DeLSoLRo

99 civic ex manual. My car has had a bad iacv for about 2 weeks now. I've ordered a replacement that should be here by this weekend. When car warms up idle will fluctuate from 1k-2k randomly and throws P0505. I've cleared the code, removed the cable clip from iacv and idle doesnt change or drop or anything.

My question is, can a bad IACV cause a cooling system to overheat/spill out coolant through rad cap? I've had to refill the radiator every other day now with how much coolant it spills out the cap. The system was bled properly and reservoir was always topped off before the iacv went bad. It's possible it could be the water pump or radiator/cap is going bad or even the headgasket, but i dont have a way to pressure test the system and tbh im ready to just fix it and sell the car and not trying to waste more money than I have to. Just looking for suggestions.

Bleakened

I went through overheating hell and just ended up replacing everything I possibly could.

You might have a bad cap if it's coming out from the cap and spilling everywhere. Do you have a resevoir?

Does the fan come on when hot? You can check to see if the water pump is working by turning the car on without the rad cap on and see if anything is flowing. When the car starts to go over the mid-way point on the temperature gauge, feel your lower rad hose and see if it's hot. If not, you might have a stuck thermostat.

Have you check for bad head gasket yet? Check your car's oil level with the oil dipstick. If you notice froth on the dipstick, there may be coolant mixed in with the oil due to a faulty head gasket. If you were losing that much coolant due to a bad head gasket, you'd see white smoke coming from your exhaust all the time.

DeLSoLRo

I have a reservoir. Fans come on. I installed a new honda thermostat like 4 months ago. No smoke or any oil/coolant in either of the systems. When I get home ill wait for it to cool down and open the radiator, top it off and watch. I HIGHLY doubt its a headgasket/water pump, but its not improbable.

Bleakened

Check that lower rad hose when it's hot too. See if it's hot or not when everything else is.

If everything checks out, sounds like you got a plain ol' coolant leak somewhere or your rad cap is defective and spilling coolant outside rather than dumping it in the reservoir.

civicb1812345

i had a bad cap do, did the same thing, replace your cap its like 12$ then go from there

DeLSoLRo

Replaced the cap and it stopped leaking but then I noticed a small pool of coolant building up around the top plastic edges of the radiator. I just went to advance and picked up the cheapest radiator they had using a promo code but I noticed it has 2 oil cooler plugs, common sense tells me the only thing traveling through that compartment would be oil so i shouldnt have to worry about it, but just in CASE my mechanical savyness isnt up to par; will I have to close them up or does it not make a difference?

Im at work so I cant test it out.

Bleakened

Yeah, keep them plugged, last I remember, manual tranny's don't use those lines.

Let us know if anything got better when you can test it.

DeLSoLRo

Replaced radiator, didnt bother with those oil cooler lines since those are only for automatics. Overheating stopped. Now to work on the p0505 and p0420 codes ive been getting.