ANOTHER OVERHEATING BONGO, HOPEFULLY SORTED

[francophile1947]

Not with you Peter
I've just looked at the diagram and it seems to agree with what I said - hose from bottom of radiator goes to the thermostat.

[The Great Pretender]

You are right dandy, hot from engine into rad at the top. Cooler from bottom of radiator back to engine. BUT then to thermostat, and that IMHO the thermostat position is the problem.

[Harry]

But surely the temp sensor part of the thermostat is on the hot side..so when it gets hot it will let cool water through into the system but not so near the head as to crack it?

[The Great Pretender]

You would think so harry, but there are other requirments, the main one being cooling the temperature around the exhaust valves (the hottest part of the head)

[alphabetter]

But surely the temp sensor part of the thermostat is on the hot side..so when it gets hot it will let cool water through into the system but not so near the head as to crack it?

If you read back to the middle of this monster thread you will find out that the main learning point is that the thermostat in the Bongo is almost certainly in the RETURN path from the radiator to the engine.

So in Bongo land the termostat is on the cool side not the hot side.

[Harry]

Yeh but ...Yeh but...the water/coolant can't be cold/cool on both sides of the thermostat when the engine is warmed up. Surely the idea of a thrmostat is for it to open to let water flow past and/or increase circulation when part of the system gets too hot. If the sensing part of the thermostat is on the hot side then the thrmostat will open letting coolant through. When the coolant cools down the thermostat will shut down again.

It probably matters not where the thermostat is placed as long as it allows extra flow when required to do so. In our bongos its in the return circuit...thats fine..water/coolant transmits heat very well and the heat will be transmitted through the 'hot' coolant to the thermostat. The thermostat does not need water flowing past it to make it operate.

H

(Ex Aircraft Systems Technician -
Hopeless case when doing hands on car maintainance)

[dandywarhol]

Here's one to think about...........when the system is pressureised and therefore no air in it, does coolant actually circulate or is it the heat which transfers??

[Vanmanerik]

What difference to the engine would it make if the thermostat was in the top hose, just on the water outlet of the cylinder head, as in a 'normal' setup.

I have one or two ideas but would like to see if any-one else has them before posting them.

[antique]

great pretender the heads always seem to crack around exhaust valve i dont no if thats any help to you all ?

[francophile1947]

What difference to the engine would it make if the thermostat was in the top hose, just on the water outlet of the cylinder head, as in a 'normal' setup.

To my mind, this change would then allow the water to circulate through the radiator as soon as the engine was hot. This would result in the coolant being overcooled with the standard thermostat, so a higher temperature thermostat would probably be required (as fitted in most cars).

[Peg leg Pete]

Well since changing the thermostat a year ago, our Bongo as run fine, we have lot's of hills around us, winter/ summer and our bongo has run at nomal temperature

[Peg leg Pete]

Replaced thermostat, like for like

[francophile1947]

Replaced thermostat, like for like

Why would you fit anything else Peter?

[Peg leg Pete]

due to your last post -so a higher temperature thermostat would probably be required (as fitted in most cars).

[francophile1947]

due to your last post -so a higher temperature thermostat would probably be required (as fitted in most cars).

Ah! - that only applies if it was put in the top hose and the radiator came in to permanent use. Cars with "normal" cooling systems have higher rated stats.