Help needed. Cooling system problems.

[Peter.N.]

How many miles has it done? If its anything over 100k and it hasn't always had a good concentration of antifreeze, the radiator could well be furred up, no ammount of flushing will cure it only a new rad will.

Peter

 

[Markc79]

It said 85k when we bought it. I reckon it's been clocked but there is no obvious sign. Screws seem clean, no fingerprints inside plastic, numbers all straight etc.

I've done the easy thing and called the AA saying it just started bubbling. See if he can spot the problem. New rad not the end of the world is it?

 

[Burnerman]

Hi Mark
It would be a good move, if you could, to remove the top rad hose, together with the bottom one, and get a hose pipe in there just to give it a good flush.
Pouring water into the expansion bottle, as you are doing, will clear the engine block.
So - with that being done, refill the system with water and start up, and see how long it takes to boil over.
When the thermostat opens, the radiator and top hose gets hot - but not before then. I'm not trying to be patronising here, but are you sure you put the stat in the correct way round? Thats important.
So - if the fault persists - and I've got a funny feeling it will, the next step is to have a garage check for combustion gases in the air space above the coolant. This is done by bubbling the gas through a blue liquid - the liquid turns yellow if combustion gas is present.
Its a long job to access the water pump as the timing belt has to come off, so its worthwhile trying to rule out the simpler things first.....I'm just sorry I can't be more specific!
John

 

[Markc79]

I'm 99% sure I put the thermostat in right..Got me thinking now though!

I'd better go to B&Q in the morning to buy a hose pipe. I really hope this works. Was laid off from work not long ago so finances are tight hence the need to try to fix it myself. Not to mention buying the shed of a car in the first place!

The combustion gasses option sounds complicated and exspensive!

mustn't grumble though as there are people far worse off than me.

Thanks again John. Will try that and then if no joy I'll have to concede defeat and get a pro to take a look.

Cheers.

 

[^neo^]

if it's taking 15 mins for it to blow, i reckon it's a simple one.

Once you have given everything a good flush through, you need to bleed the system. Easiest way is to leave the expansion tank cap (bottle you fill with water lid) of with the engine running, and keep the bottle filled to the brim. When the thermostat opens, water should gush out of the bottle. When it does, turn off the engine and top up the bottle.

Running it purely on water isn't ideal itself (but ok for testing purposes), as the coolant (antifreeze) does bring the temp of the water down alot. Dont know what engine is in yours, but if it's the duratec (will say on the top of the engine) they do run very hot.

When it is up to temperature, check all the hoses feel roughly the same temperature (ish). If you have a red hot one and a stone cold one, either you have a blockage or the waterpump is shot.

The other thing worth checking is the pressure relief valve in the expansion tank cap, and the cap itself. If the rubber seal / washer is iffy, then the cooling system wont get pressurised, and could be the cause of all your problems!

 

[Markc79]

It's a Zetec engine. 16v.

I left the engine running with expansion cap off. The water just bubbled up after 10mins and overflowed. The water only rises when the cap is off. When I turned the engine off it sounded like water was draining away in or around the 'stat housing. The small hose that goes into the top of the 'stat housing gets very hot as does the large hose below. The hose I took off to drain the rad is also cold. The fan seems to have stopped working (checked the fuse but seems ok) and the temp gauge on the dash hasn't worked at all since we've had the car.

There is no 'mayonnaise' on the oil refill cap nor is there any sign of water in the oil or oil in the water. I checked the dipstick. there is no steam coming from the exhaust. Just a small puff of white when started up or when it's a cold day.

When the engine is cold the water seems to drain and sit in the engine somewhere. When it warms up after 10-15mins it comes back and bubbles over. There is no water coming from the underneath of the car ie waterpump. There is no noise coming from the area of the pump either other than the usual engine noise and the sound of the belt.

The heater blows cold. No hot air at all even when the engine is hot.

I have replaced the 'stat. It is the right way around too thank god lol. Not that it has made much difference.

Just going over old ground now I think but thought if I wrote everything here it may help.

Thanks again.

 

[Peter.N.]

It sounds as though its just boiling, this will cause the water to rise in the expansion tank, partly because of expansion and because the steam being generated is pushing it out. If the fan is not working when stationary it will boil, the heater not working could be an air lock, the only other thing I can think of is that the pump has failed, although you did say that the radiator gets hot, didn't you?

 

[Markc79]

No the radiator stays cold.

 

[Peter.N.]

Sounds like water pump failure, although I didn't think these were prone to it. Is it diesel or petrol? The 1.6 diesels had a small metal pipe that got blocked and caused it to boil, dont know if the 1.8 is similar, can't remember what it did, its a long time ago...

 

[Burnerman]

The pressure cap on the expansion bottle only opens when the water pressure within reaches 14 psi.....this has the happy effect of allowing the engine coolant temperature to reach about 120 deg C on a hot day, without the coolant being expelled. Therefore, boiling within the system with the cap off isn't necessarily an issue....however, as your rad remains clay cold, it seems like there isn't any circulation indicating a faulty thermostat (replaced) or water pump, unfortunately.
You can tell if your engine has an air lock by squeezing both the top and bottom hoses when the coolant is full - you should see the water level in the header tank start to rise slightly.
John

 

[Markc79]

Anyone have any idea how much a new pump would cost me..? lol

It's going into the garage next week. My wallet is getting upset already.

 

[^neo^]

a new pump itself will be around £30. As for fitting, whatever they want to charge you!

 

[Markc79]

I'm guessing they'll charge a bit more because of the pumps location. I'm hoping to get change from £150!

 

[Burnerman]

Its listed as a job just under 3 hours, mate - longer if your car has air con.
They'll also fit a new timing belt, maybe tensioner at the same time.
With that, including coolant and pump - its got to be a canny bit more than £150.
Do ask around though - and specify exactly what you want doing.
John

 

[Markc79]

Right. No air con so that's a bonus.

I can stretch to £200 next week. Any more and it'll have to wait til i raise more funds. Fingers crossed it's somthing simple and cheapish.

I can hope can't I..? lol