Coolant

[iggypop]

Have just changed coolent, used the first method on the fact sheets, but it did not make alot of sence to me. Anyway when i started ran the engine at 2500 rpm steam started to flood out of the breather pipe so i stopped the engine. In the end i topped up everthing and put the bung back in. At first the heaters would not work, but now they have started to work but i still cant get the bottom pipe hot, is it supposed to be hot ? . I have never had any water probs and i am wishing i had left it alone Thans Ian.

[haydn callow]

I would suggest you DO NOT use your bongo untill it is bled properly. This hasn't been done.
If you would like to ring me at 6pm I will go through it with you. (just off out).

[Simon Jones]

Try this method - based on info given to me by a Bongo expert & it worked sucessfully.

1) Fill expansion tank to the flange / join - leave cap off
2) Run engine for about 10 mins till it gets hot, all the time checking level in tank & topping up as req'd
3) Set front & rear heaters to hot, with fan set to 3
4) Open bleed pipe, with it angled down
5) Drawer off 2 litres with someone else topping up so the level does not drop. The water will be frothy - thats ok
6) Run the engine to 2500 rpm until the fan starts, that shoud be when the thermostat opens. The level may drop at this point
7) Repeat steps 4) - 6) several times. It can take up to an hour to get it until there are minimal bubbles coming from the bleed pipe
8 ) Put the cap on & run for a while.
9) Stop engine & carefully remove expansion cap. There should be pressure in there, but not enough to cause any coolant to come out, but the level should rise a few mm. Replace the cap
10) Allow to cool down for several hours, or overnight
11) Remove the cap & check the level - it should have dropped (possibly as much as a litre). Top up to the max line & keep an eye on it for the first fews days

There seems to be debate about what constitutes a 'warm' bottom hose. Some people say the pipe hardly warms up at all, & others (myself included) have had it hot to the point where you can't hold it. If you have a Mason alarm fitted, you can see the temp guage drop when the fans kicks in as the thermostat opens.

Good luck - keep at it

[haydn callow]

agree with all Simon says above. My only comment is that whilst bleeding and after quite a while (30 mins min) Revving to 2500 for 5 mins then tickover (keep repeating) there will come a point when the bottom hose will become HOT. At this point the stat has opened and a "glug' of air will bubble out. Keep bleeding for 5 more mins and job done.
The most important thing is to be sure it has been done properly..Don't take any risks.

[iggypop]

Thanks alot, also where does the temp reading come from ?, the engine or the rad.

[waycar8]

Thanks alot, also where does the temp reading come from ?, the engine or the rad.

the temperature sender on the top of the head towards the front, it has 1 wire coming from it.

[iggypop]

Thanks alot, also where does the temp reading come from ?, the engine or the rad.

the temperature sender on the top of the head towards the front, it has 1 wire coming from it.

Ah, i wondered if that was it, so with engine switched off i pulled the wire off but still got the same reading, unless it was not the right one.

[waycar8]

http://img100.imageshack.us/my.php?imag ... der4dr.jpg

hope thw picture helps, courtesy of a previous post by taxiback

[iggypop]

Try this method - based on info given to me by a Bongo expert & it worked sucessfully.

1) Fill expansion tank to the flange / join - leave cap off
2) Run engine for about 10 mins till it gets hot, all the time checking level in tank & topping up as req'd
3) Set front & rear heaters to hot, with fan set to 3
4) Open bleed pipe, with it angled down
5) Drawer off 2 litres with someone else topping up so the level does not drop. The water will be frothy - thats ok
6) Run the engine to 2500 rpm until the fan starts, that shoud be when the thermostat opens. The level may drop at this point
7) Repeat steps 4) - 6) several times. It can take up to an hour to get it until there are minimal bubbles coming from the bleed pipe
8 ) Put the cap on & run for a while.
9) Stop engine & carefully remove expansion cap. There should be pressure in there, but not enough to cause any coolant to come out, but the level should rise a few mm. Replace the cap
10) Allow to cool down for several hours, or overnight
11) Remove the cap & check the level - it should have dropped (possibly as much as a litre). Top up to the max line & keep an eye on it for the first fews days

There seems to be debate about what constitutes a 'warm' bottom hose. Some people say the pipe hardly warms up at all, & others (myself included) have had it hot to the point where you can't hold it. If you have a Mason alarm fitted, you can see the temp guage drop when the fans kicks in as the thermostat opens.

