LS400 - return of the boot seal leak

Razor61 · April 15

I know this subject has had a lot of attention. However, I just wanted to share my experience of this and it may help someone else.
As documented in another post about my current car over the last 2 years or so, the boot was leaking into the spare wheel well when I first bought the car.
I removed the old seal, cleaned, sorted all the rusty areas (the lip in the boot lock area was quite rusty with a small hole) and then painted the lip areas and fitted a new boot seal (still available at the time)

Lip in the boot latch area after painting etc and before the new seal:

I left all the boot trim out the car for quite a while to make sure it wasn't leaking. All good and I've been in and out of the wheel well to get the locking wheel nut on lots of occasions over the last 2 years.
A few weeks ago I went into the boot under the floor to get the locking wheel nut, to my surprise and horror the area was very wet and the cardboard box for the locking wheel nut was soaking.
Removed everything and left it all to dry, it wasn't a swimming pool in the wheel well but it was wet and the spare tyre was all wet . First reaction was, maybe I have been too vigorous with the power washer when rinsing off the snow foam when I washed it. So I left everything out of the boot and washed the car as normal, looked in the boot, it was dry and I couldn't see any water so it wasn't the power washer rinsing and 'forcing' water into the boot.
I left the main plastic boot trim off the car so I could get to the boot lid catch area to see where the water was getting in, during the last few weeks I kept checking and sure enough it was leaking in behind the boot lid catch area, running down onto the wiring bracket and dripping into the wheel well. So it's the classic place for the issue.
The dilemma was, do I remove the boot seal and 'seal' it all with something? It's a new boot seal, although it's 2 years old, and I didn't fancy that idea at all.
I figured that my issue was the lip around the boot latch area that was rusted in the beginning, it wasn't great when I got the car, and isn't sealing correctly even with a new boot seal.
Long story short, the lip wasn't flat in this area so - seal completely removed - straightened the lip, cleaned all round the boot lip (it's shocking how much crud accumulates in 2 years), refitted the seal and left it off the affected area round the boot lock - applied some black CT1 sealant to top of the lip in this area - pushed the seal back on and applied a small amount of CT1 on the inside and wiped off any excess. I prefer to use CT1 because it remains pliable and, in my opinion, is the best stuff to use on rubber seals/trims etc. because it sets like rubber. Pic below shows the area.

Few weeks have passed with washing, driving and bad rainy/stormy weather. No leak so far and I'm pretty sure I would have seen anything leaking in.
I also pulled the seal away further along periodically to see if the water was creeping along but it was all good and dry.
While I was at it, I also re positioned the boot seal so one of the notches on the outer side of the seal was in line with the centre of the boot latch, something I saw on the Car Care Nut channel for the 600,000 miles Lexus.
I had previously positioned the 'join' in line with the centre of the boot latch with the 2 x notches positioned equidistant along the bottom.
Maybe the boot seal wasn't in the correct position, either way it looks ok now but time will tell and I thought is was cured 2 years ago.

Stanwithaplan · April 15

Well fingers crossed Razor. I truly hope you've got it licked this time.

I thought I'd solved my leaky boot with Captain Tollys around the rear window but if anything I've made the problem worse.

My water is ingressing from the seams and metal "vents?" Under the back shelf.

Now the roof lining over the rear window is wet. So my latest working theory is back to sunroof vents, either being blocked or maybe theres a joint or crack where they presumably run through the rear pillars?

I did get Lexus mechanic to blow them through with an air hose on their initial inspection 18 months ago but will rod them this time. Then if needs be I'll have to remove the rear panels and drop the roof lining. I'm not looking forward to that job.

Razor61 · April 15

6 minutes ago, Stanwithaplan said:

Well fingers crossed Razor. I truly hope you've got it licked this time.

I thought I'd solved my leaky boot with Captain Tollys around the rear window but if anything I've made the problem worse.

My water is ingressing from the seams and metal "vents?" Under the back shelf.

Now the roof lining over the rear window is wet. So my latest working theory is back to sunroof vents, either being blocked or maybe theres a joint or crack where they presumably run through the rear pillars?

I did get Lexus mechanic to blow them through with an air hose on their initial inspection 18 months ago but will rod them this time. Then if needs be I'll have to remove the rear panels and drop the roof lining. I'm not looking forward to that job.

Thanks, I'll be checking more often now.
Yeah, I think you are on the right track with the sunroof drain/s at the rear or something and 'rodding' it with one of those flexible things with a brush on the end may do the trick. I think the Car Care Nut described the sunroof and drains as 'a controlled leak'.

Dropping the roof lining and panels along with all the boot linings is probably the only way to get a good look at what's going on and get to the rear drains to rod them from the top down, I'd prefer to rod them from the top down rather than pushing any crud into the sunroof area inside and then it gets washed back into the drains. Maybe the rear drains can be accessed from the top using a flexible rodding thing with the sunroof open or partially open and some of the sunroof 'garnish' removed.

Malc1 · April 15

Is your car standing at an angle / slope ever when it’s driving rain ?

Mine only ever stand flat on the road when parked ………. and I have never seen any water ingress …….. over 25 years or so !

