Expansion Cap Replacement?

[King Fisher]

Nick's spring loaded expansion cap has become a three piece unit, with the sprint seperating from the rubber plug, and from the top part that holds it to the top of the swirl tank. Anyone know where to get a nice shiny new one?

[Gerald-TVR]

On the swirl pot? are you sure thats the correct place for it? how about the expansion tank
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Seriously possibly Halfords FC53 (I think) or TVR CarParts

[techbotics]

I got a matching pair in Stainless Steel from a classic car seller on eBay

lovely

cheers D

[greymrj]

The Alternative Parts List gives the following information:

Radiator Pressure cap (swirl tank). 025K 005A

UnipaRT grc 1110
Quinton Hazell FC53 15IBS

Halfords or any reputable motor factor should be able to match to one or the other of those numbers. Both the Steve Heath 'bible' and the parts list put the pressure cap on the swirl pot not the expansion tank........although I know there has ben lots of debate on this one!

[techbotics]

Oh no he went there... I prefer mine on the expansion tank

[Gerald-TVR]

techbotics said:

Oh no he went there... I prefer mine on the expansion tank

Me too - Where's Mark

[jimed]

Can of worms here again - I put the pressure cap on the swirl pot on the S3C and had no problems - main reasons being that is what it was originally supplied as (also Steve Heath's book) and a concern that the expansion tank isn't really designed to take pressure ....
Jim

[techbotics]

All good and sensible reasons.

How much water is in your swirl pot? I found it kept dropping so now use gravity to fill it the water level is easy to monitor from the expansion tank.

If the system is working propperly either way should work. I find this way around more reliable with regard to keeping the swirl pot level where it should be.

Cheers Damian S3

[mep12345]

Gerald-TVR said:

Me too - Where's Mark

Ignoring you all

[Gerald-TVR]

mep12345 said:

Gerald-TVR said:

Me too - Where's Mark

Ignoring you all

Te He

[King Fisher]

Pressure will escape from any place it can, and looking at the system on the S, the pipe from the swirl pot goes to the expansion tank, so even if you did mix the caps up, it doesn't really matter. However, it is meant to go on the swirl pot, Nick's spoken to a few people on this and they all confirmed it (if you read the Steve Heath Bible Mk2, it states TVR released a press release stating the owners handbook was wrong, and that the cap is supposed to be on the swirl pot).

Also, a mini cap looks suspiciously like the correct fitting for the top of that swirl pot....?

[techbotics]

Where ever you put it the blanking caps are usually known as 0lbs.. should be infinity lbs IMHO..

Anyhow I went for one of these :

eBay 0lbs SS cap

and one of these for the expansion tank lol..

eBay 15lbs cap

I like my shiny bits..

Oh and this is the TVR notification..



I think it was because some early expansion tanks were not designed to take pressure. Its the refilling bit using the vacume that seems unreliable or to require a special cap in the swirl pot.. on my car gravity works better.

Thanks

Damian S3

[v8s4me]

If the pressure cap is fitted to the swirl tank won’t it act as a non-return valve and stop expanded and pressurised coolant being sucked back in to the system when it’s cooling down?

[phillpot]

v8s4me said:

If the pressure cap is fitted to the swirl tank won’t it act as a non-return valve and stop expanded and pressurised coolant being sucked back in to the system when it’s cooling down?

Not if you have the correct cap which has a one-way valve arrangement (mentioned in the service bulletin above) in the centre that opens under suction/vacuum.

never really understood why, if the system blows "x" amount of water out when it gets hot then sucks it back in when cool, why not just leave "x" amount of water out?

[v8s4me]

phillpot said:

Not if you have the correct cap .....

Ah...I suppose that's the point isn't it. How many cars still have the "right" cap fitted? If you're not sure, or sure you don't have the "right" cap, then wouldn't it be better to have it on the expansion tank?

[King Fisher]

techbotics said:

Where ever you put it the blanking caps are usually known as 0lbs.. should be infinity lbs IMHO..

Anyhow I went for one of these :

eBay 0lbs SS cap

and one of these for the expansion tank lol..

eBay 15lbs cap

I like my shiny bits..

Oh and this is the TVR notification..



I think it was because some early expansion tanks were not designed to take pressure. Its the refilling bit using the vacume that seems unreliable or to require a special cap in the swirl pot.. on my car gravity works better.

Thanks

Damian S3

Hi Damian, excellent thanks for that! Will Halfords stock one of these items?

[dutydog]

techboltics how did you get your cap to seal on the swirl pot?

[Top Gear TVR]

I HAVE SOLVED THE CAP HERE, CAP THERE MYSTERY!

So in answer to the question;

Should the pressure cap be on the Header Tank OR the Swirl Pot, then the correct answer is in fact YES.

Only when asked should it be on the plastic expansion tank should the answer actually be NO.

I feel like YODA now.

I think the issue is in the language because the notice below has re-named the Swirl Pot a Header tank!!!

[DamianS3]

dutydog said:

techboltics how did you get your cap to seal on the swirl pot?

I gave up had the swirlpot sealed and left pressure cap on expansion tank worked well but made filling up a pita but you can get a filler that goes inline to rad top hose if you wanted that said once full I had no more problems. Will post pics later now I have a different engine it's available ss £50 + post and packing..

Cheers

Damian S3 (aka techbotics)