much use these days so the 12V Battery drops to 12.5 volts after a 7 days or so. I've been charging it up via a CTEK charger (from the engine bay terminals) and noticed signs of water under the Battery tray. Today, I removed the Battery (it is relatively new as the previous one got damaged by being fully discharged due to lack of use). Under the Battery tray was full of water which does not appear to be acidic (no smell and didn't burn my fingers)!

Anyway, I cleaned up all the water and rinsed it out with clean water, just in case. I was thinking that maybe the Battery charger is damaging the Battery (too much voltage/current) but it is designed for charging AGM batteries.

I discovered this thread and the penny has dropped! My car has been rear ended TWICE in the last few years by idiots driving too close and not paying attention. In each case, the bumper cover has been replaced with the parking sensors and associated trims. A different garage did each repair.

Now I am convinced that this may well be the source of the leak and I'll start checking the areas suggested.

I noticed that there are two removable rubber bungs in the floor pan of the Battery recess. Can these be removed to allow any future water to drain or do they need to be kept in place. When removed, the road surface below is visible so they seem to be clear for drainage purposes?

Any advice appreciated.

ColinBarber · February 25

1 hour ago, Johntechx said:

I noticed that there are two removable rubber bungs in the floor pan of the battery recess. Can these be removed to allow any future water to drain or do they need to be kept in place.

You can remove them to drain water but I wouldn’t leave them out otherwise road water/spray will start to get in.