Boilling water?

[s2belgium]

I have a problem with my S2 ABY '94. When i put off my car after driving, the water begins to boil in the hose coming from the watermanifold to the big radiator. When i'm driving, the water stays 90°C and the water won't boil. When the car is idling there is still no problem, car gets to 92°C then the fan will kick in, water still not boilling. It begins to boil as soon as i put the motor off, when their is no watercirculation. It only boils in the watermanifoldhose. Weird is that the afterrunpump won't work cause the sensor of the pump is in the manifold where the water seems to boil. The temperature stays normal on the dashgauge. I' have no waterleaks.

So i tought it was my afterrunpump, i've changed it together with 2 sensors in watermanifold + sensor in the big radiator(also new). I've also tested the pump by connecting the 2 wires from the afterrunpump sensor, it works.

After changing all this still had the problem, so i've brought my S2 to the audigarage. First they tought it was cylinderheadgasketleak, but it wasn't. They searched for two weeks, today they called me to say the car was OK. So i drove it home, when i got home and putted the motor off, it was still boiling. Called the garage, they say that they can't do nothing anymore, that everything was checked correct and that it is normal that it boils a "littlebit". Now, I think this is not normal.

Does anyone here on the forum has had a similar problem? don't know what to do.

grtz

[Trist28]

I had same issue with mine, thought it was a problem but checked a mates, his was the same, and have since checked another, does the same. You can feel bubbles in the top hose only, when car has been run and just turned off. Stops after a few mins. I wouldnt worry or waste yr money trying to fix it. Think its just the water in the turbo getting heated when not circulating and needing somewhere to go, if water sits in something way above 100 deg it will try to boil.. Would be interested to see if other motors do the same though?? Same in 3 so that settled my mind!!

[Rusty]

A small leak can make it a little more prone IME, also worth checking that the after run pump is working correctly. Do a search to identify the temperature sensor and then bridge the plug to check it's working.

[driftin jo]

Is the system holding pressure ?
If not it will boil water when shut off .
If you undo the cap of any s2 when shut off the pressure release will allow the parts of the cooling system that are above 100 deg to boil water .
The pressure in the system raises the boiling point of the water .

[bigdan]

I had this recently, turned out to be the head gasket blowing and forcing water out from underneath the exhaust manifold. When the water was hot and up to pressure, it would leak, drop the pressure in the system and boil the water in the top hose.

I have changed the cylinder head gasket and skimmed the head. The system now holds pressure, but i cant say that i've noticed it boiling since. Unless i release the pressure by opening the expansion cap...

Hope that helps?

Dan

[s2belgium]

Hi guys, thanks for the fast reply. I'm sure i don't have a leak, just fitted samco-kit, have 2x new radiators(big and small) and new waterreservoir with pressurecap(don't know the right word in english). The water stays on the same level. When the car is turned of after driving there is alot of pressure in the hoses, so i think it keeps pressure.

@ trist28: i really hope your right, i don't know anybody who has an S2 to check on. The garage says the same, that it's normal.

@ rusty: afterrunpump works correctly, i've put the 2 cables that were on the sensor together and it works

Now i was thinking to put a sensor for the afterrunpump that opens quiker, +/- 90°c, so it won't have time to boil. If it's normal that it boils, i would like to fix it, maybe with a sensor that opens faster. I'm going to order one,then let you guys know if it helped.

If my headgasket wasn't good anymore shouldn't it build up pressure when i'm driving also? Now there is only a high pressure when the motor is turned of.

thanks a lot

[BrianSmith_S2]

The pressure in the system raises the boiling point of the water .

As does the correct type and mix of antifreeze additive.... what you got in your S2

[220bhp]

When this happens is the top hose hard or fairly soft.Water wont boil under pressure,but if you loose pressure when you turn the car of it will start to boil in the head as the temperature will start to rise as soon as you turn the engine of,as has been said most cars will make a little noise for a while, my s2 always has, but my S6 doesn't but that could be because of the extra space under the engine bay in the S6.