Cooling problems - Mazda Bongo!

Old 12-12-05, 06:18 PM
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Cooling problems - Mazda Bongo!

Hi all...

I am using a Mazda Bongo 4x4 Turbo Diesel, aged 1994 in New Zealand.

I have just bought it from a backpacker for a good price, due to its cooling problem, but I am so far unable to sort out! Would appreciate any advice...

So far I have flushed the system through the top and reverse flushed from the bottom. All pipes appear to be free. The thermostat is working as is the water pump. Circulation appears to be ok, and there is no leeks or water loss.
I have partially blown the radiator cores backward (from fan to front).

The symptoms...

From cold, the temp. rises at a normal rate. It will hover on mid-range (normal) for maybe 5km's before continuing upwards towards over-heating. All in all, in average driving conditions (air temp around 24c) I can go maybe 20km's before I have to shut down to cool. Oh, and the "radiator light" illuminates on the dash board from cold. This will flicker randomely on and off as it heats up. Is this light related to temperature or pressure in the engine block or the radiator?

When I flushed the system through, not a great deal of rust/crap came out. I am sure everything is working as it should be - so am thinking all it can be is the radiator simply is not cooling the coolent enough? Perhaps the passage ways are too corroded inside to do their job?

Any advice - hugely appreciated! I am a backpacker and can't affort to go to the garage!
Kind Regards....
Old 12-12-05, 11:37 PM
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well, good luck for starters. You may want to check that the fan is coming on, im not sure if its electric or not, and if its not, its probably the theromstat or the water pump.
Old 12-13-05, 03:35 PM
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I agree with zzzz1486. You say the thermostat is good. How did you test it?
I would replace it rather than test it. If that does not cure the problem, the impeller may have broken loose from the shaft in the water pump.
Old 12-14-05, 02:07 AM
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Hey guys - thanks for the replies.

I am sure the thermostat is working ok because a) there is evidence of recent replacement, such as a brand new gasket poking out. And b) running the engine from cold, I keep my hand on the outflow pipe and as the motor warms up I feel the hot coolant begin to flow through.

As regards the water pump. Well, I guess I am mostly just wishing/willing it not to be that! I reckon I can handle (with my limited tools/workspace) replacing the radiator - the water pump I could not!

The water seems to be getting around, and there are absolutely NO leaks anywhere.

Since writing up my post, I have given the rad a really jolly good flushing again, from the top, from the bottom and also used Rad Flush (though do these fancy chemicals every work?). I've also blown out the rad with an air-line. Each time I have done this, it really seems a little better. Or, I could be dreaming!

The mystery continues. Maybe I should just hitch-hike on my travels instead!

Thank you all.

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