Incontinent Superspec

[Guest mikelmg]

My new Superspec keeps dumping its coolant. After a few short journeys during which I left a trail of coolant back to the house, I conducted a few tests:

 

As the engine warms up all is OK until the water temp reaches about 90 deg C. Then a constant trickle of coolant is dumped from the header tank pressure overflow (I know it is the overflow because I have re-routed the drain pipe over the side of the car).

 

At about 100 deg C the electric fan kicks in and the flow of coolant through the overflow stops.

 

The fan stops as the temp drops below about 90 deg C. All is OK until the temp rises again and about 95 deg the overflow starts again - until the fan kicks in, when the overflow stops. Pattern continues (until, presumably, it runs out of coolant!).

 

I have checked all the pipes, clips and unions and there are no other leaks.

The system seems to be working as all the various bits heat up in sequence as the coolant flows around.

I have bled the system, so no airlocks.

 

I have fitted a 15 psi pressure cap (the same thing was happening with a 13 psi cap, but I thought a change would solve the problem).

I am using Halfords 50% antifreeze.

 

I thought I might have overfilled the header reservoir, but there appears to be no improvement as the level of fluid drops.

 

Any thoughts out there as to what might be happening?

 

I hope someone can help as I am only able to drive the car in and out of the garage at the moment!!

Edited May 15, 2009 by mikel

[Redspec]

Hi

 

What engine are you running.

 

Steve

[Longboarder]

I'm assuming it is not actually boiling which is one cause of water loss.

Draw the system on a sheet of paper with all the pipes, rad, engine, headers, bottles etc and a rough layout of the relative heights of the various bits. You can then track what flows where. Knowing air rises to the top of whatever it's in and can't drop down to flow to the next place so stays there you can see where air might sit. Use this diagram to check design of the system

Air expands a lot when hot. Water expands much less. Trapped air will blow out lots of water. A full system will blow out some, perhaps half a pint so it needs half a pint of space to expand into if all works as it should.Fresh water will contain some air which will 'boil out' when hot to make a new airlock.

One of the best ways of bleeding the system is to run the engine on the drive with the car level, rad cap or header cap off till it nearly boils and let it cycle through several fan cycles. Stand by with watering can and just keep topping up the tank. Should become stable after a while. Refit cap and let it cool. Where the water is in the header is now the max line for water. If a little below that line then there should be no water loss when it gets hot. If above you will always blow some out.

If design is good and you have established a max fill line, don't overfill but it still keeps happening then you may have a head gasket leak allowing combustion gas to be blown into the cooling system, displacing water.

 

Nigel

[TonySuperSpec]

If its a Rover I had the problem and it was the themostat

 

Took it out pressure was much lower and I managed to bleed correctly and then all was well

[Guest mikelmg]

Hi

 

What engine are you running.

 

Steve

 

Steve,

 

It's the Rover T series 2 ltr non-Turbo

[Redspec]

Hi

 

As you say new superspec is this problem new as well?

 

It could be a case of wrong plumbing as i belive the instructions on the kit were wrong in the first place here is a post of a thread and I can say my car runs with no problems now (I got the car from stan)

 

HTH

 

http://community.rhocar.org/index.php?show...mp;#entry114998

 

Steve

[Guest Nigel Novice]

There was an issue with Rover cylinder head gaskets for no apparent reason giving up at around 60000 miles, not sure which engine it was but an ex work mate had it happen on his 75, try and get a check done on the coolant for signs of head blowing

[Guest mikelmg]

The problem now seems to be cured - fingers crossed.

I fitted a 20psi rad cap, which seems to have prevented the fluid from dumping as the temperature rises, and also seems to have lowered the operating temp - now 80-90 deg, rather than 95-100.

During a run of about 20 miles covering town and motorway and with an outside temp of about 22 deg, all was watertight and dry.

 

Deep joy!

[Redspec]

Great news I hope you have many more DRY miles

 

Steve