Exploding coolant pipe

[fodBONGO]

Hi all

Driving home on Sunday evening and the temperature gauge started behaving peculiarly. The temperature would creep up to somewhere around the 3/4 mark and then drop back to normal. I turned the heater on to see if this had any effect and the next thing to happen was the temperature gauge going off the scale followed by a loud pop and clouds of steam. Lifting the seat showed that the c.40mm diameter flexible pipe which connects the coolant system to the engine had burst in a spectacular fashion.

The van was serviced about 4 weeks ago which included a full replacement of the coolant. I noticed that the level had dropped below the "low" level and topped it up on Friday before setting off. It looked as though coolant had been coming out of the overflow pipe.

The van is in the garage having the pipe replaced and the coolant refilled but I am unsure what the initial cause might be. Has anyone ever experienced this problem or might know the cause.

Another worry is that we had to drive about 400 m or so before being able to pull of the road after the burst. Is this likely to have caused lasting damage to the engine? The engine did not cut out at any point.

Thank you in advance for any help you might be able to provide.

[mikeonb4c]

I chose to replace a large bore rubber hose in that area some years back as it had developed a bulge, so i can imagine one giving out due to age and years of being in a pressurised system (though of course none of us can know all of what might have happened to our Bongo before we bought it). Was the garage that did the coolant change experienced at bleeding Bongo systems? How old is the Bongo and has it had any other coolant system incidents? The standard temp gauge is very damped so you have to assume that all the time it was beyond the 11 oclock position things were far from right. You might have (had) a blockage/crudded up system (any sign of rust colour in the coolant / header tank staining)? Do you have a low coolant alarm or an engine block temp gauge fitted (both are useful). Were you losing coolant at all in previous months? Any steamy / white exhaust and/or lumpiness on starting. Any or all of these could indicate a head/head gasket problem which, if present, would likely overpressurise the coolant system and thus cause a hose to blow. I'm assuming its a diesel engine Bongo?

P.S.the heater radiator is always in circuit so unless the extra cooling effect on the coolant tipped something over the edge, its probably a red herring. Coolant would i imagine come out the overflow if the system had been overfilled and/or it was over-pressurising and/or coolant was boiling in the heart of the engine. On an old Bongo my inclination has always been to think they need new critical components throughout if there is any suspicion the circulatory system is not working efficiently (i.e. new radiator, new thermostat, new temp sensor for rad fan control, new water pump, and test rad fans are working and the sensor is triggering them when it should). All this costs, but generally less than buying a VW!

[fodBONGO]

Hi mikeonb4c, thanks for replying so quickly.

It's a 95 diesel.

What remained of the pipe didn't look in terrible condition unfortunately. A weak pipe that gave way would be a nice easy fix. Fingers crossed this is the case though.

The garage isn't a bongo specialist so unsure of their experience. What are the consequences of it not being replaced/bled properly?

I had only needed to top the coolant up once in the year we have owned the van. This was the reason I asked for the coolant to be changed as I topped up with water.

Never any problems starting the engine or strange emissions and no obvious signs of rust/staining. No low coolant / temp fitted either I'm afraid.

[g8dhe]

The garage isn't a bongo specialist so unsure of their experience. What are the consequences of it not being replaced/bled properly?

Very BAD, like cracked head, the coolant system needs care and attention, especially if its old rubber 20+ years old! Most garages these days use vacuum filling that can cause the pipes to collapse flat, on old rubber this can cause new cracks and pinholes to appear

[mikeonb4c]

Hi mikeonb4c, thanks for replying so quickly.

It's a 95 diesel.

What remained of the pipe didn't look in terrible condition unfortunately. A weak pipe that gave way would be a nice easy fix. Fingers crossed this is the case though.

The garage isn't a bongo specialist so unsure of their experience. What are the consequences of it not being replaced/bled properly?

I had only needed to top the coolant up once in the year we have owned the van. This was the reason I asked for the coolant to be changed as I topped up with water.

Never any problems starting the engine or strange emissions and no obvious signs of rust/staining. No low coolant / temp fitted either I'm afraid.

Hmmm you might have some issues needing investigation by a Bongo savvy mechanic. Where are you based roughly? There are one or two very good mobile mechanics also. I'd be very wary of driving it until you know exactly whats going on. Also make sure the current garage are briefed on proper procedure for bleeding as it is crucial and incorrect procedure could have caused your problem. Good luck and keep us posted.

[fodBONGO]

I'm not too far from Bristol. Based on feedback on this forum I should look into ADS for some diagnostics unless there are any other recommendations.

I will show my local garage the fact sheet on the members area to ensure the system has been bled properly.

I will keep you updated. Many thanks.

[Bob]

ADS Know Bongos well.

[mikeonb4c]

ADS Know Bongos well.

They certainly do, and they're not unfamiliar with Bob either

[fodBONGO]

Hi all

Just an update on this one. The van is back from the garage and appears to be his happy self again. No evidence of any head gasket issues. Touch wood, we got away with it.

I chatted with the mechanic asking how he did the coolant replacement and he showed me the bleed pipe under the passenger seat and discussed the process so I'm confident he didn't just fill from the rad/expansion tank and be done with it. I've gave him a copy of the fact sheet from the members area the second time around and no problems. He mentioned that the coolant level dropped on the first couple times he took it out for a test but has remained stable since.

I think the problem was a combination of the coolant level dropping after being replaced (maybe an air lock) and me not being diligent enough at checking levels. Next step a low coolant alarm.

Thanks for all the help on this one.

[mikeonb4c]

Great news, that all sounds normal and thanks for the update.

[knpenny]

good news and definitely a coolant alarm, especially on the oil burners