Bongo Fury

The Great Pretender wrote: But did you feel the hose at the rad end?

Must admit I didn't TGP. But I can't see how the temperature could vary much along two feet of water filled hose???

Aethelric wrote:

The Great Pretender wrote: But did you feel the hose at the rad end?

Must admit I didn't TGP. But I can't see how the temperature could vary much along two feet of water filled hose???

Your measuring temp outside of the hose where the turbo and exhaust are. If it is coolant temp it could be passing back towards the rad through the bleed hole in the stat.
If you get the chance also try the sensor on the bottom of the small hose from the tank where it feeds into the heater pipework.

The Great Pretender wrote:

Aethelric wrote:

The Great Pretender wrote: But did you feel the hose at the rad end?

Must admit I didn't TGP. But I can't see how the temperature could vary much along two feet of water filled hose???

Your measuring temp outside of the hose where the turbo and exhaust are. If it is coolant temp it could be passing back towards the rad through the bleed hole in the stat.
If you get the chance also try the sensor on the bottom of the small hose from the tank where it feeds into the heater pipework.

Hmm, passing towards the rad! that means the flow is the other way!!
Whatever direction, I do think there is a flow, maybe a bleed, which does not rely on the thermostat opening as the temperature starts to rise as soon as the engine starts. This is easier to see on a cold day as the starting temperature is very low.
I put the probe on the far side of the pipe from the engine - it will be getting affected by heat from the engine, and cold from passing air too. It is pressed hard against the pipe though and covered with three layers of tape so I think the pipe surface temperature is dominating.
I'm happy to try any location that the probe lead length will permit.
Dave

lizard wrote:All this seems about average from what I have read on this subject. Normal running, temp is normal (are all Bongos running at same temp?). Idling, temp rises and stabilises. With high speed and uphill running, temp can rise even higher. Can normal running Bongos suddenly develop problems (design/manufactoring fault, not breakdown because of age) and overheat without any previous problems.

Complete conjecture, but maybe a bongo will run for quite a while with a partially blocked radiator, i.e. no flow through the bottom hose. The cooling around the rest of the system may be adequate for most conditions. The lack of sensitivity of the temperature guage would mask the problem. But a combination of events, hot days, heaters turned off, heavy loads, slow moving traffic etc. may push it beyond its reduced cooling ability.
Also continual non catastrophic overheating due to a blocked radiator may weaken some components which may spontaneously fail prematurely.
If the posts on dodgy japanese anti-freeze and incompatability with UK anti-freeze are correct than many bongos may be running around with blocked rads without their owners knowledge.
As I said, complete conjecture.
Dave

Aethelric wrote:

lizard wrote:All this seems about average from what I have read on this subject. Normal running, temp is normal (are all Bongos running at same temp?). Idling, temp rises and stabilises. With high speed and uphill running, temp can rise even higher. Can normal running Bongos suddenly develop problems (design/manufactoring fault, not breakdown because of age) and overheat without any previous problems.

Complete conjecture, but maybe a bongo will run for quite a while with a partially blocked radiator, i.e. no flow through the bottom hose. The cooling around the rest of the system may be adequate for most conditions. The lack of sensitivity of the temperature guage would mask the problem. But a combination of events, hot days, heaters turned off, heavy loads, slow moving traffic etc. may push it beyond its reduced cooling ability.
Also continual non catastrophic overheating due to a blocked radiator may weaken some components which may spontaneously fail prematurely.
If the posts on dodgy japanese anti-freeze and incompatability with UK anti-freeze are correct than many bongos may be running around with blocked rads without their owners knowledge.
As I said, complete conjecture.
Dave

And if the coolant is flowing through the degassing tank and not the bottom of the rad any particles in the system will fall out of the system where the movement is lowest as in a central heating system.

Can I join in?

