Expansion tank

stina

stina

New Member
Hi guys
Any ideas on fitting an expansion tank to my rad ? Is it a good idea , how many of you have done it , ( a picture would be great ) what tank do i need ? I plan on uprating the rad when the cash is flowing a little freer ! Thought this would be a worth while little project in the mean time . No panic don't have a temp issue ( now i've done it ! ) Just thinking future reliability . Heard the SD1 tank has been used by some . Any ideas where to find one ? ( don't say on a SD1 )
Cheers stina
 
Stina,
one of my cars had one fitted when i bought it, it is from an SD1, and I also got one with another car i bough but haven't fitted it yet.
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Alot of the people I've spoken to swear by this addition. Car has never overheated, usually sits around 1/2 ways up the guage.
Regards,
Dave
 
As I have mentioned on other threads in the past, it's not so much an overheating issue but a cost issue in that you need to refill with anti freeze all the time to preserve your ethylene glycol concentration in the Radiator if you are of the persuasion to fill the radiator to the neck all the time.

graeme
 
Yep, excellent plan. Probably the first technical mod we all do to them! Means your cooling system becomes fill and forget, instead of having to top it up every time you go out. There's the even more desirable brass version of this tank on Ebay at the moment:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=120704138032&ssPageName=STRK:MEWAX:IT

The plastic version would be much cheaper. But just think of the possibilities - " I'm just going to polish the brass dear"

Chris
 
Im pretty sure the series Land Rovers had a painted brass header tank at some stage
 
Hi guys .
As ever thanks for advice and the pictures . Anyone know what pressure the caps need to be ? Am guessing the tank needs to be higher than the rad ? Also anyone out there got one to sell ?
Cheers stina
 
Expansion tanks and breather tanks are slightly different. With an expansion tank the original rad cap is retained and the tank is there to accommodate surplus water from the system (and is designed to drain back once the coolant cools off), i.e. the expansion tank does not form part of the pressurised system.

The breather tank has a dual function in that it is part of the pressurised cooling system and used to bleed air from the system (hence the change of the rad cap to a blank). Most important to ensure the breather tank cap is mounted at the highest point on the cooling system to operate efficiently and prevent air locks.
 
I agree on the two different functioms, but I've always used the terminology the other way round!

Whichever terminonology you prefer, what you require on a P5B is a blank cap on the radiator and a pressure relief cap on the auxilliary tank.

Chris
 
Just the ticket, and yes, your standard rad cap will fit. In fact this looks suspicially like the SD1 tank. I wonder if this is a BL parts bin phenomen and they just picked the nearest to right for the MG?

Chris
 
Hi Chris
Yeah i wondered the same . Their are also a couple on there for a midget that look the same . If i'm not lucky with that one it should be easy to track down an MG part .
Cheers stina
 
chrisyork said:
Yep, excellent plan. Probably the first technical mod we all do to them! Means your cooling system becomes fill and forget, instead of having to top it up every time you go out. There's the even more desirable brass version of this tank on Ebay at the moment:
Click to expand...

I've been pondering this...

I've not got an expansion tank on my 3500, but I've not needed to adjust the fluid level (other than the coolant changes when necessary). Why do you suggest that without one it requires regular topping up?

The car came with an expansion tank in amongst all the spares, is there any reason I shouldn't fit it?

:)
 
Tofufi wrote,...
I've been pondering this...

I've not got an expansion tank on my 3500, but I've not needed to adjust the fluid level (other than the coolant changes when necessary). Why do you suggest that without one it requires regular topping up?

The car came with an expansion tank in amongst all the spares, is there any reason I shouldn't fit it?
Click to expand...

Hello Tofufi,

First off a question if I may,..how many miles would you drive per year and how often do you change your coolant?

Now from my observations and from what I have been reading on the forum, the P6B engines seem to have a propensity to shed coolant via the radiator overflow. Now I don't know if this applies to all compression ratios equally or rather one more than the others. My original 10.5 : 1 CR engine always required topping up in terms of coolant, probably every few weeks and more so in hot weather.

Why would this be? Well assuming that the radiator cap is in good working order and sealing as it should, and no head gasket problems are evident, then all I can suggest is due to the added temperature inside the heads from the higher compression ratios, this exacerbates the coolant loss problem.

To add credance to my thoughts is that my original engine behaved in this manner both with the original tin head gaskets and later with composite gaskets. There was however a marked increase in coolant loss during the period prior to the original tin gasket's replacement owing to their failure. There was no coolant loss from hose leaks or elsewhere.

Now the decider for me,...my new 4.6 does not use coolant at all!! Once the system is filled that is it, no topping up is required. When I check it 12,000 miles (20,000km) or 12 months on average later, the level is where it was set...right at the bottom of the filler neck with the engine off and cold, dropping by 2cm or so with the engine running, which is what it is supposed to do. If I add coolant above this it will displace the addition, and then settle as indicated.

So for my original engine an expansion tank would have been useful, but for my 4.6, it would be redundant.


Ron.
 
Very curious. I've not previously come across a V8 that didn't suffer from this problem - now two come along at once! All the engines I've met before would gradually lower the level in the rad until it was around 1 1/2 inches below the top of the cores, then stick there. That would be over the course of under a week of daily use. But of course that is wasting valuable radiator capacity, so the incentive is to fill up, then the process repeats.

I wonder if this is connected to the freedom of water circulation through the inlet manifold? We've discussed at length the propensity of the carburettor tower coolant bleed to block. And I know Tofufi has a 4 barrel carb on his. Perhaps we have just discovered a key link to the controversial fuel vaporisation issue? I can't tell you how Lucky performs, because I simply assumed it would behave as my experience and fitted an expansion tank before finding out.

This is one for some comment from Harvey - is there a link between V8 radiators that don't need topping and engines that don't suffer vaporisation?

Chris
 
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