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Discussion Starter · #1 · (Edited)
Hi, I have an RD1.

I bought new sensors (thermo switch & fan/radiator fan switch), the relays are good (even switched them around).

But yet the vehicle is still overheating if you drive it a little hard. The fan is kicking in 'late'.

What could cause the fan to kick in late? I use water in the system for 5 years.

The next thing I'm going to try is to clean the radiator, flush the system and use coolant again.
 

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Everything in Moderation
2006 CR-V EX, 5MT
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If you have replaced the thermostat with an aftermarket one, it is probably causing the hot running.

Buy a Honda part.

Also, plain water does not provide as much boil-over protection as coolant. AntiFreeze has a higher boiling point than water....and the surfactants in the coolant allow it to coat the metal, providing better heat transfer.

https://en.wikipedia.org/wiki/Surfactant
 

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I have never had issues with aftermarket thermostats from reputable brands (dont buy cheap crap online).

That said Carbuff is right, using just water is a very bad idea.

Fans kick on at a specific temperature reading from the sensor. These sensors are something to NEVER BUY ANYTHING BUT ONES FROM HONDA.

As for overheating I see no mention of replacing radiator cap (this can cause overheating because it cannot release pressure when needed or is not holding pressure, one of the first things to start with)

Next is water pump, if it's not working correctly because it wasnt changed when timing belt was changed which is required it can be failing.

Finally, the head gasket. If driven while overheating its very possible the head gasket is now leaking. In rare occasions this has caused the head to crack, but very rare in Honda Engines.

Sent from my SM-G950U using Tapatalk
 

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Discussion Starter · #4 · (Edited)
I believe I sourced the issue now or is close to it. Head gasket is out of the scenario, it's fine.

The water hose in the back (near the fan switch) just burst on me while driving slow.

The water in the system is very brown (rusty) and the top hose gets really while the bottom hose is warm.

I believe there is pressure in the system (causing hoses to burst.. as this is the 3rd hose to burst in 3 months (lol)).

So tomorrow, i'm replacing that hose, sending the radiator to get cleaned professionally and replacing the radiator cap. What u guys think?

If all else fails then its the water pump eh (due to hoses keep bursting.. there must be pressure).

Question: how hot should the bottom hose get? I find it was significantly cooler than the top, tho still warm.
 

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I believe I sourced the issue now or is close to it. Head gasket is out of the scenario, it's fine.

The water hose in the back (near the fan switch) just burst on me while driving slow.

The water in the system is very brown (rusty) and the top hose gets really while the bottom hose is warm.

I believe there is pressure in the system (causing hoses to burst.. as this is the 3rd hose to burst in 3 months (lol)).

So tomorrow, i'm replacing that hose, sending the radiator to get cleaned professionally and replacing the radiator cap. What u guys think?

If all else fails then its the water pump eh (due to hoses keep bursting.. there must be pressure).

Question: how hot should the bottom hose get? I find it was significantly cooler than the top, tho still warm.
The water pump wont generate any real pressure. It just forces coolant through the system. Running plain water in a cooling system is very detrimental to longevity. Causes corrosion on pretty much everything. I've seen impellers on water pumps rust completely off from running plain water. If there is a bunch of crap in the system and it coats the radiator fan switch, it will take longer to transfer heat to the switch.
 

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2016 CRV Touring AWD
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Coolant being brown tells me that it hasn't been changed in years. The anti corrosion elements in it long ago stopped working.
Your radiator is probably blocked.
Radiator are surprisingly cheap. Since you are pulling it anyway, replace it. Less downtime.
Any hoses not recently replaced should be replaced when doing this.
 

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Discussion Starter · #7 ·
I believe I sourced the issue now or is close to it. Head gasket is out of the scenario, it's fine.

The water hose in the back (near the fan switch) just burst on me while driving slow.

The water in the system is very brown (rusty) and the top hose gets really while the bottom hose is warm.

I believe there is pressure in the system (causing hoses to burst.. as this is the 3rd hose to burst in 3 months (lol)).

So tomorrow, i'm replacing that hose, sending the radiator to get cleaned professionally and replacing the radiator cap. What u guys think?

If all else fails then its the water pump eh (due to hoses keep bursting.. there must be pressure).

Question: how hot should the bottom hose get? I find it was significantly cooler than the top, tho still warm.
The water pump wont generate any real pressure. It just forces coolant through the system. Running plain water in a cooling system is very detrimental to longevity. Causes corrosion on pretty much everything. I've seen impellers on water pumps rust completely off from running plain water. If there is a bunch of crap in the system and it coats the radiator fan switch, it will take longer to transfer heat to the switch.
Impellers huh. Thanks. Well if all else fails (4 brand new hoses), new radiator caps.. senors.. etc it must be the pump. I'm trying this last flush and clean now. Currently refreshing the overflow bottle as it was really mucky on the sides.

Coolant being brown tells me that it hasn't been changed in years. The anti corrosion elements in it long ago stopped working.
Your radiator is probably blocked.
Radiator are surprisingly cheap. Since you are pulling it anyway, replace it. Less downtime.
Any hoses not recently replaced should be replaced when doing this.
After this last hose, the 4 hoses will be basically new now. I'm going to collect the radiator from cleaning soon. I also believe that it has blockage. I'll let you guys know what the cleaners said about it.

Last night when i poured in new water in the radiator it basically bubbled back up brown lol.

So when i get it back im going to flush it with water, flush with coolant then pour new fresh coolant in it again.

If all else fails well.. water pump ey?
 

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Discussion Starter · #8 ·
Put on the new hose. Clean radistor. 50/50 coolant (PRIME brand). No overheating. Fan takes longer to kick in because this coolant is damn good i noticed but the guage never goes up too far. It idles lower now and when it goes just a lil over hslf the fan kicks in. Tested it by running the Jeep hard.

So i guess the issue was rust/blockage holding back the heat from the sensors!

Thanks everyone for your advice. I'll update this again if something else happens.
 

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that nastiness is why you must use antifreeze. if your system had a bunch of rush in it then heater core, water pump and radiator need replaced.

No vehicle should ever be used like that, almost as bad as never changing the oil.

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