Cavanman01

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About Cavanman01

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  • Lexus Model
    GH450h
  • Year of Lexus
    2006
  • UK/Ireland Location
    Dublin

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  1. 2006 Gs450H Seized Front Calipers

    I think the GS450h is well overbraked in it's original configuration so the loss of half the braking force wasn't quite the issue it might have been. I wouldn't consider myself particularly light on brakes, but to be honest I noticed nothing wrong until I actually looked at the brakes themselves. Given the mix between hydrid and mechanical braking I assume that the brake control system on the GS450h must be continuously managing the amount of braking required (as suggested by the pedal pressure) and the bias front to rear, based on the amount of regeneration occurring etc. It appears that it does quite a good job but does highlight that the pedal feel and response is purely artificial. I was shocked at the amount of rust on the pistons and I would have thought that more protection, either through the material or through an appropriate plating tor coating, would be the safest route. The outer seal is much more than just a dust seal in this case. When changing pads it would be important to push back the pistons using suitable packing pieces and a g-clamp rather than the big pliers that the Toyota garage must have used. I was amazed at the effect that just a small tear in the outer seal could have.
  2. If I can provide any additional information, please let me know. Before I started the job, I had hoped I'd be able to take lots of pictures and provide a precise location and view of the offending grommet, however with the tight access etc. I found it impossible to take any meaningful images. A better quality boroscope, with better lighting, would probably make the biggest difference as locating the grommet was the single biggest hassle I had. Given the size of the gearbox and the available space, I don't think loosening anything would be of any benefit. Given the state of the exhaust bolts etc. on my car I would be afraid to move anything on the exhausts for fear of breaking flanges, pipes etc. Just a note. When checking the carpets etc. it may be necessary to actually lift the carpet to check underneath. On my car, the top of the carpet felt barely damp and it was only when I lifted the sill cover (it can be lifted without tools but is very tight) and checked below that I discovered the extent of the issue. If you're not experiencing any misting on the inside of the window, then I think you may be OK. As the condensate itself drips onto a hot gearbox/motor/generator (I'm not sure why Lexus thought that a good idea) it may be the case that a pool of condensate on the ground would be rare when the car as irruning as it probably evaporates from there. Best of luck.
  3. Hello, I just thought I'd document my experiences with seized front calipers on my 2006 GS450h. Apologies for the long post, but hopefully there will be some useful information in here. When I originally searched for information on seized front calipers, I didn't find too much information. Rear calipers seem to be more of a problem... I bought my car in Dec 2014 so didn't have it that long. (I originally typed this up in April but only getting round to posting now...) As these cars get older, I think this may become more and more of an issue, given how easily I think this can happen. Looking at some of the US sites, seized front calipers seem to be common enough for various Lexus cars in the US. I could go into the whole story and background to this, but I don't think it would add to the usefulness of the post and would reflect badly on me, as someone with an interest in his cars and who should have noticed this much much sooner... In summary... This process was prompted by a slight noise from the front left disk when turning left. What started out as a change of brake pads turned into new pads, new disks and two new calipers. The first indication of the issue was that the inner brake pad was actually seized in the caliper on the left hand side. This is first time I have ever encountered this on any car I've had. When I got the pad out (after much prising, cursing etc.) I found the pistons for the inner pad on the left hand side were also seized. The reason why this was not noticeable when driving was, unbelieveable to me, that the right hand side was in exactly the same state; the inner pad was seized in the caliper and the pistons were also seized! The biggest suprise was that I hadn't noticed any issue with the brakes until very recently when I began to think I had a warped disk. I'd driven several GS450hs before buying mine and the brakes seemed to be no different on mine. I believe the pads were seized before I bought my car. Both sides had a seized pad, hence the braking effort was similar. Perhaps this a case where the brake actuator etc. really does provide a totally artificial feel. The only symptom (in hindsight) was that at times, when the road was damp or slippy, I felt there was too much rear brake bias in the car. This I put down to excessive regeneration rather than brakes so never investigated further. Note: there is no electrical or electronic switch on the Lexus to warn of worn pads. There is a spring on one pad designed to be very noisy when it touches the disk. This spring is on the inner (and seized) pads so there was no warning of worn pads in my case. When I had looked at the service records for my car, the brakes were changed in a Toyota garage in 2013 so I had been confident the brakes were in good condition. I think this problem arose because the outer rubber seals were damaged when the pistons were being pushed back when the brakes were being changed. In the seals for the affected pistons I noticed a small nick in each seal of approximately 2-3mm in each. The pistons themselves appear to be mild steel with a chrome or hard coating on the piston walls. The pistons may just be highly polished with no other protective coating. In any case the pistons themselves, where exposed, seem to have rusted very heavily and very completely. I believe this car might have lived beside the sea before I bought it, leading to even greater and more severe rusting. This rust seems to have moved from the top of the piston, which is uncoated, down under the side coating. This has made the sliding surface rough and has also been sufficient to trap the piston in the aluminium caliper. I managed to extract one of the seized pistons and I've put a picture of it here. Given the condition of the piston, I would not be willing to risk reusing this piston and caliper on what is a heavy and quite fast car. If a piston is seized, I think it could be dangerous to push it back in without inspecting everything throroughly. As I was under a certain amount of time pressure, I decided to go ahead and purchase two brand new calipers from Lexus. These were expensive but at least I know what I have. I've had a chance to do some more searching since and I've seen rebuilt calipers for sale for $70 dollars or so each. Given the damage to the pistons on my caliper, including the pistons that haven't seized, I would only be comfortable if all pistons were renewed and all seals, inner and outer were changed.
