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On my way to work this morning I noticed that my temperature gauge was rising quite dramatically... so I pulled over and popped the hood and this is what I saw (photos below).
I tried topping up the coolant (had some in the trunk) and keeping on driving just so I could make it to work, but it quickly started overheating almost immediately.
Any thoughts on the source of the leak? It seems to be coming more so from the filler (overflow?) tank than the rad itself, but I could be wrong. Can you replace just the overflow tank? Would a radiator replacement possibly solve this leak? If so i will order and install this weekend. Just don't want to replace the radiator if that's not the cause of the leak. I checked the rubber coolant hoses that I could see and don't seem to see them leaking.
You mentioned that you topped off the coolant - did you top off the reservoir or the radiator? The reason for the question is that the radiator cap works as a 2-way valve. When the pressure within the radiator exceeds the rated pressure (108kPa), the coolant is allowed to flow outward. Once the pressure drops below atmospheric (in vacuum), coolant is drawn from the reservoir back into the radiator. As long as the pressure within the radiator remains elevated, adding coolant to the reservoir will not help to refill the radiator.
All said, I suspect that your radiator cap has failed, most likely due to a broken spring or a cracked seal.
You mentioned that you topped off the coolant - did you top off the reservoir or the radiator? The reason for the question is that the radiator cap works as a 2-way valve. When the pressure within the radiator exceeds the rated pressure (108kPa), the coolant is allowed to flow outward. Once the pressure drops below atmospheric (in vacuum), coolant is drawn from the reservoir back into the radiator. As long as the pressure within the radiator remains elevated, adding coolant to the reservoir will not help to refill the radiator.
All said, I suspect that your radiator cap has failed, most likely due to a broken spring or a cracked seal.
Thanks for the reply! I topped off the reservoir. When I topped off the reservoir, I filled it to the 'full' mark. After just a few minutes of driving, the reservoir was pretty much empty from what I could see.
So the problem could be as simple as replacing the $10 metal radiator cap? If the radiator cap has failed, is it typical to see the coolant leaking out of the reservoir like we see in my case? And not out of the cap itself?
Look closely at the second pic. You have a very large leak where the upper radiator hose attaches to the engine. You can see a very heavy pink/white build up peeking out from underneath the engine cover. 2 10mm acorn nuts hold the cover on. Pull it off and get a better look.
The reason for having a pressurized radiator is to keep the coolant from boiling (around 212°F), and that liquid coolant has a much better heat transfer property than vapor coolant. If the radiator cap fails to maintain pressure, the liquid coolant rapidly expanded into vapor which occupies many times larger in volume than its liquid counterpart.
The reservoir cap is essentially a "dust cap" which does not provide containment capability. When the radiator cap allows vapor coolant (in much larger volume than its liquid counterpart) to enter the reservoir, a spill-over occurs via the reservoir cap. In extreme cases, the plastic cap can even pop open and make a bigger mess.
Look closely at the second pic. You have a very large leak where the upper radiator hose attaches to the engine. You can see a very heavy pink/white build up peeking out from underneath the engine cover. 2 10mm acorn nuts hold the cover on. Pull it off and get a better look.
Good catch. I just took the engine cover off and I found a crack in one of the smaller diameter hoses, see photos: would the Lexus dealership have this hose in stock?
Originally Posted by rkw77080
The reason for having a pressurized radiator is to keep the coolant from boiling (around 212°F), and that liquid coolant has a much better heat transfer property than vapor coolant. If the radiator cap fails to maintain pressure, the liquid coolant rapidly expanded into vapor which occupies many times larger in volume than its liquid counterpart.
The reservoir cap is essentially a "dust cap" which does not provide containment capability. When the radiator cap allows vapor coolant (in much larger volume than its liquid counterpart) to enter the reservoir, a spill-over occurs via the reservoir cap. In extreme cases, the plastic cap can even pop open and make a bigger mess.
I see, thank you for that information! I did not know that was how the radiator cap worked. I will source a new radiator cap. Is this something I should get at the Lexus dealership or will any auto parts store have one that will work?
