Madmike84

2001 civic LX 1.7L
Things I've tried for cooling fan:
Bleeding air out of system
New rad cap
New rad fan switch
Testing relays (good)
Testing fuses (good)
Jumping the rad fan switch connector (runs when jumped)
Wiring direct power/GND (runs)

Condenser fan:
Ac does not work and compressor does not run so the fan may not turn on anyway, but the relays and fuses are good and the motor is good.

I first noticed the fans not running when I started losing heat at idle/low speeds and the car started to overheat one time. I noticed my overflow was completely full and leaking out. I checked for bad HG BUT compression is good and there's no sign of hydrocarbons in the coolant. The FSM says to try some tests for the condenser fan, and it ended up saying the under hood fuse box is bad?!?

Madmike84

So when I test no.3 for condenser fan to body gnd I have voltage. Also it's been like 45 degrees here lately so maybe the cars isn't getting hot enough for the cooling fans to kick on. But I should still be able to hit the ac button and turn the fans on correct?

ezone

This should be all you need to worry about. They will run when needed.
BOTH radiator fans should run when you did this. If only one ran, the other needs fixed.



It can take a damn long time with the engine running before the coolant gets hot enough to NEED the fans to run.
If there is any breeze at all blowing through the radiator it may not need the fans to run at all.

No, because your AC was already broken in the first place.


Head gasket is blown. Period. End of story. Game over.
Your FSM will not diagnose a blown head gasket.

Madmike84

I could still have a blown HG even with no hydrocarbons using block tester and good compression? Only test I haven't done for HG is the pressure test to see if coolant is leaking into cylinders.

Colin42

And that pressure test is the only test a blown head gasket presents itself on these cars. Go read the sticky

And it's not coolant leaking in, it the exhaust pushing the coolant out which is why the overflow pukes all the coolant out

ezone

There's probably a dozen different ways a head gasket can fail. Most people only know to check for one or two of those.

Hydrocarbon? You mean CO2. Most of these will pass that check easily while the breach is small.

Cooling system pressure test won't find it, while the breach is small.

Most of these will pass every check most people can think of, while the breach is small.




The head gasket in this engine fails in one particular manner 99% of the time.........I go directly to the one test that can prove it every time.

Just about everything is covered in the first post of this thread: https://www.civicforums.com/forums/3...reference.html

Madmike84

Ok thanks for the advice on the head gasket , but I still have fans that won't run?

Madmike84

Which one do you use to prove it every time? Well if I do have a blown HG my fans not running probably is what caused it. Only one fan runs when jumped.

ezone

Pressurizing the cylinders with shop air.
I made the 11 minute video...it's all in real time. Only edit was 0.5 seconds, the word sh** was taken out LOL
Nah. These engines are well known for the problem, and even more well known for being incredibly hard to diagnose it.

BOTH fans run when you jumpered the temp switch connector? If the temp switch is ok, they will run when they are supposed to.
You lost heater output because there is an air pocket in it, caused by the head gasket displacing liquid out of the radiator.

Madmike84

Ok that's pretty cool man! I did actually try to do that one too. I don't think I did it right tho. I made my own hose and air wasn't getting into the cyl fully. I have a compression tester now so I will use that. When I tried it I don't think I had one of my cyl at tdc. I will rewatch the video and try again. I'll post up results in about an hour or so. So if I see the coolant move at all it failed the test?

Only the cooling fan runs when jumped. The condenser fan does NOT run when the rad switch is jumped. I can individually jump the relay sockets and they will both run.

ezone

ANY rise means the cylinder is leaking into the cooling system. Fail.

The video doesn't show the entire setup, just the test. The video was made just to document how quick it could be done....and it ended up on here after that.
It didn't show the ratchet on the crank pulley, my knowing which cylinders are up/down/compression stroke, etc. ...but in under 10 minutes I have solid proof, and I know exactly which cylinders are leaking.

On that car, both fans should always run together no matter which system requested them to turn on (AC or engine temp). I'd grab a wiring diagram and dig into it further. The coil side of both fan relays share identical circuits so if one gets signals but the other doesn't, then yea the fusebox could have a problem, but I haven't seen one bad here.

But if the engine did not overheat, that single fan not working is not the likely cause of your head gasket issue (still needs to be fixed though). It ran hot and lost heater output AFTER a bunch of liquid was displaced out of the radiator.
Like I said, the head gasket is a well known issue with the 1.7 engines.

Madmike84

I can get the cyl where they need to be I'm getting ready to do it now. I have a diagram so I will look deeper. Thanks for your help I really appreciate it. I'll post back with results in a few. It needs timing belt anyway so It'll be a perfect time for the timing belt kit!

ezone

Our shop air pressure runs as high as 170 PSI, that makes it easy to find a breach.

If using a small compressor.... 90-120 PSI may not be enough pressure to show a breach, or it may take a long time to show it.

Madmike84

I was using 120lbs of pressure. #2 and #3 blown. Had to rig up some new fittings or I would have been done quicker. So now I gotta get these fans figured out before I start running it again. I can't complain I only paid 500 for it and it's in pretty good shape other than the what's going on right now.

ezone

Once you get to the point of yanking the head off, make sure to have it checked for warpage.
IIRC .002" is the max warp spec.

Madmike84

Will do I'll have the machinist at work check it out with me. I'm pretty sure he has a straight edge to use to check it. I'm sure I'll be back about my fans I'm pretty much lost at this point. Thanks for all your help!