coolant level check

[auto_cran]

What's the proper/best way to check the coolant level? By the overflow tank or by removing the plug on top of the thermostat housing?

With a cold engine, should I see any coolant when I remove the plug at the top of the thermostat housing?

Chris

[Workshop Help]

Given your year model TR7 has the early thermostat housing, note the filler plug is to be used only for initial filling of the cooling system. Periodic monitoring of the coolant level is by observing the overflow bottle or the overflow metal tank and adding coolant as needed.

We good folk with the later thermostat housing can still fill our systems by removing the housing and pouring coolant thru the thermostat hole. Once the system is filled to the brim, reinstall the thermostat and housing. Run the engine to operating temperature with the heater on then shut the engine off. When cool, check the level in the metal overflow tank and add coolant as needed.

Mildred Hargis

[auto_cran]

Thank you Mildred.

After refilling and burping the system last week (all through the thermostat housing), today I removed the plug and was surprised that I could see the top of the thermostat and no coolant.

But the overflow bottle is 3/4 full.

Good?

Chris

[FI Spyder]

When the engine coolant cools it contracts creating a vacuum and it should suck the coolant from the bottle into the engine to keep it full. When it didn't there was a lot of overheated engines and warped heads. If it doesn't I would suspect an air leak in the hose or where it connects to the bottle.

They went a long way to solving this problem with the brass tank that was mounted up high. Of course if you have a water leak and don't keep the tank at proper level, that doesn't do you any good either.

- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

[Workshop Help]

As mentioned, the filler plug is only for initial system filling. Once this is done, leave it alone. Add coolant to the overflow bottle/tank.

Here's a shortcut. Since we're dealing with a closed system, use the ol' squeeze trick to confirm it's integrity. Give the top radiator hose a squeeze just after the engine is shut down. File away in the inner recesses of your brain how the hose feels, firm, much like your flexed bicep. This is due to the expanded pressure from the hot coolant. As the engine cools, this pressure will gradually diminish in the hose but not completely. The next morning, again feel the top hose and remember how it now feels.

With these two information tidbits rattling around in your gourd, you will have a gauge to determine the state of the union there in your garage.

Mildred Hargis

[Hasbeen]

I fitted the radiator overflow tank, [about one liter plastic rectangular bottle] from one of our Toyota Cressidas in the 7. It is a near perfect fit in the gap beside the radiator.

The overflow from the header tank is plumed into that, & a 14Lb rebreathing radiator cap is fitted. Rather than sit about 2" down in the header tank, even when the system was working perfectly, it now is only 3/4" down after cooling.

Even with the air con working flat out on our over 100 days, the gauge never gets above quarter, which id 88C at the thermostat housing.

Hasbeen

[dmtrmp6]

G'day all

I have a similar install to Hasbeen, but with plastic overflow tank from Mitsubishi sigma/gallant (mid 80s). Overflow from metal header tank plumbed into the plastic overflow tank with two way/rebreather fitted on original metal header tank. Rarely/never need to top up and no longer get the overflow discharge on road after top up/initial start. Heated excess flows from metal header tank to the plastic overflow and drawn back into the header tank when cool. Need to ensure the outlet end of overflow flow hose from the metal header tank remains below fluid level in the plastic overflow tank, initial fill in overflow tank of 75 mm/3 inches. Level in overflow tank rises and falls as coolant moves between header tank and overflow tank as engine heats and cools. The two way/rebreather cap has 2 concentric valves in the seal area - larger/outer opens under pressure (like conventional radiator cap) , smaller/inner opens under vacuum hence two way flow. Rgds, Daryl M.

[DutchTriumph]

A while ago I got some parts, and this was in the box. The plug on top of the thermostat housing is replaced with an airblead from a central heating system.



This one was useless, but I liked the idea. It fits perfectly and it seems to work!
When first started after installation nothing came out, but when the engine warmed up first came the air out followed by some coolant.

Just need an extra small key in the toolbox



Cheers,
Peter

1977 TR7 FHC, 1976 Spitfire 1500