Cooling system

[dandywarhol]

Just to avoid confusion TGP - are you calling the headertank the top tank on the radiator or the plastic expansion tank?

[The Great Pretender]

Just to avoid confusion TGP - are you calling the headertank the top tank on the radiator or the plastic expansion tank?

According to The guy in charge of electronics at a motor manufacturer, on the Bongo it is a failed attempt at a degassing tank.
What happened when you reved the Bongo, did the pressure rise and fall with revs as mine does or is it just pressure build up?

[dandywarhol]

Revving barely changed the pressure - it stayed at 5 for yonks til i raised the temperature by increasing the revs to around 3500 - it then fluctuated between 9 and 11 psi but more as a result of temp change as the fans cut in and out.

[Aethelric]

Revving barely changed the pressure - it stayed at 5 for yonks til i raised the temperature by increasing the revs to around 3500 - it then fluctuated between 9 and 11 psi but more as a result of temp change as the fans cut in and out.

I would not expect the pressure to change very much. It does not take much of a differential pressure across the pump to push the water around the system.
TGPs system though can have a closed thermostat just after the pump so its pushing "against a closed door" hence a high pressure.

Dave

[Aethelric]

I have to admit I haven't read all this thread, but the bits I have seen seem to mostly confirm what we suspected before.

Is there anything that contradicts the basic flows shown on this diagram that I drew ages ago? (click on the image to get a full-size version)


I am pretty sure the connections are right because I looked very hard at all the diagrams from the stuff I assembled on lushprojects.com. I also checked against what I could see on my car.

I don't think the heater system is directly linked to the header tank circuit.

I can't cope with all these words. Must Have Pictures

Hi alphabeta, what do the dotted lines signify? You have a dotted connection to the front heater from the header tank.

Dave

[The Great Pretender]

Revving barely changed the pressure - it stayed at 5 for yonks til i raised the temperature by increasing the revs to around 3500 - it then fluctuated between 9 and 11 psi but more as a result of temp change as the fans cut in and out.

I would not expect the pressure to change very much. It does not take much of a differential pressure across the pump to push the water around the system.
TGPs system though can have a closed thermostat just after the pump so its pushing "against a closed door" hence a high pressure.

Dave

Im getting posts dissapearing, if this 1 works, the stat closed allows the coolant into the heater pipes and pressure is less, higher pressure comes when the stat is open.

[alphabetter]

Hi alphabeta, what do the dotted lines signify?

Nothing in particular - just trying to separate the flows through the heaters from the rest of the cooling system.

You have a dotted connection to the front heater from the header tank.

Doh! You are quite right - I withdraw my earlier remark!

[dipstick]

'You have a dotted connection to the front heater from the header tank.'

This is correct, it does not go direct to/from the heater but it joins the heater return pipe to the crankcase very close to the coolant exit pipe on the heater and is a smaller dia pipe than the return pipe.

[Grahame at work]

Update on Experiment 1

Cos there was a lot of white stuff around this morning I was running the engine while clearing it. When I got in I noticed that the expansion tank hose temperature was slightly above that of the top hose – not by much - 1½ to 2 degrees.
The usual queue on the way to work wasn’t slow enough to watch for any length of time but when I got to work and parked I watched the readings for a while before switching off.
I assume because of the cold weather the hoses had not warmed up as much as yesterday and they were both still below 60. The refresh time of the two channels is not the same and also quite slow – I think for power saving as it only runs off 1 AAA cell.
However, on average the reading for the tank hose appeared to be leading the top hose reading.
See also the readings I posted at the end of the first run – the tank hose is a couple of degrees above the top hose.

Now are these observations a function of the hose diameter, or something,
- or is it a tantalising clue?

If the white stuff holds off over lunch I may get the chance to refine / adjust the method.

This is far more interesting than what I do for a living.

Regards Grahame

[Grahame at work]

Experiment 1.1

revised method


moved the tank hose sensor to the smaller 'in-coming?' hose and used self amalgamating tape to try and remove wind chill effect.

Let it idle for a while - initially the tank hose was one step ahead of the top hose but by the time I switched off the readings were


Questions questions questions

I'll see what I get when I head home tonight.

Regards Grahame

[Simon Jones]

Grahame, where did you get that 2 channel thermometer from? I'm looking at buying / making something similar & would be interested to find out. Thanks

[Grahame at work]

Simon,

£7 from our local garden centre - Its a Gardman or is it Gardmon? inside/outside temperature monitor.

It uses glass bead therminstors, one on a length of wire and one mounted on the circuit board. I removed them both and fitted them on long wires.

I was trying to find a cost effect method of getting temperature measurements when I found this at the weekend. I think its brill for the price - saved me a lot of messing about.

Only thing is I'm not sure what the max reading is - when I tested it out before I changed the cable every time I put it in the boiling kettle it went to HH.H. that may be because of the water shorting the wires though!

By the way it has min & max readings accessed by the right hand switch - could be useful.

Regards Grahame

[Aethelric]

I have to admit I haven't read all this thread, but the bits I have seen seem to mostly confirm what we suspected before.

Is there anything that contradicts the basic flows shown on this diagram that I drew ages ago? (click on the image to get a full-size version)


I am pretty sure the connections are right because I looked very hard at all the diagrams from the stuff I assembled on lushprojects.com. I also checked against what I could see on my car.

I don't think the heater system is directly linked to the header tank circuit.

I can't cope with all these words. Must Have Pictures

How about this


I still think there is a bleed through the stat from the bottom hose somehow though.

[haydn callow]

That looks good to me...Question...If the stat is not open and the coolant is not being "pumped" round....how does the rear heater heat up so quickly ??..I find it hard to belive this is down to convection.
I had a back boiler which heated 2 x upstairs rads and one downstairs rad. The downstairs rad never got even warm untill I put a pump in the system.
Always more questions than answers

[Aethelric]

That looks good to me...Question...If the stat is not open and the coolant is not being "pumped" round....how does the rear heater heat up so quickly ??..I find it hard to belive this is down to convection.
I had a back boiler which heated 2 x upstairs rads and one downstairs rad. The downstairs rad never got even warm untill I put a pump in the system.
Always more questions than answers

Hi Haydn, if the stat is not open then coolant from the header tank is split three ways - into the front heater, the rear heater and the "other" stat input. I believe that the different diameters of pipes used are to distribute the water in a predetermined proportion.

When the main path through the stat opens and the "other" stat input is closed the coolant from the header tank is then only split two ways - to the heaters.

The pumps output is into the top hose. Its input comes either of the stats inputs and somehow from the heaters return through the block.

I THINK... (but it seems logical to me)

I have no idea what is happening about the turbo though.

Dave