When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Am curious if this mystery gets solved for us all. I just noticed today that my Dad's 06 LS 430 reservoir tank was bone dry, but radiator was full. I added 22 ounces to the Full line.
When I removed the reservoir tank cap I noticed the cap gasket stayed on the tank instead of staying seated inside the cap. I am not sure if that contributed to the lost coolant. I used a wireless endoscope and could not find a drop of staining anywhere around the engine or radiator (although I didn't specifically look into the fan shroud). I thought I knew every place to look, seeing as how my 460 is in the shop for a valley plate leak that was also hard to discover. I will take another look at the fan shroud but so far the coolant level has not dropped today from the Full line. When you guys replaced the reservoir cap, did it come with a new rubber seal too? The rubber seal is round with an slot cutout:
Big thanks to @PCW for the fan shroud photos and teaching us where to look. I went back out to the garage and confirmed that I have the same leak behind the reservoir tank, hidden by the fan shroud. I used this
Video and photos below. Is this an easy or inexpensive DIY? Do we just need to order a new fan shroud (with affixed reservoir tank)? Now that I know where to look, I believe it is possible for others to squeeze a smartphone into the space to get an angled shot or maybe borrow a gf/wife's pocket mirror.
***Exercise caution when getting near the fans. I don't know if the LS 430 fans run when the car is off like in some past Hondas. Maybe unplug the car battery first. ***
EDIT: Interesting that the endoscope link takes you to a Walmart page. I bought mine from Amazon so click the little Amazon icon instead, although it does appear Walmart has it for less.
As long as the coolong system is properly purged of any and all air the reservoir attached to the fan shroud is merely an overflow tank. When the car reaches normal operating temps the coolant expands pushing the surplus volume into the external reservoir. When the car is turned off and becomes cool again the coolant volume contracts which sucks the fluid back out of the reservoir into the radiator. If the radiator is full when the car is cold the reservoir doesn't need to be full. I have a feeling some people are filling the reservoir when cold then when the car gets hot and pushes the excess volume into the reservoir there's nowhere for it to go. Neither the cap of the reservoir or the hose to the radiator are tight enough to hold the pressure and fluid escapes....
If you have a coolant splattering issue keep the external reservoir half full at the most and check the short hose to the radiator to make sure it's not clogged.
As long as the coolong system is properly purged of any and all air the reservoir attached to the fan shroud is merely an overflow tank. When the car reaches normal operating temps the coolant expands pushing the surplus volume into the external reservoir. When the car is turned off and becomes cool again the coolant volume contracts which sucks the fluid back out of the reservoir into the radiator. If the radiator is full when the car is cold the reservoir doesn't need to be full. I have a feeling some people are filling the reservoir when cold then when the car gets hot and pushes the excess volume into the reservoir there's nowhere for it to go. Neither the cap of the reservoir or the hose to the radiator are tight enough to hold the pressure and fluid escapes....
If you have a coolant splattering issue keep the external reservoir half full at the most and check the short hose to the radiator to make sure it's not clogged.
This does make sense and is exactly what happened to our 2007 Sienna. I filled the reservoir to full because it was between Full and Low. The next time I opened the hood there was coolant splattered everywhere.
However, I am not seeing anywhere near the same level of splattering in the LS. I also normally keep my wife's ES coolant near full without issues.
What you're saying, bradland, makes complete sense but don't new cars cone with full coolant tanks? Seems the manufacturer would design the cooling system to tolerate full cold reservoir tanks -- at least just to the full line. In all my decades of car care, the Sienna was the first time I saw the overflow tank literally overflow!
This does make sense and is exactly what happened to our 2007 Sienna. I filled the reservoir to full because it was between Full and Low. The next time I opened the hood there was coolant splattered everywhere.
However, I am not seeing anywhere near the same level of splattering in the LS. I also normally keep my wife's ES coolant near full without issues.
What you're saying, bradland, makes complete sense but don't new cars cone with full coolant tanks? Seems the manufacturer would design the cooling system to tolerate full cold reservoir tanks -- at least just to the full line. In all my decades of car care, the Sienna was the first time I saw the overflow tank literally overflow!
Newer cars have fresh hoses and o rings on the reservoir cap. A 12+ year old 430 has hoses and plastic parts that are brittle and tired. These older parts don't seal as well as they used to. I changed my timing belt recently and when it came time to purge the cooling system of air I discovered the overflow hose from the reservoir cap and the hose to the rad were both clogged.
Well at least we are still moving forward towards a solution. In my case I dont have to add coolant nor is my reservoir ever empty although I dont drive the car very often. I am not sure if once u get this leak that it will continue to get worse and worse and end up draining the tank like yours did. But it seems to me if u have a bone dry tank u might have a crack at the bottom of your tank......because to be bone dry is pretty extreme. Mine is just leaking several drops from the res cap ( i think ) then from the top of the tank the drops get forced to the back of the tank where the fans spray the residue flat against the back of the tank. I have replaced all of my caps and res hoses.......and still have the issue.
Well at least we are still moving forward towards a solution. In my case I dont have to add coolant nor is my reservoir ever empty although I dont drive the car very often. I am not sure if once u get this leak that it will continue to get worse and worse and end up draining the tank like yours did. But it seems to me if u have a bone dry tank u might have a crack at the bottom of your tank......because to be bone dry is pretty extreme. Mine is just leaking several drops from the res cap ( i think ) then from the top of the tank the drops get forced to the back of the tank where the fans spray the residue flat against the back of the tank. I have replaced all of my caps and res hoses.......and still have the issue.
Not wishing you a worse problem, but if you've replaced all the hoses and caps then is it possible there is a small crack somewhere? Have you tried a pressure test (although I don't know how to do that myself)?
Just wanted to add that we got the LS 430 in April 2016 with 48K miles and it needed just an ounce or two of coolant every 5,000 miles. I don't know at which point the leak accelerated towards an empty tank. It is at 68K miles now and no other indications of a leak (no puddles, engine temp always steady, heater working, etc.). Just one of those things to keep an eye on. The part is about $195 from Lexus after taxes or $166 online shipped. Not too bad and appears to be a simple unbolt and replace.
