Coolant reservoir bubbling and boiling over.

 

I've had a few people say head gasket but no other signs of the head going / gone. No smokey exhaust fumes. No milky oil etc

 

From the pictures it looks like there's to much coolant but the levels are ok it's just when it's overheating the coolant rises and lowers to normal levels when cold / cooling down

 

I've tried uploading a video but only allowed 2mb

Edited January 12, 20251 yr by Gary1988
Title wasn't helpful

Try replacing the expansion cap if not done already.

Also do a CO2 sniff test to check for exhaust gasses.  There doesn't need to be any exhaust smoke or milky oil for a blown headgasket, all depends on where the gasket breaks.

27 minutes ago, TomsFocus said:

Try replacing the expansion cap if not done already.

Also do a CO2 sniff test to check for exhaust gasses.  There doesn't need to be any exhaust smoke or milky oil for a blown headgasket, all depends on where the gasket breaks.

Hi thanks for you reply.

 

What would replacing the expansion cap solve?

On the sniff test what should it smell like?

 

Thanks 

1 hour ago, Gary1988 said:

Hi thanks for you reply.

 

What would replacing the expansion cap solve?

On the sniff test what should it smell like?

 

Thanks 

The cap holds pressure on the coolant to raise the boiling point.  As the level is rising in the reservoir it may not be holding enough pressure.

A sniff test is an actual test, not sticking your nose in it lol.  It is an archaic term now though.  They seem to be called a 'CO2 leak detector' nowadays.  Can be bought fairly cheaply on eBay or Amazon.  Though I would expect any local garage to test it for free as they should all have the kit to do it.

6 minutes ago, TomsFocus said:

The cap holds pressure on the coolant to raise the boiling point.  As the level is rising in the reservoir it may not be holding enough pressure.

A sniff test is an actual test, not sticking your nose in it lol.  It is an archaic term now though.  They seem to be called a 'CO2 leak detector' nowadays.  Can be bought fairly cheaply on eBay or Amazon.  Though I would expect any local garage to test it for free as they should all have the kit to do it.

Nice one mate.

 

You can tell i know naff all about cars lol just know how to drive them 

On 1/12/2025 at 6:01 PM, TomsFocus said:

Try replacing the expansion cap if not done already.

Also do a CO2 sniff test to check for exhaust gasses.  There doesn't need to be any exhaust smoke or milky oil for a blown headgasket, all depends on where the gasket breaks.

Hello mate.

 

I bought one of those kits that goes intot the coolant tank with the blue dye..Followed the instructions to the letter. Took coolant tank cap off started the car waited until the car was warm i put the funnel into the coolant tank and filled the tube to the fill line. Put the pump bulb into the top then pump the air through for literally 4 minutes to make sure i was doing right. No coolant came through the funnel so and it stayed blue.

 

I also read somewhere that you can do the same test using exhaust fumes. I did that and it turned yellow instantly, but isn't this a good thing cause it shows the Combustion gasses are going the right way. Out the exhaust and not up through the engine right.??

3 hours ago, Gary1988 said:

Hello mate.

 

I bought one of those kits that goes intot the coolant tank with the blue dye..Followed the instructions to the letter. Took coolant tank cap off started the car waited until the car was warm i put the funnel into the coolant tank and filled the tube to the fill line. Put the pump bulb into the top then pump the air through for literally 4 minutes to make sure i was doing right. No coolant came through the funnel so and it stayed blue.

 

I also read somewhere that you can do the same test using exhaust fumes. I did that and it turned yellow instantly, but isn't this a good thing cause it shows the Combustion gasses are going the right way. Out the exhaust and not up through the engine right.??

Excellent.  That is very good news.  It means the headgasket hasn't split between the cylinder and the coolant ways.  We can now rule out headgasket failure.

Did you try a new cap for the reservoir?  They're so cheap it's always worth trying with a fault like this.

Next questions - How long does it take to overheat?  Does the radiator feel hot?  Do the heaters get hot?  Does the radiator fan come on at all?

3 hours ago, TomsFocus said:

Excellent.  That is very good news.  It means the headgasket hasn't split between the cylinder and the coolant ways.  We can now rule out headgasket failure.

Did you try a new cap for the reservoir?  They're so cheap it's always worth trying with a fault like this.

Next questions - How long does it take to overheat?  Does the radiator feel hot?  Do the heaters get hot?  Does the radiator fan come on at all?

