ANOTHER OVERHEATING BONGO, HOPEFULLY SORTED

[2sticks]

What I want to know is where all this crud comes from in the Bongo.

21 years ago I bought my disabled son a new automatic astra diesal van fitted with hand controls. Two weeks ago I drove
it to a scrapyard to dispose of it, and that was only because someone reversed into it at the traffic lights instead of going
forwards. I think my son was in tears when I drove it away because he wouldn't change it for anything else even though I
tried for the past 10 years.

However, the point is, when I took it to the scrapyard it had done 187,000 miles and in all that time it had never had the cooling
water changed, it was just topped up with anti freeze when the concentration was low. Also, it never had new glow plugs, or
anything else for that matter, the engine only had regular oil changes and the usuall filters, brake pads etc. I have the complete
service history to prove it.

The van never had any cooling problems and when I finally condemned it to death, I felt it would probably would have carried
on for another 100,000 miles.

So, as I said before, why does a Bongo have so much crud and where does it come from ?, I think it's a japanese crud fairy
that's sneaked through customs.

[Jamesnjane]

theres talk of the japanasse anti freeze being really thick, and being stuck on docks and stuff doesnt help. but i understand what you say i know other cars not japanesse that have overheating problems, i owned a renault 5 turbo which was exactly the same for over heating the problem was not antifreeze or grud in the system, just a turboed little engine that ran hot, im coming round to the idea its just not a very good system which we need to over come (im running mine with a holey stat) dont forget the japanasse drive them around alot less and at lesser speeds, we get them and do 70-80mph+

just my thoughts

[grumpo]

There has been a suggestion that Japanese anti freeze has a different
chemical composition to ours and that there may be some incompatible
reaction between the chemicals.

If this is true then it may be a good idea to drain and flush the system
immediately the vehicles enter this country. True or false ?????.

[antique]

hi grumpo ,draining is not enough get the rad flow tested, i use sercs in portsmouth for rads they will tell you all about the jap antifreez, 9 out off 10 rads i have flow tested get replaced as they are part blocked, buy a new rad and feel the weight off old and new ?

[Peg leg Pete]

Mine definitely ran better after a complete flush and correct coolant added

[Vanmanerik]

Hi francophile1947, the inline thermostat came from a Rover, not sure which model though as once a car gets into a srapyard and bits have been taken etc. its not wasy to recognise. I understand Rover 25, 45, 75, Land Rover Freelanders, Renault 4, 5, and Fuego's all have something similar.

I would imagine a radiator would clog up with sediment if it is as little used as suggested in previous leads, at least a regular circulation would spread the crud around the whole system.

When I get time I intend to remove the rad, soak it either with coca-cola or vinegar for 24 hrs to loosen any crud, give it a good flush through with clean water, fill it with hot water to check for any cold spots to see if all the crud has been removed, if it appears usable reassemble it to the bongo incorporaring the inline thermostat in the top hose and remove the lower thermostat and see what happens.

[francophile1947]

Thanks Vanmanerik - didn't realise so many cars had inline thermostats. Like you, I'd like water to flow regularly through my rad, so I will eagerly await your results.

[dandywarhol]

There are different types of antifreeze and they aren't all compatable - see HERE

Vanmanerik........the cooling system will happily run at well over 100 deg C, as long as it is pressurised - up to around 120 C in the Bongo's case until it boils.

IMO it's starting to get a bit silly now with alternative thermostats etc. The system was designed by engineers who know what they're designing and the vast majority of Bongos and other Jap imports are working away just fine - unless the system gets clogged up and it can't cope - not a design fault but a maintenance problem........sort out the bad maintenance and the problem will disappear. The cooling systems are CLOGGED UP.........most probably by incompatable antifreeze.

2 sticks......I agree with what you're saying about 21 YO astras and the like but there was different (toxic) antifreeze used then and much more lax regulations on emissions and pollution.............rattly ol' Astras, Escorts and Renaults worked away just fine - only the early 90s diesels began to get a bit more sophisticated.............the current HDI/TDIs are now really beginning to give problems when they get to medium (for a diesel) to high mileages - a lot of it caused by low/non sulphur fuels - sulphur helps to lube the pumps/ injectors..........

[Vanmanerik]

If its a maintenance problem and not a built in problem how come most of the Bongos that took part in the 'Is your bottom hose cold' questionaire were cold pipes so you are saying most of the Bongos have been badly maintained?

It looks to me as if it is a problem that if the coolant is not maintained correctly then you could have a case where the radiator cruds up, but is this a maintenance or a design fault? I cannot think of another case where the rad cruds up because of lack of circulation, so is the lack of circulation the problem, if so it is not a maintenance problem.

If you look at most other cars that have a similar set up they all have similar problems as the Bongo and they or their owners have all tried different ways to alleviate this problem.

