high spots in coolant system ?????

[bobngo]

bleeding the coolant systems on bongos, seems to be probably the biggest pain in the gluteas maximus known to man,
now maybe i do,nt understand something ,but the answer seems easy ,
get a diagram of the whole bongo system , print horizontaly, showing the relative heights of each pipe/component, and fit bleed screws at the high points of the sytems

in other words similar to a household central heating radiator, the pipes comes in at the bottom , so the radiator becomes a high point in the system, so fit a bleed point at the top of the radiator.

whilst i admire and have mason and haydyn callow alarms , these only detect the symptoms of a problem, they are not a prevention/cure,

so can someone tell me why this can,t be done ????

or do we need to find people who know something about water ????
ferdinand de lesseps (suez canal)
joseph bazalgette (london sewrage system )
thomas crapper (flushing toilet )
s

[missfixit70]

There is already a bleed point at the top of the rad - the expansion tank, the bleed hose takes care of the engine as a high spot, the only other real "high spot" is the front heater matrix.
It's not a daft idea to fit bleed valve/s, it's been mooted before to fit automatic self bleed valves, but to me, going through the bleed process is checking the system is doing what it should, it doesn't take that long.

[Alacrity]

They are simple to bleed if you have a vacuum bleeding tool, which anyone with access to a compressor should have. Simplicity itself, took me about 15mins to do mine after a rad change, never used a drop since & everything worked as it should straight away.

I am sure this is the way they would have been done at the factory as it is so quick & effective.

[dave_aber]

I've got the compressor, (and a pela pump). What kit do you use in addition to the compressor to make a vac bleeding kit?

[Mountain]

yep, the trapping potential of the front heater seems to be a bit of a design flaw. I think a heater matrix bleed pipe to such out that stubborn airlock.......

Alacrity
Do tell....give us a link or some pics as I have access to a compressor too.

[rita]

yep, the trapping potential of the front heater seems to be a bit of a design flaw. I think a heater matrix bleed pipe to such out that stubborn airlock.......

Alacrity
Do tell....give us a link or some pics as I have access to a compressor too.

http://sealeytools.co.uk/vehicle-servic ... _7180.aspx

[dave_aber]

Hmmm...

I'd seen that type of kit before, at around the £70 mark. I was hoping you had found a £25 version!!

Might try the pela-pump method as discussed on the MG Rover forum mentioned on here recently.

[bobngo]

every car i,ve ever had, has always been ,just pour the coolant into the radiator cap, job done , none of this mucking about with "correct procedures" ,"vacuum systems" etc etc.

haveing spoken to a well known bongo garage ,who said they do use the vacuum system, but that is not always 100%, and sometimes needs a second attemp, this does not fill me with confidence.

miss fixit said there are bleed points at various places, but these are obviously in the wrong places ,or there are not enough of them, which makes the whole thing sound like a poor design ,in an otherwise excellent vehicle.

so does anyone know exactly where the air gets trapped, the front heater matrix has been suggested as one possibility,
are there any other known suspect areas ???

sorry to keep on about this , but i am really pleased with my bongo , except for this one dubious/annoying point, and i really would like to get to the bottom of it, and maybe resolve the issue once and for all

[Mountain]

These problems are an issue with a lot of mid mounted engines and not just Bongos. The coolant rather than flowing from a radiator situated just in front of the engine has to flow up and down....of course air will get trapped in the 'up' places. The head in the case of the Bongo . There is also the low stat too.

What I think we have design wise, is a compromise. The benefits of a mid mounted engine vs the problems caused by coolant having to flow further and longer and in a more convoluted way.

Elementary physics would denote that a self bleed mechanism at the highest point would work.....but then we have the heater matrix acting as a trap and scuppering that idea.
From my own limited experience the height of the front heater matrix seems to be the main airlock spot. Of course this is also where the flow is most restricted too.

As I understand(or perhaps misunderstand) things the front heater matrix is an integral part of the coolant flow rather than a 'supplementary' part.

Another turbo diesel vehicle I owned had a similar bleeding issue. The one difference being air trapped in the heater matrix did not go straight back into the engine, rather it ended up trapped in the highest hose and could be released via a bleed screw.

So, I do agree. there are design flaws in the coolant system. mainly a high heater matrix and a low thermostat. However, there is the bleed hose which takes care of the stat. The high front heater matrix is the problem.

I have thought the bleed pipe could be routed to the header tank via a non return valve?
Or, an extra short bleed tube on or nearer to the heater matrix?
or lower the heater matrix and re-route the air intake?

[bobngo]

hi mountain ,that does make alot of sense, i must now have alook at this front heater matrix , and see what can be done.

i do,nt know why ,but i,ve always thought that the rear heater would be one of the problems, be being farthest away from all else, i even thought of blanking it off, or giving it a bypass, since i do not use it.

so now i think i,ll have to have a good look at the whole situation, before i do anything, as this does seem to be more involved than i first thought.

the biggest problem though is me ,ive got this problem stuck in the brain ,and it will continue to annoy me until i have clarified it in my mind.

[nfn]

I just looked at the MG/Rover forum that was mentioned showing a Pela used for refilling coolant:
http://forums.mg-rover.org/showthread.php?t=315806

A bit of a hassle to make the kit -- but quite creative. The key will be making sure there is no leakage around the rubber bung or the system will refill with air mixed with coolant.

Pela pumps are quite a useful tool: I used my Pela after changing a brake caliper and hose. I connected a small (but strong) rubber hose between the brake bleeder valve and the end of the Pela hose, then pumped the pela and the brake pedal a few times to get it flowing. Then it's just a case of keeping the brake fluid reservoir topped up and watching the clear bit of hose on the Pela until there are no more air bubbles. The system needed no further bleeding to get a firm brake pedal. So much easier than the standard brake bleeding procedure.