If the car only overheats at 100kmh +...

Does that mean :

- the radiator is gone
- thermostat is gone, or is stuck shut?
- water pump
- something else?

Cant get my head around what it could be, I flushed out old coolant, and refilled it with new.

Car doesnt overheat what so ever with town driving, stop and start, 90km<

But once Im on the freeway, if I go over 90-100, or go up hills, car overheats straight away

What could it be? Yes I am taking it to the mechanic but want to be weary of what is going on incase they give me some story to rake in more $$

cheers

I would remove the thermostat to check if it has failed shut. Also, is your waterpump working fine?

Not sure Aaaron man, how can I tell if the waterpump is gone? I forgot all about that one aswell

When you replaced the coolant and bled the air out with the engine running, was there flow through the radiator filler hole? You can see the coolant flow past if the water pump is working.

Simple checks you can do before taking to the mechanics:
- Stick your head under the car and look for obvious leaks.
- Check that the radiator cap gasket is intact (this doesn't mean the cap is ok! It may not be drawing or releasing from/to the expansion tank).
- Check expansion tank/overflow bottle hose isn't pierced (to the radiator cap spout).
- Check for air in the system (bleed air out correctly - search DIY's).
- Check thermostat is opening - After a decent drive (~10mins or so); carefully put your hand on the bottom hose and check the temperature in comparison to the top hose. If the top hose is hot and the bottom hose is cold (or cool) there's a fair chance your thermostat is not opening.
- Check radiator for blockages and/or efficiency - As with the thermostat check; when hot (if you can get to it) place your hand flat on the radiator fins at the top of the radiator, then at the bottom of the radiator - if there is a massive temperature change the radiator could be blocked.
- Check that the radiator fan is cycling on and off (when engine is warm - at idle).

Could be an individual component, as above or build up in the system causing a blockage.

I'd say it's overheating only on highway or hills simply due to being at higher revs than normal.

Engine works harder = makes more heat.

Let us know how you go.

omgzilla... Yea I know engine gets higher rpm = more hot, but I didnt seem to have this problem before..

So aaron ,if I turn my car on, take the cap off ,and if I cant see the coolant travelling in a circular motion, it means somethings blocked?

Quote:

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Originally Posted by Chriskoss

omgzilla... Yea I know engine gets higher rpm = more hot, but I didnt seem to have this problem before..

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Cooling systems components fail after time dude. Just need to try and keep on top of it before they do more damage.

Quote:

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Originally Posted by Chriskoss

if I turn my car on, take the cap off ,and if I cant see the coolant travelling in a circular motion, it means somethings blocked?

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It could be a blockage or also indicate that the pump isn't pumping.

Addition to original post: fluid won't flow in circular motion - when looking through the radiator cap spout it should travel one way or the other (read: left/right - not circular/clockwise etc).

Dannggg.. I dont believe I saw the coolant mixture travelling

Is it safe to turn my car on while cold, take the cap off, and watch the coolant on idle..

Is there something to do with the heater being on aswell when doing this?

Quote:

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Originally Posted by Chriskoss

omgzilla... Yea I know engine gets higher rpm = more hot, but I didnt seem to have this problem before..

So aaron ,if I turn my car on, take the cap off ,and if I cant see the coolant travelling in a circular motion, it means somethings blocked?

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Not exactly a circular motion, You should see some flow of coolant when you take out the cap. Stick your finger in and even try to feel the flow

Quote:

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Originally Posted by Chriskoss

Dannggg.. I dont believe I saw the coolant mixture travelling

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Is the radiator full of coolant/water though? It will have to be full in order for you to be able to see the 'flowing' effect.

Quote:

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Originally Posted by Chriskoss

Is it safe to turn my car on while cold, take the cap off, and watch the coolant on idle..

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Yes, actually better to do it when its warm, but not HOT - opening system while hot will scald you!

Quote:

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Originally Posted by Chriskoss

Is there something to do with the heater being on aswell when doing this?

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It shouldn't make any difference having the heater on when checking for coolant flow from the pump.

Having the heater on will expand the system or allow the coolant to flow through the heater box aswell as the motor etc. When the heater is turned up and the interior fan is on this helps pull heat away from the cooling system - in turn lowering the overall engine temperature.

When bleeding the cooling system the heater should be on and interior fan on aswell.

most common cause of overheating during highway driving etc is the radiator being partially blocked. Over the years sediment builds in the cooling system and finds it way to the radiator where it builds up from the bottom up, partially blocking it and reducing its effectiveness. Flushing wont get rid of this type of sediment, the radiator needs to be removed, taken to a radiator shop and they will professionally clean it. Or replace it if your extreme or want an alloy one etc.

