Civic Overheating!!

[RAYRAYCIVIC]

Hey people,
Im new to the forums, I have joined after buying a daily POS '85 Civic GL. I hope there are some people familiar with these lil cars (1.5lt carby fed engine). I picked her up and drove away sweet but found that the car soon heated up a little quick for my liking! It usually sits just under the red zone, however today on a longer journey the car hit the reds! And not the good ones either :p

There is enough coolant in there, but I topped it up a bit tonight anyway to see if it would make a difference - it didnt.
The fans turn on once the car heats up a lot.
The radiator pipes get hot, and they have no obvious blockages.
Turning the AC on doesnt make any difference that I can see - I think its because there is no belt around the pulley :thumbdwn:
Will do a coolant flush and oil change soon but I have a feeling that it wont do much... Im leaning toward a busted thermo or radiator but dont know which it could be..
Any ideas? Or any tests to try other than the ones mentioned?
Any help appreciated!
-Rayray

[EuroDude]

Could be a number of things..

Old coolant
Bad thermistat
Blocked radiator
Blocked FITV (not sure if carby's have one though)

[OMG.JAI xD]

broken temp sensor? maybe it turns the fans on too late :/

above is all the possible.. just adding one more :D

[RAYRAYCIVIC]

But even when the fans do turn on the temp doesnt reeeaally cool down so much.. Once it goes high the only way to bring it down I have seen so far is to turn the car off! I still have to try the heater trick..
Thanks for the replies though!

Any way to check the radiator or thermo?

[EuroDude]

put the thermo in the fridge for a while, then see if it moves when you poor hot water on it

[aaronng]

Don't need to put it in the fridge. Just tie string to the thermo, put it in a cup of 100 C water and see if it opens. There are aftermarket ones that fail closed. OEM Honda ones fail open and are safer.

[RAYRAYCIVIC]

Ok so take out the thermo, and test if its opening right. Just undo the radiator hose and I should be able to just unbolt it yea? Ive never played with thermos before! And haven't touched this engine yet!
Also has anyone ever put coke in thier radiators overnight to let the acid clean it?? Im wondering if its worth trying..

[aaronng]

Ok so take out the thermo, and test if its opening right. Just undo the radiator hose and I should be able to just unbolt it yea? Ive never played with thermos before! And haven't touched this engine yet!
Yup. There is a DIY here that tells you how to remove and reinstall the thermostat. Just follow that.



Also has anyone ever put coke in thier radiators overnight to let the acid clean it?? Im wondering if its worth trying..
Trust me, you don't want sugar in your radiator. Coke is a poor acid anyway. You get similar acidity using just soda water. Acidity comes from the carbonated water, not the flavouring.

Why do you need to clean your radiator? Have you been using just tap water for your coolant?

[RAYRAYCIVIC]

no i just bought the car and have no idea what the previous owners used.. I had a feeling the radiator might be on its way out!

I didnt realise soda water was so acidic! Do you think its a good idea to use it overnight?
Thanks heaps for the help aronng!!

[aaronng]

no i just bought the car and have no idea what the previous owners used.. I had a feeling the radiator might be on its way out!

I didnt realise soda water was so acidic! Do you think its a good idea to use it overnight?
Thanks heaps for the help aronng!!

I wouldn't even use soda water. I'd rather disconnect both radiator hoses and spray water at high pressure into the radiator to flush the crap out.

[SHOGUNOVDDRK]

hi ray ray...and welcome to the love of owning a old school civic :D btw where are you located?

i myself own a 86 hatch back :angel:

could you please answer these questions below to help diagnose

if your coolant is fine then that may be a good and bad sign...

have you been putting water in the radiator?

is there any leaks coming from the car?

is it water or coolant? how long does it take to leak?

where is the leak? Is it to the left or right and is it at the front or towards the back :zip:

how many k's/minutes does it take to get to redline when driving/idle?

recently i had similar signs to what you have atm and did all the necessary check ups for what it was.....turned out that my water pump crapped out :eek: (can you blame it for 20 years of good service) ive since had that replaced aswell as the timing belt and a couple of other miscelanious parts replaced :D

btw you have pm :D

[egSi]

can you tell if it is the old standard radiator?

[SHOGUNOVDDRK]

who me?

[OMG.JAI xD]

ever checked the colour of the coolant?

older hondas use green .. well not sure realli but my eg uses green lol

check if coolants been mixed .. colour matters ya knoh?

or else you get this cooly crystal thingo mabobs in the radiator =]

[SHOGUNOVDDRK]

coolant should be green when entering and exiting

btw the coolant is supposed to go into the reserve and the water is supposed to go into radiator.....fyi

[aaronng]

coolant should be green when entering and exiting

btw the coolant is supposed to go into the reserve and the water is supposed to go into radiator.....fyi

Coolant is meant to go into both the radiator and overflow bottle.

[RAYRAYCIVIC]

I have coolant in both reserve and radiator. There are no leaks and the colour is green!! Looks like standard radiator but im not 100% sure on it.

[destrukshn]

take out the radiator
put a hose from the top
and let it run, see if it flows and exits normally, as it goes in, is how it has to come out.
also, check your thermostat, see if it opens.

[SHOGUNOVDDRK]

Coolant is meant to go into both the radiator and overflow bottle.

i was told otherwise when i went to a honda dealer looking for a oem radiator

[aaronng]

i was told otherwise when i went to a honda dealer looking for a oem radiator

Start avoiding that dealer. ;)

[OMG.JAI xD]

Start avoiding that dealer. ;)

lol amen to that..
=]

[AsH_]

i fill up my radiator and overflow res. and i check it a week or two later and my overflow res. is empty.

what's with that?

[aaronng]

i fill up my radiator and overflow res. and i check it a week or two later and my overflow res. is empty.

what's with that?

Was it after you drained your radiator of old coolant? You are meant to let the engine run until the thermostat opens and you have to also turn the heater on. Keep topping up your radiator and overflow tank as required until the level doesn't drop anymore.

[AsH_]

^ when i was topping up the coolant...

i am due to flush the coolant...

[aaronng]

^ when i was topping up the coolant...

i am due to flush the coolant...

Probably a leak somewhere. Is the oil under your oil filler cap or your coolant brownish in colour?

[AsH_]

my coolant is green... as i've topped it up recently...

but the reservoir has a lot of brown chalky residue...

[aaronng]

but the reservoir has a lot of brown chalky residue...
Might be a small leak...

[AsH_]

i had my timing belt changed and they said i didnt need to change the water pump...

they said the seal had a small leak but it may of been caused by an air bubble...

[RAYRAYCIVIC]

Hey people I still havent fixed the problem - I cant get the thermo out.. Seems as though the radiator hose has never come off the thermo housing before! It is jammed hardcore.
Before I go gunho at the hose, Im wondering does anyone think it could be the anything but the thermo? There are so many components, senders and sensors Im just wondering if I should bother with the thermo when it definatly turns the fans on (eventually and they dont cool the car down).
Thanks people
-Rayray

[englee]

I suggest you check the water pump. Is the water circulating properly?

[RAYRAYCIVIC]

How do I check the water pump? Isn't the test for that if the car is on and the radiator fluid stays still with the cap off?

[englee]

How do I check the water pump? Isn't the test for that if the car is on and the radiator fluid stays still with the cap off?

Yeah. Thats the easiest way. Start your engine with your radiator cap off and wait for the thermostat to open. You will be able to see the coolant start to flow.

[RAYRAYCIVIC]

In that case Im pretty sure its not the water pump.