deerman2701

So my 99 civic lx been having some problems before the gauge was on h all the time now that we changed the fan switch, temperature sender, and thermostat it was working fine in he middle of h and c all day yesterday, today it was getting close to h but when i revved up my car it seemed to drop why is this

ferio252

I have the same problem too!!! I replaced the head gasket but I have yet to test drive it. I have a D16Y7.

SOHC_4dr

bleed the system first. if it doesn't help you may need a new water pump. if the wp dont help then start looking all over for any bad ground wires.

instructor74

I have never seen a honda water pump fail and cause overheating like this. I agree with burpping the system and make sure you don't have any air in it esp after replacing all the parts you did. Grounds can cause flaky gauge readings so its another good place to look and both checks don't cost you a thing.

deerman2701

Ok so some updates i just got back from a 30 min or so drive nothing in the hot range but it flucuates between half and 3/4 or a little more, when it gets hot and i stick it in neatral and rev it up the gauge drops also the person working on my car used about half a bottle of straight antifreeze in comination with the remaining coolant in it can this do it?

D3vin

You should check if you water pump is leaking, but from your previous post, could it be your hoses?

deerman2701

I didnt see any leaking at all anywhere but i will look again what else could this be today when i drove it for 10 min in cold weather it got to h in about 10 minutes but when i revved it it dropped i dunno whats wrong can this be a blown head gasket or bad gauge i dunno what else to check

deerman2701

What would even cause the gauge to rise and fall rapidly like that

justa4banger

i changed the waterpump on mine and now it wont go past halfway so i say your waterpump

deerman2701

I dunno what else

davefromPA

put your heater switch to "hot". park on an inclining angle. **when cold** open up your radiator cap and turn the car on for 15 mins or so. make sure all the air is out of the system. that will cause ALL of the problems your having. rule that out first before replacing stuff. this is called "burping" the system

EGTurboB16

Burping the system will probably fix it, but you said someone mixed the antifreeze from a bottle with the stuff already in your car? Did you make sure the antifreeze in your car and the stuff in the bottle were the same color? If not, you could have a potentially more serious problem on your hand, but that's more than likely not the case, because your car is still moving which is a good sign. You should also check to make sure the thermostat isn't in backwards, yes it can happen.

Jimster480

it could be that the water pump is bad. The teeth on the water pump can wear away or break off, causing it to only move water @ high RPM's.