thead

my 99 civic have been overheating only at idle. i also noticed the coolant resovoir is full, but it seems like there is not much coolant in motor or an air buble in motor somewhere. i tried bleeding it but it doesnt have a bleed screw next to thermostat. it only has heat when i rev it up a little, no heat at idle. seems like a headgasket blown maybe. i dont have any fancy equipment to test, but i saw a test kit that has blue liquid that turns yellow when it detects combustion gases in the coolant, the test kit is $53. is it worth buying or is there a cheaper way to see if my head gasket is blown? i have no white smoke out exhaust as far as i can tell. thanks

Former User

Is the coolant level low when you remove the radiator cap?

thead

it is not up to the top of the rad fins, but close. i can add a little and then i will see coolant covering the top of the fins

Former User

Fill the radiator with coolant and then bleed the system.

Bleeding the cooling system may take 20-30 minutes.

1) Park the car on an inclined driveway with the front end higher than the rear.

2) Push/turn the dash heater lever/**** to MAX heat. Fan need not be on.

3) Follow the directions in the diagram below

thead

i already tried that bleeding method last week, it didnt really take any more colant and didnt see any air bubbles coming out either. i waited for engine to heat up then felt both upper and lower hoses and they were hot. but car still over heats when i idle. thermostat is a couple of years old.thanks for the quick post

thead

i also noticed if i put car in nuetral while its over heating and rev motor and hold idle higher the temp gauge goes down. maybe the higher rpms moving more coolant thru radiator

d15bvtechatch

iTrader: (2)

put your heater on full blast and jack the car up a little so the radiator is higher than the engine, then do all that ^^ stuff ^^^

Former User

OP - bleed the system again.

jbpnoman

AFTER replacing the couple year old thermostat with a Honda unit. Aftermarket thermostats are known for not lasting. Aftermarket parts in general are known for not lasting.

thead

i guess i will buy another honda thermostat and prob a rad cap also and try the bleeding again. if that dont work then i will buy the $53 liquid test kit. and check for blown head gasket. might not fix if gasket is blown. going to be a huge job to replace gasket, car has 260k miles and everything is rusted and is not going to come apart. thanks for your help

hondata760

is your fan turning on?

brettsb16a2

I have never had a problem bleeding air out of a civic, it take few minutes, 5.7 in a trans am and gm 3400 yes but never a civic. I use one of those coolant fill funnels, usually yellow and the kits comes with all teh fittings. A blown head gasket willl also make lots of bubbles in the coolant. I really never use that tool for detecting exhuast but yes it works well. I had found on my 2000 si that it reads hot at idle and would cool as soon as i started moving again and driving down the highway (100,000 miles plus on original engine, battery almost 5 years old at the time). After replacing the battery it went away. Go figure. A low voltage issue or ground, or positive issue may cause a false reading of the dumby gauge showing inside the car but plug in a scan tool and the temp will be normal. But for every vehicle that i have had with a blown head gasket affecting the cooling system it will conitinually blow bubbles in the cooling system.

brettsb16a2

Im not say that your battery is an issue but i knew my engine wasnt getting hot but the cluster gauge said it was. Other things, 1. check to make sure coolant isnt leaking from your ac drain. 2. The small heater hose gets overlooked and they develope pin hole leaks. A coolant pressure tester is a great tool to have, and im sure they are cheap at china freight tools. 3. Check drivers side front of engine at bottom of engine to make sure it isnt leaking from water pump. Put some bars leak in it if you don;t have time to fix it now, that crap i s pretty amaazing.

thead

well i rented a pressure tester and a liquid block tester. i pumped the radiator up to 15 psi and it held that pressure for 5 min no leaks detected. so i used the block tester after a while when car was warmed up i pumped the tester and it took awhile but the blue liquid turned clear or slightly yellow. i repeated the test a few times and had same result.
how can there be a head gasket leak from combustion chamber to coolant passage but show no loss of pressure when tested with the pressure gauge?

strategy400

Because combustion pressure is a hell of a lot more than 15 psi. You may have a miniscule pinhole leak in your headgasket or a crack somewhere. Combustion gasses can be forced through but coolant can't be sucked in (gasses in the coolant no coolant out the exhaust). In a massive failure you will get white exhaust smoke, coolant in the oil etc. Look under the oil cap for evidence of moisture. Be happy if its just a gasket.

The reason your reservoir is full is because the leaky headgasket is pushing all the coolant out of the radiator past the cap and into the reservoir. Then coolant in the system is low causing air in the system, possible cavitation in the pump, loss of cooling efficiency. This is more apparent at idle (lack of solid coolant flow through head) and perhaps overcome at speed (for now).

Hate to say it but maybe time for at the least a headgasket change (check/mill the head/valve job?), at the most an engine rebuild (mill head/deck block/check for cracks) or replace engine. If you continue to overheat your engine you risk ruining the temper/integrity of the metals in your block, head, rods, crank etc. - the parts they reuse during a rebuild.

Go to a reputable shop pay them well and thank them kindly. The fly by night places will ruin your castings and other costly parts.

Former User

Use a precision straight edge to check whether the head and block mating surfaces are flat -- see service manual for specifications.

strategy400

That^

thead

i cant believe head gasket is gone! car only has 260k miles on original gasket. hehe. but really car has been great to me, it owes me nothin. i just added up everything online and its only $250. do i need new head bolts or can i reuse old ones, my civic is a 99 SOHC?. going to check and see whats realy rusted and might try to tackle it my self. i did the timing belt/pump/tensioner about 120k ago so i will replace it again.
also when u pull the head can u leave the intake manifold on and just remove exhaust?

thead

im getting a list of parts to order now. do i need to buy new head bolts? also can i take head off with intake still attached?

hondaDaIntegra

i think you will have to remove the intake to remove head. price head bolts and if its in ur budget replace them.