Coolant & Bleeding

Bleeding Bongos… sorry, rephrase that… bleeding the coolant in Bongos, comes up repeatedly on Bongo social media and forums. In this section, I will continue to add some of the most useful advice, as it becomes known to me.

Water and antifreeze/summer coolant
The whole system holds about 13 litres so you will need 4½ to 6 litres of antifreeze in your system. It has been recommended to use red antifreeze – Triple QX. (Three bottles). It has also been recommended not to mix antifreezes (many other vehicles use blue), so perhaps, where necessary, flushing thoroughly, refilling, bleeding, etc.

What’s the difference between antifreeze colours?
From what I’ve read, it seems that blue lasts about 2 years and red up to 5 years. Some colours can be mixed, but apparently, mixing blue and red causes it to form sludge. Also, although frost protection may show as adequate when testing, it seems to be that the corrosion inhibitors can deplete over time, but less so in the red mixture. (The Blucol website offers some useful comparison information). You can look at an original forum thread on the subject, here.

‘Best tip is to fill through the bleed tube and make sure you give the lower hose, lots of squeezes as the van is running up to temperature.’ – Julian Rogers

Bleeding a 2.0 Ltr Petrol Bongo
2.0 Ltr petrol engines are bled like ‘normal’ vehicles. You bleed using a drain plug and fill through the header tank – none of the palaver of the diesel and V6 petrol engines. (No bleed tube, but a bypass connection back to the de-gassing tank and uses the third port at the top left-hand side to feed the gasses back into the tank directly).

Bleeding a Diesel or a Petrol V6 Bongo
Take a look at the videos below, introduced by Ian Maynard (aka Bongo Master) of Bongo Fury, showing the bleed process done by Haydn Callow and Kirsty (aka Missfixit70). The method demonstrated is probably the longer way of bleeding – taking up to 40 minutes, but nevertheless, is very thorough.

Note: You may need to watch the first video on YouTube (link below, or on video after pressing play).

Part 1 of the Bleeding a Mazda Bongo/Ford Freda (All videos produced by Missfixit70, Haydn Callow and Northern Bongolow, to help Mazda Bongo owners, Ford Freda owners, and garages, to understand what is involved, and what to expect, when refilling the Bongo coolant system. They also add the disclaimer that ‘this Method is not the only method. It is not written in stone. It is purely a demo to show you our method’. The videos have been included below for ease of access).

  1. Find another person to help you with this job
  2. Wear gloves that prevent you from being burnt as water gets hot
  3. Hold bleed tube, with funnel attached, higher than the expansion/header tank
  4. Fill radiator (coolant eventually rises up bleed tube into funnel)
  5. Fill expansion/header tank (coolant eventually rises up bleed tube into funnel)
  6. Release radiator cap until it overflows and then re-secure
  7. Lower bleed tube slightly until coolant appears in funnel
  8. Use the seesaw method – lowering and raising the bleed tube slowly a few times, until no more air bubbles are seen
  9. At no time throughout, should the funnel or the expansion/header tank become empty
  10. Start the engine
  11. Continue seesawing for bubbles
  12. Once warm, apply the throttle gently, up to about 2,000 rpm
  13. Level will drop in the bleed funnel
  14. Check front and rear heaters for warmth – but no need to leave fans on
  15. Seesaw up and down with the throttle – high position with throttle applied, lower when throttle released
  16. Feel the bottom hose. It must go hot. When it is hot, the thermostat has opened
  17. Check that both heaters blow hot air
  18. Pour off surplus coolant from bleed funnel, into a bucket, ending up with coolant just below the funnel and level with the top of the bleed hose
  19. Carefully remove the funnel, drop the hose lower until water dribbles out and re-fit the hose bung and its clip. Now clip the hose back in place on the chassis
  20. Check the level in the expansion/header tank and replace the top

Simpler Method

Some people have said they do the following:

  1. Fill the system as much as possible when cold
  2. Start the engine and reach normal hot temperature
  3. Remove the bleed tube bung (don’t use funnel or add water to bleed tube)
  4. Bleed the system, making sure expansion/header tank does not empty and bleed tube doesn’t take in air
  5. Make sure bottom hose gets hot

Note: Whichever method is used, you will probably continue to see very small bubbles, created by the water passing through the water pump. The main thing is to rid the system of larger air bubbles.


Tip - BongoBuddy.co.ukTo help with filling the expansion bottle, or an occasional top-up, you could keep a small funnel or a small watering can with a narrow spout. (For an occasional top-up, I found a small collapsible funnel in TK-Max and keep it attached to the inner wing).
funnel - bongobuddy.co.uk funnel - bongobuddy.co.uk

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