Overheating

[MalcW]

Hi all. I just popped out for a quick local trip our 2.5 diesel. On the way back the temperature gauge suddenly went up quickly, so I pulled in before damage was done. There was water dripping from the short overflow hose that comes from the header tank filler, but no other leaks. The radiator was stone cold and the header tank level is OK. I left it 5 minutes or so, during which time it cooled surprisingly quickly. When I set off it came rapidly up to normal temperature and stayed there. A sticky thermostat perhaps?

[cmm303]

Possibly, or an airlock.

[Bob]

I'd recomend not driving it until you find the cause of this.

I don't know if the thermostat could be 'Sticky' but sounds like something is wrong somewhere.

You're likely aware that overheating can lead to head failure so this isn't to be taken lightly.

[cmm303]

Wise words from Bob.

Personally I would carefully bleed it on the drive, monitoring hoses for warming up as they should and obviously checking for air bubbles, and the temperature staying where it should. Then look for leaks etc. but hopefully make it "safe" to drive to a Bongo doctor. If in any doubt, avoid driving.

Below is a good tip that comes courtesy of Northern Bongalow who knows about these things:

to quick check for airlocks,

with the engine not running squeeze hard and quickly the top hose out of the head, listen for the air moving about, squeeze the bottom hose from the rad back to the stat housing, again listen for air moving, if its full you may hear the jiggle pin clicking on the thermostat, it wont click if air is present here, it will click if the water is lifting the jiggle pin as it is a float when the water hits it it shuts.

to check for air in the heaters you either loosen a clip on each side of the heater unit/s or run the engine to see if they get hot (this has obvious risk to the head).

[Bongolia]

My twopence worth, flush it and swop the stat.

[Northern Bongolow]

do a pressure test on the system, this will involve putting positive pressure into the system, this shows where the leak could be. to easily do this fit a bike pump with a gauge fitted to the little pipe at the side of the cap that you spotted the leaking coolant, use an adapter of some sort, then inflate the system to 1 bar and see if it holds the pressure, if not start looking round the van or check the floor, most leaks show up quickly. fix the leak then bleed and off you go.
the only leaks that sometimes are harder to spot are water pump leaks and heater matrix leaks into the van.

[Long]

I had a over heating problem back few months ago. when i over heated.. coolant boiled out of head tank like your case. my bottom hose was still cold. indicating no flow.

what i did was:

bleed system extensivly, to make sure air bubbles are gone,
didn't fix it
check engine oil for signs of coolant
no signs
check coolant for signs of oil
no signs
pressure test,
held 15 psi (1bar) for 1 min+
check for leaks around the car
no leaks
changed thermostat
changed rad cap
bleed system again

i haven't had any problems with over heating since then. when high rev drive, bottom hose is warming up and getting hot, when on low rev drive bottom hose cools. high rev heat low rev cool.. etc so there is flow.

in your case i would check to make sure there is flow, could be rad is clogged or there is an air bubble, or thermostat is not opening properly or another problem i didn't list.


good luck.

[MalcW]

Thanks all for your advice. I've checked out what I can and all seems OK. The van is due an MOT in the next couple of weeks so I have booked it in early with a garage less than a mile from the house - happily they are familiar with Bongos. They will pressure test the system etc. and see what they can find. And hopefully get it through the MOT.

I've only had it for a year and really like it, so I don't want to stop being a bongonaut just yet.

[MalcW]

So, it turns out that the immediate problem was due to a sticking thermostat, which has now been replaced. There was also a slight leak from the radiator, which wasn't in great nick and has been replaced as well. There was also some welding required to the front crossmember, so that was done and undersealed while the radiator was out. The good news is it wasn't a cracked head, and I now have a shiny new MOT.

[mikeonb4c]

So, it turns out that the immediate problem was due to a sticking thermostat, which has now been replaced. There was also a slight leak from the radiator, which wasn't in great nick and has been replaced as well. There was also some welding required to the front crossmember, so that was done and undersealed while the radiator was out. The good news is it wasn't a cracked head, and I now have a shiny new MOT.

Excellent news and hopefully that's an end to it.

[Bob]

Very good news.

[MalcW]

Excellent news and hopefully that's an end to it.

Definitely. Fingers crossed. And the only advisory is a small chip on the windscreen, which is a relief.

[Gasy]

Great getting a new mot isn't it

But I would definitely get that chip on the windscreen sorted
Before it starts attracting seagulls
They can make a right mess of your motor

Excellent news and hopefully that's an end to it.

Definitely. Fingers crossed. And the only advisory is a small chip on the windscreen, which is a relief.

[Bongolia]

Great getting a new mot isn't it

But I would definitely get that chip on the windscreen sorted
Before it starts attracting seagulls
They can make a right mess of your motor

Excellent news and hopefully that's an end to it.

[mikeonb4c]

Excellent news and hopefully that's an end to it.

Definitely. Fingers crossed. And the only advisory is a small chip on the windscreen, which is a relief.

Oh I've got one of those. Had it ten years now, just refuses to spread so I can make an insurance claim