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What is the significance of cooling fans turning on when bleeding the cooling system. I recently bled the cooling system of my 2008 Honda Civic and SIL’s 2002 Honda CRV and in both cases, I held the throttle to 2500 RPM’s for what seemed like forever and the fan’s just won’t turn on. The temp gauges were settled at the halfway point and staying there and there was good burping action on my funnel (I bought the one that Eric uses that mounts to the radiator neck). But the fan’s just never came on?!
If I turn on the AC button, the fan’s come on.
What am I missing? And how long should it take?
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When the fans turn on.That symbolizes that the thermostat
has indeed opened and reached operating temp. sometimes
when bleeding the fans either take a long time or don’t
come on due to air in the system.It causes cavitation until
the air works its way out.Ok I understand, but how long does it normally take for the fans to come on? I gave up after 30 minutes.
What I like to do is let the car idle and come up to temp
before I raise the idle. I found that raising the idle to
soon makes the wait time longer due to rapid coolant movement.My 2006 Honda Pilot is starting to develop a small leak in the radiator. I’m considering tackling the job of replacing it myself but have a couple questions and concerns about it. First off, do you know if my car has a bleeder valve like the civic did in that video you did on bleeding out cooling systems? if my car has an electronic throttle device as opposed to a throttle cable, does this mean I have to get inside the car and hold down the gas pedal? My car also has automatic climate control, does this mean it’s still the same procedure for turning the thermostat all the way to hot?
[quote=”musiccity365″ post=90423]My 2006 Honda Pilot is starting to develop a small leak in the radiator. I’m considering tackling the job of replacing it myself but have a couple questions and concerns about it. First off, do you know if my car has a bleeder valve like the civic did in that video you did on bleeding out cooling systems? if my car has an electronic throttle device as opposed to a throttle cable, does this mean I have to get inside the car and hold down the gas pedal? My car also has automatic climate control, does this mean it’s still the same procedure for turning the thermostat all the way to hot?[/quote]
You might want to start your own thread for this.
To answer your question, I have a question. Is the heat on, or the blower? If so, this will cool the system down while you try and bleed it. You should have the temp lever full HOT and the fan OFF to bleed the system. If it’s taking a long time, check to see if you have an aftermarket thermostat. If so, I’d recommend swapping it out for OE.
I’ve tried bleeding three vehicles, all with Chevy 350s of varying year models. All vechiles I’ve used the yellow funnel that attaches to the radiator with an adapter. I’ve tried different approaches. Just letting the engine idle until it reaches operating temp, holding the RPM at 3000 until the vehicle gets to operating temp, and alternating between 3000 RPM and idle until the vehicle gets to operating temp. In every instance at some point, maybe after 5-8 minutes, the coolant in the funnel will begin bubbling violently and pretty much erupts all over the engine bay. I would like to think that I don’t have exhaust gases leaking into the coolant in all these vehicles and I’m doing something wrong. Please help. This is frustrating. I wish there was a smiley pulling out it’s hair to accurately express this, but unfortunately they do not have hair. 🙁
I think it is 2026 when the Federal mandate for gas mileage goes to 55 mpg (don’t quote me on this but it is something like that). So, the car makers are starting to do all sorts of things to get the mileage up. One of those things is increasing the temperature at where the cooling fans come on. The waiting until the fans run trick is only going to work on vehicles where you know the thermostat opening temperature and the radiator fan starts running temperature are about the same. The engineers also know that the hotter the cooling system is run the more efficient it is. Another reason for delaying the running of the radiator fan.
[quote=”cycleguy04″ post=124998]I’ve tried bleeding three vehicles, all with Chevy 350s of varying year models. All vechiles I’ve used the yellow funnel that attaches to the radiator with an adapter. I’ve tried different approaches. Just letting the engine idle until it reaches operating temp, holding the RPM at 3000 until the vehicle gets to operating temp, and alternating between 3000 RPM and idle until the vehicle gets to operating temp. In every instance at some point, maybe after 5-8 minutes, the coolant in the funnel will begin bubbling violently and pretty much erupts all over the engine bay. I would like to think that I don’t have exhaust gases leaking into the coolant in all these vehicles and I’m doing something wrong. Please help. This is frustrating. I wish there was a smiley pulling out it’s hair to accurately express this, but unfortunately they do not have hair. :([/quote]
Simply put, the larger the engine, the more heat it produces, the quicker it comes up to temperature, the easier it is to bleed. I’ve bled everything from diesels that require 20+ liters of coolant to little car that take a whole 6 on a good day. The smaller the engine, the harder and longer it takes to bleed. Makes no sense, it’s just the way it is.
Anyway as to OPs question, yes it is related to the vehicle reaching operating temperature and the cooling fans should ALWAYS come on with the AC. Assuming the engine was cold when you started I simply look for; no more fluid being taken into the system, consistent heat coming from the heater vents, use the ones that point straight at you so you can feel any changes, then I basically check to make sure both rad hoses are hot. The level of effort put into bleeding also has to do with how much of the system was open.
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