I have done the same as Aethelric – I fitted a thermocouple to the return hose several weeks ago. I was restricted to the length of the cable and could only fit it on the flexible hose in front of the scavenger fan where it is about level with the bottom of the alternator. So that’s about ½ way between the stat and the radiator. It was fitted to the top of the hose with a ty-rap (not too tight).
I have since tried it in a couple of positions – pushed down the out cover on the hose from the engine down to the stat; on the return? hose from the heater that enters the stat pipe work on top of the stat and now I’ve put it back to the return? bottom hose.
In the positions of the heater return? and fed into (out of?) the top of the stat I got predictable readings. On the heater hose it read about 50C after warm up and stayed there. On the fed into / out of the stat I got readings of around 65/70C that remained fairly constant. For both of these positions I only got to run to and from my place of work or short runs to the shops and usually only got up to temperature (on my Mason modified temperature gauge) at the end of the trip.
The reason for putting it back to the bottom rad hose is that I got more interesting readings there.
Within the first week I did one longer trip to work, taking my wife to her work in the centre of town and then back out to mine. The temperature stayed at the ambient temperature for that morning until the mason gauge got up to the 11 o’clock position and as the mason gauge moved up to the 1 o’clock position the hose temperature rose to around 20C. As I drove out of town it went up and down between 30 and 15C. However, when I reached the usual traffic queue the mason gauge moved up to the 2 o’clock (or higher) which is normal but the hose temperature continued to climb. The queue was about a mile long and stop start all the way. By the time I got out of the queue the hose temperature had reached nearly 70C but dropped rapidly when I got moving at around 20 mph.
Now this has not happened since – I have been monitoring that hose temperature again for a couple of weeks and that has included a trip down to the Borders and the temperature rarely goes over 30C.
Before I went to the Borders I fitted an LED to monitor the voltage on the cooling fans. I wanted to know when they came on relative to the bottom hose temperature, i.e. when I had measured that high temperature were the fans on or off? My attempt to monitor the fans has not been entirely successful; I made the connection to the ‘high speed’ circuit (there are two supplies to the fans, one low speed and one high speed) on the assumption that the low speed was for the A/C and the high speed for the engine coolant. When I tried it out by turning on the A/C my LED came on but I decided that when the low speed circuit turns the fan the high speed coils actually generate voltage and so my LED will illuminate when either circuit turns the fans on.
However, I have not had time to re-arrange it and I have run with it like that for a couple of weeks now. The results are confusing. The light comes on when the mason gauge shows very high (sounds good) but stays on for a long time even when the mason gauge has dropped to 1 o’clock for some time (not so good). Basically I have got inconsistent data from the fan monitor so I’m planning to fit a more elaborate LED bar graph with 4 LEDs, one each for the drive from the ECU to each relay for each fan (including the scavenger) as well as the point already monitored.

So that may or may not help the debate –

At the time I thought the high bottom hose temperature was normal – as the normal cooling effect from the radiator stopped as the van had stopped moving at any speed but the engine didn’t cool down at all as it revved up to keep pulling away – so increase in temperature of the coolant flowing through the radiator. But having now got a longer run of data and seen that the fans apparently come on at relatively low temperatures I now wonder if that was an overheating condition narrowly missed.
If so was it because the fans didn’t come on for some reason?

My intention is to try and monitor the temperature sensor for the fans and see what that is doing. Nor sure how I’m going to do that but probably use the multi-meter to watch the voltage.

As a matter of interest I purchased a temperature monitor today – its really for the garden and doesn’t appear to read above 65 / 70 but it has a dual display so I’m hoping to replace the internal sensor with another external sensor so that I can monitor 2 hose temperatures at the same time – any suggestions as to which 2 positions to monitor?

Long winded but I hope relevant

Keep up the debat (where is Dandy?) I think we might get enlightenment at the end

Regards Grahame

Glad to have you onboard Grahame, the more that probe the system the more we will find out. And yes Dandy, where r u................ Haydn has gone very quite to.

