Bongo Fury

Why does the rad flow top to bottom as most of the time it isn't doing that?

me thinks that when the stat opens this part of the circuit has the largest bore pipes with the highest pressures,the pump shoves it round the circuit, and the thermal rise in the engine/head also assists.

plus if the rad is doing its job it should cool as it enters,and cool is heavier than warm so should fall and leave low. it only needs to do this when the stat opens as the temps are rising, at the other times enough heat may be lost in other ways to allow the top of rad loop to cope by just circulating the hot coolant round the system,as in the warm up period.

maybe.

At what temperature does the rad start to flow top to bottom, and when is it fully operational?

that has to be the stat opening temp, and fully open temps hasnt it

quoting steve on the other thread 82 ish to 96 fully open..

Northern Bongolow wrote:that has to be the stat opening temp, and fully open temps hasnt it

quoting steve on the other thread 82 ish to 96 fully open..

Assuming the stat needs 96c to be fully open to allow the rad full flow, how often do you think a clean coolant system would reach that temp under normal running?

The Great Pretender wrote:

Northern Bongolow wrote:that has to be the stat opening temp, and fully open temps hasnt it

quoting steve on the other thread 82 ish to 96 fully open..

Assuming the stat needs 96c to be fully open to allow the rad full flow, how often do you think a clean coolant system would reach that temp under normal running?

Need to correct the 96 Ady quoted. 96 is where the head flow to stat is closed off. As binky quite rightly said, 110C is the FULL flow from the rad. (me and my gob )
Sorry - carry on the pair of you. This may get interesting

The Great Pretender wrote:

Northern Bongolow wrote:that has to be the stat opening temp, and fully open temps hasnt it

quoting steve on the other thread 82 ish to 96 fully open..

Assuming the stat needs 96c to be fully open to allow the rad full flow, how often do you think a clean coolant system would reach that temp under normal running?

As previously mentioned, the 96 should read 110 FULLY open.
In answer to your question, I wouldn't think it would ever get to that under normal driving conditions.
OK Mel, I bit - where are we going?

an idicator of when, may be when the fans are called in mel.
these only come in when the stat has lost the plot,so to speak.
switching point is 106.

ECU control of fans is "over 108 c" in the manual.....

50% ratio of G12+ type OAT coolant has a boiling point of 136c

to add few pence to the debate....... will follow more when I get to Silverstone tomorrow

mikexgough wrote:ECU control of fans is "over 108 c" in the manual.....

That's the scavenge fan temp isn't it? (p 83 - cleaning fan - no 3)

Can't find it now, but I'm sure I found rad fan switching temps in the manual of mid 90's for low speed & 104ish for high speed (as well as being very similar in actual measured values on top hose on several bongos)

Re the coolant type, on my bonnet & most I've looked at it has a big yellow sticker that says "use ethylene glycol coolant for aluminium engines"

widdowson2008 wrote:

The Great Pretender wrote:

Northern Bongolow wrote:that has to be the stat opening temp, and fully open temps hasnt it

quoting steve on the other thread 82 ish to 96 fully open..

Assuming the stat needs 96c to be fully open to allow the rad full flow, how often do you think a clean coolant system would reach that temp under normal running?

As previously mentioned, the 96 should read 110 FULLY open.
In answer to your question, I wouldn't think it would ever get to that under normal driving conditions.
OK Mel, I bit - where are we going?

It's not where, but where the coolant isn't going is where I hope we are going..................

If the bypass closes at 96c and gets to 110c before fully open it would be logical to conclude that the rad is not fully operational during normal running.
So is the top to bottom rad a bad idea?
As the flow enters the rad top chamber then out to the degassing tank any debris can fall out slowly filling the bottom chamber or cores, or both with crud. This over years creeps towards the outlet blocking more and more of the radiators cores. The Bongo's excellent cooling capabilities compounds this problem by rarely calling on full flow through the rad.
It is then when asking the system to give 100% it cant

missfixit70 wrote:

mikexgough wrote:ECU control of fans is "over 108 c" in the manual.....

That's the scavenge fan temp isn't it? (p 83 - cleaning fan - no 3)

Can't find it now, but I'm sure I found rad fan switching temps in the manual of mid 90's for low speed & 104ish for high speed (as well as being very similar in actual measured values on top hose on several bongos)

Re the coolant type, on my bonnet & most I've looked at it has a big yellow sticker that says "use ethylene glycol coolant for aluminium engines"

Nothing to add to this thread... Just dipped in for the notifications on its progression...

& to say Kirsty check this thread...!?? http://www.igmaynard.co.uk/bongo/forum/ ... =3&t=50252

Don.t mind me!!

The Great Pretender wrote:

widdowson2008 wrote:

The Great Pretender wrote:
Assuming the stat needs 96c to be fully open to allow the rad full flow, how often do you think a clean coolant system would reach that temp under normal running?

If the bypass closes at 96c and gets to 110c before fully open it would be logical to conclude that the rad is not fully operational during normal running.
As the flow enters the rad top chamber then out to the degassing tank any debris can fall out slowly filling the bottom chamber or cores, or both with crud. This over years creeps towards the outlet blocking more and more of the radiators cores.[/color]

Think you may be changing the rules mid discussion here a bit Mel.
Crud build up will obviously make the system inefficient, but we started out talking about a clean coolant system didn't we?

widdowson2008 wrote: Think you may be changing the rules mid discussion here a bit Mel.
Crud build up will obviously make the system inefficient, but we started out talking about a clean coolant system didn't we?

I don't think so. TGP is asking that to see how often the rad will get a good throughflow to stop it clogging at the bottom. I've felt my bottom hose a few times and don't think the thermostat opens much at all, because the hose is rarely more than warm, indicating that most cooling is done by the heater rads and top of the main rad. It seems a silly system to me, which may well be prone to clogging

Ahhhhhhhh - penny drops
However, I think the stat does open (mine does anyway cos I can see it on the TM-2) but only a very small amount, allowing a trickle through the rad. So going back to Mels point, he is probably right.
Personally, I don't think you are going to get the bottom hose more than luke warm cos if the rads doing its job properly then by the time coolant gets to the bottom, it will (should) have lost most of its heat don't you think?