Car overheats when I accelerate too hard and levels down when in motion. Fan is running, coolant is filled and no leaks. Is this the coolant system which needs replaced or the heads?

  • do you need to add coolant sometimes and do you see any kind of smoke come out the tailpipe pipe and if so what color? May 24 '17 at 4:17
  • I dont see smoke and it started getting worse after i did a flush of the coolant
    – Hi-Lighter
    May 24 '17 at 4:36
  • 1
    Sounds like air trapped in the system. Did you burp the system after you flushed it?
    – NitrusInc
    Mar 26 '18 at 12:50
  • Instead of throwing expensive parts at this car, you should spend your time & money on proper diagnosis and repair procedures. There is a standard troubleshooting procedure for engines that overheat. This is covered in detail in the Honda (OEM) service manual. This is the most efficient and economical way to solve this problem.
    – Tim Barber
    Aug 23 '18 at 21:05

Based on your comment I would guess first some kind of clog in the cooling system, potentially in the radiator, or deteriorated fins on your water pump.

  • Yes I added coolant flush cleaner I noticed the previous owner put some kind of sealant liquid and it might have clogged the radiator? With the flush cleaner I am hoping it will clean any debris that might be clogging the system. Tomorrow morning I will buy another radiator to see if that solves the problem but I am hoping its not the head gasket, since I dont see water in the oil dipstick nor smoke coming out of the exhaust.
    – Hi-Lighter
    May 24 '17 at 6:57
  • The sealant may have clogged other parts of the cooling system as well like the water passages in the block or the heater core. Hopefully the new radiator will solve the problem. Not sure how to clean that sealant crud from a cooling system. May 24 '17 at 7:03

Doesn't sound like a clogged rad to me, because above 30-40mph a lot of air will be passing through it and thus cooling the coolant. Check that your fan is working well first, and if that then go to check where all that sealant went!

  • 2
    I'm not sure how a clogged radiator is going to cool at speed? If the coolant won't flow through a radiator or is severely limited in it's path through a radiator, it's not going to keep the engine from overheating. Sep 21 '17 at 20:41

there are a couple of options no one else touched on, so i'll give it a go. Before buying a radiator, I would simply try changing the thermostat. They are about $10 at the most. Make sure you install it correctly. When they get old, they can "stick" where they will inconsistently open at the correct temp. Keeping cool at speed does imply the fan isn't working properly though, because it is really only useful when idling. Another option to consider is that your sending unit is malfunctioning.

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