Coolant hissing

[phedders]

Ok, my Bongo is losing cooland and I don't yet know where. (I have some of that UV die on order...) I have searched high and low and can't see any sign.

Over the w/end I fitted a mason - quite scary to see the temp guage go up to 2 o;clock and move about - but also reassuring knowing I have more real resolution. And knowing that I have YAB to warn me if it gets above normal...

So.. yesterday I did two 30 minute urban runs. At the end of both runs the coolant level had gone down a little. There was no sign of it being pushed out of the header tank overflow BUT the overflow tube was hissing.

Am I right in thinking that this is either because - the cap/tank seal is bad (new cap or tank) OR that the system is over-pressured and venting?

When I was getting some help from AA friend l last week, we ran the engine for a while with his pressure test doodah on the tank and the pressure seemed to be fine. He tested the cap and it vented at 1.1bar.

Any ideas?

[spout]

Being a new Bongo owner I have been reading all the threads on overheating/coolant loss with interest.
It appears that the system is air tight and gets pressurised as it warms up, but over the weekend I noticed what looked like an overflow on the header tank (without a pipe attached).
How can the system be pressurised with an overflow? Or is it not an overflow?

[haydn callow]

The over flow from the neck of the tank should have a short pipe attached but it's not important.
If you take the cap off you will see that the "overflow is half way down the neck. The cap seal is below that onto a ridge lower down. If you overpressure then that bottom seal lifts and releases via the pipe. the metal cap does not have to seal for it all to work but it's better if it does. If you hear a hissing from the pipe it may just be the bottom seal leaking and a new cap could be the answer.

[bigdaddycain]

Could spout be reffering to the other "tube" on the upper left hand side of the expansion tank? (the one that has no pipe attached).

[haydn callow]

Yes but !! thats not a tube just a solid spigot which has no purpose..Could be a moulding spru cut off.

[bigdaddycain]

Yes but !! thats not a tube just a solid spigot which has no purpose..Could be a moulding spru cut off.

There ya go ya see!.. I never knew that! It looks (to the layman) that it's some kind of overflow tube... ( i know the next sentence will get quoted for double entendre purposes) I have never stuck anything in that hole to see if it goes all the way in or not. (wait for it ).

[daveblueozzie]

Well obviously on Sunday you was not watching me and Snowkiter sticking a piece of wire in it ,to see if it went anywhere. you was too busy jangling with Kawasaki Kid and Dabs to notice.

[waycar8]

Yes but !! thats not a tube just a solid spigot which has no purpose..Could be a moulding spru cut off.

There ya go ya see!.. I never knew that! It looks (to the layman) that it's some kind of overflow tube... ( i know the next sentence will get quoted for double entendre purposes) I have never stuck anything in that hole to see if it goes all the way in or not. (wait for it ).

, on the old bongo, i checked that pipe................the reason being when i bought the new rad from ebay, it was the one with the extra overflow in the neck of the rad, i thought ha... brain storm moment.....i will get a piece of hose and run it up to the header tank and stick it on the extra pipe on the header tank , then i realised it hadnt a hole through it .

i thought about drilling it, but was worried about getting bits of plastic into the coolant in the header tank, or damaging the header tank itself, so didnt bother

[haydn callow]

If that "stub" was not solid you would have no pressure in your system. Defo don't even think of drilling it.

[bigdaddycain]

Well obviously on Sunday you was not watching me and Snowkiter sticking a piece of wire in it ,to see if it went anywhere. you was too busy jangling with Kawasaki Kid and Dabs to notice.

Oh i saw you and pete having a poke around but i couldn't determine how much penetration was attained by you both.

[waycar8]

If that "stub" was not solid you would have no pressure in your system. Defo don't even think of drilling it.

yes i did think about that but, if it was connected to the rad using a hose, surely it will stay presurised?

[daveblueozzie]

im not mechanically minded, but if it was connected it would then push air through the system.

[haydn callow]

You would have to use "proper" hose and a clamp at each end. My advice...don't do it. there is no point. The tank cap should "pop" before the rad cap.

[dandywarhol]

You would have to use "proper" hose and a clamp at each end. My advice...don't do it. there is no point. The tank cap should "pop" before the rad cap.

Yeah, but surely the spurious radiator should have it's stub blocked off incase it does "pop" it's valve - it would remain a hidden problem otherwise.......

On the subject of radiators - quality radiator design has small "deflectors" inside the water tubes to divert the coolant to the outsides of the tube so the passing air can cool it better. Cheap ones don't and the coolant passes straight down the middle of the water tube so the coolant barely touches the sides - Result? the cheapo ones don't cool as well.........y'get what y'pay for I suppose.....................

[haydn callow]

I'll go along with that.... and also fit a plain blanking cap instead of the pressure cap which serves no useful purpose on the Rad.