too much pressure in cooling system

itarumaa

Hi,

I got a Daewoo Matiz, it has problems with cooling system,

first the heater core blow, then new core was fitted, that failed month later, then temporary connection was done, that failed, then new connection, that failed and now it has been ok for couple of weeks, expect it is constanty building up pressure (too much) in the system,

now that pressure goes out inside the dashboard from the temp connection, really good it has not failed but it will fail anyday now,

So what should I do, I think I could drive without pressured system, since there will be water anyway to cool down the engine, but what would be the easiest option to get the pressure out from system, maybe make a small hole with needle in some of the hoses? At the moment my expansion tank cap is really loose, so that takes some of the pressure out.

Andrewf20

Is your blead valve okay? Its usually on the radiator or expansions tank. Check its not clogged up / blocked. I hope you havent got the expansion tank full to the brim.

Put holes in hoses? I dont see how thats the best solution. Whats to stop most of the water / coolant leaking out, resulting in overheating of the engine.

It could be possible that combustion chamber gases are leaking thru the head gasket. If your head gasket is on its way out, you can check by looking for signs of whiting in the oil.

itarumaa

Hi,

the car has gone through some overheating issues from the past, but luckily both coolant (well water actually) and oil looks fine, so I think head gasket is ok, I really hope so...


One reason might be that expansion tank cap does not work like it should, so when engine heats up it does not release the pressure out of the system,

I have to try find this blead valve to see the situation, but I think it should be located in expansion tank cap,

and the expansion tank is filled up to max (no more), but at the moment it goes under min in one-two days, so it takes a lot of coolant at the moment, even more interesting is that coolant just vanishes without the trace, I think it transforms to steam and goes out of the temp connection
lets hope for the best, thanks for reply

peasant

If you run your cooling system with pure water, that could explain part of the problem.

Water without coolant fluid boils at 100 degrees, lower (ca 90) when it's pressurised. Adding coolant/anti freeze actually raises the boiling point to well over 100 degrees.

You may well be driving around a pressure cooker, constantly under steam.

Get the cap of the expansion tank replaced (can't cost much) and all the water drained from your cooling system and replaced with the proper mix of water / coolant and bleed the system so that there is no air left in it.

itarumaa

Hi, yes I am thinking the same thing, changing that cap first and put coolant in,

at the moment the car does not even have a heater core, but it will have it soon, but at the moment no point to put heater core, since the pressure might destroy it anyway,

so I need get this pressure problem fixed first, then new heater core and maybe even have heating inside the car in cold mornings:)

milltown

Actually, raising the pressure raises the boiling point. That's the whole point of the pressurised cooling system in the first place.

My money is on a head gasket.

Andrewf20

Also check your Viscious fan coupling. If its dead the fan may not be spinning fast enough to draw heat away from the rad. Heres a test to do. When the engine is idling, poke a folded up newspaper into the fan, if it stops with ease, then it probably needs replacing. The fan should have slip, but should also be quite resitive to stopping.

If the impeller on you water pump has broken off or the thermostat is stuck closed, then the coolant in the engine wont get pushed around the system to the rad. A trip to the garage sound in order, if not done already.

itarumaa

Thanks for replies again, I will not take the car to garage at no point, don´t trust them,

Car was actually NTC´d so I have two years to driving ahead, no problems with emissions etc,

I think I will start to investigate the problem with the expansion tank cap and see what is the story, hope it helps.

As for head gasked, there are no markings like water in the oil, white smoke from exhaust or bad coolant, but lets see, I´ll keep you informed,

thanks again.

itarumaa

milltown wrote:

Actually, raising the pressure raises the boiling point. That's the whole point of the pressurised cooling system in the first place.

My money is on a head gasket.

It seems that milltown user is right, that is the reason why it is raising pressure, today the problem was really bad, so it seems some fast fixing is needed,

any ideas about the costs of parts and labor?

milltown

I could be way off the mark but I would expect around the €500 mark for gasket kit, labour and head skimming. You may get away with a few hundred less if you find a cheap mechanic and take a chance on not skimming the head.

Plenty of users here with more in depth knowledge of the trade and prices though.

itarumaa

My mechanic will see the car today, luckily he does not charge so much:)

I am correct to assume that timing belt has to be removed as well?

Any Daewoo specialist in the forum?

MercMad

The Matiz does not have a viscous fan it has an eelctric one. Run the engine to ensure it cuts in after about 10 minutes or so from cold, usually when the gauge goes past 3/4 mark.

It sounds to me like your expansion bottle cap is faulty. That is where the releief valve is. Is the cap is not working and the car overheats it will blow a hole somewhere !

Driving with the cap loose will only lead to overheating as the engine coolant will reach 100deg + and boil away. As mentioned, with the cap in place the water temp goes over 100deg, sometimes to 110 depending on the release pressur eof the cap.

Any car with a loose cap will boil up in a day or two !

Fill with coolant, replace the cap, and if you still have problems get the system pressure tested, but ensure you have checked the fan first. Also set the hetaer controls to full whyen topping up, and do this witha cold engine !

itarumaa

Hi,

I ordered the cap and it should be arraving on monday,

at the moment I drive with cap loose & some coolant added and at least today car worked fine, but of course it loses a lot of coolant,

Fan was replaced before, since old one broke down (the whole fan) so it was replaced by second one, should be ok.

itarumaa

Hi,

I cleaned up the cap completely and it seems that problems are gone, new cap should be arriving soon, I´m so happy that head gasket seems to be ok

thanks for help:)