MGF 1.8 soft top radiator

[mac391]

Hi all,,
hope you can help here !!

THE PROBLEM..
My beloved 1996 MGF 2 seater is losing coolant faily quickly. If i top up the expansion tank, it will empty and start to overheat within a 5/6 mile drive. Yes i have pulled over and let it cool before topping up again and it has never overheated to the point of RED. I Have let it run idle on the drive and looked underneath for signs of water loss, nothing at all. I did notice though that the carpets on drivers side footwell and under the seat were soaking wet !!
I have traced all the coolant pipework underneath the car from engine bay to rad and its all visible with no obvious leaks eccept for underneath the driver and passanger seat there is a protective plate that the pipework is covered by so i can't see.
The radiator is in immaculate condition aswell.

One strange thing is, if i top the coolant tank up and let it run idle on the drive the coolant level remains the same and doesn't appear to lose any. When i drive it down the road and check, the level drops ??

WHAT I HAVE DONE..
I have removed the coolant cap and watched it as the car runs idle and can see it seems to be circulating fine.
Been online and just discovered there are 4 bleed nipples to the system, i released the one on the radiator and water came out (whilst engine running) so I assume nothing is blocked and no air is in the system. it got dark to check the other 3 though.

I'm completely mystified ?
Any ideas anyone ??

I'm no mechanic but got a general idea on things.. Sorry for the long post btw..

Thanks for looking,, Andy

 

[Burnerman]

The K series engine is absolutely notorious for cylinder head gasket failure, so do get this checked out first.
A competent garage will take a sample of the air above the coolant in the expansion bottle, and they will bubble this air through a blue liquid. If the liquid turns yellow it is detecting products of combustion i.e head gasket failure.
This is known as the 'sniff' test.
John

 

[Peter.N.]

...it could be also that the pressure in the cooling system due to a failed gasket has made the heater matrix leak, hence the water in the car.

Peter

 

[mac391]

Thanks Burnerman & Peter N

I was realy hoping for a leaky rad !! I've read a lot about HGF problems so looks like the garage it is..

Thanks again guys..

 

[Mursal]

Would usually bypass the heater if its leaking, using a joiner pipe.

This will allow you to see if the engine coolant system is OK (ie head gasket)
without spending a fortune on the heater matrix (radiator) only to find more
engine trouble.

As the car is getting older keep a close eye on costs as this type of
complaint can be very expensive in terms of labour costs to put right.

MGF not the easiest car in the world to work on