MK2 Coolant Expansion tank!

Any one fitted one , I see a kit on e-bay , was about £115 , it’s only a tank and a bit of hose !

We all know hot water expands , on the MK2 jag’s , it’s got nowhere to go , would be nice to have the rad full all the time :thinking:

Hi My car is fitted with an E type expansion tank attached to the heater box and this not only keeps the rad full but helps with the water level in the heater. Been on for years, normal cap on rad and 7 lb cap on expansion tank. I think some Leyland cars have this tank also. I would send a photo but I dont know how on this site Cheers Brian

Austin, MG, Rover… there is a plastic version too. MG I think. Standard BMC parts bin.

Hi Brian, 7th icon from the left upward facing arrow, click on this and then follow the prompts.

Without an external expansion tank the rad is full when the water is at operating temperature.

Robin_O_Connor
https://forums.jag-lovers.com/u/robin_o_connor Robin
O’Connor Regular
December 19
Hi Brian, 7th icon from the left upward facing arrow, click on this and
then follow the prompts.

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In Reply To
jaguarbrian
https://forums.jag-lovers.com/u/jaguarbrian brian loftus
December 19
Hi My car is fitted with an E type expansion tank attached to the
heater box and this not only keeps the rad full but helps with the water
level in the heater. Been on for years, normal cap on rad and 7 lb cap
on expansion tank. I think some Leyland cars have this tank also. I
would send a photo bu…

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https://forums.jag-lovers.com/t/mk2-coolant-explanation-tank/399675/4
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Thanks Robin I think I may have sent the photo
Are you in Oz ? I worked on my friends car in Sydney

Nope NZ, enjoying the weather and Pravda racing. See the flag?

Yes, that is what I fitted to my 3.8S decades ago. You have a spring pressure relief cap on the expansion tank and a flat cap on the radiator to make the system work properly.

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I have a plastic overflow on my car, without a pressurized cap. The coolant fills up when the engine is hot and then draws it back in, works flawlessly. It was a generic piece from summit racing I believe, I will add a picture tomorrow.

I have a brass one that shape for my ‘66 ‘S’ as well

Thanks for the feed back , look’s like another mod to do ,
So I am right in saying the tank don’t have to be higher then the rad ?
Like the look of your set up john_Quilter :thinking:

Hi Robin Sorry mistook the flag Sadly only visited once to Rotorua and had to see the hot springs and swim in the hot waters there Hired a car and got addicted to Marlborough wines most nights
Privileged

to meet your rugby team when they won the cup in 2015
Sonny Bill is huge!!

I do not have an expansion tank but I made an overflow tank from a beer can :slight_smile:
If you fill Mk2 radiator full, it pukes little bit out after driving. Annoying if that happens to your
garage floor or somebody’s driveway. So this overflow tank holds the puke.
See my overflow beer can at;


Köpi

I have a bypass pipe going to the neck of the rad , the inlet is below the pressure cap !
If I put a T connector on there , and run a hose too a expansion tank , anyone see a problem with it :thinking:!
Will a 800ml (1.4 pints) tank be big enough ?

126107002_418745019508395_696656978431023437_n s-l1600 (5)

No the expansion tank does not have to be higher than the radiator. It never was with this basic system as used on MGBs, MG1100s, and Austin Americas etc. When the engine and radiator cool down a small vacuum is developed and it sucks the overflow coolant back into the radiator. You do need the flat cap on the radiator however.

Mine works with the pressurized cap on the radiator. The overflow hose is between the plunger and the cap. I believe the way it works is, as the coolant expands, it pushes the plunger up and overflows into the hose, which runs to the BOTTOM of the expansion tank. As it cools, the plunger closes, but there’s a one way valve that allows it to suck the coolant back in. I didn’t quite believe it at first but the tank fills and empties consistently. And the tank itself has a cap on it but its not sealed tightly.

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Flat cap ? do you mean the one that’s not got a spring , ie the pressure cap ?
As my bypass hose is just like a small top hose , I would have thought it can all stay as it is , like I said , just add a T , with a hose going to the tank , water could travel in and out of tank at will :thinking:

What you have should work fine since you added an extra tube to the neck below the spring cap. Most radiators do not have that feature.

No , it was on the 240/340 Radiators , looking for a tank now !