Polar end cap - any help gratefully received.

[echo801]

Hi

I'm on my fourth polar end cap in a year, and I can't think what to do to stop it regularly splitting.

 

 

As you can see it bulges alarmingly and is very much distorted from its original shape.

I've just put this one on and I'm going to check the engine every 20 minutes.

 

I'm sooo fed up having to keep replacing it and clean up the mess in the engine bay.

 

Any help or advise anybody??

 

Engine is a 1979 Austin Rover 1800 taxi engine and the end cap is A3-783 END CAP SMALL POLAR HEAT EXCH M/FOLDS

 

Many thanks.

[Nobber]

Sounds to me like you have an over pressure problem.

(eflunts know about this sorta' fing)

Edited February 12, 2008 by Nobber

[RobinJ]

I'm on my fourth polar end cap in a year, and I can't think what to do to stop it regularly splitting.

I'm sooo fed up having to keep replacing it and clean up the mess in the engine bay.

 

Any help or advise anybody??

 

Engine is a 1979 Austin Rover 1800 taxi engine and the end cap is A3-783 END CAP SMALL POLAR HEAT EXCH M/FOLDS

Caused by expansion as the water heats up, sometimes exacerbated by air locks in the system or sludge build up in the skin tank.

Any history of overheating?

Does it only happen after you have been running for some time?

What is the release pressure on the filler cap? (usually 7-13 lb, but might be labled in Pa) With a header tank, cap on Polar should be sealed (no pressure release in the middle), check there is no blockage in the pipe to the header tank (fill up header tank and remove Polar cap, water should run out).

Can get thicker walled end caps. Could insert a short piece of pipe (same dia. as the tube stack would be) in the end of the Polar upto the other lip on the end cap and put an extra jubilee clip around it.

[Yoda]

Not one of the worlds best designs is it. Also fundamentaly flawed by the use of poor materials. Make sure that it doen't take any weight or vibration and that your coolant mix is correct.

[Chris-B]

Not one of the worlds best designs is it. Also fundamentaly flawed by the use of poor materials. Make sure that it doen't take any weight or vibration and that your coolant mix is correct.

 

Just out of curiosity what pressure is your tank cap ?

[steelaway]

Hi

I'm on my fourth polar end cap in a year, and I can't think what to do to stop it regularly splitting.

 

 

As you can see it bulges alarmingly and is very much distorted from its original shape.

I've just put this one on and I'm going to check the engine every 20 minutes.

 

I'm sooo fed up having to keep replacing it and clean up the mess in the engine bay.

 

Any help or advise anybody??

 

Engine is a 1979 Austin Rover 1800 taxi engine and the end cap is A3-783 END CAP SMALL POLAR HEAT EXCH M/FOLDS

 

Many thanks.

 

 

Hi There

I dont know the first thing about these engines or the need for a rubber elbow.

Why cant you drill and tap the manifold for a 15mm hose connection and blank of the 50mm hole?

Alex

[blackrose]

Hi There

I dont know the first thing about these engines or the need for a rubber elbow.

Why cant you drill and tap the manifold for a 15mm hose connection and blank of the 50mm hole?

Alex

 

I don't know the first thing about them either or what they do, but if the flow of hot water is from big end to narrower end then it's obviously having to cope with a tremendous amount of pressure. If it's doing what I think it's doing, then the hot water from the engine wants to expand but instead is being forced into a narrower channel. Is there any way you could use a bigger pipe on the narrow end and buy a different size end cap?

 

If not, then the other thing you could try is some reinforcing tape around the whole joint. Some sort of heat resistant self-amalgamating tape perhaps?

Edited February 12, 2008 by blackrose

[tired old pirate]

would suggesting global warming be facetious?

[steelaway]

would suggesting global warming be facetious?

 

Its not a global warming - its a polar end!

[tired old pirate]

Its not a global warming - its a polar end!

 

Shit has it finished?

[steelaway]

Shit has it finished?

 

Thanks alot - spat wine all over miscreen

 

Alex

[echo801]

Caused by expansion as the water heats up, sometimes exacerbated by air locks in the system or sludge build up in the skin tank.

Any history of overheating?

Does it only happen after you have been running for some time?

What is the release pressure on the filler cap? (usually 7-13 lb, but might be labled in Pa) With a header tank, cap on Polar should be sealed (no pressure release in the middle), check there is no blockage in the pipe to the header tank (fill up header tank and remove Polar cap, water should run out).

Can get thicker walled end caps. Could insert a short piece of pipe (same dia. as the tube stack would be) in the end of the Polar upto the other lip on the end cap and put an extra jubilee clip around it.

 

Thanks for everybody's help and advise.

Basically: the only history of overheating is when the cap splits which first happened around May last year, since then it's a regular feature; the pelease pressure is 7lbs; when I remove the cap, and add water to header, the coolant flows quite freely.

If you could tell me where to get a thicker walled cap then that would be great (current replacement from ASAP Supplies.

I tend to agree that it is most probably an air lock in the system; any advise on how to remove it is welcome.

Again thanks to all.

Rick

[RobinJ]

If you could tell me where to get a thicker walled cap then that would be great (current replacement from ASAP Supplies.

I tend to agree that it is most probably an air lock in the system; any advise on how to remove it is welcome.

Noticed on the shelf, you can get two stamped with Polar, but one is obviously stronger then the other?

Depends on how your engine sits in the boat, but usually there are the plugs for feeding the heater circuit at each end of the block (possibly where the calorifier connects), good place to let the air out from! May help if you top up with boiled water or increase the ratio of antifreeze.

[Tony Brooks]

Hi There

I dont know the first thing about these engines or the need for a rubber elbow.

Why cant you drill and tap the manifold for a 15mm hose connection and blank of the 50mm hole?

Alex

 

 

I think this looks like a dry exhaust boat so answer assumes that to be the case.

 

1. Because there is a big hole under the rubber cap where a heat exchanger stack can be fitted for heat exchanger cooled boats. If the problem persists I think I would look for a welder who can weld cast alloy and get the big hole blanked with a heavy plate that can have a suitable fitting screwed into it.

 

2. - Large hole in & small hole out. This should not be a problem. The pump forcing the water through is a centrifugal pump which will just spin if it has to produce any significant pressure - they pump lots of volume but a low pressure.

 

3. Expansion cause by air. Pascal's law says pressure is equal throughout a system so the pressure cap is subject to the same pressure as the end cap and so should open and vent excess pressure. if pressure did manage to build up to that extent is should simply push the air out of the system or compress it.

 

Have you managed to fit a long neck pressure cap into a small neck filler? I think this would be difficult, but you never know.

 

If this was a heat exchanger boat the water inside that cap would only be warm, not hot, and only at the pressure in the exhaust, so it may be a material thing as someone has already mentioned.

 

I think I would be seeing if a Bowman end cap could be persuaded to fit.

 

Not sure how far this gets us, but I think it is bad material.

[RobinJ]

I think this looks like a dry exhaust boat so answer assumes that to be the case.

Expansion cause by air. Pascal's law says pressure is equal throughout a system so the pressure cap is subject to the same pressure as the end cap and so should open and vent excess pressure. if pressure did manage to build up to that extent is should simply push the air out of the system or compress it.

Possibly also exacerbated by the fact the exhaust is underneath it, so warm rubber is subjected to low pressure! Ballooning !

[Wrinkley]

Possibly also exacerbated by the fact the exhaust is underneath it, so warm rubber is subjected to low pressure! Ballooning !

I had a rubbery one on my 1.8 BMC that eventually split. I ordered a new on from Midland at Penkrige mail order. Came very quick and was a different shape, made of a soft plasticy stuff but fitted the same.

 

Try one from a different supplier?

 

Graham

[alan_fincher]

I know this is an old thread, but I've just found it when looking for something else.

 

Have you solved it yet, or is it still ongoing ?

 

I can't see any way that the pressure on that connector should be any greater than the 7 psi cap you say you have on the header tank.

 

I've a similar connector, with a 7 psi cap, and no way does it ever baloon up like in your picture.

 

I can't actually see how a 7 psi cap can fail so that it doesn't operate until the pressure is a lot higher, but that's what looks like is happening to me. I can't believe there is only 7psi (i.e. "not a lot"), in there.

 

I'd at least try replacing the cap, just to rule it out - it will not cost much.

(I think you can find you can buy one in Halfords - I see to remember the Sherpa Van is still listed, and that's what it uses).

[Olitronic]

I am having the same problem with a CB Marine BMC 1.8, i need a 4th Polar end cap, in 4 months, and they have gone up from £16 to £21! Did you manage to sort this out or find a better alternative?

[alan_fincher]

Is yours bulging/balooning up anything like as much as the picture from the original poster, please ?

 

What is the release pressure of your "filler cap".

 

I really don't understand how this can happen, if you have a fully working cap designed to release the pressure at something perhaps no higher than 7 psi.

 

That's really not a lot, and if the pressure in the system were no higher than that, I can't see the "rubber" being balooned up to anything like the size shown.

 

I've a 7 psi cap on a BMC 1800, with the same Polar end cap, and nothing like this happens.....

[alan_fincher]

I am having the same problem with a CB Marine BMC 1.8, i need a 4th Polar end cap, in 4 months, and they have gone up from £16 to £21!

Hi,

 

We have not heard back from you on the questions I asked ?

 

Have you managed to resolve your problem ?

 

Curious about Calcutt price.

 

I've just bought a Polar A3/783 as a spare, and they charged £14-78 + VAT = £17.37. Not cheap, but less than your £21.

 

The type I got is a different design from that in the OP's picture. When I have a moment, I'll post a picture.

 

EDIT:

 

Just compared Calcutt Boat's price for Polar caps with those at Midland Chandlers....

 

A3/703 (Blanking end cap) £12-08 Calcutt, £14-50 Midland

A3/783 (The part discussed here) £17-37 Calcutt, £20-80 Midland

A3/728 (Oil Cooler End Cap) £7-64 Calcutt, £11-00 Midland.

 

Total cost of all 3 at Midland £46-30

Total cost of all 3 at Calcutt £37-09

 

Still expensive but saving at Calcutt is £9-31

 

From what I can see ASAP Supplies are a bit more than Calcutt, but still well less than Midland Chandlers.

Edited June 25, 2008 by alan_fincher

[alan_fincher]

Here is what the Polar A3/783 connector currently being supplied by Calcutt looks like.

 

 

 

You will see it has a smaller 'dome' than the old one, as it reduces down after the point it is attached to the heat exchanger.

 

This one takes a 22 mm pipe on the outlet.

 

When we had one like you have pictured, ours had a 28mm pipe, despite Calcutt saying that such a thing had never been manufactured. It's just about conceivable that our original had been manufactured at 22mm, and stretched to fit a 28mm pipe, but they are so inflexible, it seems unlikely.

 

I had to create a converter to go from 22mm on the end cap, to the 28mm rubber pipe to the skin tank.

[smileypete]

That sure does look like a daft bit of design

 

What about a silicone reducing elbow onto another reducer, eg:

 

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?Vie...em=250252547314

 

Edit:

 

Something that might help keep pressure in the cooling system down, is to check the expansion tank is the right size, and has a minimum level of coolant (leaving more airspace) in it.

 

cheers,

Pete.

Edited June 25, 2008 by smileypete