Bongo Fury

Simon Jones wrote:I read in one part of the thread that coolant came out the expansion tank but it was also mentioned no coolant was lost. One of these cannot be correct. Sounds to me like either the water pump is not doing its job, there is a blockage somewhere or there is an airlock in the system. Get an external temp sensor connected to one of the heads and you will be able to get a better idea of what is happening. On my V6 I think the hottest its got is about 96C on the climb to Applecross (Bealach na Ba), which if you know it, is basically like driving up the side of a mountain.

Just for info value a long sustain climb up 500ft made Diesel Bongo hit 99C here so I just stopped for a bit !

I am imagining that if your coolant is hitting boiling it is definitely going to be coming out from somewhere at that stage, overflow, seal round expansion tank, a tiny pipe hole. a pipe end seal. I think it might be worth trying to understand where the cooling inefficiency is that is letting it get that hot.

A thorough coolant system flush maybe, blocked channels in some parts of the engine, a fan not working that should or not running fast enough, rad as someone suggested, have you checked your oil level and/or changed it recently ? That is an important coolant which people forget (6 or so litres of it). Just a few thoughts.

One thing to be mindful of is that stopping when the engine gets hot will stop the flow of air which is required to cool it. Ideally you want to keep the engine running to allow the water pump to circulate the coolant. A while back, a Bongo owner did some tests a found that changing down from 4th to 3rd gear resulted is cooler engine temperature as the water flow was much faster. This is opposite to what you might think as running faster will result in higher friction but I guess the design is such that the pump performance will always cool at a faster rate than engine creates heat.

On my V6, the return from the radiator to engine is anywhere from 5 to 25C cooler that the head temperature which demonstrates how much cooling it actually does. Stop moving or turn off the engine and the coolant temp will rapidly rise to match that of the engine.

Simon Jones wrote:One thing to be mindful of is that stopping when the engine gets hot will stop the flow of air which is required to cool it. Ideally you want to keep the engine running to allow the water pump to circulate the coolant. A while back, a Bongo owner did some tests a found that changing down from 4th to 3rd gear resulted is cooler engine temperature as the water flow was much faster. This is opposite to what you might think as running faster will result in higher friction but I guess the design is such that the pump performance will always cool at a faster rate than engine creates heat.

On my V6, the return from the radiator to engine is anywhere from 5 to 25C cooler that the head temperature which demonstrates how much cooling it actually does. Stop moving or turn off the engine and the coolant temp will rapidly rise to match that of the engine.

Very good points made.

Had a conversation with Daydreamer to day...he is going to have a Mazda radiator fitted and a Mazda stat....also a full flush.....
Hopefully that will sort it out.....
V6s do run quite cool so as long as the system is working well hills should not be a problem.

Well done, Haydn.

Perhaps my brother might listen to you.

Makes me glad I had the sense to get mine flushed when the Bongo competent garage suggested it after a turbo coolant leak and subsequent refill/bleed. Hope it all settles down, good luck.

Daydreamer ....It would be advisable to get your garage to check the COOLING FAN operation, if the vehicle overheats the fans/s should kick it, if they don't there is a serious problem. If the vehicle/engine overheats stop immediately Switch off engine and let the Fans do their business.

Good Luck

teenmal wrote:Daydreamer ....It would be advisable to get your garage to check the COOLING FAN operation, if the vehicle overheats the fans/s should kick it, if they don't there is a serious problem. If the vehicle/engine overheats stop immediately Switch off engine and let the Fans do their business.

Good Luck

If I were to stop and switch off immediately, the fans would stop. Better to keep the engine running for a while. I do this whenever I stop when it's hot.

Jillygumbo wrote:

teenmal wrote:Daydreamer ....It would be advisable to get your garage to check the COOLING FAN operation, if the vehicle overheats the fans/s should kick it, if they don't there is a serious problem. If the vehicle/engine overheats stop immediately Switch off engine and let the Fans do their business.

Good Luck

If I were to stop and switch off immediately, the fans would stop. Better to keep the engine running for a while. I do this whenever I stop when it's hot.

The solution is to switch the Ignition back On to activate the fans (If the engine is Overheating )not simply when Hot.

Good Luck

teenmal wrote:

Jillygumbo wrote:

teenmal wrote:Daydreamer ....It would be advisable to get your garage to check the COOLING FAN operation, if the vehicle overheats the fans/s should kick it, if they don't there is a serious problem. If the vehicle/engine overheats stop immediately Switch off engine and let the Fans do their business.

Good Luck

If I were to stop and switch off immediately, the fans would stop. Better to keep the engine running for a while. I do this whenever I stop when it's hot.

The solution is to switch the Ignition back On to activate the fans (If the engine is Overheating )not simply when Hot.

Good Luck

I agree with Jill. Doing what you suggest will cool the radiator, but the coolant in the engine will get hotter as it picks up heat from the engine - better to let engine tick-over so that the water pump is circulating the coolant.

I agree with keep the engine running to cool it down
And fans on full
The fans are cooling the radiator water so you won't to keep it circulating with the engine running
Scavenger fan is pointed at engine yes but unless you have done the fitted SWITCH MOD
That don't come on until engine is real hot

Don't forget that switching the A/C on will switch on both rad fans and if you crank the temp and fan up to the max, the blower will help take the heat out the coolant.

Thank you all for the great info and Haydn for chat the other week. Also sorry I haven't been able to update anyone or log in for the last few weeks but the good news is it's all fixed. New Rad, stat and flush has sorted it out and I have to say a big thanks to Clingwyn (Clyngwyn) Garage for the excellent work. Sincerely appreciate all the excellent support from here, thank you all again.

I agree with Jill. Doing what you suggest will cool the radiator, but the coolant in the engine will get hotter as it picks up heat from the engine - better to let engine tick-over so that the water pump is circulating the coolant.[/quote]



And Will the coolant circulate if the possible overheating issue (which is Normally the Case)is caused by a Stuck Shut Thermostat.

How would you know ?..

If you whack the front and rear heater on full with the engine running then you effectively have two extra radiators to take the heat out the system.