Overheating - bottom hoses

[blackbongo]

We have an overheating problem which we've tried to resolve but no joy. Have also hunted on the forum so apologies if I've missed a similar problem and solution. The problem started 2 weeks ago where the temp gauge needle went to the extreme heard a big clunk then temp gauge back to middle. The same day needle went sky high again and heard lots of spitting and glugging coming from reservoir tank pulled over immediately. Went through process of bleeding system as outlined on Fury website and refilling antifreeze a number of times. No warm air came through heaters so suspected airlock. Bled again - this time some warm air from front blowers but not much but did get some heat from rear blowers. Still overheating. Now there is no heat from either blower and still overheating. Top radiator hoses are red hot and bottom hoses are ice cold and water is spitting out of the reservoir tank overflow. Any ideas gratefully received!

[francophile1947]

With water spitting out, I'm afraid it sounds like the head or head gasket Is there smoke or steam from the exhaust and what engine have you got?

[blackbongo]

Doesn't seem to be steam from exhaust but it is quite smoky on start up settles down though. Engine is 2.5 diesel 1996. Feared head gasket but was hoping it might be something simple. cheers

[francophile1947]

Sounds like it's just got gases leaking into the cooling system and pressurising it - I'm afraid it definitely sounds bad

[blackbongo]

oh no, thanks for replying though.

[Northern Bongolow]

dont give up that easy, where exactly are you.
hot top hose and cold bottom hose could just mean it hasnt been bled properly.
go on youtube and type in bleeding a mazda bongo,the 3 videos on there may help.

[widdowson2008]

....temp gauge needle went to the extreme heard a big clunk then temp gauge back to middle. The same day needle went sky high again and heard lots of spitting and glugging coming from reservoir tank ............ No warm air came through heaters so suspected airlock. Bled again - this time some warm air from front blowers but not much but did get some heat from rear blowers. Still overheating. Now there is no heat from either blower and still overheating. Top radiator hoses are red hot and bottom hoses are ice cold and water is spitting out of the reservoir tank overflow. Any ideas gratefully received!

How about this possible scenario (based on description of events).
Bottom hose is exposed to the elements, and if the antifreeze mix was weak, particularly with the recent very cold weather up North, bottom hose frozen.
Run engine - top hose sends VERY hot coolant to the radiator (as it should). At the same time, coolant at the same temperature is being sent to the stat via the bypass (as it should).
Stat opens, but because bottom hose is frozen there is no flow from the radiator, so engine gets hotter and temperature gauge goes high.
Heat will eventually be conducted through the rad down to the bottom hose and melt/release the frozen blockage, which could explain the 'BIG CLUNK' and the temperature gauge falling back to normal.
And, could this scenario have caused air to be drawn into the system?

[helen&tony]

Hi
Steve...
my thoughts exactly on the bottom hose and freezing...antifreeze may not be up to spec. Also the rad may have a problem --blocked/ frozen..but not too sure about drawing air in...unlikely, unless the system cools rapidly and the rad caps are not functioning...
Cheers
Helen

[widdowson2008]

It was the 'BIG CLUNK' that grabbed my attention.
Grabbing at straws with the 'drawing air in' - DBO currently has a similar heater issue.http://www.igmaynard.co.uk/bongo/forum/ ... 56#p465456 Wonder if it's the same problem?

[blackbongo]

Thanks for replies. Going to give bleeding it again one last try this weekend to see if it could still be an airlock if not will bite the bullet and get it to the garage will let you know how we go. Thanks again