Tuesday, May 8, 2012

Coolant Leak Shuts Down Car

One failing on these cars is the crappy heater control valve on the side of the engine.  Mine was very corroded internally before, so I cleaned it up before reinstalling.  Now, it leaks coolant in steady small stream as I am driving.  Unfortunately, the location of the valve puts it right above the distributor, so the coolant leaks onto the distributor cap.  Distributor caps do not like to get wet - the car starts running rough or dies altogether.  On my last trip downtown and back, I had to keep restarting it with the clutch since it would die at random intervals!

To address this, I am cutting off the valve and making one out of standard plumbing.  You lose the adjustability from the cockpit, but that never worked well anyway.  In fact, I have the heater core itself isolated from the system, since that was leaking coolant onto my feet in the past, and the core needs to be replaced or repaired.  Since I am not driving the car in the winter, it hasn't been a priority.

See this site for a description of the fix I am doing.  I'll post my own pics as well.


At least I am not alone in this - it seems the heater valve on MGA's and MGB's is a problem - or at least the modern replacment valves are a problem.  My first one lasted over 50 years, so it's hard to say that it was really that terrible.  The new ones apparently leak out of the box.


  1. Sounds like you had a serious car situation there! But I think you were able to manage the repairs on your own. The cooling system is one of the most important parts of your vehicle, along with the heating system. Coolant leaks can lead to vehicle overheating. Better give it some love and attention before it leads to a more serious car trouble. [Michelina Douglass]

  2. The coolant system of a car has various components, so identifying the leaking part is the first thing to do. It can be on the water pump, shaft seal, radiator or in the heater cores, and freeze plugs. And, don't forget to check the engine itself. You can have it fixed by temporary means, or better yet to think for the long-time solution. :)


  3. How’s the car? It’s good that you’ve fixed the problem, but you might want to find a more permanent solution to it. Better yet, get an expert to look at it and have it fixed. Yes, it would cost you, but you can enjoy some peace of mind knowing it won’t break down on you anytime soon.

    @Tyra Shortino