BMC Radiator cap help please

[JojoF]

Hello. I need to replace the radiator cap on a old engine...its a bmc 1.6...have been to Euro car parts as directed there by most other places I contacted. I cant find what sort...ie the bar number, or short or long neck...seems to be a lot to consider and i dont know enough. Grateful for help. Thankyou jojo

[magnetman]

Austin J4 had BMC 1.5D engines. 

 

Maybe if you can find a numberplate for one and put it into the website it might work? 

 

 

[JojoF]

Thankyou...you got me now tho as not sure how I would do that . Jj

[magnetman]

It might be a different cap anyway because the boat engine has a heat exchanger not a radiator. 

 

ASAP supplies are good for this sort of thing. Online orders only. 

 

If you do locate the right item buy two of them. Its one of those odd things you think you will never lose but it can happen so having a spare is wise. 

 

 

[beerbeerbeerbeerbeer]

I tend to get odds and ends like that from Calcutt Boats. 
If you ring they are extremely helpful. 
Trouble is they charge at least £12(?) for any delivery. So worth ordering a few things to make it worth while. Caps should be under a tenner. £7 or £8 I think. 
 

 

1 minute ago, magnetman said:

If you do locate the right item buy two of them

 Yes, I nearly suggested getting a spare. 
I’ve had them fall apart. 

Calcutt Boats: 01926 813757
 

[JojoF]

Thanks I will try them. Shame the numbers on the cap have worn. We were told it was a 4...what might that relate to? Thanks jj

[magnetman]

Mine (1.5D) are AC Delco 50kPa pressure caps.

 

This is about 7psi. 

This one maybe 

 

https://www.ebay.co.uk/itm/352732020847

 

 

It has a mark G.490 on it as well as LBS 7 (7psi). Austin group vehicles. 

 

The code seems to be GRC101. 

[Tracy D'arth]

Don't use a higher pressure than 7 or 5 lbs  or you will blow your heat exchanger rubber connections and end cap.

[beerbeerbeerbeerbeer]

5 minutes ago, Tracy D'arth said:

Don't use a higher pressure than 7 or 5 lbs  or you will blow your heat exchanger rubber connections and end cap.

Particularly if they’re old pipes. 
I put some of my cooling problems down to having the wrong cap on. Used to have a 13lb cap and as soon as I repaired one leak it’d spring another leak. I’ve a 7lb on now. 
Old pipes had perished in places too, which is never going to help. 
Not had any trouble for a year now. Touch wood  

[Tony Brooks]

10 minutes ago, Tracy D'arth said:

Don't use a higher pressure than 7 or 5 lbs  or you will blow your heat exchanger rubber connections and end cap.

 

I echo this, especially if you have a Polar exhaust manifold.

 

I think we are all assuming that you mean a BMC 1.5, but even if it is a 1.8, it won't make much difference.

 

You can easily see the difference between the long and short length caps if you visually compare them.

 

The 4 probably relates to a 4 psi opening pressure.

 

My advice s to find an independent motor factors, take the cap to them and ask for a 4/5/6 cap that matches length wise. Independents are far more likely to take the time to find it for you.

 

For canal use a 1.5 is unlikely to have problems if run without any pressurisation. In fact I think Calcutt operated their hire boats with an open coolant header tank.

 

 

 

 

[ditchcrawler]

[JojoF]

Thanks All

I was of course mistaken engine is a 1.8...oh dear. But learning! And Calcotts have been stars so all sorted now. It was Short reach 4lb . Thanks.

[Tracy D'arth]

1 minute ago, JojoF said:

Thanks All

I was of course mistaken engine is a 1.8...oh dear. But learning! And Calcotts have been stars so all sorted now. It was Short reach 4lb . Thanks.

Its Calcutt.  Glad you sorted it, 4lbs is good. Thanks for publishing that and the fact that it is short reach, may help another boater when they do a search here.

[Tony Brooks]

I would be very wary of assuming all 1.5s have a short reach cap. Some older ones used a long reach. his may also go for older Perkins 4-xxx engines.I don't know, but suspect all 1.8s use a short reach cap. 

[JojoF]

Sorry to get Calcutt name wrong. They have been great. 

[Slim]

21 hours ago, JojoF said:

Thanks I will try them. Shame the numbers on the cap have worn. We were told it was a 4...what might that relate to? Thanks jj

PSI  Pounds per Square Inch

[JojoF]

Oh! Thankyou...Good to learn. 

[alan_fincher]

21 hours ago, Tony Brooks said:

 

I echo this, especially if you have a Polar exhaust manifold.

 

I think we are all assuming that you mean a BMC 1.5, but even if it is a 1.8, it won't make much difference.

 

You can easily see the difference between the long and short length caps if you visually compare them.

 

The 4 probably relates to a 4 psi opening pressure.

 

My advice s to find an independent motor factors, take the cap to them and ask for a 4/5/6 cap that matches length wise. Independents are far more likely to take the time to find it for you.

 

For canal use a 1.5 is unlikely to have problems if run without any pressurisation. In fact I think Calcutt operated their hire boats with an open coolant header tank.

 

I've not read the entire thread, but, as usual, Tony's advice is spot on

 

Particularly as he emphasises possible issues with the use of a Polar header tank.  The available "Polar" rubber end caps are not Polar - they are very poor copies using the original polar moulds, and very prone to frequent failure.  To make matters worse the cost of those copies is ridiculously high.

 

I no longer have a BMC, but when I did was eventually able to source a cap of either 3 PS or 4 PSI, (can't remember which), which finally meant I could stop regular replacement of those  end caps.

 

A second piece of advice, (if relevant), is that  a Bowman end cap can be persuaded with a bit of jiggling to replace a crap "Polar" copy.  These may well withstand 7 psi, but I chose to use Bowman caps with a 3 or 4 PSI radiator cap, after which all was fine, and I never had any further failures.

[Tony Brooks]

1 minute ago, alan_fincher said:

I've not read the entire thread, but, as usual, Tony's advice is spot on

 

Particularly as he emphasises possible issues with the use of a Polar header tank.  The available "Polar" rubber end caps are not Polar - they are very poor copies using the original polar moulds, and very prone to frequent failure.  To make matters worse the cost of those copies is ridiculously high.

 

I no longer have a BMC, but when I did was eventually able to source a cap of either 3 PS or 4 PSI, (can't remember which), which finally meant I could stop regular replacement of those  end caps.

 

A second piece of advice, (if relevant), is that  a Bowman end cap can be persuaded with a bit of jiggling to replace a crap "Polar" copy.  These may well withstand 7 psi, but I chose to use Bowman caps with a 3 or 4 PSI radiator cap, after which all was fine, and I never had any further failures.

 

All true, but my answer on the hire fleet was when converting from heat exchanger to keel cooling or overhauling a keel cooled engine, was to have the ends of the manifold welded up so no rubber caps involved. You just need to find a decent jobbing aluminium welder.

[Tracy D'arth]

On the right angle connector end caps, it pays to put another hose clip on the narrower part of the rubber to prevent it expanding too much.