Coolant coming out of expansion tank overflow pipe

marmaduke · Post by **marmaduke** » Sat Jan 07, 2012 8:44 pm

Need some help!
I've got coolant coming out of the expansion overflow pipe and not sure what to do next. Its been to the garage and still the same problem. Although its had a new radiator (about 6 months ago) and new hoses (last month). The garage are stumped as to why this is happening and have come to the conclusion that it could be the head gasket. Although nothing else is coming up to relate to the head gasket. Has anyone any suggestions?
I don't want to give up on the Bongo, last year I had new rear arches put on and this year over the last 2 months I have spent nearly a grand.
I would really appreciate any advice.
Cheers

Driver+Passengers · Post by **Driver+Passengers** » Sat Jan 07, 2012 8:59 pm

Can your garage do a 'sniff test' to check for exhaust gases coming out of the coolant header tank? I believe that would confirm a head gasket failure if there was one.

dave_aber · Post by **dave_aber** » Sat Jan 07, 2012 9:00 pm

A duff cap on the tank could cause this too. Cheap and often overlooked.

stuc · Post by **stuc** » Sat Jan 07, 2012 9:35 pm

dave_aber wrote:A duff cap on the tank could cause this too. Cheap and often overlooked.

This was the cause of my problem a coule of months ago, bought a genuine cap from mazda, about £12.

widdowson2008 · Post by **widdowson2008** » Sat Jan 07, 2012 9:51 pm

stuc wrote:
dave_aber wrote:A duff cap on the tank could cause this too. Cheap and often overlooked.
This was the cause of my problem a coule of months ago, bought a genuine cap from mazda, about £12.

Was the cap fixed securely? I think you would be surprised how many (including myself

) who have cocked up this way with the same result as you describe.

Northern Bongolow · Post by **Northern Bongolow** » Sat Jan 07, 2012 9:57 pm

get them to do a good pressure test, any leaks will poss let air in, and may lower the boiling point with this result. and have a look at the bleeding a mazda bongo videos on youtube then ask your garage if they have bled it correctly.

Dannyboy · Post by **Dannyboy** » Sat Jan 07, 2012 10:11 pm

Hi,

I had this problem not long ago. I think it is probably due to a blockage of some kind in the cooling system.
The coolant needs to go somewhere and takes the path of least resistance, in this case out of the expansion tank.
My problem was resolved by replacing the radiator although you appear to have done that recently.
It could easily be the cap as suggested by others. If a replacement does not work I would search for a blockage somewhere.

Good Luck.

marmaduke · Post by **marmaduke** » Sun Jan 08, 2012 2:38 pm

Thanks everyone for your advice. I'll go with a new cap for now, any suggestions where I can get one?
Cheers

marmaduke · Post by **marmaduke** » Sun Jan 08, 2012 2:41 pm

Stupid question.. probably!! is the expansion cap the same type of cap as a radiator cap?
Doh!

dave_aber · Post by **dave_aber** » Sun Jan 08, 2012 3:05 pm

The short answer is "it might be".

The expansion tank cap is designed to release pressure at 1.1 Bar. The radiator cap is designed to not release pressure at all - but a 1.1 bar cap can be fitted to the radiator as it has no outlet pipe in the neck, so if the cap inner seal were to lift at 1.1 bar, there would be nowhere for the pressure / coolant to exit from.

So, you may well find that you have a 1.1Bar cap fitted there. It will have "1.1 Bar" printed on the sticker. If so, it's worth a go swapping them round.

As a side-note, some replacement radiators DO have a vent pipe which would allow a pressure release cap to work and dump pressure - this outlet must be blocked off on a Bongo.

widdowson2008 · Post by **widdowson2008** » Sun Jan 08, 2012 3:17 pm

Was in the process of answering but Dave beat me to it, and he is spot on.

This recent post contains a graphic which may explain things.
http://www.igmaynard.co.uk/bongo/forum/ ... 2&start=15

dave_aber · Post by **dave_aber** » Sun Jan 08, 2012 3:54 pm

To be fair, your animation does explain it so much better than my ramblings, even if they are (sometimes) quick!

marmaduke · Post by **marmaduke** » Sun Jan 08, 2012 4:27 pm

Thanks for that, do you know where I could pick one up?

dave_aber · Post by **dave_aber** » Sun Jan 08, 2012 5:21 pm

I got a replacement 1 Bar one for a Toyota Starlet recently from a local motor factors. Seems that the Japanese radiators / tanks are a standard neck size. I would doubt Halfrauds would stock them, but you never know. Have you got an independent place local to you?

marmaduke · Post by **marmaduke** » Sun Jan 08, 2012 5:39 pm

Thanks I will look around. Just checked the radiator cap and its a 1.1 bar so swapped them around. However now the van won't start! I did run it for a while yesterday so not sure why its like that today!

I am slowly giving up on it. The garage I took it to is a Bongo specialist and they did a pressure test which showed no leaks and they did a sniff test which was inconclusive.

At this stage of the game I am thinking of selling it on as I spent more than I should on it and can't afford to spend anymore on it.

Thanks for all your advice.

Coolant coming out of expansion tank overflow pipe

Coolant coming out of expansion tank overflow pipe

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