Easiest way to tell is get the car to operating temp and (depending where your fans are!!!!watch out they can go even if the car is turned off!!!) try to get your hand on the radiator core fins and feel if there is a great temperature difference between the top of the radiator and the bottom, the top will prob feel to hot to hold your hand there for over a second or so, but if blocked you should be able to hold you hand on the bottom for atleast a few seconds or longer if really blocked.

Like i said watch out for the fans. I'm not saying this is definitely your problem, just saying that at our workshop this is the most common cause of overheating at high speeds

Sounds right to me mechanic, I only bought the car not long ago and the coolant looked real old, so I assume its now blocked because of not being cleaned alot.

Where is the thermostat just for good measure is it at the end of the top radiator hose?

I just want to know what it could be before some shop says its 500 bucks for a new radiator etc when it could just be a cheap fix like a new thermo

its on the engine. black follow the top hose. it'll lead you to a metal casing.

Quote:

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Originally Posted by SuiJin

its on the engine. black follow the top hose. it'll lead you to a metal casing.

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thought so, thanks.. bloody user manual duznt say where lol

its a common honda fault when you dont use honda coolant
and use cheap coolant or water
its you radiator partially blocked

So I need to get it cleaned out?

And where can I grab the coolant from Lan?

cheers

Quote:

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Originally Posted by Chriskoss

So I need to get it cleaned out?

And where can I grab the coolant from Lan?

cheers

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best to buy a new generic new radiator from wreckers
for a price of a clean out

coolant from honda lol

New? from wreckers.. lol riight

Quote:

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Originally Posted by Chriskoss

New? from wreckers.. lol riight

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Wreckers also order replacement parts. I buy my transmission fluid and coolant from wreckers. They give me new bottles and not stuff that they drain out from the wrecked cars.

Quote:

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Originally Posted by Chriskoss

New? from wreckers.. lol riight

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you have much to learn

sometimes asking doesnt hurt you mite find out some thing useful

^ Agreed! It seems some people don't like listening or appreciate other peoples help sometimes.

I wonder why I bother at times...

Not exactly intended towards Chriskoss.

Hahah funny that, I never knew about wreckers doing that sort of stuff!

Thanks all for the lesson and helpful info!

Quote:

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Originally Posted by Chriskoss

omgzilla... Yea I know engine gets higher rpm = more hot, but I didnt seem to have this problem before..

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It's not so much the rpm over 100kmh, but that the engine is producimg a sustained power output above Xkw to maintain 100+kmh (i.e. the power required to overcome the aerodynamic drag above 100kmh, mostly). To produce X power will generate Y heat as a 'waste' product (i.e. less power would = less heat, which a marginal cooling system may be able to cope with). If the cooling system is marginal it may have trouble getting rid of this much heat regardless of the rate of airflow passing through the rad core.

In urban driving the engine will also at times be producing more than Xkw but this may not cause overheating because it will only ever be in short bursts, so the heat produced when producing this power will not deposit enough heat into the obviously marginal cooling system to cause a noticable problem.

I'd be placing my money on the radiator being on it's last legs. My advice is to pull the rad out and have a good long look at the core fins, looking for 'fin rot' (or if you're lucky, merely being externally blocked with debris, which will impede airflow and thus heat transfer). While the rad is out reverse flush it with a hose, noting how easily the water passes through it. Better still, have a competant mechanic have a look at it.

Quote:

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Originally Posted by Chriskoss

So aaron ,if I turn my car on, take the cap off ,and if I cant see the coolant travelling in a circular motion, it means somethings blocked?

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When the engine is cold you won't be able to see any coolant flow through the radiator because the thermostat will prevent it until the engine is up to temperature.

To look for coolant flow in the rad, take the cap off when the system is cold, then start the engine and allow it to idle up to temperature while monitoring flow at the filler orifice. Don't take the cap off a hot cooling system...

Quote:

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Originally Posted by teh_mechanic

most common cause of overheating during highway driving etc is the radiator being partially blocked. Over the years sediment builds in the cooling system and finds it way to the radiator where it builds up from the bottom up, partially blocking it and reducing its effectiveness. Flushing wont get rid of this type of sediment, the radiator needs to be removed, taken to a radiator shop and they will professionally clean it. Or replace it if your extreme or want an alloy one etc.

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Also common is 'fin rot', where the copper fins (the fins are what actually dissipate the vast majority of the heat) oxidise over time (accelerated by heat and moisture) and become ineffective. Often the paint acts as a membrane that holds the copper oxide in it's original fin shape, making it look as if the fins are OK, but if you touch them they crumble.