  4. I just thought I'd document my experiences with the evaporator drain on my 2006 GS450h. Apologies in advance for the long post... I first noticed the issue when I found that condensation was appearing on the inside of the windows of the car. This is always a sure sign that there is water in the interior of the car. Initial searches failed to find anything until I decided to lift the rear carpets of the car. When I did so I found the sound deadening foam and underside of the carpet completely saturated. This is a common enough phenonmen due to the waterproof nature of the carpets preventing such water reaching up. There was probably 1.5 litres of water in total in each side. Having researched the issue through the web, I found that the air-con evaporator drain on the 2006 GS models is a known issue, with the drain becoming blocked and the condensate, which would normally puddle under the car, instead drains directly into the car interior. In hindsight, I don't recall ever seeing a pool of condensate under the car in the past. I was lucky (I think) that only the rear carpets were wet. The carpets and underlay under the front seats was mostly dry. There are many great posts on the various Lexus sites describing the issue and detailing how it can be addressed. The evaporator drain is on the "roof" of the transmission tunnel and is designed to allow the water to drain onto the gearbox and run down to the ground. There are a number of TSBs from Toyota and the latest ones describe how to remove the offending drain grommet by yanking it out with a pliers from below the car. I think the most recent TSB for this issue is the following: http://st.club-lexus(blocked word)/attach/u/7cff5226.pdf While this can be done for the IS and GS300 and GS350 models, it seems the fix for the GS450h remains to remove the evaporator unit and replace the drain grommet with a new one. This requires complete removal of the dash and console and was not an option for me. The method recommended in the TSBs for the IS and GS models is to disconnect the exhausts, loosen the rear gearbox crossmember and lower the rear of the gearbox until the grommet can be accessed and removed with a set of long pliers. Some people have commented that it is possible to remove the grommet without lowering the gearbox or loosening the exhaust. Having worked on the GS450h, I believe this option of lowering the transmission will probably not work for the 450h. The "gearbox" on the 450h appears to almost completely fill the transmission tunnel. In addition, the GS450h has a cladding on the interior of the tunnel, further restricting access. This cladding is about 10mm thick and is bonded to the tunnel and does not appear to be fitted to the IS or other GS models. There is about 15mm of clearance along the sides of the gearbox. Even if the gearbox was lowered and the heatshields removed, I don't think it would be possible to reach around the gearbox to access the grommet as the gearbox on the GS450h is very tall. Here's what I did. I was lucky to have access to a pit to do this work, but a 4-post lift of some kind would be even better. I removed the lower tray under the gearbox (2 nuts, 4 screws). The first challenge is to locate the position of the grommet. It is not possible to see it directly at all from under the car. I used the "endoscope" I bought from Lidl some time ago to locate the grommet. The position as detailed in the TSBs is confusing and I was eventually able to find two photographs on the web which helped me locate the position. For reference, the grommet is in the roof of the tunnel, roughly in line with the support bar providing support to the exhausts. In the attached photos, you can see the flexible portion of the boroscope taped to the support bar for the exhausts. If this sounds easy, it took me one day to locate the grommet with the endoscope! Part of this was because I did not know where to look and partly to the quality of the Lidl endoscope (I think it was €75 a couple of years ago). The Lidl boroscope requires that the camera is about 10mm from the area you want to look at. I imagine a better quality scope would provide better lighting and have a camera that would allow a wider view. I believe the cladding on the transmission tunnel also makes it more difficult as the grommet is further recessed in a cutout of this cladding compared to cars without the cladding. I taped the scope in position when I had the grommet in view as even the smallest move meant the grommet disappeared from view! Once I had the grommet in view, I then had to access it. I first used a long gas welding rod to create a tool I could use to probe for the grommet. To access the grommet, it was easier to come from the front of the gearbox, coming from the alloy crossmember, and feeding the wire across the top of the gearbox. I don't think it would be possible to do this from the side of the gearbox. When I located the grommet with the wire (quick to say, but it took at least an hour to even see the end of the rod in the boroscope screen...), I touched the grommet and about 1/2 cup of water came out! I don't think the grommet was blocked with debris, but had just sealed itself, perhaps due to little use of the car over a period of weeks. It might be the case that closing all the vents, stopping the heater channels under the front seats and turning the fan up full might have opened the drain.... Even given the access and means to reach it, it would be still impossible to remove the grommet. I just needed to rip it up as much as possible. To do this I created another tool using copper brake pipe I have from other projects. I basically replicated the shape of the initial tool and flattened and created a barb on the end of the tool to rip the grommet. The copper piping allowed the tool to be stiffer than the welding row, but with enough flexibility to allow it to be manvoured into place. With practice, I could locate the grommet first time, almost! Coming from the front of the gearbox allowed me to use my hand higher up to brace the piping as I moved the end of the pipe to rip the grommet. I think I was able to rip the grommet sufficiently so that it won't be a problem again. After I did all this, I ran the air-con at full cooling and was pleased to see a stream of water from the drain.
  5. Welcome to the Lexus forums Cavanman01 :)

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