Good luck - keep at it

Thanks, am going to have another go after work today, hope i sort it as i am giong to east sussex on friday. Step 8 "put the cap on" is that the cap on the bleed pipe or the expansion tank or both. Thanks again Ian.

[iggypop]

I would suggest you DO NOT use your bongo untill it is bled properly. This hasn't been done.
If you would like to ring me at 6pm I will go through it with you. (just off out).

Thanks i havent used it, just parked it up, and also the gauge did not get above where it norm is as i dident let it. I have just read your see saw method and i am going to give that a go today , as it is all ready full of fresh coolant after being flushed. All the best Ian.

[dandywarhol]

All that Simon says in post 3 BUT the bleed pipe needs to be HIGHER than the engine, the Mazda recommended way is to hang the pipe from the steering wheel. If it's not higher then there's the likelihood of air entering the system via the bleed pipe and you've wasted your time

The bottom hose will get hot enough not to touch when you've sat at 2500 rpm for 5/10 mins.

[Simon Jones]

Iggy - after you've released about 2 litres from bleed pipe, put the bung back in. The header tank cap should be off for most of the bleeding, otherwise the pressure will build up.

Dandy - I take your point - that is what the manual suggests. The info I was given was from a very reliable source. My undertstanding is that we are trying to remove the airated water from the system. By keeping the pipe downwards you are keeping water flowing in the pipe & thus preventing air getting into the system from an open bleed pipe. I would say it is the same principle as bleeding brakes where the end of the pipe is kept submerged.

I would always advocate following manufacturers process, but the info in the manual is quite ambiguous. All I can say is that the method described got me out of the poo when I got an air-lock in Poland. I've been thinking about an alternative approach to bleeding, but I need to formulate the process & perhaps try it on my van before unleasing to the forum for a public flogging

[Peg leg Pete]

When I recently bled the system I popped an exstension pipe onto the bleed pipe to raise the pipe higher, it resulted in the air being released much easier

[haydn callow]

I put my bleed pipe into a funnel and raise it up. I keep adding coolant to the header tank and funnel. This way no air can sneak back in . Raising/lowering the funnel (see/saw method) causing the coolant to keep finding it's own level does the trick. Also when the stat finally opens this can be observed by the "glugs" entering the funnel. Keep the tank cap off and only put the bung in the bleed pipe when all bubbles/froth has settled.
Useing this method (many times) although The coolant alarm monitors the level in the tank I have NEVER needed to top up. So ! ALL air must have been expelled during the bleeding process.

[mikeonb4c]

I put my bleed pipe into a funnel and raise it up. I keep adding coolant to the header tank and funnel. This way no air can sneak back in . Raising/lowering the funnel (see/saw method) causing the coolant to keep finding it's own level does the trick. Also when the stat finally opens this can be observed by the "glugs" entering the funnel. Keep the tank cap off and only put the bung in the bleed pipe when all bubbles/froth has settled.
Useing this method (many times) although The coolant alarm monitors the level in the tank I have NEVER needed to top up. So ! ALL air must have been expelled during the bleeding process.

Haydn - I like the sound of this. From my first (and only) coolant change experience, which went well but was not relaxing, could I ask:

1) How do you deal with flying between topping up (or just supervising) the bleed tube in the cab, and the need to keep topping up the header tank before the level gets too low? I didn't have the coolant alarm fitted when I did mine. I guess having one will at least make it easier next time round to ascertain when header tank level needs attention

2) How do you secure the bleed pipe and container so that they don't move and spill coolant inside the car. Also, in your opinion, how real is the risk of a burp causing coolant to splatter all over the headlining. I'd hate a dirty Bongo