VX - Bleeding, Cooling Problem including Swirl Pot

[Tazio]

I have just replaced my original K series rad, with a new Radtec and 11 inch fan. I also took the opportunity to instal an 82 degree stat.

Since then I'm blowing coolant out the top of the pressure cap on the swirl pot, and nothing I do in terms of bleeding seems to help

Starting from cold, and with the level of coolant in the expansion tank below the max level, as it warms up, the level of coolant continues to rise up to and past the expansion tank overflow pipe. The overflow is connected to the neck of the swirl pot, this connection is above the pressure cap seal, so the coolant cannot re-enter the cooling system as it can't get past the pressure cap seal

it is forced out the top of the pressure cap.

If I unscrew the pressure cap on the swirl pot the level in the original expansion tank falls back to normal.

I've had a sniff test done on the gases in the expansion chamber, there are no hydrocarbons so it rules out a gasket issue, so symptomatically it looks like trapped air, but I am buggered if I can get rid of it...I know all the tricks, raise the front etc, the rad gets hot top to bottom, the hoses are all hot , I've massaged them etc..what next?.

There does seem an issue with the swirl pot connections, if the expansion tank overflow was 'teed' into the hose from the manifold, the overflow water could be returned to the cooling system, then just use the connection in the neck of the swirl pot as a bleed to the air.

Anyone have any thoughts?, I'm having a John Cleese moment, and feel like hitting it with a stick.....

 

Alan

[Mavic82]

Alan,

personally I am not sure that the swirl pot is needed but putting that to one side. Have you drilled a 1/16th hole in the upper side of the stat? That helps and means a perm bleed past the stat.

also I installed a banjo on the radtec top bleed screw and fed this back via a T piece to the header tank. Simply raising the car and allowing it to warm up and it self bleeds.

i can only assume you have air trapped somewhere, are all your hoses below the header cap?

 

[Tazio]

Thanks Guy, I have a 3mm hole in the stat, but I've taken that out for the time being and yes all the hoses are below the cap.

The way the expansion tank fills up suggests to me that there's air somewhere which as the engine heats up the air expands and displaces the water into the tank.

 

Shame you can't create a vacuum in the cooling system....

[Jim_Harvey]

I've had two cars that were really difficult to bleed (Peugeot 106 and mini). This is based on Peugeot special tool XXXX but has worked on both cars. Be carefull-coolant gets v.hot.

Find a piece of plastic waste pipe about 15" long and a suitable rubber seal from a waste pipe compression fitting, so that you can jam it in the neck of the expansion tank sticking vertically upwards without it leaking.

Fill with coolant to between max/min levels. Start the engine and let it warm until the coolant reaches about 6" from the top of the pipe. Let it cool for a few minutes (the coolant level drops) then run it again until it rises to 6" again. You may well be able to see bubbles rising to the surface in the pipe, beware of it spitting though. When you can run it for 5 minutes or more at a time, increase the revs to about 1500 and watch for bubbles/ overflowing. If ok run at about 2000rpm.

When there are no more bubbles allow it to cool right down. Put an old bath towel around the expansion tank and pull the pipe out (yes, it makes a mess) and replace cap.

I think that air gets trapped in the cylinder head when refilling with coolant, expands rapidly when the engine heats up and pushes a lot of coolant out. This method allows some room for expansion and ensures the coolant level is above the highest point in the system. You need to run fast enough to push any trapped air out.

The cars above took 2-4 hrs to bleed fully. Hope this helps.

 

[k.russell]

Now the alan. On the return to the expansion tank do you have the plastic restrictor in place. Have you replaced this pipe, check if there was a restrictor in the old one if you haven't thrown it away. Small plastic or aluminium blank around 15 mm long with perhaps a 2 mm hole. My car suffers exactly those symptoms if this is not fitted. Will see if I can find info in archive. 

[Tazio]

Kev,Thanks for responding. The new pipe from the inlet manifold connects to the swirl pot via a reducing fitting.

The real issue is the water which fills the expansion tank and overflows into the neck of the swirlpot, but it doesn't have a route back into the cooling system, so I gets blown out.

 

If I could get the all the air out...

 

 

 

[F355GTS]

Alan

 

Can you post a pic of the installation?

One thing I found on mine was that ti was critical the small cut out in the gasket clear fo any sealant (gap goes between the two ports on the head)

 

I never had min/ max markings on my swirl pot but IIRC I used to fill it to just over the lower hose

[Paul Deslandes]

Take the rad cap off and remove the radiator top bleed screw, jack up the front of the car as far as you can, start engine and the air will find its way out.  Keep topped up.

If that doesn't work, and I'd be surprised if it doesn't, put the car on the level and remove cap, bleed screw and the bottom hose from the radiator to drain out all the coolant into a bucket.  Replace hose and then jack up front as above.  With rad cap and bleed screw still removed, refill slowly to allow air to escape.  Start engine with car front still in the air.  Keep topped up and when air has stopped coming out, refit bleed screw and cap.  Lower car and it should be ok.

Paul

[Paul Gibb]

The topmost small hose plumbs into the bottom of the exp tank, the one below is from the inlet manifold to the swirlpot.  I rarely have any coolant at all in the exp tank. Hope this helps you Alan.

[Tazio]

Thanks for all the inputs everyone, I'll just have to persevere ....

Much appreciated