Guys,
As some of you might know, there is no low coolant warning on the GS, my car is 10 years old now and I am worried that i might have a hose or valve leak and break my car. When should I replace the hoses to be on the safe side and what should be replaced other than the top, bottom hose and the hoses going into the radiator cap area? any valves?

 

I would replace the water pump if it hasn't been replaced.

 

Ditto the above. Check your fluid levels regularly for any noticeable loss. Check regularly for pink crusted coolant indicating a leak.

If the hoses are no longer pliable and are hard/brittle, its time to replace them. Squeeze them by hand to check.

You can see these hoses, thermostat, and how to replace the water pump here:

 

No need to be worried about something that hasnt happened. Plus if there is a leak youll will more then likely see steam coming out of the from under the hood. Like others mention do a water pump if you havent. Slap a new thermostat, new serpentine belts and bobs your uncle!

 

thanks guys. I already did the waterpump 6 months ago. I am concerned cuz of no indication of low coolant. but from Ibidu1 comment seems that the car is quite reliable. I am a lazy dude and cant keep up with checking hoses every few months + there are areas that are hard to reach. I think I should change this habit if i want to be on the safe side . My plan for now is to replace the thermostat

 

My habit is to give the car a quick under-hood checkup everytime I refuel. I set the gas pump to fill up, meanwhile that gives me enough time to pop the hood and check the oil, coolant, washer fluid and brake fluid.

 

Just hopefully fixed a small leak i had at the reservoir tank. I'd clean up dried coolant only to see more dried coolant later. It didnt appear to be a huge leak, but eventually my fluid levels went down because of it.

Turns out my radiator cap was broken. Had no idea until today when I decided to replace it thinking it was just worn--but no, it was actually missing the center piece! The new cap had a plunger looking thing in the center, while the old cap had nothing but a loose rubber gasket that i pulled off. My guess is the rubber holding the diaphragm in became brittle and out came the spring..not sure where the spring went.

Just something to look out for if you see weeping or crusted fluid at the reservoir neck. I've been driving for 30k miles and never figured it out until now. Surprised it held any pressure. In the picture, the old one is the left one. The right one is the new cap. The pieces of the old cap are probably lodged in my radiator somewhere, but it's not blocking enough flow to overheat for 15k miles so i'm just going to leave it alone. Going frame by frame in my water pump video, the cap was already broken way back when.

 

that is very helpful ez12a, i will check my radiator cap first thing in the morning. I have a tiny leak which requires me to fill the reservoir every now and then. really appreciate your input

 

Check the top seal of the radiator, I had mine leak awhile back. Its under the radiator core support and it was hidden, if you see pink slime know that coolant has been leaking from it. It was coming from the top plastic and rubber seal on the whole top of the radiator.

 

THanks, that is exactly where was my leak. please help me out, do you think i should replace both top and bottom seals? or just the top seal? is there any other part i need to buy other than the seal itself?

 

At the time I wasnt able to find a dealer with my radiator in stock nor aftermarket, so I took my radiator to a radiator repair shop and they took apart the radiator and replaced the seal and top plastic.

I wouldnt suggest you drive this car until you fix the leak, because you can easily over heat the engine and cook your engine. Glad you found the leak!

Its probably easier for you to buy an aftermarket at local auto parts or a used low mileage one off car-part.com

Here is one I found on ebay : https://www.ebay.com/itm/06-08-Lexus...s=Make%3ALexus Model%3AGS350&hash=item48a4560846:g:J48AAOSwY~lZ-9ht&vxp=mtr