SS100 Overheating

[NATONEIL]

Ladies and Gentlemen
I note that Ray and Malcolm have been discussing over heating in another thread and because I had also suffered from this in the past I thought I would share my thoughts.
The principle problem is that the "as designed" heat sensor sits at the top of the radiator, where it needs to be, and if you have lost water because of overheating then the sensor becomes uncovered and no longer switches the electric fan on. A 4.2 ltr XK engine goes through a series of heat fluctuations over the course of a drive and it is not uncommon for the water level to drop to a level below which the sensor can control the fan.
I fitted an override to the electric fan, (moving the overdrive pull switch to a position where I could use it without taking my hands off the wheel and putting the override pull switch in the original O/D switch hole.) and considered fitting a tall expansion tank to the left of the radiator as sold by "Pop Browns".
I have still not fitted the expansion tank because a practical mechanic, now sadly deceased, suggested that I fit a temperature sensor with a better operating range. I now have one which comes on at 85C and goes off at 75C. This was simple, cheap and effective and is worth trying first.

[Brunel100]

Neil
Some very good points. I will follow your suggestion of changing the sensor but I’m sure there must be a Suffolk out there which has been fitted with an expansion tank. It would be great to get feed back from those owners and how successful the mod has been

[NATONEIL]

The Pop Browns stainless steel tank would fit and work, of that I have no doubt. The Pop Browns on-line catalogue is not easy to use, you will find the tank I have looked at in their radiators section.

[lowebird]

Neil,
Just before you hit the bottle ( it is New Years Eve ) what is this Pop Brown you refer to? I hope you have a Happy and not too peaceful New Year and we look forward to meeting up somewhere, some time.

[MalcolmB]

Interesting ideas and the change of switch seems simple enough. I just think that as cars evolved with pressurized cooling it is no bad thing to keep more of the coolant in the system. I am still at the design stage but I think I can fit a rectangular alloy XP tank above the alternator. It may need to be cut down and rewelded so I am playing with a cardboard replica to start. (apologies to Spike Milligan!)
Cheers Malcolm

[NATONEIL]

Hi Reg

Pop Browns is a Street Car parts supplier who supply parts for many of the custom car/hot rod enthusiasts in Norfolk/Lincolnshire. They are a well established and trusted company. With the hot rod crowd requiring form and function Pop Browns are a good source of well designed but unusual parts. The website is popbrown.co.uk. The radiator on your C type has a large capacity header but you will recall that the radiator on the SS is narrow. A Pop Browns overflow tank is a small diameter tank which is mounted vertically and could be easily attached to the radiator hoop. Although I have not fitted one, if I ever do any European summer touring, I might splash out the £50 to buy and install one.

[Brunel100]

Gents
The same expansion tank is on Ratsport.com where there is rather more detail and prices. I contacted Pop Browns re details and prices but no reply as yet. I’m planning to go ahead with the 15” version fitted to the offside radiator hoop where there is more room.

[NATONEIL]

Ray
I have never heard of Ratsport but the website is impressive, so I will add it to my car bits database. Thank you

[lowebird]

Thanks Neil. When fitted, does the system allow for the overflow to be drawn back in somehow? If not, it sounds just like my overflow bottle that I fitted to my hot Escort a lifetime ago, it was an empty Fairy Liquid bottle !!

[NATONEIL]

yes I think it does, as the radiator cools it draws a slight vacuum and sucks the water back in

[Brunel100]

The expansion tank has two pipes on the base. One is to take the overflowing coolant when the main spring in the cap comes under pressure, about 15 psi +. When the engine cools and because it’s a closed system the fluid in the expansion tank is syphoned back through a secondary sprung valve in the cap to restore the volume in the system.
This is why the connection pipe must be strong enough to take the suction pressure and not collapse. The other pipe is merely an overflow if the volume of the expansion tank is exceeded.

[Brunel100]

A quick follow up on the stainless steel expansion tanks being discussed, I’ve ordered mine from Pop Browns as they were almost half the cost of Ratsport.com Over £35 cheaper.

[Brunel100]

I’ve now done 500 miles without any issues. Only recently has weather been hot enough to cause problems previously encountered but no water has needed to be added every time I’ve checked. Hearside of Engine did not offer enough room so I ran the overflow pipe through a tubular carrier on the chassis cross member.
Regards
Ray Mason

[Brunel100]

I seem to have managed to lose the photo or the expansion tank I’ve fitted which would make rather more sense of the script. Watch this space!,

[Brunel100]