Technical Cooling system acting strange

[Yasho]

Hello all. I'm having a bit of an episode with the cooling on my mk2 1.2 16v. It started with my heating going away and the car couldn't switch from petrol to lpg. I thought it was air inside the system, tried bleeding it out and while doing that, revving the engine, it started to spew out the coolant. I've had to bleed the system many times before and it's never done that. Maybe if I've filled it to the top it would rise when it's heated up but the fan would kick in and it'd just spit a bit of coolant. This time it threw a lot of it out and fan never started spinning. I flushed the heater core, heating and lpg came back, but while bleeding the spewing of coolant continued. The fan would kick in at 98 degrees, however I think it should be at 95. By the time it does start spinning coolant starts boiling and spewing out if I don't put the cap on the expansion tank. I thought maybe the system is clogged somewhere else, put in some radiator flush in the system (which I didn't really want to do), did multiple flushes with water, but in the end, no effect. Changed the temperature sensor and the rheostat on the big radiator. No effect.
Finally gave up, bled the system and called it a day.
What's bothering me is this: first, the temp gauge goes to the middle after too long time driving and sometimes plays around a bit. It's warm outside now so it should go dead center and stay there in a matter of minutes. Second, the other day there's been a build up of pressure, cause there was a big coolant leak from the expansion cap after I'd parked the car. I'm sure the coolant level wasn't high and I've been driving it for two weeks since last flush. Fan didn't kick in again if it was too much heat. I usually wait for the fan to stop when I hear it and then turn the engine off. Hasn't happened again since. I check the pressure every time I get home.
So, yeah. Bit of a read, but it's been going on for some time and I can't explain it to myself anymore. I went to a place I trust a while back when I thought the fan was the problem, the guy said the car is fine and couldn't find a fault. Reading a lot of other forums some people suggest that this is all a symptom of a head gasket on it's way out the door.
Any thoughts would be appreciated.

 

[judderbar]

Do some basic checks on the radiator fan wiring.

1. With the ignition off remove engine fuse box black relays R6 and R7. R7 is the large black one. R6 is next to it on the engine side next to the three fuses. normal speed fan should operate when you put a piece of wire in the large connectors in the fusebox for R6. Then with that wire removed high speed fan will operate with the piece of wire in the large connectors of R7 position.

2. Once you have the fans working like that you can check the relays. With the ignition off one of the smaller fuse box relay connections has 12 volts. If you stick a thin wire onto the other connector that does not have 12 volts and replace the relay, the fan should operate when you put the other end of the thin wire onto the earth of the battery.

3. Since the mechanic must have read the fault codes the wiring from the relay to the engine computer must be good.

4. If you remove the sensor connector, and the fan wiring worked correctly, and then you turn on the ignition, normal fan speed should begin even when the engine is cold

5. According to my french manual normal Fan speed should come on at 98. High speed comes on with air conditioning or when the temperature is 101C. (The needle begins to move at 50C)

6. I did some tests with a clear DIY radiator hose with the cap off on my 1.2 16V. The entire circulating fluid was full of small bubbles. There is no way you can run the engine with the cap off without it quite quickly boiling over. You should not need to bleed the cooling system on a service basis and the cooling liquid should remain clear rather than rusty.

 

[Yasho]

Do some basic checks on the radiator fan wiring.

1. With the ignition off remove engine fuse box black relays R6 and R7. R7 is the large black one. R6 is next to it on the engine side next to the three fuses. normal speed fan should operate when you put a piece of wire in the large connectors in the fusebox for R6. Then with that wire removed high speed fan will operate with the piece of wire in the large connectors of R7 position.

2. Once you have the fans working like that you can check the relays. With the ignition off one of the smaller fuse box relay connections has 12 volts. If you stick a thin wire onto the other connector that does not have 12 volts and replace the relay, the fan should operate when you put the other end of the thin wire onto the earth of the battery.

3. Since the mechanic must have read the fault codes the wiring from the relay to the engine computer must be good.

4. If you remove the sensor connector, and the fan wiring worked correctly, and then you turn on the ignition, normal fan speed should begin even when the engine is cold

5. According to my french manual normal Fan speed should come on at 98. High speed comes on with air conditioning or when the temperature is 101C. (The needle begins to move at 50C)

Thank you for replying. I will try, though I think the mechanic has already done it. I already tried removing the temp sensor connector and the fan spun immediately.

 

[judderbar]

If the gauge takes a long time to go to the normal position and/or the temperature moves up and down as you say then the thermostat at the engine end of the top hose is not working correctly. They are cheap to buy. You just have to clean up the surfaces before putting the silicon on since silicon does not stick to old silicon.

Maybe you are going in circles with this problem? It is normal for the engine to boil over with the cap off. And it happens quite quickly. Even more so it happens quite quickly when you just filled up with fresh water with air in it. So it might not be abnormally hot at all.

But it is not normal to have to keep bleeding the system. If the head gasket was gone you are likely to have water in the oil or oil in the water. Given what the mechanic told you then most likely you have some ordinary leaks here and there.

 

[Chris parry]

Air? Or exhaust gasses?

