TR3a overheating

[Wsl]

Just thought I would share a few tips on ways to prevent overheat on these cars. 

I have a 1960 TR3a, and despite an engine rebuild, rad flush etc, after 5 min in heavy traffic the engine  would seriously overheat. The temptation of course would be to fit an electric fan. But this is how I solved the problem.

It is essential that  all the water ways in the head, and especially the block are completely free from sludge, and corrosion. A very messy way of doing a partly successful job is to remove the head, fit liner retainers, and put a pressure washer down the the waterways and blast away! Don’t forget to open the block drain tap.

new thermostat housings.

fit a new an original style brass bellows thermostat (with the brass sleeve). This makes sure that the bypass system is cut off when engine is warm). Otherwise the water will keep circulating around the engine and not the radiator.

radiator - new core, or new radiator, without starting handle hole. Flushing dose not work.

fan - old tin fan, remove and fit blue plastic TR6 fan.

fit the ducting kit in the apron.

I have also fitted a TR4 catch tank for any surplus coolant pushed out, and can be used again. Also when topping the rad up note that the ‘neck’ of the radiator in these cars is used as an expansion tank, so only top up to the point where you can just see the coolant, any more and it will just be expanded out.

One final point that I have only recently noticed, the radiator cap (4lbs) . Make sure that the rubber washer ‘ bottoms out’. Some replacements appear to use a very thin rubber washer, whereas the originals use a thicker one. This will prevent the system from being pressurised, and will lead to loss of coolant.

Now use 100% coolant - no water. I use Ford Superplus, but there are others on the market. To prove the value of this just at look at the photos of my liners on page 2 of my ‘figure of 8 gasket’ post, that I have just removed after 26 years use, without any corrosion or sludge build up.

my car now never overheats, and will tick over all day long without any overheating problems; and I don’t have an electric fan.

John Roberts

 

 

[Lebro]

50% water, 50% ethalene glycol antifreeze works well, (change every 2 years) used that in my engine since 2013, coolant always comes out same colour as when I put it in.

I agree about re-coring the rad with no starting handle hole, I use electric fan only, & bellows thermostat with sleeve. Only goes above normal temp when stationary, & drops down when the fan kicks in.

Bob

Edited August 25, 2023 by Lebro

[RobH]

16 minutes ago, Wsl said:

Now use 100% coolant - no water. I use Ford Superplus,

Bad idea, that stuff is not suitable for classic cars, it is formulated for modern ones. It is OAT (organic acid technology) incompatible with  brass and solder radiators and other materials used in classics.  Our cars need a silicate-based antifreeze. 

 

 

Edited August 25, 2023 by RobH

[Deggers]

23 minutes ago, Lebro said:

50% water, 50% ethalene glycol antifreeze works well . . .

Hi Bob, any particular brand you favour over another? 

[Wsl]

Hi robh

interesting, I have been using this coolant in my TR3a, and my every day car a 1970 MGBGT for 26 years with no ill effect at all, I agree that the most efficient mix for cooling effectiveness is actually 50/50. But being ‘ old school’ corrosion has been a the bane of my life ( not quite, but you know what I mean - women come a close second sometimes ).

look at the photos, and you will see the absolute immaculate condition of the liners after 25 years. The theoretical stuff is OK, but it’s not always how it pans - out in real life situations. Thanks but I’ll stick with what I know works in real world.

These were only a few tips help anyone withe TR cooling issues.

regards John Roberts

 

[RobH]

59 minutes ago, Wsl said:

I agree that the most efficient mix for cooling effectiveness is actually 50/50.

Actually the best for cooling is 100% water, since water has the best specific heat capacity, about twice as good as pure glycol.  Not very practical though as you need some corrosion inhibitors and antifreeze properties. 

50/50 mix has about 0.8 of the cooling property of water but has about 2.8 times the dynamic viscosity meaning it doesn't flow as well so is worse at shifting heat.  (100% glycol is 15 times worse for flow so is much poorer at shifting heat).  50/50 is probably the sweet spot though between cooling/anti-corrosion/antifreeze properties. 

I'm not doubting what your experience is John - but "ye cannae change the laws of physics". 

 

It's worth remembering. that the cooling system is designed to stabilise the temperature of the coolant only and that the temperature gauge only reads the coolant not the engine itself.  How much heat is removed from the engine depends on the properties of the coolant.   That means that a poor coolant will sit at the right temperature as determined by the thermostat and shown by the temp gauge, but the engine may actually be much hotter than it would be with pure water because less heat is being removed in total.    

 

Edited August 25, 2023 by RobH