overheat
01-27-18, 04:10 PM
#1
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overheat
Hey guys, just purchased a 2011 Lexus is350 awd last friday. It randomly overheats while I am driving, it wont get to the red overheat zone though. The temperature will rise a little while I am driving and will go back down to normal temperatures about 10-15 seconds later after it rises a bit. I've cleaned the engine bay and took it for a drive and noticed it does shoot some coolant out. I find this weird because on the carfax not even 1k miles ago the car had its radiator cap replaced, the radiator hose clamp replaced, water pump replaced and a antifreeze coolant flush. So having a coolant problem was the last thing I thought could happen lol, any ideas? Car is sitting at 151k.
01-27-18, 04:43 PM
#2
I would be looking at the thermostat as it is this that actually controls the temperature by allowing coolant to flow into the rad to be cooled or not. Could be sticking ocassionally and the freeing.
Are electric rad fans coming on when required and working ok?
Keep an eye on underside of oil filler cap for milky/brown sludge as you may have a head gasket Problem causing the over heat.
paul m.
Are electric rad fans coming on when required and working ok?
Keep an eye on underside of oil filler cap for milky/brown sludge as you may have a head gasket Problem causing the over heat.
paul m.
01-27-18, 04:49 PM
#3
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I would be looking at the thermostat as it is this that actually controls the temperature by allowing coolant to flow into the rad to be cooled or not. Could be sticking ocassionally and the freeing.
Are electric rad fans coming on when required and working ok?
Keep an eye on underside of oil filler cap for milky/brown sludge as you may have a head gasket Problem causing the over heat.
paul m.
Are electric rad fans coming on when required and working ok?
Keep an eye on underside of oil filler cap for milky/brown sludge as you may have a head gasket Problem causing the over heat.
paul m.
lol
01-28-18, 10:03 AM
#4
IMO it's pretty rare a thermostat fails but they always get replaced during trouble shooting. I'd flip the AC set to cool. Verify the Fans come on. If not, start there checking fuses and relays. Assuming they do come on, it is likely they are helping cool it.
Is the evaporator core plugged with debris?
Is the Radiator Core plugged with debris?
Documents indicate the radiator cap **may have** been replaced. Double check that it works. proper. If the block has trapped air and the cap is not sealing on itself, the inner landing will push water out rather than build pressure in the block. The caps outer rim prevents the cap from leaking. The next inner seal must seal with the mating part on the block (check for debris on both surfaces). And finally the little flap must seal on itself so that when it cools a vacuum form in the block and it will pull coolant from the reservoir. In short, a leak anywhere and as the system won't pull a vacuum and refill and it overheats when at running temperature. Tiny leaks matter!
Read this entire thread and VERIFY your coolant reservoir cap is installed correctly!!!! https://www.clublexus.com/forums/is-...l#post10045654
Look at the tab on the reservoir - its pointed to the engine. THIS IS BACKWARDS. The engine can not refill when it cools down...
Thanks for the Pictures Mike!
Is the evaporator core plugged with debris?
Is the Radiator Core plugged with debris?
Documents indicate the radiator cap **may have** been replaced. Double check that it works. proper. If the block has trapped air and the cap is not sealing on itself, the inner landing will push water out rather than build pressure in the block. The caps outer rim prevents the cap from leaking. The next inner seal must seal with the mating part on the block (check for debris on both surfaces). And finally the little flap must seal on itself so that when it cools a vacuum form in the block and it will pull coolant from the reservoir. In short, a leak anywhere and as the system won't pull a vacuum and refill and it overheats when at running temperature. Tiny leaks matter!
Read this entire thread and VERIFY your coolant reservoir cap is installed correctly!!!! https://www.clublexus.com/forums/is-...l#post10045654
Look at the tab on the reservoir - its pointed to the engine. THIS IS BACKWARDS. The engine can not refill when it cools down...
Thanks for the Pictures Mike!
Last edited by 2013FSport; 01-28-18 at 09:54 PM. Reason: Clarity...
01-28-18, 02:48 PM
#5
Agreed, the thermostat has got to be one of the most reliable mechanical components on the car but they have been known to be faulty, this can be due to poor hysteresis or neglect ( the use of water only in system without any corrosion inhibitors for example) Thread starter mentions good service history so hopefully not the latter.
The reason I mentioned stat is because Thread starter states expansion cap and circ pump has been replaced and the stat ( not mentioned) has a major role in regulating coolant temp.
The info above on the orientation of the cap in regards to the small bore hoses is enlightening and something I would have not spotted. So yes unless your coolant system is totally air tight you are going to get an overheat problem as system needs to be pressurised.
you may be able the Hear where you system is leaking from if you are prepared to get up close with the engine running!
paul m.
The reason I mentioned stat is because Thread starter states expansion cap and circ pump has been replaced and the stat ( not mentioned) has a major role in regulating coolant temp.
The info above on the orientation of the cap in regards to the small bore hoses is enlightening and something I would have not spotted. So yes unless your coolant system is totally air tight you are going to get an overheat problem as system needs to be pressurised.
you may be able the Hear where you system is leaking from if you are prepared to get up close with the engine running!
paul m.
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