Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Radiator sealants

Hi, preparing our 1973 +8 for the winter here in Scandinavia, I'm about to change the radiator anti-freeze coolant (yes, suitable for aluminium engines). By adding more of this stuff to protect down to some - 30 C, there is an enhanced risk of leaks. We have encountered leaks before, mainly at the bottom hose connection to the radiator. Currently I'm using two clips, which kind of cured the problem. Question is now if we should use a Radiator Sealant /Stop leak additive to prevent leaks? Would there be anything that talks against this? And is it a permanent fix? Thanks for your views and advise. Cheers /Finn

I would advise against using sealants which could gum up some critical part.

When using two hose clips ensure the screw adjusters are 180° apart or nearly so.

Use a refractometer to measure actual freezing temperature of your coolant once circulated around engine. The one linked also measures battery electrolyte specific gravity.

K seal is the only one I recommend and use in the race cars
Getting a pinhole leak from track debris can really spoil your weekend

K seal stays liquid in the cooling system- until it finds a hole then it seals it
I know Lister Storm LeMans car qualified for the 24hr race using K seal to seal up a failing head gasket- which is a good enough recommendation for me!

Another vote for K Seal too, all the breakdown callout lads who know their stuff carry it

+ yet another vote for K-seal

After a boil up in the queue for the Blackwall Tunnel one evening (almost 4 hours to do 1/2 mile!) I asked around what precautions to take before taking the car to Techniques for a proper inspection, and they recommended K-Seal very strongly.

Like Simon they use it in all their race prepared cars just as a precaution.

I take Richard's point about it being better without, but more modern formulations have largely ameliorated that one.

I experienced a weeping gasket between the timing chain cover and the engine block but only after the engine cooled down. A TM expert recommend K-seal which did the trick and that was four years ago.

Both hoses have been changed to original OEM and the clamps have been changed to stainless solid types, not the flimsy wire type clamps. In the bottom I've installed 2 clamps. We didn't have a puddle of coolant under the car, but merely traces. The problem turned out not to be the radiator itself or the drain tap, but stems from the lower radiator spout not being 100% round any longer. As I've learned that cooling system sealant is used even on new cars, I have no problem using it. Just happy the problem has been solved. Thanks for your advise and inputs. Cheers