Cooling issues still

[mayk19]

Can anyone help please,

I've had some overheating issues recently, after sniff test the garage didnt recomend it was head gasket so we looked to change radiator and pump (just in case). I've also lost no coolant over time.. but Bongo was overheating on up hill runs.

On test, they havent had the Bongo overheat again but are concerned that once the fans kick in at around 94 degrees they don't appear to stop until down at 60 degrees. They checked the thermostat but this appears to be opening at 90 degrees.. that sounds a little high. I guess.. to answer my own question ! that I should just get the stat changed to be safe.

BTW, the old radiator weighs a lot more than the new... weather thats an indication of the old one silted up ?

Thanks for any advice.

[missfixit70]

As we keep saying, change the stat for a Mazda original, it's only @£20, it's what controls the temperature, if it doesn't work right you'll kill your bongo. It should open @ 82 - 85 degrees & have a minimum of 8.5mm lift at 95 degrees so it can shut off the recirc port on the top of the stat housing with the top disc.
Pan test the new one a couple of times to make sure it's ok & make sure the jiggle pin is secure in it's hole ie make sure it can't jiggle out, I'll expand on that one later

[mayk19]

Ive asked them to change the stat.

Cheers.

[Northern Bongolow]

and make sure the port at the top of the stat housing is clean,or the stat disc will not seal the opening when the stat opens to the max.

your symptoms sound like the above------
the stat manages to control the temps, just, then when under load it heads towards overheat,and the only thing that stop it poping something is the fans!!!!
i would also fit a new gen mazda temp sensor and a gen mazda fan switch.

these 3 things are relatively cheap and are the key things that control/monitor the system.

[mayk19]

Cheers Ady.

[mikexgough]

i would also fit a new gen mazda temp sensor and a gen mazda fan switch. these 3 things are relatively cheap and are the key things that control/monitor the system.

Totally agree....... often with certain areas of a vehicle (anti roll bar etc) best off replacing all the components that are likely to give grief at once rather than to replace one component at a time....

[widdowson2008]

Just to add to what has already been said, at 90C, the stat should have opened by 4mm.
Another 1.5mm and it should have closed the head return port.
That stat sounds a perfect example of knackerdness.
Definitely your problem. Nice when they are that easy and better still when no damage has been done.

[mayk19]

mmmmmm, perplexed !

Change, Rad, stat, burts pipe and water pump.. The garage just called saying all thats done, but there not 100% certain that all is well... They want me to come over at 3:30 and take a look at the Bongo up on the ramps as they have a theory !

Will post up on here later.... I think I'm heading towards head gasket here and to stop putting it off !

[missfixit70]

I'm afraid HG/cracked head could well be right, sniffer test often won't pick it up
I went through everything over a 4 month period & kept finding straws to clutch at until it reached a point where it was airlocked every time I went to start it from cold, so had to bleed it evey time, system was pressurising, hoses were solid after a run. Upshot was, head was gone Gasket was ok apparantly, but there was water in no 2 cylinder, nothing visible on the head, but I'll get it cleaned up & see if I can see anything when i get a chance.
New head etc & all running fine thanks to Allans who went above & beyond to get mine done (all metal pipes & hose replaced at the same time) before their holiday

[gmaczbongo]

The stat is not for cooling purposes, it is to help the engine warm up quicker and help keep it at the proper temperature.
Problems are when it is stuck open, engine can run cooler than it should and the choke etc can come back into play and fuel use goes up. When stuck closed, engine overheats as the water cannot get to the radiator to cool down.
If engine is overheating, remove stat and this will prove stat is not a problem.
When air coming into the radiator is cold and the engine temp lowers too much, the stat will start to close or close and will stay there until the engine warms up again. This is governed by the stat opening value.
You do not mention if the garage know how to bleed a bongo properly.
Could this be the problem after the new rad etc was fitted.
Why are they showing you something on the bongo and not just repairing it.

