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Greetings my fellow Lexus members. I have an 01' RX300 w/ 131k miles. I was driving around about a week ago and noticed my engine temperature was almost redline, so I stopped and checked under the hood. The coolant seemed to be leaking (it leaked before but I put bars leak in it a few years ago and it stopped the leak), but I put bars leak in it again, so the leak has stopped for now. But the engine overheating still remains. The coolant reservoir is indeed full, oil dipstick is fine. The coolant leak was on the Driver side rear, leaking onto my transmission, but it isnt leaking anymore. My water pump was replaced about 2 years ago.
Symptoms -
Engine overheating only when driving (sometimes harsh, like downshifting). Engine temp slowly goes back down when idling and stays stable at the right temp when in park and not driven.
No smoke coming out the exhaust
A/C Fans are working and heater and a/c works. What could the problem be?
FYI I just replaced a couple spark plugs and coils due to a check engine light, but that got fixed.
I was reluctant to answer as quite a few things have been done and some may prevent logical diagnosis. Addition of leak stopper can make thing bad.
I would suggest look at the coolant temp switch (which is different from temp sensor). Once you reach certain temp this sensors starts cycling the elec. fan.
You can have a bad thermostat too (but the leak stopper may have messed it up).
I was reluctant to answer as quite a few things have been done and some may prevent logical diagnosis. Addition of leak stopper can make thing bad.
I would suggest look at the coolant temp switch (which is different from temp sensor). Once you reach certain temp this sensors starts cycling the elec. fan.
You can have a bad thermostat too (but the leak stopper may have messed it up).
Salim
I will double check tomorrow to see if my fans come on at all or not by itself.
I am planning to replace the thermostat first, then if the problem still persists, I plan on flushing the radiator and using Toyota pink coolant. I have never heard of toyota pink coolant till now. I've always used Peak 50/50. Bad idea eh?
If you have any more suggestions please let me know. I don't know why it's giving me such a hard time :/
Agree, leak stopper is something you use when your radiator starts leaking on a rainy night in the Australian Outback. It addresses the symptoms and not the cause.
Rip that radiator out and replace it with a new one -it is probably so clogged up it can cool nothing.
i'd start with a block test. A full coolant reservoir could be a bad sign of a head gasket leak. It the results are fine..then i'd look into the coolant temp switch and t-stat as salim has mentioned.
I will double check tomorrow to see if my fans come on at all or not by itself.
I am planning to replace the thermostat first, then if the problem still persists, I plan on flushing the radiator and using Toyota pink coolant. I have never heard of toyota pink coolant till now. I've always used Peak 50/50. Bad idea eh?
If you have any more suggestions please let me know. I don't know why it's giving me such a hard time :/
I try to steer away from oil, gas, coolant comparison discussion. My answer is look at the user manual and see the specs and contents of the fluid. Default working solution is use what the manufacturer uses. In this case you have 2 major options ,,, Toyota-concentrate red and premix pink. There is now a super expensive life long ... (not a viable option if you are having problems as it may go to waste).
People just go for a 50-50 (preferred) distilled water mix. I use the mixture guide on the conc bottle. More water gets you better heat exchange but the freezing point creeps up.
Google RX300 coolant switch and you may come across the cooling system PDF. I recommend DIYers to purchase the service manual volume II.
I think a clogged radiator just might be my issue. I'm thinking about replacing it first now. Would it be a waste of $ if I flush the coolant system then replace the radiator? If the radiator does not work, I will proceed to swap the t-stat, then the temp switch. I will be using Toyota pink coolant for the first time too. Also, does a radiator have to have welding done?
The radiator should come as a whole unit and you should not need to weld.
AC condenser may have to be removed and that means evac and recharge.
Since the winter has not set in, you can test out your system with distilled water only. The antifreeze is getting expensive. Once things check out and before freezing temp arrives you can put the right coolant.
Replaced the thermostat and drained coolant that was dark brown. I found out what was leaking before. It's the seal or whatever this thing used. Can someone tell me what part this is and what the red things are? I need those rings or seal or whatever to fix the leak. This is the pipe that connects from the lower radiator hose to the thermostat cover. I don't know what it's called.
The O ring is needed, but both metal pieces must be in good shape and cleaned out. The inlet pipe end must be in proper shape (no metal loss due to corrosion). If metal is missing then get a new or used one.
When you replace T. stat, you atre supposed to re[place this O ring (put soapy water to help parts slip on) and the gasket around T. stat.
Hey guys, just wanted to give you an update. My RX is now fixed! I drained the coolant and changed the thermostat. Put new coolant in and wallaaaaaah! She runs like new and not even a single coolant drop! Thank you all for your support and courtesy of taking the time to help a fellow member out!
08-25-15, 08:55 PM
RX300 Overheating
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