How hot did the engine get? Your not going to like this but here's my guess as to what happened.
That hose has been leaking for quite a while to leave a build up like that. The engine got extremely low on coolant which caused it to run hot. My experience with MANY Toyotas tells me that as soon as the temp gauge hits about 3/4 the way up the gauge, the damage is done. Blown head gasket and/or warped aluminum head. This damage causes combustion pressure to enter the cooling system and is much higher than the 13-16 psi the stock radiator cap is rated for. The pressure opens the radiator cap and the pressurized hot coolant basically explodes into the reserve tank.
I sincerely hope this isn't what happened to you but it is a very real possibility if the car ran hot.
How hot did the engine get? Your not going to like this but here's my guess as to what happened.
That hose has been leaking for quite a while to leave a build up like that. The engine got extremely low on coolant which caused it to run hot. My experience with MANY Toyotas tells me that as soon as the temp gauge hits about 3/4 the way up the gauge, the damage is done. Blown head gasket and/or warped aluminum head. This damage causes combustion pressure to enter the cooling system and is much higher than the 13-16 psi the stock radiator cap is rated for. The pressure opens the radiator cap and the pressurized hot coolant basically explodes into the reserve tank.
I sincerely hope this isn't what happened to you but it is a very real possibility if the car ran hot.
Yikes, that's bad news. I had just noticed it rise to just below 3/4 when I had a chance to pull over on my commute.
What would you suggest as my next course of action? Fix the leak and see what happens? Or is further testing involved?
Definitely fix the leaky hose. Put a new cap on it. Fill the cooling system, bleed it, then keep a keen eye out for any unusual symptoms (coolant level dropping, engine running hotter than normal, white smoke from the exhaust, etc.) Hopefully you'll be ok but if the damage is already done you won't hurt it more by driving it.
Definitely fix the leaky hose. Put a new cap on it. Fill the cooling system, bleed it, then keep a keen eye out for any unusual symptoms (coolant level dropping, engine running hotter than normal, white smoke from the exhaust, etc.) Hopefully you'll be ok but if the damage is already done you won't hurt it more by driving it.
Thank you very much for the help! I really do appreciate it. I'll head down to the Lexus dealership now to get the hose and cap.
Hopefully everything is fine, but I guess we'll see!
Please post a side-by-side picture of the new and old radiator caps. I'm interested to see the damage, if any.
Will do! I'm hoping to swing by the dealership later this afternoon to grab it (and hopefully the new radiator hose as well if they have them in stock)
Don't forget to grab some coolant while you're there. After topping off the coolant (directly into the radiator), don't forget to purge the system of air pockets by turning the cabin heater to Maximum heat with the engine running.
Assuming you have no engine damage, after the repair I'd carefully inspect all coolant hoses and clamps in the system and proactively replace coolant hoses that show signs of age/deterioration. If you are keeping the car for the foreseeable future, it may also be a good time to have coolant system flushed and coolant replaced.
Based on years of posts over time LS430s seem to have a weakness with the radiator and overflow tanks leaking and failing as they age so it is important to periodically carefully inspect the cooling system any time you do any maintenance to the car to insure you catch cooling system problems before they become major.
Assuming you have no engine damage, after the repair I'd carefully inspect all coolant hoses and clamps in the system and proactively replace coolant hoses that show signs of age/deterioration. If you are keeping the car for the foreseeable future, it may also be a good time to have coolant system flushed and coolant replaced.
Based on years of posts over time LS430s seem to have a weakness with the radiator and overflow tanks leaking and failing as they age so it is important to periodically carefully inspect the cooling system any time you do any maintenance to the car to insure you catch cooling system problems before they become major.
Great advice! Will do.
Also, the dealership had to order in the hose and radiator cap, so won't be able to do the fix until later this weekend hopefully if the parts come in on Friday.
11-13-18, 10:25 AM
[HELP] Major Coolant Leak Diagnosis