Quote:

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Originally Posted by teh_mechanic

depending where your fans are!!!!watch out they can go even if the car is turned off!!!

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The fans aren't really dangerous because they are only light plastic blades driven by relatively weak electric motors. In the old days when fans had large / sharp edged stamped metal blades driven directly from the crankshaft they were very dangerous, and could do real damage. Still, be cautious of the electric fans because they could cause minor injury, but not terrified...

I warmed my car up to operating temp, stuck my finger in the rad, couldn't feel any flow of coolant

And the fans didnt seem to go on?

Also the top rad hose became hot but the bottom was not

Diagnosis lovely gents?

How long did you let it run for? were you reving it, cause if you leave it to idle it will take awhile before the fan will switch on. all hondas do.

Have you checked your thermostat yet?

Quote:

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Originally Posted by jords

How long did you let it run for? were you reving it, cause if you leave it to idle it will take awhile before the fan will switch on. all hondas do.

Have you checked your thermostat yet?

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+1

If the engine is dead cold , it will take a good 20 minutes of idle for it to warm up enough for the rad. fan to come on.

Try this dude. Disconnect the fan switch(located directly on the SIDE of the thermostat housing - grey clip + 2 wires) and short it (use a wire or a paper clip) See if the fan comes on. If so , fan and switch is OK.

Replace thermostat as suggested above. And properly bleed all air from coolant system

Couldn't change it til I get home 2 syd thats where my tools are which means driving the car back from newcastle again which means stopping every 10 mins to let the engine cool lol.
I just took it to the mechanic, hopefully its just the thermo and not the whole radiator

cheers

If the thermostat won't open completely then it could cause your problem.

yeah im hoping its just the thermo, well see!

I would be surprised...

Ended up being the radiator. They said it was 95&#37; blocked, and needed new hoses and stuff too.
$645 bucks too! :O I just spent 500 on the damn car fixing a main seal too, god what a money pit

HOLY RIP-OFF BATMAN!

*Pats self on back for telling you to feel-check for radiator blockage first lol.

Could've saved yourself some serious coin! Would have cost you less than half of what you've just paid!

At least you're sorted now ;)

new rad n labour should only cost u around 300ish.

u mst of got a good radiator =D

So, have you confirmed that the problem is fixed? Or does the needle still go up in temperature with the new radiator?

BTW, use Honda coolant next time to help avoid radiator corrosion problems.

well for 645 bucks i sure hope the fukn problem is fixed.

every1 tells me 300 for a new rad.. but my rad was 350.. plus extra 2 fit it and a few hoses

called up another place they said like 450 so yeh i got ripped off for sure, but even 450-500 seems a shit load just for a peice of metal and some coolant.. sigh

Quote:

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Originally Posted by Chriskoss

well for 645 bucks i sure hope the fukn problem is fixed.

every1 tells me 300 for a new rad.. but my rad was 350.. plus extra 2 fit it and a few hoses

called up another place they said like 450 so yeh i got ripped off for sure, but even 450-500 seems a shit load just for a peice of metal and some coolant.. sigh

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How did they test the radiator? Did they disconnect the bottom hose and try to spray water from the top to the bottom?

They just said was 95&#37; blocked lol, which is probably true

O well, you win some you loose some

ripped off.

yeh ur tellin me man..

the reason why it was so expensiv is cuz they charged 210 to ''diagnose overheating problem''..

the rest was ok.. 330 new rad.. 20 coolant etc.. a few little hoses

but 210 to stick a hose into the radiator.. hmm.. why bother being lawyer or docter if u can make 210 in about 10 seconds lol

Quote:

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Originally Posted by Chriskoss

yeh ur tellin me man..

the reason why it was so expensiv is cuz they charged 210 to ''diagnose overheating problem''..

the rest was ok.. 330 new rad.. 20 coolant etc.. a few little hoses

but 210 to stick a hose into the radiator.. hmm.. why bother being lawyer or docter if u can make 210 in about 10 seconds lol

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It doesn't quite work that way haha... and the money is pretty lousy to be honest.

But if you'd read my post (#5 on Page 1) you could've worked it out for yourself!

This is why I said I wonder why I bother sometimes..." earlier.

you shouldn be going over 100kms anyway chris.. your only on greens :O

naughty naughty

well even if I worked it out for myself, which I tried, bill would of still been the same, dont really care anymore, so thankyou all for the help and input!

ssshh kyal.. i seen you fang your lil civic.. newcastle roads ftw lol

hahahahaha :D