View Full Version : Losing Coolant

09-06-2006, 10:59 AM
Hey Gang,
Yesterday I noticed that my '73 TR6 was leaking coolant. I haven't looked closely at it as yet, but at first glance the fluid appears to be streaming from the rear of the engine where the transmission meets. I remember that the Roadster catalog mentions that if your water heater valve goes bad, you will loose your coolant. Would anyone know if this is true and could I be having that problem. Like I mentioned, I haven't been underneath as yet, but the hoses and water pump appear dry. Has anyone ever had a freeze plug come out the rear of the engine, I hope that isn't the case.
Thanks for taking a look,

09-06-2006, 11:11 AM
My heater valve is a source of coolant leakage. I think I just need to replace it. But if that's the case with your car, it should be visible with the hood up and engine running.

09-06-2006, 11:26 AM
The leak is a steady stream at idle. Would the heater valve release that kind of leaking to puddle up under the car. I will check it before the weekend. As for now, I'm just trying to get some ideas on some trouble spots that other owners may have experienced.

09-06-2006, 01:46 PM
Opition #1
If you have a "Frost Plug" failure, simply install a Block Heater. These are directly installed in the frost plug locations (usually one per engine) I saw a plug blow on an old Valiant years ago and this is how it was fixed.
We use these in the winter here in Canada to keep the blocks of our regular vehicle warm enough to start. Should be about a $25.00 item. And no you don't have to plug it in just think of it as a very effective cork

Second option:
Check the heater valve, hoses and all connections (especially by the firewall) by simply wrapping with small cotton rags. You will easily detect soggyness,if these are failure points

Geo Hahn
09-06-2006, 03:55 PM
If it is a freeze plug...

I had a freeze plug pop out the back of the head on my TR3. Rather than pull the head I repaired it with a rubber plug that had a nut & bolt and metal washers on each end... specifically made to replace freeze plugs.

You jam the rubber plug in and tighten the nut... the washers squeeze the plug (making it larger diameter) to fill the hole.

Worked fine until I had to pull the head for a valve job 20 years later.

09-07-2006, 08:36 AM
Also check the coolant return pipe that runs under the intake manifold and circulates coolant through it. If at all in doubt replace it with one of the new stainless steel replacements from TRF or Moss. See pipe here: https://www.zeni.net/trf/TR6-250GC/41.php

09-08-2006, 01:46 PM
The leaking coolant location has been found. Thanks to all of you who responded. The hose from the firewall (heater core) was defective. I'm really happy it wasn't one of the plugs at the back of the engine. I replaced both hoses and I'm back on the road once again.