When driving around it doesn't over heat. After doing that test I took it for a spin for a good hour. Broke the law a couple times driving at high speed LOL. But driving with a constant flow of air it stays normal. It's only when the car is stationary but still runninh does it then begin to overheat. The radiator fan hasn't been kicking in either.

 

3 hours ago, TomsFocus said:

Excellent.  That is very good news.  It means the headgasket hasn't split between the cylinder and the coolant ways.  We can now rule out headgasket failure.

Did you try a new cap for the reservoir?  They're so cheap it's always worth trying with a fault like this.

Next questions - How long does it take to overheat?  Does the radiator feel hot?  Do the heaters get hot?  Does the radiator fan come on at all?

And yeah I bought a new cap also 

9 hours ago, Gary1988 said:

The radiator fan hasn't been kicking in either.

Ah, that'll be the issue then.

There isn't enough airflow over the radiator when stationary, so the fan should come on at around 93c if 2 speed, or 97c if single speed.  (Both types were fitted to petrol Mk7s so not sure which yours will be.)

Next test should be the fan motor.  If you can use a spare piece of cable to put a direct battery feed to the motor plug that's the best test.  If not, check all fuses and relays relating to the radiator fan.  They should be listed in your handbook.  If you don't have a handbook, they are available online here.  ford.co.uk/support/owner-manuals

2 hours ago, TomsFocus said:

Ah, that'll be the issue then.

There isn't enough airflow over the radiator when stationary, so the fan should come on at around 93c if 2 speed, or 97c if single speed.  (Both types were fitted to petrol Mk7s so not sure which yours will be.)

Next test should be the fan motor.  If you can use a spare piece of cable to put a direct battery feed to the motor plug that's the best test.  If not, check all fuses and relays relating to the radiator fan.  They should be listed in your handbook.  If you don't have a handbook, they are available online here.  ford.co.uk/support/owner-manuals

Hello,

Definitely something wrong with the fan system on a whole because I've got an OBD2 reader here and I used it to monitor the coolant. The car started overheating at 113⁰c and the coolant started bubbling and the rad fan hadnt kicked in. So I started driving around I kept the OBD2 reader in to monitor the heat when driving around the car cooled down to about 89⁰c.

Think I can safely say it's not the head but something is definitely wrong with either the radiator fan, thermostat, water pump etc.

Would you agree based on what I've said so far?

 

 

1 hour ago, Gary1988 said:

Hello,

Definitely something wrong with the fan system on a whole because I've got an OBD2 reader here and I used it to monitor the coolant. The car started overheating at 113⁰c and the coolant started bubbling and the rad fan hadnt kicked in. So I started driving around I kept the OBD2 reader in to monitor the heat when driving around the car cooled down to about 89⁰c.

Think I can safely say it's not the head but something is definitely wrong with either the radiator fan, thermostat, water pump etc.

Would you agree based on what I've said so far?

As it cools down on the move, that pretty much rules out the thermostat and the waterpump.  It's only the fan that I suspect myself.

2 hours ago, TomsFocus said:

As it cools down on the move, that pretty much rules out the thermostat and the waterpump.  It's only the fan that I suspect myself.

Hello again. 

Update! 

 

I took it to my local garage and put the car on the lift. He pulled the wire out of the bottom of the fan motor thingy, & whilst connected to the battery He manually used some machine to test the fan. The fan came on for literally a split second then lost power and went off..

Think we / i can safely say the fan as a whole is nackered..

 

On 1/16/2025 at 12:41 PM, TomsFocus said:

As it cools down on the move, that pretty much rules out the thermostat and the waterpump.  It's only the fan that I suspect myself.

Helloo Tom..

Update. 🙄

 

So had the fan changed for a brand new Ridex one. Had it fitted by local garage today.

Car still overheating when stationary fan still not kicking in. 

Mechanic gonna look into it tomorrow he had to finish early today.

Any ideas? As expected it's beginning to give me a headache

Cheers 

7 minutes ago, Gary1988 said:

Helloo Tom..

Update. 🙄

 

So had the fan changed for a brand new Ridex one. Had it fitted by local garage today.

Car still overheating when stationary fan still not kicking in. 

Mechanic gonna look into it tomorrow he had to finish early today.

Any ideas? As expected it's beginning to give me a headache

Cheers 

If it was tested using a machine but through the car before then that should rule out fuses and relays.

I don't think your model has a fan controller.  

Temp sensor could be giving the PCM/controller false readings.

Hopefully the mechanic will know how to diagnose tomorrow.