Rx400H Sunroof Drain Holes

ChiefSi · January 9, 2015

Guys,

Just had a call from my mate at Lexus. He's asked me to make sure that the drain holes at the front of the sunroof are not blocked.

He's had two in recently with hybrid Battery failures which have been caused by water flowing down the back of the sunroof and collecting in the hybrid Battery compartment, one of which they couldn't isolate and has been written off.

I'm checking mine when the wife gets home, the water should flow down the holes and out under the front wings.

Sorry if this has been covered but I thought I'd share it just in case.

Cheers

Si

stevet · January 9, 2015

Thanks for the information. There are also documented problems with the rear lights & tailgate strut brackets leaking water into the hybrid batteries.

nelmo · January 10, 2015

How do you know if they're blocked? Pour water into them?

I've been having worrying issues with lots of moisture on the inside of my windscreen after heavy rain. I can't find water anywhere else (the mats are all dry for example) and I've been in the car in heavy rain and can't see any obvious leaks.

I've looked at the sunroof but no obvious leaks but, like I say, how can you tell if the drainage lines are blocked?

ChiefSi · January 10, 2015

To test open the sunroof, at the front underneath/behind the deflector you will see two pea sized holes in the corners, pour some water in and watch to make sure it drains. It should drain out under the front wings.

If not clean the muck out of the holes and use a compressor to clear the line.

Cheers

Si

DanD · January 12, 2015

How do you know if they're blocked? Pour water into them?

I've been having worrying issues with lots of moisture on the inside of my windscreen after heavy rain. I can't find water anywhere else (the mats are all dry for example) and I've been in the car in heavy rain and can't see any obvious leaks.

I've looked at the sunroof but no obvious leaks but, like I say, how can you tell if the drainage lines are blocked?

Interesting post... I have been having the same issue. I have been putting it down to the fact that my wife mainly uses the car for short journeys that are not long enough for the inside of the car to dry out fully. Having said this, I don't remember having a similar problem in previous years.

Like you, I cannot find any leaks or dampness anywhere...

Vicmeldrew · January 12, 2015

How do you know if they're blocked? Pour water into them?

I've been having worrying issues with lots of moisture on the inside of my windscreen after heavy rain. I can't find water anywhere else (the mats are all dry for example) and I've been in the car in heavy rain and can't see any obvious leaks.

I've looked at the sunroof but no obvious leaks but, like I say, how can you tell if the drainage lines are blocked?

.

I had loads of moisture on my windscreen after rain. It turned out to be water in the boot well. There's a thread from last year, if you look for something like "water ingress" you should find it. I'm not saying you have same problem but it solved my condensation problem.

nelmo · January 13, 2015

I had loads of moisture on my windscreen after rain. It turned out to be water in the boot well. There's a thread from last year, if you look for something like "water ingress" you should find it. I'm not saying you have same problem but it solved my condensation problem.

I remember that thread - didn't you virtually take the car apart to fix it? I'll look it up and check mine...thanks.

nelmo · January 13, 2015

http://www.lexusownersclub.co.uk/forum/topic/87267-water-ingress-rx400h-2006/

That old thread, for reference...

Vicmeldrew · January 13, 2015

I had loads of moisture on my windscreen after rain. It turned out to be water in the boot well. There's a thread from last year, if you look for something like "water ingress" you should find it. I'm not saying you have same problem but it solved my condensation problem.

I remember that thread - didn't you virtually take the car apart to fix it? I'll look it up and check mine...thanks.

Pretty much. Everything I did is posted in the thread you found.

It is still dry, I do check it after periods of heavy or prolonged rain.

Hope you can find your leak and post any useful information.

Ezzie · October 17, 2019

Oops, I think I’ve just replied to another thread.... not the one I originally posted on... oh well..

Thank you chaps, I didn’t put email notification on so after a week of various attempts to bottom this, I’ve come back to the forum to post again, only to find your replies.

Ok, I popped a coat hanger gently down both front drains. The driver side released immediately and water now flows through to the ground. The passenger side is not so happy, a drop or two makes it, and I can see the water puddling on the extreme right of the passenger floor carpet footwell. So it is blocked most likely at the end of the drain pipe.

I also removed the rubber bungs on the undercarriage and managed to get water out there too, but the underside of my carpets at the front remain sodden, the top of the carpets, thanks to my water vac, feel slightly damp but not wet.

The rear carpets in front of the back seats are also mildly damp, and all dampness is pronounced in areas on the passenger side. There was, initially, water in the boot, under the plastic stowaway tray, so I mopped that up, and none has returned since despite pouring rain.

I first noticed water ingress several months ago during a monsoon like downpour... the passenger side front window pillow A? was really wet where it meets the roof, and the passenger side front floor was soaked. I cleaned it all up and it seemed fine, but now think it has been leaking ever since but only in very heavy rain, and therefore not really noticeable.

