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I just replaced the head gasket and had the head checked and machined. I installed a new Honda thermostat, Temp control sensor A on the thermostat housing and Temp sensor B on radiator return, and the Engine temp gauge sensor. In one of Eric’s videos of bleeding the cooling system it says the cooling fan should kick on but mine doesn’t seem to until the engine is pretty warm above mid point on the temp gauge then both fans kick on.
Right now the engine run just below the middle of the gauge, but also will rise above mid point on the temp gauge. When the temp go up above mid point both cooling and condenser fans kicked on. But the radiator cooling fan doesn’t come on by itself before the engine reaches the upper end of the gauge. The temp gauge has gone about 3/4 of the way up towards red line. With the new temp sensor the gauge is more responsive then before the old one. With that said I’m not sure what is normal.
I’ve Jumped the A sensor and the cooling fan comes on with the ignition switch is in the on position. The fan relay appears to work because when I turn on the A/C both fans come on and turn off when the compressor cycles on and off.
The A/C diode shows resistance in one direction, and the green wire from the diode to relay shows continuity.
I’m wondering if Sensor A on the thermostat is faulty. I can feel the temperature difference between the bottom radiator hose and the top radiator hose, which is telling me the radiator is working and the thermostat must be opening up. But shouldn’t the cooling fan turn on sooner before both fans turn on and the engine is hotter than it should be. I bled the cooling system several times and its full.
Any help is appreciated.
Pete
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Hmmmmm…. While I am not totally fluent in Hondas I know that in Toyotas that the radiator sensor controls the cooling fan…. Which leads me to some questions…
What is the condition of the radiator? are there missing cooling fins (I have seen this be the culprit of overheating engines) or possibly any blockage in the radiator (or any part of the system)
Have you checked the temperatures of the radiator (top and bottom) with a laser thermometer?
Since you have replaced sensors already, I don’t suspect them yet… I do, however wonder about the condition of your radiator and why your head head gasket blew before….
JMHO
-Karl
I haven’t figured out why the head gasket started leaking as the radiator is about 5 years old and the garden hose flush looked good as I had good flow out the bottom hose, before I hooked it up. All the fins are in good shape. No leaves and junk between the radiator and A/C condenser. I also can feel the temperature differences between the top and bottom hoses as the engine heats up.
I don’t have a laser temp gun but thinking of getting one or using electronic meat temp probe, not very accurate but I have one that I might try just to get some reading off the thermostat housing and the return pipe.
Thanks for the input…
It may be worth saying that on Toyotas if you disconnect the radiator sensor (or if it goes bad), it will default to running the fan all the time… If you have time, you may want to try to disconnect the radiator sensor on your vehicle and run the vehicle and see if the fan is running… At least that will let you know if it controls the cooling fan…
Just my 2 cents…
Karl
I have the same car. While simple, the cooling system is a bit odd in behavior. Its been fun fixing and messing around with it…
When bleeding the system I rarely have the fans kick on when I think they should. I’m not entirely sure but I think both fans should kick on anyways. I’ve never seen just one turn on.
A good CD5 cooling system should not have them kick on so easily. So to bleed it all I do is fill to the point where I see it come out of the bleeder valve. Close it. Start the car and then fill slowly until I can’t anymore. And then I make sure the reservoir is at the full point. From there the system will bleed itself. You may have a slightly rough idle for a few drives but it will go back to normal. The system bleeds itself.
Your engine should not usually heat up past the middle needle even without the fans. Unless its 90˚ out and you’re in stop and go traffic.
I’ve never had it go above 210˚. But oddly enough after having the coolant freeze on me and then changing the newer but now broken thermostat for an old one I had, the temps have actually dropped quite a bit, even though the thermostat I had before was new.
Anyways…
Heres a link to the FSM
https://drive.google.com/file/d/0B3nQTmw6qDjBcDBSR09uYTZTYmc/edit?usp=sharingGo to page 1145. That has cooling fan trouble shooting and wiring diagrams. You can also test the resistance of the switch while placing it in water over a stove, much like the thermostat test. Water boils at 212˚F so a little before that is when the switch should activate.
So whats your coolant ratio?
Do you have anything under the hood thats modified?Thank you for the help. Honda doesn’t have the feature if the sensor fails or switch is disconnected that the fans will kick on. I put the A sensor (thermostat housing) back in and when the engine temp is reached both cooling and condenser fan kick on. When the engine is hot and turned off the cooling fan kicks on from sensor B at the cylinder head outlet pipe/upper radiator hose. It kicked on yesterday after I test drove the car. The fan stayed on for a while and then turned off. I don’t recall the last time I heard the fan kick on after driving it and I wonder if that contributed to excessive temp changes in the cylinder head before it started to cool. It appears things are working as it’s suppose to now.
The car is stock all original. The mixture is 50/50, new water pump and thermostat as it was due and I had already ordered the timing kit. I test drove it yesterday before the snow storm and everything seems to be working as it should. Temp is below mid point on the gauge and after driving it and then running at high idle to kick on the fan’s both fans turned on and then off when the engine temp cooled down. After I shut the engine of, the Passenger side (radiator cooling fan) kicked on and ran for a while until it timed out and or the temp dropped as I went inside and then checked on it a few minutes later and it was off. It seems to be doing what it’s suppose to, and both fans run when the A/C is on. It looks like it’s fixed but going to keep an eye on the temp.
[quote=”Fatdog” post=86065]The car is stock all original. The mixture is 50/50, new water pump and thermostat as it was due and I had already ordered the timing kit. I test drove it yesterday before the snow storm and everything seems to be working as it should. Temp is below mid point on the gauge and after driving it and then running at high idle to kick on the fan’s both fans turned on and then off when the engine temp cooled down. After I shut the engine of, the Passenger side (radiator cooling fan) kicked on and ran for a while until it timed out and or the temp dropped as I went inside and then checked on it a few minutes later and it was off. It seems to be doing what it’s suppose to, and both fans run when the A/C is on. It looks like it’s fixed but going to keep an eye on the temp.[/quote]
Glad you are getting the issue resolved. keep us posted if things change.
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