Malc

NB. There had been condensation damp on the spare wheel on my new Mk1 when I bought her last August……. due to the rubber backed mat fitted over the normal standard boot, floor mat ……. Malc

Razor61 · April 15

Car is always at a slight angle on the drive, sloping to the rear so water doesn’t pool.
Maybe the capillary action of the water working its way down to the problem area happens or is accelerated when the car is moving, motion and air movement maybe. I vaguely remember reading it somewhere and the more the car is driven in all weather then the higher the chance of the ‘classic’ leak. I’ve soaked the boot and around the seal with lots of water and nothing seems to happen until the car has been driven.

Malc1 · April 15

It's placing me in the rare " camp " of never ever ever had this issue in any of my several Ls400s ........... and cars always only ever been parked on the flat wherever over the decades 🙃

Malc

Razor61 · April 16

That is indeed rare Malc, every LS400 I have looked at over the years has had water ingress in some form or another. i.e. boot seal, sunroof drain pipes not located correctly, antennae drain missing or draining into the boot, holes in the rear inner wings to name a few. Some worse than others, 'swimming pools' in the boot (wheel well or the pockets at the side) to 'tell tale signs' that water has been present at some point like the spare wheel in a mess with corrosion and white crud on the inside of the wheel. Maybe not puddles of water but condensation and dampness means there is moisture present somewhere or has been.

Malc1 · April 16

Blessed are the Good eh 🤩

Malc

Razor61 · April 17

On 4/16/2024 at 12:21 PM, Malc1 said:

Blessed are the Good eh 🤩

Malc

No comment🤣

Chris Skelton · May 1

I recently saw a car advertised…was it a Lexus?…where the seller had had the sunroof sealed.As my partner isn’t a fan of ‘wind in her hair’, this would suit me. Anyone share this approach? Would seem to solve one source of water.

Tulpen · May 2

My 460 has a sunroof which I have only opened once - to check if there was any rust (there wasn't). One of the reasons I drive an LS is because it is whisper quiet. I have the aircon on all the time and I'm a happy bunny!

runsgrateasanut · May 3

On 4/16/2024 at 10:33 AM, Razor61 said:

That is indeed rare Malc, every LS400 I have looked at over the years has had water ingress in some form or another. i.e. boot seal, sunroof drain pipes not located correctly, antennae drain missing or draining into the boot, holes in the rear inner wings to name a few. Some worse than others, 'swimming pools' in the boot (wheel well or the pockets at the side) to 'tell tale signs' that water has been present at some point like the spare wheel in a mess with corrosion and white crud on the inside of the wheel. Maybe not puddles of water but condensation and dampness means there is moisture present somewhere or has been.

Quote

'tell tale signs' that water has been present at some point like the spare wheel in a mess with corrosion and white crud on the inside of the wheel. Maybe not puddles of water but condensation and dampness means there is moisture present somewhere or has been.unquote.

When I opened my boot a few days back I noticed water all round the rim of the Spare Wheel. Couldn't see any water in the tray but didn't lift out wheel. Seems to be condensation as plastic Tarp on top of Boot lining and none in Plastic Wheel insert.. Car has been covered with a Tarp over back window space until recently and today will be a good opportunity to see if my "Cabrio" rear window has not allowed rain to enter the Car or boot. If it should ever stops raining. Bl**y Geoengineering!!

Malc1 · May 3

It’s that damned unnecessary Plastic Tarp on top of the standard boot lining that’s causing the condensation…… I doubt it’s water ingress, well it doesn’t need to be !

I had this exact same issue on my 91 car last August with a rubberised back, thick black mat over the standard boot lining ……. really damp / wet on the spare wheel 😰 …… condensation

Malc

dragonf1y · Monday at 06:11 PM

I have a boot leak issue with my 1997 LS400 and I have followed the same procedure as Paul (Razor 61) by removing the original seal, sanding down the rust, applying Bilt Hamber Hydrate 80 and then priming and spraying across and up the sides of the boot lip where the seal runs. I also used CT1 right across the bottom horizontal lip but I still had a leak. I have just received an after market seal for the car but as it is open ended does any body know the best place, when fitting, to place the ends to form a join, of sorts. Is it better at the top or along the horizontal lip?

I have just received the seal and haven't attempted fitting it so maybe it's obvious, I just don't know.

Malc1 · Monday at 08:53 PM

Are the originals joined anywhere or is it a one piece ?

I’ll check mine tomorrow in the daylight for you

Malc

dragonf1y · Monday at 09:21 PM

Hi Malcolm, the original is one piece although the join is not hard to spot.

Malc1 · Tuesday at 10:00 AM

I've just checked both my 91 J and 95 N reg ones and they both appear to be totally seamless non-joined rubber pieces .... and parked on the flat and with rain free boots 🤞

Malc

dragonf1y · Tuesday at 10:35 AM

Thanks Malcolm. I think I’ll fit the two ends together, first of all, where water is least likely to gather and push it on the lip from there and see how that goes.
I’ll probably try tomorrow subject to weather and report back in due course as to success or otherwise.