Overheating issues and coolant bleeding

[jna203]

Hi there,
I've had ongoing overheating issues that garages can't seem to get to the bottom of.

1st overheated, no coolant, they identified a leak and apparently fixed it, next overheated again, no coolant said I needed a new radiator, replaced the radiator, overheated again, coolant still there, identified that the thermostat wasn't opening (stuck shut) they removed that (without replacing) and it's been okay for a little while but running lower than overating temperature (they said that will be okay for the summer). It recently overheated again but I stopped before it got too hot, waited for a few minutes, drove on and it was okay for another 30 miles before I got home with no issues.
We are going for longer trip tomorrow and I thought to reassure myself I'd just make sure it's bled properly. Whilst bleeding it using method on YouTube video (https://youtu.be/6Jpa6yYGDtk?si=oULpvyxiWPEdaZcl)- there was still the odd bubble coming out after a good 15 mins of bleeding. Then all of a sudden coolant was no longer coming up and down the bleed pipe whilst raising and lowering, and also no sign of leak (i.e. no evidence of coolant spill). I then ran it in idle for another 15 and it didn't overheat (temperature gauge it back at the old operating temperature -just below mid way). Through lack of better judgement I'm going to risk the longer trip tomorrow (don't want to miss an Easter bongo opportunity) but was wondering if anyone knew what the issue was? I'll take back to the garage next week but they seem to be going through a trial and error method. They don't think it's head gasket but maybe there is still air getting in somewhere.

Any help much appreciated!

Any help much appreciated

[gilly99]

What engine type and are you using a bongo specialist garage???? Sounds very much like not!!!

[jna203]

Hi,

It's 2.5 diesel 4wd. Think it's 1999 (t reg)

No not specialists bongo, I've taken it to two garages for second opinions.

Thanks

[gilly99]

Strongly advise you only use a specialist garage for anything to do with the cooling system on these diesels.

The last bit of your bleeding description does not sound great.... "Then all of a sudden coolant was no longer coming up and down the bleed pipe whilst raising and lowering, and also no sign of leak (i.e. no evidence of coolant spill)". If I'm understanding correctly, that could indicate you still have a lot of air in the system. You have to lower the funnel below the level of the cylinder head port (with header tank full at all times + hot).... and have a thermostat fitted and be squeezing the bottom hose to make sure its hot and circulating/pushing any airlock out.

[Northern Bongolow]

Did they replace the water pump. They leak out of the (telltale hole) when hot then seal when cooling down. Get a dentist mirror and torch and check the pump housing for signs of a leak

[jna203]

Thanks for the help so far. Decided not to risk going away. Put some more coolant in the header tank and radiator this morning and there were loads of bubbles coming from the radiator so there is definitely air getting in somewhere.
When I was topping it up it looked like there was coolant coming from a small pipe at the bottom of the radiator (see picture) but I'm also not sure if I was overspill from when I had slightly overfilled the radiator. I tightened up the knob even tighter it it did appear to stop it. The other thing I noticed is there are lots of creases/dents in the new radiator , not sure how as it's new, so not sure if that effects the functionality as well.

During a 30 minute drive the temperature was back down to under operating temperature (due to thermostat currently missing) which is how it was before it overheated recently.

Will try to check the water pump as that has not been replaced yet and hopefully in it's current state will get me to a bongo specialist garage (nearest is in bristol) after the bank holiday weekend.

Thanks again

[Bob]

ADS Are pretty good, if it’s a longish run it might be worth considering recovery rather than risk the engine.

[gilly99]

If you are in Bristol, then ADS down in Ashton Gate are really great - anything to do with cooling, belts, or engine/gearbox or turbo it's well worth the extra for a bongo specialist. If you take it ADS with those symptoms, they will almost certainly check compression on each cylinder. Also, get them to fit a low coolant alarm - it's an absolute must have IMHO. Once you have it sorted, then NJ Autos in St. George's park are pretty good for general mechanical work.

Don't be fooled by the temperature gauge. If there is an airlock, and it sounds like there is, then potentially no water at top of the head and the temp gauge is then dry and likely reading low, when in fact the engine/head could be cooking away.

[haydn callow]

When you have got to the bottom with the issues and had them fixed, do consider fitting a low Coolant Alarm….”Haydn Alarms” have a Bongo specific alarm which was developed many years ago with the help of this web site.