WOW.......so many posts to catch up on...............just back from a wonderful 8 days in the Hebrides - no interweb malarky

Good stuff Grahame - you kept that quiet when I saw you in the Borders

Aethelric's on the right track I think - not conjecture...........

These pressure readings look quite high TGP, especially when the blow of pressure is around 16.5 psi I was expecting a bit lower. every psi equates to approx. 1.5 deg.C of temp rise before boiling then the coolant's pretty damn hot at 15 psi

I'll try to get some pressure readings in the tank this week................

Hi Grahame
Excellent data. Do you know where the temperature sensor(s), that switch on the fan, are located?
As regards your sensors, it may be interesting to see how much heat is lost as the coolant comes into the radiator and leaves by the other top hose to the header/degassing tank. I think that this path is a major part of the heat dissipation process, but I could be wrong (not unusual). If there is not much differential temperature, I'm wrong.

Dave

dandywarhol wrote:WOW.......so many posts to catch up on...............just back from a wonderful 8 days in the Hebrides - no interweb malarky

Good stuff Grahame - you kept that quiet when I saw you in the Borders

Aethelric's on the right track I think - not conjecture...........

These pressure readings look quite high TGP, especially when the blow of pressure is around 16.5 psi I was expecting a bit lower. every psi equates to approx. 1.5 deg.C of temp rise before boiling then the coolant's pretty damn hot at 15 psi

I'll try to get some pressure readings in the tank this week................

You like Hadyn are confusing pressure with temp.

Grahame
I notice that your "normal" temperatures in the bottom hose are lower than mine. This could all be accounted for by thermal coupling to the hose of course, or it may signify a different degree of radiator clogging.
A. If a radiator is partially clogged then there will be a low flow through the bottom hose, hence its temperature will be more affected by the ambient temperature so the hose temperature will be lower.
OR
B. If a radiator is partially clogged then the general temperature of the coolant will be higher so the hose temperature will be higher

A and B can't be true simultaneously, but A may be true when the engine is quite cool and B may take over if the engine begins to overheat. Also overheating may cause an increase in pressure in the radiator and thus a higher flow into the bottom hose (provided that there is a lower pressure part for it to go of course). which means we move to situation B.

Alternatively at 12.40am it could be the beer talking. Time for bed.

PS hey the clock on this forum is still on GMT

I don't think i'm confusing it TGP - the 1.5 deg per psi is only an approximation.
What I'm surprised at is the pressure on your gauge @4000 rpm is pretty close to the cap valve blow off pressure.

dandywarhol wrote:I don't think i'm confusing it TGP - the 1.5 deg per psi is only an approximation.
What I'm surprised at is the pressure on your gauge @4000 rpm is pretty close to the cap valve blow off pressure.

Ok u test it.

Hi Dandy - glad you enjoyed the trip
How did the sleeping arrangements go? if you know what I mean

I was still trying to understand what I was getting in the way of data and was more interested in the rails / runners thing when I saw you.

Aethelric - I didn't know where the fan sensor was until a few days ago when Brora posted his info about the fans being on all the time in his relations Bongo. I think it is on the drivers side about half way along - Brora's photo is very interesting

As for measuring the difference across the radiator top I can try but I'm not sure that the sensors / display will be accurate enough to tell what is going on as I suspect the difference will be small. I will try it though when I have got extended sensors working and it stops snowing

I had my coolant changed and radiator flushed about two months ago (which is why I started to keep any eye on temperatures - mechanic didn't have the easiest of times bleeding the system) so I don't think I have any issue with blocked radiators. I did try and use self-amalgamating tape to fix the thermocouple but couldn't get my hands close enough to do it - hence the ty-rap so I may be getting more effect from air flow across / around the hose.

ALL,

I am also trying to get my head around the flow mechanics and I think I need a better diagramme to do that so I'll let you know if I can come up with one.

Regards Grahame