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Have you a coolant expansion bottle on your TR4?


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My car's radiator overflow pipe was started to deposit a dinner plate size puddle of coolant in the garage.

 

Doesn't happen all the time, but twice within the last fortnight after a good, fast run

 

The temperature gauge is not showing that it is overheating although it is showing ever so slightly higher than normal.

 

There's plenty of correctly mixed coolant in the radiator.

 

I'm just assuming the cause is the car just having a good thrashing in high ambient temperatures and nothing too much to worry about :unsure:

 

Would there be any benefit in having an expansion bottle at the end of the overflow pipe on a TR4?

 

Regards

 

Peter

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Hi Peter ~

 

Yes, definitely, it's a very good idea to fit an expansion tank. Remember, you have to fit a plain (unpressurised)

cap to the radiator and the pressure cap to the expansion tank. The overflow pipe needs to be a reinforced

type and not a plastic pipe which can't handle the pressurised water.

If you PM me your eMail address I'll send you photo's of the set-up on my 3A.

 

Regards ~

Tom.

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Yes!

See my article in Section B19 of the Technicalities CD. Also worth perusing Section B18 for further ideas on improving cooling.

 

TR4s without the elongated section to the radiator and which have the radiator completely filled with coolant (to the seal on the cap), will always expel coolant as soon as they run because the coolant expands. One needs to leave the coolant about 1" below the cap to allow for expansion. Fitting an expansion vessel overcomes this and ensures that the radiator itself is ALWAYS completely full of coolant.

 

Ian Cornish

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I have the expansion bottle on my 3A and it allows more coolant in the radiator and works very well. I think that it came from a BMC car but I am not sure. I was worried that it was lower than the radiator cap but that does not seem to matter.

 

It is only 30 % full and expands and contracts very well.

 

Good luck

 

Richard

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Have just fitted one to my 3, but have left the normal cap on the rad, & the expansion bottle has a vent hole. idea being that when excess pressure opens the cap, if water is at the top of rad, then it will flow into bottle, & then when engine has cooled down it should be sucked back into the rad through the one way valve in the cap.

 

Seems to work.

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My TR3B had an overflow bottle when I got it in 1981, and it does again today. TR4 gear as far as I can tell. As others have reported, they work great.

 

I do not use, and do not recommend, the closed system described by Tom. (My 1988 Jeep Cherokee had one like this, and that was enough to convince me of the value of an open system like the TR. Running pressure through a plastic expansion tank in a closed system brings reliability issues that aren't worth it.)

 

The correct radiator cap, as noted by Bob, will allow the overflow bottle to fill and siphon back on cooling. My bottle is mounted on the inner wing between the radiator and the grille and is a short length of tubing away from the filler neck overflow.

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Hi Peter,

if your car has recently started to projectile vomit its coolant then something has changed to bring this on.

Have you got too much fluid in the rad - just above the vertical tubes is enough.

Has the engine developed any other subtle issues lately.

 

The expansion tank can be useful in slightly raising the level of fluid in the system. Having the tank below the rad top level; is not the right way to do it.

 

Bob - you have effectively reproduced the original overflow bottle - except you use an expansion tank instead of a plastic bottle.

 

Remember to have the end of the overflow pipe submerged in coolant in the overflow bottle at all times.

 

Roger

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Expansion tank is under the same pressure as the rest of the cooling circuit, so should be a purpose-made, metal unit, such as the Dolomite unit which I used.

Ian Cornish

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To clarify - my expansion "device" is an unpressurised plastic bottle, overflow pipe goes into the bottom of it, & there is a vent hole in the cap, next to where the OF pipe goes in.

I may do a slight mod to add a second pipe from my vent hole to below the rad. This will avoid surplus coolant being ejected into the bonnet area

(& then towards the windscreen!) if over filled. (ask me how I know)

 

Bob.

Edited by Lebro
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We have two parallel threads going. One describes an expansion tank, under system pressure. The other is an expansion bottle open to atmosphere as fitted to TR4A onwards. Which is your preference Peter?

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Pete

 

To be honest, I'm not sure.

 

I guess that I'm looking more for simplicity so the expansion bottle as fitted to the 4A is my preference so far...

 

Regards

 

Peter

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The standard cap should be "bi-directional".

It hold pressure in until the spring is overcome at 4PSI.

On cooling there is a rubber flap which opens at the slightest sign of a vacuume in the rad.

 

Bob.

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Sorry, I wasn't aware of that. It's a long time since I had a 4. My 6 and 4A had/have a separate spring loaded valve in the centre of the cap rather than a rubber flap.

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Hi Peter,

if your car has recently started to projectile vomit its coolant then something has changed to bring this on.

Have you got too much fluid in the rad - just above the vertical tubes is enough.

Has the engine developed any other subtle issues lately.

 

 

Yes, Roger, I am sure that I'd slightly overfilled which may have been the cause, but it just seems odd to me that there is nothing at the end of the overflow pipe to catch any spillage.

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Here's the open-to-atmosphere overflow bottle on my TR3Bs inner wing, showing before and after installation. This is where my car had one originally (or at least when I got it).

 

i-sgKkWNB-S.jpgi-fszqz5f-S.jpg

 

 

 

...and before anyone comments, this is the fan blade that's on there now:

i-sJggS4D-S.jpg

Edited by Don H.
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