[missfixit70]

The stat is not for cooling purposes, it is to help the engine warm up quicker and help keep it at the proper temperature.
Problems are when it is stuck open, engine can run cooler than it should and the choke etc can come back into play and fuel use goes up. When stuck closed, engine overheats as the water cannot get to the radiator to cool down.
If engine is overheating, remove stat and this will prove stat is not a problem.
When air coming into the radiator is cold and the engine temp lowers too much, the stat will start to close or close and will stay there until the engine warms up again. This is governed by the stat opening value.
You do not mention if the garage know how to bleed a bongo properly.
Could this be the problem after the new rad etc was fitted.
Why are they showing you something on the bongo and not just repairing it.

Choke? Not on a diesel bongo
Removing the stat can also produce overheating under higher loads on a bongo as it then doesn't divert the coolant as much coolant to the rad by shutting in the recirc port on the top of the stat. It means it'll take longer to heat up, but won't control properly, not advised to run without one, even for testing purposes.

[mayk19]

OK.. Got back from Garage.. They have run him over the hill and back and the Temp guage stayed at 1pm (Haden Alarm attached to my guage).. Run for a good period at 2-3000 rpm in the garage and the concerns they still have and questions are,

1, The fans kick in at around 92 degrees but appear to stay on until back down to 60 degrees.. why are they staying on ?

2, Heater... The heater is lacklustre, not heating very well.

3, Flow diagram. Does anyone have a flow diagram of cooling system ? It appears the out (pipe down the passenger side) will be quite cool when the return side is very hot.. I may have the sides mixed up. There just concerned there maybe a blockage somewhere thats not letting water flow properly.

To confirm, I've changed the RAD, STAT and Water pump.

thanks all for help.

[mayk19]

You do not mention if the garage know how to bleed a bongo properly.
Could this be the problem after the new rad etc was fitted.

no, thats all good. garage has drained, bled, refilled system many times and its been very good. He's had all the fact sheets on bleeding, proper engineer not a parts changer.

[missfixit70]

OK.. Got back from Garage.. They have run him over the hill and back and the Temp guage stayed at 1pm (Haden Alarm attached to my guage)(Do you mean the gauge has been modified or that you've fitted a Mason alarm? Haydn doesn't supply an alarm that modifies the temp gauge, but he ddoes supply a ressistor & instructions to modify it. If it's just sitting at 1 oclock if it's modified, why isn't it going up & down as it should?).. Run for a good perioud at 2-3000 rpm in the garage and the concerns they still have and questions are,

1, The fans kick in at around 92 degrees but appear to stay on until back down to 60 degrees.. why are they staying on ?I'd say you've got an airlock/blockage or something on the heater circuit as the fan switch is taking it's reading from above the heater supply hose above the starter. The other possibility is that you've got excess temperatures in that area due to head/gasket leak

2, Heater... The heater is lacklustre, not heating very well.Do you mean the fan isn't very powerful or not very hot? if it's the fan, look at the resistor/control pack & check the fan is spinning freely, may need refurbing - http://www.igmaynard.co.uk/bongo/forum/ ... 43&t=28727 . If it's not very hot, then the matrix possibly has a blockage/airlock, maybe not bled properly?

3, Flow diagram. Does anyone have a flow diagram of cooling system ? It appears the out (pipe down the passenger side) will be quite cool when the return side is very hot.. I may have the sides mixed up. There just concerned there maybe a blockage somewhere thats not letting water flow properly. Wrong way around, bit worrying if the garage don't know which is which The supply to the heaters is the hose that goes over the starter on the drivers side, returns is the thin metal pipe on the passy side that then feeds into the stat housing. Try this lot -
http://www.igmaynard.co.uk/bongo/forum/ ... =3&t=36433 or there's a version in the factsheets somewhere

To confirm, I've changed the RAD, STAT and Water pump.

thanks all for help.

[mayk19]

Hi again,

thanks for help, quick answers,

Yes, its a Mason Alarm sorry wrong name sprang to mind.

1, Great, thats good info, will get them to check that.

2, Its not very hot, never has been since purchase.

3, Its my account of which way round the flow is, not garage. Thanks for link, found a flow diagram now ta.

Forgot to ask, the fans have four wires but only appear to be working at single speed, are they single or multiple speed ?

Cheers.