Bongo Fury

Was the last thread only 21 pages it seemed much longer at the time Lets hope that sense prevails and this thread remains civil and sex change free People were getting more overheated than bongos last time around

scanner wrote: Bongos used in cold conditions may rarely (especially if used for lots of short trips) use their radiators, when they suddenly change to running in conditions where the heaters aren't needed, the radiator can't cope with the demand put on it as it's partially or wholly silted up.

Just a theory shoot it down if you like.

Can't shoot it down cos' I don't know but, if the heaters are permanently "on", with the heat in the van being regulated by flaps altering the airflow, why should it matter when the heaters aren't needed?

I still have problems trying to understand how the stat works as the bottom hose was always cool even when the rad was hot at the bottom and all flow looked like it was going through the tank. Also if the stat was on the outlet it would control the temp where needed at the hottest point.
It also creates a restriction that under certain conditions allows the pressure in the head to be above the cap pressure, raising the boiling point and helping to stop localised boiling around the exhaust ports (the hottest part of the head)

I didnt realise this has been covered before but maybe what I did next hasnt. I removed the stat from the return and fitted one to the outlet and am playing with it. Ok so now the return from rad to engine is free to flow but guess what the hose is no hotter.

Bongo stat

I don't belive there is anything inherently wrong with the cooling system of our Bongos. There are far to many 12 year Bongos running around for that to be the case.

What can cause overheating ? feel free to add to this list.
Blown head gasket.
Jammed stat
Broken fan belt.
Coolant loss (for whatever reason)
Gunge in the system.
Damaged A/C heat exchanger affecting airflow

In any 12 year old vehicle you can expect the odd few to lose coolant which can lead to overheating and damage to the head or gasket.
The coolant loss can be caused by.

Bad luck (hose clip loose)
Old hoses giving up.
Water pump bearing failing.
Physical damage

Blown head gasket can just be a age thing and happens even on new cars.

Gunge in the system caused by.
Poor maintainace

Jammed/failed stat
Wax stats have always been a bit iffy and routine replacement (5years) should help but the odd one will always fail.

So !! to sum up. Buy a 12 year old Bongo.
Make sure the coolant is changed if in any doubt, and make sure the rad
is free from crud.
Check the belts and the water pump bearing on a regular basis.
If the hoses are original change them. and inspect all metal pipes.

For less £300 on the price of your Bongo you could fit new hoses/belts/radiator/stat.

Why do we all replace the cambelt ?? has anyone ever had one break? That money could be better spent perhaps ??

I have recently been on the Toyota HiLuxe sites and the Landrover sites, they have exactly the same problems if not worse with the older vehicles.

TGP... I belive the bottom hose is cool because the Stat is open and the rad is doing what it's supposed to do. I have also messed around with moving the stat. It never made any real differance to the bottom hose.
I think the stat is open most of the time once the temp is up to normal. Taking the stat out makes no differance once running temp is reached which does take a little longer. The bypass "thinner pipes" allow hot coolant into the heaters quickly before the stat opens.
I THINK !!

I reckon you are correct there Haydn

Haydn the highest point in the engine, the head will have problems venting air/gas the coolant pipes both connect to the engine from below. If you think of it in the same way as a central heating radiator piped from below any air or gas will be trapped in it untill you vent it. If the water comes in at the bottom and goes out rising from the top it will self vent.
Even if the system is fully vented fresh water will give off air when heated also the pump at high speed can cause cavitation if this cannot vent through the design of the system, the system is flawed.
I dont have any problems with my system and im not trying to panic people im trying to learn and with the help of others to keep our 12 year olds in good health and the stat position IMHO is part of a possible problem.

Haydn, I said earlier that the bottom of the rad was hot but the lower hose wasnt, so no or very little flow.

IMOH I don't think that...once the system is properly bled.....air can be reintroduced into the system unless there is somwhere for it to get in.....that should not be the case in a sealed system. The water pump is wizzing around but how can it be creating air?
the heating pipes are all below the surface of the coolant level in the tank.
The top of my rad is very hot but this gets less as you feel down it and the bottom is the same'ish as the bottom hose.
I could well be totally wrong (has been known) but what I say makes sense to me.

The Great Pretender wrote:I still have problems trying to understand how the stat works as the bottom hose was always cool even when the rad was hot at the bottom and all flow looked like it was going through the tank. Also if the stat was on the outlet it would control the temp where needed at the hottest point.
It also creates a restriction that under certain conditions allows the pressure in the head to be above the cap pressure, raising the boiling point and helping to stop localised boiling around the exhaust ports (the hottest part of the head)

I didnt realise this has been covered before but maybe what I did next hasnt. I removed the stat from the return and fitted one to the outlet and am playing with it. Ok so now the return from rad to engine is free to flow but guess what the hose is no hotter.

Bongo stat

You were a big contributer in last years marathon GP

Which way is the stat fitted in the system? is the bridge piece upwards?
Is it my eyes or is that bridge piece that the pin sits in offset?

And...........................I don't like the mismatch on your floor pattern

HC.........to add to your list - if the a/c heat exchanger is damaged the coolant radiator won't get enough airflow.

It is a shame we seem at odds here Haydn, it would have been nice to have you onside with your testing. I didnt start this thread to argue but to move forward.
Major places where cavitation occurs are in pumps, on propellers, or at restrictions in a flowing liquid.

As an impeller's (in a pump), or propeller's (as in the case of a ship or submarine) blades move through a fluid, low pressure areas are formed as the fluid accelerates around and moves past the blades. The faster the blades move, the lower the pressure around it can become. As it reaches vapor pressure, the fluid vaporizes and forms small bubbles of gas. This is cavitation. When the bubbles collapse later, they typically cause very strong local shockwaves in the fluid, which may be audible and may even damage the blades.

was I, and I was told drinking red wine improved the memory, cant remember who told me.
Cant tell you what way it was fitted as I was working above it when it fell out.
Yes it is your eyes. Didnt Mom tell you it would send you blind?
Aint my floor it is my workshop work surface where do you eat your lunch.
Getting back, I had a container under the Bongo when I removed it. 5ltr was lost but the tank was still up to level.

The last thing I want to do is argue with anyone...This is a place where we all put forward our points of view and then a consensus is reached. You have now explained cavitation to me and what you say makes perfect sense. I cannot disagree with facts. I thought ships/boats propellers cavitated when they drew air in from the surface. I didn't think a submarine at 300ft could create bubbles.
How fast doe's water have to travel over a surface for this to happen??
Questions..Questions

The Great Pretender wrote:I had a container under the Bongo when I removed it. 5ltr was lost but the tank was still up to level.

Can i just clarify? Did i read that correctly? You removed the stat,lost 5 litres of coolant as a result,yet the header/expansion tank was still at max? Forgive me if i got it wrong,that's how i read it...