Im taking it for an MOT tomorrow (it’s under a tarp at the moment) and will get my garage to gently blow some compressed air on the belligerent drain hole. At the weekend, I’ll try to find the rectangular slits on the undercarriage near the sills to see if I can dig out any crap (assuming the air doesn’t help).

Like many before me, it seems pretty poor such a luxury car could have such a big problem. I’ve been pretty worried the batteries could be affected (that’d be the end of it if they were). Just hope I get it sorted with the air.

If anyone had any other thoughts, please let me know.

Vicmeldrew, I have read every thread I can find, here and abroad... it does not fill me with confidence that I may solved the problem yet....

Thanks again,

E

Barry14UK · October 18, 2019

I would be careful about poking bits of rigid wire which could perforate tube in drainage system or dislodge it (I am assuming it's similar to the arrangement on other cars where rubber or plastic tube is push fit. Also, compressed air at too great a pressure/volume could cause the tube to blow off. I am not familiar with what is involved on your Lexus and how long the drain tubes are but on another car I used an old flexible speedo drive to gradually feed and turn it to clear debris. whilst adding warm but not hot water, A flexible wire of the type used to hold muslin curtains might do but make sure nothing on the end (you don't want to add to blockage) and that the end is ground not to be sharp. Drains on some cars are made of more rigid plastic and tend to become brittle.and split, also a build up of trapped water in a drain tube can freeze when temperatures fall causing tubes to split, so worth ensuring unblocked as we approach winter.

The-Acre · October 18, 2019

4 hours ago, Barry14UK said:

I would be careful about poking bits of rigid wire which could perforate tube in drainage system or dislodge it (I am assuming it's similar to the arrangement on other cars where rubber or plastic tube is push fit. Also, compressed air at too great a pressure/volume could cause the tube to blow off. I am not familiar with what is involved on your Lexus and how long the drain tubes are but on another car I used an old flexible speedo drive to gradually feed and turn it to clear debris. whilst adding warm but not hot water, A flexible wire of the type used to hold muslin curtains might do but make sure nothing on the end (you don't want to add to blockage) and that the end is ground not to be sharp. Drains on some cars are made of more rigid plastic and tend to become brittle.and split, also a build up of trapped water in a drain tube can freeze when temperatures fall causing tubes to split, so worth ensuring unblocked as we approach winter.

I absolutely agree about not using wire. I have a length of very heavy duty strimmer line with the end heated so its not sharp, works a treat!

Ezzie · October 18, 2019

Can anyone tell me where the passenger side drain hole is on the body please ie where the water dribbles put from.... My mechanic has the wheel arch cowl off and can't find it... I believe it is a slit rather than a hole, but where is the blooming thing???

BROUWERS · October 19, 2019

I once downloaded these pictures from an old thread. Hope it helps.

Ezzie · October 19, 2019

Fantastic help, thank you.

I’ve been under the car this morning with the mechanic. I showed him the drain holes as above. Nothing is coming out of any drain holes under the sill so I’m sure now it’s the receiving well for the drain tube that is blocked (the drain tube is not blocked, water flows freely). I will send the mechanic pictures of the fix from inside the car, removing plastic sill cover, then plastic cowl on nsf footwell, and then getting in via the hole to get any debris out...

LEXUSLINDA · October 22, 2019

Can someone please tell me how to access the sunroof drain holes? I have a 2008 Lexus 450H and water is pooling in the Battery bank under the rear seat. Thank you.

Barry14UK · October 24, 2019

My car is a 2015 RX450h but I would think the set up is similar to yours. I have found that on my Lexus, (I don't know if this is how it should be), the sun roof does not retract sufficiently to allow easy access to the rear drains in the tray. It might be possible to do this by upwardly tilting the sunroof although there is not a lot of room to work. You need a good light and some strimmer nylon or something similar to to find and gently feed the line though until any water in the tray empties. Compressed air at lowish pressure through a small connector could also help. You don't want to uncouple the tube from it's connection to the tray or rupture it. I suppose one way to pass the responsibility for this would be to have the job done professionally. If either of the two methods described fails it is likely that trim will need to be removed to locate and clean out the drains more easily with better access.I think cleaning out the sunroof channels should be part of planned maintenance whether the sun roof is normally opened or not because dirt will accumulate regardless and eventually lead to blockages with potential water damage. We should all take a lesson from this.

OzDundee · October 26, 2022

Great photos John (BROWERS)

#Sandy# · November 11, 2022

I know I may be going off the subject slightly, when you are trying to source a leak, puff some talcum powder in the area.
It will highlight the flow of water to help find the source of the leak.