Adding a 2nd header under the passenger seat

[cptsideways]

Has anybody thought of this?

Adding a secondary header/air bleed tank under the passenger seat, seems a simple solution to the bleeding problem. Mounted at the right height onbviously so its above the engine coolant level. It could be full in use too that's not an issue just so long as its a proper pressurised one.

Am researching ones that might fit, Audi A4 ones look handy & have inbuilt level alarms.

[cmm303]

It would need to be same height as the existing header tank, or am i missing something?

[jimmo62]

In which case simply running a second hose up to the existing tank with a t-piece into the existing expansion hose would do the same job maybe? But you would then have an additional circuit for the coolant to circulate so maybe not such a good idea?

[mikeWalsall]

Would the AC cope with an extra warm passengers bum on a hot sunny day ..??

[cptsideways]

The issue I see with the existing system is if any air in the system is not bled out (obviously not always an easy/100% reliable task) there is air in the head regardless. The problem is it really can't circulate out to the header by the nature of the ciculation design.

Fitting an additional header tank at the point where air can rise is better. With a warning light/buzzer at that point you will get a much earlier warning. Also a simple visual check will indicate whats happening. The hose is there ready for it one

Plenty of other cars have similar systems the latest Mazda2 has dual expansion tanks also lots of cars have air vent systems at their trap points which is what the Bongo should really have instead of the dead end hose!

Trying to find a single entry 8mm input tank is not so straightforward though but I'm sure something is out there probably from something old school.

[mikeonb4c]

The issue I see with the existing system is if any air in the system is not bled out (obviously not always an easy/100% reliable task) there is air in the head regardless. The problem is it really can't circulate out to the header by the nature of the ciculation design.

Fitting an additional header tank at the point where air can rise is better. With a warning light/buzzer at that point you will get a much earlier warning. Also a simple visual check will indicate whats happening. The hose is there ready for it one

Plenty of other cars have similar systems the latest Mazda2 has dual expansion tanks also lots of cars have air vent systems at their trap points which is what the Bongo should really have instead of the dead end hose!

Trying to find a single entry 8mm input tank is not so straightforward though but I'm sure something is out there probably from something old school.

Your usual intelligent questioning The only thought I can contribute is that, for some reason or other, I wonder if the worst problems of bleeding a Bongo might be associated with the rear heater circuit having to be drained. I bled my own Bongo twice, and didn't drain the rear heater, and I had no trouble. My mechanic did likewise on a couple of occasions (twice when a new radiator was fitted, since the first one proved faulty) and had no trouble. However, when (because of a corroded rear heater metal pipe) he had to bleed it after a full system refill, he said it had been awkward to bleed. It was some months after that that the head cracked. Also, until this last occasion, every time the Bongo was bled I could expect it to burp and the header tank level to drop a little after the job had been done. But on this occasion the header tank level never dropped. Now this could all have been coincidence, but I've often wondered whether a bubble could have remained trapped in the rear heater circuit and when it broke free it never made it to the header tank, lodging instead in the channels around the head area of the engine and causing a local hot spot. On the other hand, 125k miles with the last 70k involving a lot of short daily runs and a high number of thermal cycles could have been what exposed the vulnerability of the head to developing a crack (I believe they almost always go in the same place, where the casting is thin). We'll never know, but I mention all this in case it gives you any thoughts on how to improve what is undoubtedly a rather Heath Robinson cooling system.

[g8dhe]

I wonder why the 2l petrol technique wouldn't work, bring the bleed tube back up to the degassing tank under the bonnet, then any air can be safely discharged into the tank and vented / filled as normal ? No additional hardware needed no extra joints, just extend the bleed tube itself.

[cptsideways]

I wonder why the 2l petrol technique wouldn't work, bring the bleed tube back up to the degassing tank under the bonnet, then any air can be safely discharged into the tank and vented / filled as normal ? No additional hardware needed no extra joints, just extend the bleed tube itself.

Is there a plumbing diagram for these? Sounds a sensible option

[g8dhe]

Yup see the Lush projects site http://www.lushprojects.com/bongopartsmk2/ in general for mechanical diagrams.
In particular this page, hose 15-383 I think;
http://lushprojects.com/bongopartsmk2/c ... 1of02.html

[Northern Bongolow]

im all for fresh thinking and new ideas.
in my experience there are 2 main air trap spots.
one is the pipe that leaves the head to go to the rad top, because this has to drop in height to go under the drivers feet air will not be pushed down hill. (this pipe has a fill nipple just above the front axle.)

the second is the front heater matrix, this air is trapped at a high spot in the system so again has to drop down to leave the matrix.

the bleed pipe it has been established is not at the highest point in the cylinder head, so again if not bled correctly air can lodge in the ceiling of the head.

for the coolant system to circulate the above air pockets must be removed opening the bleed pipe is often not enough in itself to bleed it out and sometimes you have to manually manipulate the air out by squeezing pipes etc.

[Simon Jones]

This is the 2 litre header tank and you can see the extra pipe.



Having experimented with extending the bleed pipe up to header tank, I can confirm that on my previous diesel (at least) there is insufficient flow to push the coolant 'up hill'. If you do it, I think you'll create an air pocket in the extra pipework which will cause all sorts of issues.

[g8dhe]

I wasn't thinking so much of pushing the coolant up the tube, but letting the gas/air rise up the bleed tube and into the de-gassing tank safely away from the coolant flow itself, given the bubbles that appear in the bleed tube during the bleeding process this and the de-gassing tank itself are the only places that the trapped gas can escape. Leaving it connected whilst actually driving should mean that any other gas that remains trapped or gets in for whatever reason should escape out of the coolant flow.

The "Radiator feed" should be able to loose gas in the tank in the normal way whilst the thermostat is closed.
Adding an extension to the Bleed tube to the de-gassing tank should allow gas coming out to the Re-circ or Turbo feeds an escape route.
That then only leaves the Heater feed that doesn't have a means for gas to escape directly.

[wonkanoby]

http://www.carbuildersolutions.com/uk/b ... with-bleed

http://www.carbuildersolutions.com/uk/b ... with-bleed

what size are heater hoses

as it seems to me that spliced in and raised up high.evan if only temporary ,in one of the hoses to heater would be a good idea

[Simon Jones]

The inside diameter of the bleed pipe is around 9mm. I've used this type of valve before for bleeding which works well: