Engine Overheating at around 70 km/h

micdaws

Hi there,

Having problems with a 97 Honda Civic, 1.4 petrol. It keeps overheating at around 70 km/h. It froze over the Christmas but was fine for over a week after that?? Car has plenty of water and oil. The hose from the radiator into the engine gets red hot but the hose coming from the engine back to the radiator is staying cold or slightly warm. Also the heating will not go warm inside, there's only cold air. Can anyone tell me what's the most likely problem? Head gasket?

Thanks

Slidey

Which one is hot, top or bottom?

Does the radiator get hot?

micdaws

top! yeah the radiator i can smell! maybe circulation problem?

jimmyw

possibly blocked rad.

Slidey

If the top hose is hot chances are it is not a thermostat issue.

Take your rad out and see if a garden hose will flow through it. If not, mix yourself up some caustic soda and lay it flat on the ground for a bit. Make sure you rinse it out well before you put it back

micdaws

ohh yeah the guy in the garage said that and i thought it was that too by some stuff i read online.. he dismissed it and said it was the head gasket! im not a customer of his usually tho so he might just be trying to rip me off?

micdaws

water def flows straight through the rad! checked that already...

Slidey

Water pump should be checked so, impeller may have broken up/came off

DublinDilbert

Get your internal heater working! This is key. This will show you've good circulation in the system.

Even if the thermostat is stuck shut the internal heater should work.

Sounds like it might be a waterpump problem. Do these have a plastic impeller?

Murt10

Sounds like your thermostat is broken and stuck closed.

Murt10

Murt10 wrote: »

Sounds like your thermostat is broken and stuck closed.

Would the internal heater not work though if that was the case ?

OP, unless you are using oil and water I don't see how it is the HG, although if you keep driving it when it's overheating it soon will be. Mechanic seems a total ape too.

When you say it froze do you mean the coolant / stuff masquerading as coolant in the system actually froze ?

jimmyw

I initially thought thermos, but as was said before if the top hose is hot its probably not it.If there is mayonnaise on the oil filler and/or in the expansion tank it would be HG so not that either.It still sounds like blocked rad, or maybe pump too as was also stated.

Murt10

RoverJames wrote: »

Would the internal heater not work though if that was the case ?

Not according to this article

http://www.howtodothings.com/automotive/how-to-know-if-a-car-thermostat-is-faulty


"When the thermostat opens, heated coolant circulates through the heater core where a fan blows the radiated heat throughout the passenger compartment. Until the thermostat opens, there is no heat in the passenger compartment, a condition all too familiar to those in colder climates."

SouperComputer

Murt10 wrote: »

Not according to this article

http://www.howtodothings.com/automotive/how-to-know-if-a-car-thermostat-is-faulty


"When the thermostat opens, heated coolant circulates through the heater core where a fan blows the radiated heat throughout the passenger compartment. Until the thermostat opens, there is no heat in the passenger compartment, a condition all too familiar to those in colder climates."

That article is bollox . We'd be freezing our arses off if it was the case. There might be cars out there that wait for the TStat to open, but Ive never worked on one or seen one. Example: thermostat doesnt begin to open in my car until 92C, I have heat well before the coolant gets to that temp. Right now if the coolant is even a mere 40C its like a feckin heatwave in the car which is good because its -20C outside! So in short, the article is incorrect. Having rebuilt the engine a couple of weeks ago I could see that the heater core is plumbed into the block" loop. This is commonly how its done. Im open to further correction however.

OP it sounds like you have a blockage somewhere in the system, or your pump went out to lunch. The "freezing" part of your post concerns me.

Murt10

Murt10 wrote: »

Not according to this article

http://www.howtodothings.com/automotive/how-to-know-if-a-car-thermostat-is-faulty


"When the thermostat opens, heated coolant circulates through the heater core where a fan blows the radiated heat throughout the passenger compartment. Until the thermostat opens, there is no heat in the passenger compartment, a condition all too familiar to those in colder climates."

Article is wrong me thinks, if it was correct the entire coolant system would need to be nice and hot before any warmth crept into the cabin. Before the engine is warm enough to prompt the stat to open the heater will blow hot air in.

As an aside do you actually know what you are talking about and used the article as back up or are you just relying on the article and don't have an opinion either way yourself ?

Muckie

Had similar problem over the extreme cold spell. Car temp shot up.

Turned out the anti-freeze mix was quite low. Changed and topped up,

bring on the next freeze!

If still no joy, i'd guess its the radaitor or maybe just airlocked.

micdaws

ok i have heat in the car but the hose coming form the engine back to the radiator is stil cold/warm and its over heating more easily now! water pump?

thanks for yer help so far

jimmyw

micdaws wrote: »

ok i have heat in the car but the hose coming form the engine back to the radiator is stil cold/warm and its over heating more easily now! water pump?

thanks for yer help so far

But just to be clear, there are 2 hoses going from the engine to the rad.Top and bottom.Top is the one that the heat from the engine goes into the rad through the thermostat to be cooled, and then back to the engine through the bottom one to be reheated again.Which one of them is hot or cold?

micdaws

top is hot bottom is cold..and the bottom one is the one going through the thermo

jimmyw

micdaws wrote: »

top is hot bottom is cold..and the bottom one is the one going through the thermo

What?:eek:.Strange, well if thats the case then I would guess its the thermostat.Thats news to me about the location of the thermostat.They were always on the top hose.

micdaws

wel wen i was in the garage he pointed to the bottom hose by the engine and said it might be the thermostat ha iv no idea where it usually is but thats where he said it was!

PSKdesign

I've had same car, same year and same problem. Same checks even from a bunch of mechanics... they checked the radiator, changed water pump and finally found that head engine gone...

RoverJames

RoverJames wrote: »

Mechanic seems a total ape too.

micdaws wrote: »

wel wen i was in the garage he pointed to the bottom hose by the engine and said it might be the thermostat ha iv no idea where it usually is but thats where he said it was!

I would really go somewhere else

micdaws

trust me im going to thanks

jimmyw

Well I done a little research, and yes your garage could be right about the thermostat being on the bottom hose.I should have known this as we had 4 civics in our time, all from different years.There is a hose going from the top of the rad to the top of the engine which also has a bleed nipple there as well.The bottom hose is connected from the rad and going into a housing on the left hand side looking in from the front of the car.That's where the thermos is I think.There is two temperature sensors there as well I think.This system does not make alot of sense to me though, cause it would appear from this that the coolant flows backwards through the rad.I am sure someone will correct me on this.If this is right, then maybe it is the thermostat since the bottom hose is cold.I may be talking rubbish, but that is my thinking of it, right or wrong.