Air in the top hose/swirl pot...

[Rob_the_Sparky]

Just a question to see if anyone else has had this.

I have had a Taraka fitted fairly recently (3 or 4 years ago) but even before I had this I had the same problem. I fitted Silicon hoses ~5 years old and at the time I was a bit worried about having bled it right so kept checking the system by squeezing hoses to get the last bit of air out and found that I kept getting air when squeezing the top hose once it had cooled after a run. Since I got the Taraka fitted figured all would be fine but it still does this and it is going on too long to just be trapped air from bleeding the system. I get no loss of water, I have no overheating problems or anything else to suggest something is wrong with the cooling.

Any ideas what might be causing it? Is this just a "feature" of the car having the top hose as the highest point? I.e. best just to ignore it?

[bobfather]

What level do you maintain in the expansion pot? It could be that it is slightly too low, allowing a small slug of air to be drawn in when the engine is fully cold. Once the air is drawn in it will settle in the swirl pot and reset the expansion pot slightly higher. The normal cold level is approximately 1/4 to 1/3 of the way up. Try running it at 1/2 and repriming at the swirl pot, the expansion pot may eject a little coolant to reset its level but there's no harm in that and it'll ensure that you're not drawing air in there

[Rob_the_Sparky]

Probably a bit too much water if anything, a between half and 2/3rds full. I was considering whether I should try to remove some. Prior to that it was probably only 1/4 full but I put a bit too much in.

[bobfather]

Strange, in my experience, I've refilled quite a few times as I self service, I find I need to reprime the swirl pot for three or four heat cycles before it settles down. There's always 5mm or so air space in the swirl pot but I'm happy with that because that air is too high to be pulled into the flow. I would try a vacuum test if you can find a way to do it. It sounds like there's a leak that opens under vacuum as the coolant cools but doesn't leak under pressure.

Just a thought, was the heater matrix open last time the system was refilled. It's possible there's still some trapped air pockets working their way to the swirl pot

[Rob_the_Sparky]

I'm pondering whether the radiator cap is allowing a vacuum to build up when cooling thus drawing in air. If that were the case it could be from a large number of places. If that is likely then my first target I think will be the pressure cap, it is one from Euro Car Parts, might see if VW still sell them. I guess checking all hose clips might also be worth while.

My other thought is that it is just a bit of air in the top of the pot and I should just stop worrying about it.

Edited by Rob_the_Sparky on Monday 26th June 18:40

[bobfather]

Rob_the_Sparky said:

I'm pondering whether the radiator cap is allowing a vacuum to build up when cooling thus drawing in air. If that were the case it could be from a large number of places. If that is likely then my first target I think will be the pressure cap, it is one from Euro Car Parts, might see if VW still sell them. I guess checking all hose clips might also be worth while.

My other thought is that it is just a bit of air in the top of the pot and I should just stop worrying about it.

Edited by Rob_the_Sparky on Monday 26th June 18:40

As long as the air is a good margin above where the top pipe inserts into the swirl pot you should be okay. I'd keep an eye on it though, if the air quantity is increasing then trouble will follow

[Pete Mac]

Rob_the_Sparky said:

..........My other thought is that it is just a bit of air in the top of the pot and I should just stop worrying about it.

Edited by Rob_the_Sparky on Monday 26th June 18:40

Rob

Been there, done it.

I was convinced the Green Meanie had slipped liners/blown head gasket. Took it down to Halfrauds in Reading. They tested the water for exhaust gases and came up negative. I then replaced all hoses including the metal connector hoses (mine were corroding, I replaced with stainless steel).

I made a bleeder out of a plumbing fitting and a large funnel and then spent a lot of time bleeding the system, squeezing the hoses etc. The funnel fits on the swirl pot - amazing how the levels go up and down. I top my expansion pot up to about 1/4 full and the system seems to be fairly robust, although I still watch that temperature gauge but I am a lot less paranoid.

I have still to fit the new radiator from Aaron Radiators sitting in my garage

If you want to do a comparison and bleed your system, pop round sometime. We could also fit that stainless undertray of yours that is still sitting in my garage .

Cheers

Pete

[Pete Mac]

Picture of the little bleeder in case anyone else wants to make one up. The thread is 1/2" BSP conveniently. Fittings from your local Plumb Centre, funnel from any old kitchen shop. Pete

[Rob_the_Sparky]

Thanks for the offer Pete, it certainly is time I tried to find a spare moment to come an visit, even if just to collect that under tray for me to put on this winter (along with the new dash).

[gavgavgav]

Pete Mac said:

Picture of the little bleeder in case anyone else wants to make one up. The thread is 1/2" BSP conveniently. Fittings from your local Plumb Centre, funnel from any old kitchen shop. Pete

I've used a less elegant but very similar method, simply wedged (ruining a bit) the funnel into the hole to seal it a bit and 1/2 filled the funnel. Started the car until it flows around getting the bubbles out, squeezing the top hose. No need to get it too hot, when it stops gargling then turn off the car, pull out the funnel and replace the cap.

Second time I did it I was more gun-ho and after bunging in most of the coolant found it easier to fill with the engine running to do the final top off.

After that, then remove the cap of and fill the expansion bottle to the right level.