If it’s truly air, it’ll burp out naturally over two or three heat/cool cycles. The coolant and air entrapped will heat and displace to the reservoir. As the engine and coolant in the engine cool, it’ll contract and draw in the coolant (without air) from the bottom of reservoir.

If it’s a considerable amount of air, then it isn’t air and is likely exhaust gasses. The only way that combustion gasses can get into the coolant is through a head-gasket.

 

[judderbar]

I agree with you about the air being naturally expelled. However the punto has parts of the cooling system higher than the radiator reservoir water level. So even with a tiny leak you can get air coming back into the system. If i dont fully bleed my car it can take maybe a week before i dont get gurgling sounds from the heater. There has been a few arguments on the forum about bleeding the punto. One guy said you can just squeeze the top hose before closing the top bleed valve and deal with it like that and he got banned! I did not think his comments were wrong. Then there are the mechanics elsewhere saying you have to jack the front of the car up. I think the punto problem is mainly a problem for the garages who have to get it bled before the customer takes the car away.

 

[Yasho]

If the gauge takes a long time to go to the normal position and/or the temperature moves up and down as you say then the thermostat at the engine end of the top hose is not working correctly. They are cheap to buy. You just have to clean up the surfaces before putting the silicon on since silicon does not stick to old silicon.

Maybe you are going in circles with this problem? It is normal for the engine to boil over with the cap off. And it happens quite quickly. Even more so it happens quite quickly when you just filled up with fresh water with air in it. So it might not be abnormally hot at all.

But it is not normal to have to keep bleeding the system. If the head gasket was gone you are likely to have water in the oil or oil in the water. Given what the mechanic told you then most likely you have some ordinary leaks here and there.

Thermostat is brand new, I changed it, forgot to say. What is bugging me about this boiling is that it has never happened before, just started some months ago. And this leakage from the cap a couple of days ago also... The oil is clean on the dipstick, so I don't think it's mixing with the coolant.

 

[judderbar]

Thermostat is brand new, I changed it, forgot to say. What is bugging me about this boiling is that it has never happened before, just started some months ago. And this leakage from the cap a couple of days ago also... The oil is clean on the dipstick, so I don't think it's mixing with the coolant.

did you fully flush out the radiator?

And remember a few months ago it was winter.

 

[Yasho]

did you fully flush out the radiator?

And remember a few months ago it was winter.

Yes, both radiator and heater core flushed with garden hose after putting in the additive for radiator cleaning. Water flowing perfectly in both directions and clean...

And yes it was winter then, but the car is behaving the same way now, and I've set the coolant level right between min and max on a still hot engine couple of weeks ago.

I don't know, maybe I'm reading too much into this, but it's never behaved like that and I've had my fair share of draining, filling and bleeding this system ever since I got the car...

 

[Mike1alike]

The boiling is caused by fan's thermic fuse being blown. It is located on the fan, you can find it easy, it's where the wires goes in. There are 2 circuits, for the 2 speeds of fan. The 1st speed circuit has this thermic fuse. When it blows, the fan doesn't work anymore on 1st speed, it just kicks in on the 2nd speed. But the temperature is higher than normal and the result is what you saw, the coolant is boiling. It shouldn't be. Replacing the thermic fuse is the fix.

The temp gauge playing around is a sign that there is air in the system.

As for the heating problem, it is not enough to just flush the heater with water. Water does flow, but it doesn't go through all the pipes in the heater, just through one of them. If you live it like that, in the winter you'll find out that heating is still not working. To fix it, I can strongly recommend you this method I'll put the link. Before doing that, I was strongly encouraged by a mechanic to replace the heater, him arguing that there is no way to unclog it. I did unclogged it and the heat works great since, in my Punto.
Here is how:

I fixed the car heater (little radiator inside the car) | FIAT Punto (Mk2/2b)

Hello everyone, I will share with you this great fix, for the case your heater is not working but cooling system works fine, engine temperature is steady good and thermostat works fine. So everything works just fine, then winter comes alog and you have no heat inside the car. And also, it's...

www.fiatforum.com

 

[Mike1alike]

Here is the thermic fuse:

 

[Yasho]

Here is the thermic fuse:

Hi, one of the first things I changed was this part. No signs of improvement. As for the flushing - I did it with a radiator cleaner additive in the coolant and with the garden hose directly pushing water in the heater core both ways. The water pressure is pretty good where Iive, so I'm pretty sure that the heater core and the radiator can't be clogged now.

 

[Mike1alike]

Hi, one of the first things I changed was this part. No signs of improvement. As for the flushing - I did it with a radiator cleaner additive in the coolant and with the garden hose directly pushing water in the heater core both ways.

There is a very big chance that the heater (and possibly the radiator, too) is clogged, if you did the flushing with additive. Those are not good at all. I did that before using citric acid, with absolutely no effect. "This is the best on the market" - they said, about the additive I used.

As for that fuse, did you test it after replacing it? Do you have continuity there, on the circuit? If you feed 12V DC at the end of it does the fan spin? How did you put the new fuse on? Did you do a cold soldering or did you use a soldering gun? Using a soldering gun on that type of fuse blows the fuse.