Radiator question

Jamesnjane · Post by **Jamesnjane** » Sun Apr 08, 2007 10:55 am

Hi, i bought a new rad and theres a extra pipe that comes out of the filling cap, everything else is as the old rad, iv blocked it off with some tube and a bolt and its holding fine under pressure so far, but i was just wondering whats it for? do some bongos already have this and if so where does it go? also is the bolt setup good enough?

Thanks
J

Vanmanerik · Post by **Vanmanerik** » Sun Apr 08, 2007 11:24 am

Unblock the pipe, it is there to allow excess pressure, steam etc. to escape from the radiator under extreme conditions, if the pressure rises too high then the spring loaded valve in the radiator cap lifts/opens and releases the pressure.
Hope this helps.

francophile1947 · Post by **francophile1947** » Sun Apr 08, 2007 11:27 am

Sounds like an overflow pipe, to let the water out when the pressure cap opens. However, as the Bongo has an expansion tank, the pressure cap is normally fitted on that, with a "solid" cap on the radiator. I think you may need to make sure that your tube/bolt arrangement is very secure, or you might end up losing your coolant.

francophile1947 · Post by **francophile1947** » Sun Apr 08, 2007 11:28 am

Oops!! - looks like I was wrong!

Jamesnjane · Post by **Jamesnjane** » Sun Apr 08, 2007 11:40 am

iv removed the bolt, i thought it was open to the rad so coolant would flow out, i get it now with the cap set up. Thanks

were all learning

dandywarhol · Post by **dandywarhol** » Sun Apr 08, 2007 11:04 pm

Block it off - the system overflows via the expansion tank if pressure is excessive..........it shouldn't be there - it's not a proper Bongo radiator and is shared with something else WITHOUT the expansion tank.

Can anyone explain to me why the radiator HAS a pressure cap which allows air back in via the vacuum valve to the system if the pressure gets too much - I'd have thought a pressure cap on the expansion tank would suffice..........also the cap on the radiator reads RADIATOR USE ONLY........or something like that

Edit....I'll answer my own question here...........there's no overflow pipe on the original radiator so it can't draw in air - even more important then jamsnjane that you block it off

francophile1947 · Post by **francophile1947** » Mon Apr 09, 2007 2:36 pm

dandywarhol wrote:Can anyone explain to me why the radiator HAS a pressure cap which allows air back in via the vacuum valve to the system if the pressure gets too much - I'd have thought a pressure cap on the expansion tank would suffice..........also the cap on the radiator reads RADIATOR USE ONLY........or something like that

That Dandy is another Bongo mystery - I've only ever had a solid cap on the radiator of other cars, and a pressure cap on the expansion tank - hence my earlier posting.

Peg leg Pete · Post by **Peg leg Pete** » Mon Apr 09, 2007 9:05 pm

I think yiou should block the extra outlet, not on original radiator

Harry · Post by **Harry** » Tue Apr 10, 2007 12:31 am

Well i've run Freda without the extra pipe blanked since last August when I fitted a new rad ex ebay.

If the rad cap chooses to vent I have no probs because the expansion tank is higher up and will top up the rad.

The only way you might get it venting is if the cap is faulty/incorrectly fitted or if you get an air pocket in the very top of the rad turning to steam (in which case it is better vented anyway).

The expansion tank cap should 'pressure relieve' at a slightly lower pressure than the rad cap. If the tank cap jams then at least pressure can be released via the rad cap....I like back up systems (as we said when I used to build aircraft..half the risk of catastrophy but twice as much to go wrong

)

I also release the cap slightly after refilling the system to vent any excess air escape as part of the bleeding process.

cheers

H

dandywarhol · Post by **dandywarhol** » Tue Apr 10, 2007 1:10 am

Does anyone else have an expansion cap lower pressure than 1.1 BAR?
Both my caps are 1.1 BAR

Peg leg Pete · Post by **Peg leg Pete** » Tue Apr 10, 2007 4:59 pm

I believe both the caps are the same rating on our bongo Dandy.

Bonza · Post by **Bonza** » Wed May 16, 2007 9:14 pm

Rad cap pressures.

I have both the radiator and expansion tank caps with pressure ratings of 1.1 bar. Cant really understand why the rad has a pressure relief cap at all other than a fall back safety feature. |It has nowhere to vent to.

The rad cap is a bit ropey as regards a good seal so I go off the BongoBits at Plymouth. They produce a 0.9 bar cap as a standard Bongo part.
Check of the manual shows both caps have same part No. but are labelled No. 1 and No. 2. Check spare s/h rad in their shop and it has a 1.1 bar cap with no pressure relief (price check £21 for the plain non pressure relief valve, £8 for one with a pressure relief valve- screwy or what?).
I dont think it matters if the rad cap has a pressure relief or not as long its greater than the expansion tank.
So, whats the correct rating for a Bongo cooling system expansion cap 0.9 or 1.1 bar?
Probably doesnt matter much but who knows?
Very patient and helpful lot at Bongobits and recommended.

haydn callow · Post by **haydn callow** » Wed May 16, 2007 10:18 pm

The rad cap is just a blanking cap, the header tank is a relief cap rated at 1.1, the rad cap has the same label markings but this is just a saftey warning so you don't remove it whilst hot. If it was unmarked you could make that mistake. What I'm saying is the system as a whole is rated at 1.1 and the rad cap is just that ..A cap. If it has a outlet below, it should be blanked off or a higher rated relief cap should be fitted

Bonza · Post by **Bonza** » Thu May 17, 2007 5:32 am

Thanks Haydn.
Can you tell me where you get the figure of 1.1 bar from please?
BongoBits sell a 0.9 bar cap as a replacement.
Its only some 3 psi difference but it would be nice to know what a Bongo coolant system runs at.

Hows the coolant detector testing going Haydn?

Bonza

haydn callow · Post by **haydn callow** » Thu May 17, 2007 8:21 am

Bonza... Now you've got me there. I was going to say because it says so in the handbook/manual co's I know I've read it somewhere. I checked and in fact it is written at the bottom of one of the specifcation pages in biro.
However . My Bongo was fitted with a new rad before leaving Japan and the two caps on there both have the same label written in japanese and they also look new.

I'm afraid that is not very conclusive. I think other bongos I've seen have the same header tank cap as mine or I think I would have noticed. Of course the rad cap is out of sight.

Radiator question

Radiator question

Radiator overflow pipe.