So for me, and this may not be for everyone else, I would prefer to try and convert the system to a convential coolant system and see if this runs efficiently without detriment to the heating or cooling sysem and hopefully if it works correctly then any fears of overheating, cracking a cylinder head, blowing a gasket etc. will dissapear and I can happily use my Bongo for many years to come without this worry.

I am not continuing this lead any more as there are too many 'antis', I like to get on with a job and see it through to the end, I am not an armchair mechanic, its up to me what I do with my Bongo and you can all carry on with a very hot engine under your bums.

[francophile1947]

Hi Vanmanerik
You have a PM.

[aitch]

mine started to overheat (on the gauge) stopped and called RAC mechanic got to me and said radiator leaking topped me up to drive home and checked me after 5 miles up hill. Drove home and went to local garage in morning (diaganosed needed new radiator) then needed a new hose pinhole still causing leaks now all cured but touch and go for a few weeks

[dandywarhol]

Vanmanerik, let's not fall out over this - it is a forum, and it's only my opinion. The cold bottom hose seems to be normal, it's only through this discussion that I remembered about a friend with an overheating Golf TDI a few years back who had a similar problem when he was running at high speed - his bottom hose was cold but also had a choked radiator - the thermostat is on the return side too. Choked cooling systems are quite common, that's why radiator manufacturers are still in business - ask Serck how many they sell a week.

It's just that the problem is exasterbated by the Bongo engine being more isolated than most cars, hence it leads to serious overheating problems when the system clogs up. The coolant SHOULD be changed every 2 years - how many can honestly say that they've done that to every car they've owned in the past 10 or so years since antifreeze manufacturers changed the recipe??

It's only since this was aired on this forum by yourself and others that has got a lot of people thinking and putting in their opinions........that has to be a good thing surely? It's probably also got people more aware of their vehicles and how they work - another good thing IMO.

[grumpo]

I think 2sticks question "Where does the crud come from" is a valid point.

Depending on the local water hardness, there is only a minute amount of
disolved solids in 5 or 10 litres of fresh water. As the system is completely
sealed, it can only come from continuously adding fresh water and boiling
out the alkaline solids, or through corrosion caused by oxygenated water
which shouldn't be much of a problem in a completely sealed system.

I can't imagine that the anti-freeze manufacturers would include chemicals
that would encourage the problem, I think it more likely there are acidic
additives which would keep the solids or corrosion products in suspension
until the time when the system is drained and fresh water and anti-freeze
added.

So the question is, is it better to replace the coolant every two years, or
is it better to test the concentration and only add anti-freeze to maintain
the required concentration, which most service centres appear to do as
part of the annual service.

Not being a chemist or anti-freeze guru, I would be interested in a more
definitive answer to the question. Tell us more Dandy.

Another point to consider is that there is a distinct design relationship
between the total cold water volume and the air volume in the expansion
tank. As the water expands with temperature it compresses the air and
increases the pressure. If the cold water level is below the minimum
indicated mark, the system may not develop enough pressure to stop
the water boiling at high temeratures, if the cold water level is above
the maximum indicated mark, the system may produce too much pressure
and open the relief valve, when it cools down, the contraction will cause
a vacuum which will allow fresh air to enter the system and so further
exacerbate the oxygen corrosion problem.

Unfortunately, the plastic expansion tank becomes opaque over time and
it's not always possible to see the actual cold level unless you remove
the cap and test it with a wooden dipstick or something equally reliable.

This topic appears to be going beyond the bounds of normal comprehension.
I think i'm getting too old to care any more and would sooner not worry
about it and spend the money when something goes wrong !!!.

[Peg leg Pete]

Dandy I totally agree with you on changing the coolant every 2 years, until I flushed and changed the coolant to one brand, I had intermitant overheating problems, culminating in a replacement engine. the repacement engine soon began to have the problems of the old engine, this was because when the engine was replaced, the garage did not do a coolant change. So I would advice anyone who is unsure of the quality of the coolant and the level of flow through the system to get them checked and changed for peace of mind

[Jamesnjane]

why do some people think that just because its been built by engineers thats its perfect, most cars have design faults be it interior or mechanical, some cars are known for certain problems and the bongo by the look of it is overheating just like other cars i know, theres nothing wrong with trying to overcome this im fully surportive of the ones looking at changing the stat location i bet when there up and running (if it works of course) they will sleep alot better at night then the ones left standard. i run with a holey stat not ideal but its a weight of my mind when driving around knowing theres good circulation around the rad.

just to let you know about the inline stat housing, some cars have a stat that you push into the hose and hold with a jubilee, just a thought. i would give some more things a try myself but times running out iv got to be away with my job soon so dont have the time.

get over it, the bongos not perfect. i still love mine to death