bleeding air out of water cooling

[D n D & K]

hello all

well have finally got the water pump fitted and the fact sheet states bleed air out of sytem just wanted to check what this means and how to do it correctly

[waycar8]

there is a bleed pipe that comes off the engine and over the the alternator and is attached to the chassis, just unclip the pipe and take out the bung at the end.

if you have the fact sheet, then just follow those instructions, if you dont bleed it you will get air in the system that cant escape and just works its way around the engine, resulting in an overheating issue, and most likely a cracked head.

[haydn callow]

Cannot stress strongly enough how important it is that the system is bled correctly. It must be done correctly with a Bongo. If not big troubles are ahead.

[D n D & K]

right ive looked at the fact sheet for changing coolant and followed instructions as best i could . only thing i did not understand was it said start engine with bleed bung out this just resulted in the coolant being pushed out and the level in expansion tank drpping rapidly so i put the bung in and left it running with expansion cap off . i followed the rest of the instructions left it idling and every thing seems fine heating gets hot temperature is normal but the only thing is the bottom rad hose does not get warm . the water in the rad is red hot and the top hoses are warm .
anyone have any advice

[haydn callow]

Right. Well !! not right really.
Take the bung out of the bleed hose and get a fairly large funnel. Cut the outlet of the funnel so you can just force the bleed hose up inside.
Now !! put a bit of wire or somthing through the rim of the funnel.
Under the passenger seat you will see a bit of metal you can now hang the funnel on.
O.K. hold the funnel at about the same level as the header/expansion tank.
Fill the tank to the full mark and half fill the funnel.
Get someone to release the Radiator cap till coolant comes out and replace cap.(thats the radiator cap, not the header tank cap) (header tank cap should be off for the whole bleeding process)
Start the engine and rev at 2500 for about 10 mins. If the coolant drops in either the tank or funnel keep topping up. Make sure the heaters are blowing hot then switch them off. Let it idle for 5 mins. Then rev at 2500 again. Raise and lower the funnel and the level in the tank should raise /lower at the same time. (see saw method) Now keep revving untill the bottom hose gets hot (stat now open) This can take 30/40 mins. Rev/idle/rev/idle
You will when the stat opens get bubbles/froth in the funnel.
When all has settled down and with engine still running (rubber gloves on ) lower and remove funnel..let coolant be flowing out of bleed hose as you put the bung in (hot...hence the gloves)
At no point let the coolant in the tank drop below the the low mark.
Job done,
You MUST get that bottom hose hot (stat open)

[cheffy34]

Well Haydn, i like these bleeding posts cause im preparing myself to change the coolant in my v6 in the near future, BUT iv'e tried everything to get my botom hose hot, hasn't yet happened, my scav fan never comes on and iv'e tested it to see that it works and it does and iv'e never had TOUCH WOOD a overheating prob, which makes me nervous about bleeding it

[haydn callow]

If you stick with it ..it will get hot...It can take 40 mins...has to rev high...then idle....rev high....idle,,,,It will open all of a sudden.....it must happen unless the stat is jammed |(unlikley) Stick with it.

[John the sparky]

Cheffy, if you are just changing coolant, I think BDC did it differently.....

you'll have to check when he returns, but I thought he trickled water into the header tank and ran coolant out through the blled pipe, after a while water is clear, the start refilling tank with bucket of coolant water instead of hose.... think he used 10 - 15 ltrs to ensure it was all through....

strikes me, that as long as the level doesn't drop, there is no possibility for air in the system this way... but will take 2 people... and if the level drops too quick you can always pop the bung back in, or raise the hose to slow the flow....

I'm sure I read that!? but, if like I did, you swap hoses.... then it's irrelavant



John

[haydn callow]

You still need to get the Stat open to purge all the air out. I have done the "see saw" method myself at least 6 times and it has always been 100%. Allens of Plymouth showed me how to do it.
I'm sure the other ways work, but I know this way and I will stick by it. You also have control over the concentration level of the coolant as you premix it/

[John the sparky]

have to say, I used see saw as well Hadyn, but I changed to Flippas hoses

just saw this way and thought it would be easier, as less variables to worry about, could you not start once the stat was open, or would the water cool the engine and close the stat back up again?


John

[haydn callow]

Make sure the pressure cap is off whilst bleeding. The stat will open sooner with no pressure in the system

[D n D & K]

ok when i was trying to bleed the system as said before when i removed the bung i had water pumping up out of the pipe so returned the bung when i removed the radiator cap water came out of there i had the cap off the header tank whilst doing all this . When the stat opens does the fan come on as well as before i new about the breather pipe and had the engine running the fan came on and hada lot of bubbles come into header tank .
when i have turned of the engine and come back to it later the level has dropped a little but now below min .

haydn if i go for your method should i drain the system out again or can i do it from where i am now and just put a funnel on the breather and take cap off header tank

[haydn callow]

You can do it from where you are now...No need to drain.
If you want to phone me, please do.
You can get my No from the web site below.

[D n D & K]

is it ok to ring you now or shall i give you a call some time tomorrow

[haydn callow]

ring now
01458 270230