logansuttle

My 95 Civic DX overheats and the fan doesnt turn on. It has a new head gasket, thermostat. fan switch, and flushed the radiator. If i take the radiator cap off the temperature stays right under half way. But once i put it back on the temperature rises. The bottom radiator hose felt cold and when i took it off the thermostat housing it was dry and no coolant came out. I tested the fan relay and fuses and they are good. It was idling rough and was fluctuating rpms. Could it be the water pump? or radiator cap? also what are the signs of a bad water pump?

Joseph Michaud

Symptoms are a squeal and a slow constant drip from the water pump and overheating. God forbid it seizes on you and burns up your timing belt. Overheating alone could be your fan not kicking on properly, or your thermostat is stuck. The thermostat is very easily replaced, and the fan isn't that tough even with an aftermarket one.

​​​​​​You said your fan isn't coming on. That is the problem that started my cooling nightmare. Even if your fan comes on but rattles, blows fuses.. Replace it. You can buy aftermarket fans that come with an inline thermometer, or you can be like me and run the negative to a switch to manually flip it on and off. I had it initially set to be on all the time. I replaced the sensor, and checked the circuit, and gave up and went with the manual switch.

My delaying dealing with this ended up causing my water pump to go bad, and a new radiator. Replacing the water pump is something that can be done yourself, but it's not as easy as most cars, because it requires you replace the timing belt with it. Plan to replace the timing belt/water pump every 75k miles. The book says 90k, but considering you will probably destroy the engine if it ever snaps, I opt to be more conservative with that.

logansuttle

I am in the process of taking off the water pump now. I am going to replace it. Why would the idle be fluctuating? i cleaned the iacv screen. The car was sold to me cheap because it had a blown head gasket. i fixed that and it is still overheating. How will i tell if the water pump is bad?

mk378

New gasket may have blown. If someone drives overheated until the car will go no more, the engine is almost certainly going to be toast.

Did someone put stop leak in and clog up the radiator? When you "flush the radiator", water should flow very freely through it.

Idle will fluctuate if the cooling system is not completely full.

The only way a water pump fails so it will not squeal, not leak, yet turn but not pump is severe corrosion such as by using plain water in the system. This is really rare.

Joseph Michaud

The idle issue could be the FITV (Fast Idle Thermo Valve). Until I took this off, cleaned it and turned the screw in almost all the way, it would pulse high low any time at idle. Was embarrassing.

As for the condition of your head gasket.. Are you getting any oil or coolant contamination?. When you pulled the head did you have it checked for warpage?

You should probably be able to tell if your radiator is clogged by unplugging the bottom hose and running a garden hose in the top. If the water from the garden hose backs up and comes out the top, it's probably bad.

logansuttle

i havent drove it since the new head gasket. I have just started it and let it idle. i flushed the radiator already and have now flushed the heater core. i pulled off the water pump but it is good. im going to replace it anyway and i also checked the thermostat and it is good. When i pulled the head off it i had it checked for warpage and cracks and it was good. Could the cause be the radiator cap?

TomCat39

These two items based on the fact you have replaced coolant system parts and the head gasket would indicate the air has not been purged from the system. If no coolant is getting to the thermostat housing, the fan won't kick on as it won't get hot enough to throw the thermal switch.

logansuttle

how do i purge the air out of the system?

Jimi Hondrix

Easiet way to check a water pump is remove the radiator cap (coolant filled to top) and watch water flow after the thermostat has opened fully (basically operating temp). With a properly functioning water pump coolant should be flowing swiftly in one direction. However, a water pump can partially fail and not spin as fast as it should. It can do this without signs of squealing or leaking and pretty common before final failure (squealing/leaking). When it's partially failed it can cause intermittent or constant overheating.

Of course be cautious anytime removing a radiator cap from a pressurized, hot coolant system. Use a rag to open cap, open partially to allow pressure to escape for a minute or two, and stand as far back as possible while doing so. Better yet... remove cap when engine is cold, start engine and allow to reach operating temp occassionally checking coolant flow (waterpump) in radiator in the meantime.

TomCat39

I was going to point you to the faq, and then the link to "How to bleed cooling system" but the link goes to the incorrect page of the 92-95 manual. So I have listed the process in the post below. Also edited the post as I confused the FSM page and you stop at step 9. Step ten would be start the engine and check for leaks.

https://honda-tech.com/forums/honda-.../#post50317523

Jimi Hondrix

1) Put front of car on jack stands and raise stands as high as possible
2) Climate control on max heat. Fan "off" position.
3) Run engine while on jack stands. can use a funnel in radiator neck to avoid spill-over
4) After reaching operating temp rev engine by manually opening throttle blade.
5) Rev to about 2000-2500 rpm for a minute or so and do this intermittently a few times to remove as many air bubbles as possible
6) Will know when bled properly as at first there may be large bubbles but the bubbles should eventually/progressively get smaller as more air is expelled from coolant system.
7) Normal for tiny bubbles (while revving engine) in system so don't expect it to be completely bubble free. At idle bubbles should be almost non-existent.
8) Top up coolant in reservoir to max after bleeding system and expect to add more coolant the next day after heat/cool cyle
9) End of system bleed.

Hopefully, while you are bleeding the sytem the radiator fan will come on. Another way to try and force the radiator fan to come on is to turn on the air conditioner.

TomCat39

The one "tip" not in the FSM is raising the nose of the car, whether by parking on an incline or jacking up the front onto stands like Jimi mentioned and I mentioned in the post I linked.

Anyways, above is the FSM pages for bleeding a 92-95 by the book. Assuming your motor is stock to the 95 DX chassis you have. Start from Step #8 on the first page I posted.

Jimi Hondrix

Can't argue with the service manual..Pentosin Pentofrost A3 coolant can be used as well and is msot likely the manufacturer of Honda (blue dye) coolant anyway. The spec sheet ingredients are identical.
The service manual diagrams are always very helpful.

tamboo

in 20 years i've never had air problems til i changed ect sensor recently.
after that major bogging nightmare and block coolant drain plug stripped yikes!
this solved the problem but took a couple weeks of all of the above plus
alternating between 30 seconds of reving to 3k the 30 seconds of idle.


there's also a $120 or so vacuum system but luckily i didnt get that desperate lol.