Bongo Fury

A good point about the gunge build up though - they look like pretty small passages for the blown air to pass through

Need to have a look at mine sometime - they're pretty small as standard, any improvement to it's efficiency will help

I decided to experiment this weekend before looking into the cause of the "gunking up"
I fitted K type temperature probes to the top of the engine & inside both the inlet & outlet of the intercooler.

After getting it up to running temperature & performing some measurements I removed the radiator & discovered that while it was bunged up a fair bit internally & the vanes outside it wasn't a leak after all!
Above the air scoop are two pipes that lead to the AT & it was ATF that was leaking down the entire length of one of the pipes, (from just under the main air intake by the battery) dripping on the intercooler scoop & then being blown into the rad vanes to attract all dust etc to make a nice gloop.

as can be seen, the temperatures after I cleaned it all are lower on both inlet & outlet even though it was 6'C warmer outside! I can only assume that the pressure on the inlet side isn't as great now (due to better flow through the radiator) so hopefully that is putting less of a strain on the turbo now. It does beg the question of how hot the inlet gets in the middle of Summer!

Testing was over two days, before air temp 2'C & after air temp 8'C
before cleaning:
Steady 30mph___40mph____50mph_accelerate medium___accelerate hard
inlet___33______37_______48_________upto 64__________upto 89
outlet__10______20_______28_________upto 30__________upto 55

After cleaning:
steady 30mph___40mph____50mph
inlet___22______25_______32_________upto 55__________upto 84
outlet__6_______10_______13_________upto 19__________upto 35

One day soon I'll finish the marathon 100,000 overhaul & find out how much I've improved the mpg

I barely understand all of this TOny, but the figures look impressive. Does it mean hat the intercooler is most likely doing a hell of a better job getting air into the turbocharger? Could you 'feel' a noticeable improvement. I'll be very interested to hear if you have achieved a significant improvement in responsiveness/power/fuel economy. Also, do you think it likely that we are all suffering from somewhat gunged up intercoolers or is yours due to a definite fault?

Keep us posted

Mike

Mike,
The air is sucked in through the intake (by the battery) & passes through to the air filter. It then passes around the back of the engine to the turbo. This then compresses it (to get more air per bang in the cylinder & therefore more efficient) but it then gets hot (decreases efficiency) so we cool it by the intercooler.

Because of oil/crud build up within the very small channels inside the intercooler I believe the turbo was having to work harder at shoving the air in which had the side effect of making it hotter at the intake.
By cleaning the rad internally air passage is easier, the intake air is therefore cooler - possibly also lower pressure.

By cleaning all the vanes externally the rad is now more efficient at cooling the internal air as well! It then passes up to the intake manifold (where the EGR connects) & after all that gets blown up!

Yes it did seem to be a lot more responsive than yesterday!

From the earlier comments I reckon after 10 -12 years of oil mist from the turbo there is a probability that more than not will be like mine internally & only with oil leaks etc like mine externally

Thanks Tony - this really is a most interesting post. Clearly worth Bongo owners putting this on their checklist as its sounds v quick and simple to do an outside inspection to make sure you don't have a problem. If you do its well worth fixing it. Otherwise you might have an underperforming Bongo but - without another to compare it with - no be aware of it.

But first, to get my back mended

What did you use to clean inside tony?

I took the two rubber hoses off the top. It looked clean inside, no obvious gunking up. Poured paraffin down one side & noticed that it took time to equalise to the other & only appeared to be using the bottom channel.

After swooshing it from side to side for about 5 mins it appeared to start flowing through the second channel. As it was cold I decide to fill the whole thing & leave it for a coffee....

Poured out 1/2 the paraffin but was still blocked when swooshed. Covered the ends with thick polythene & elastic bands & spent 10 mins turning the rad from side to side. Took off the plastic to see & it was then obvious that all the channels were now clear.

Washed thoroughly with hot soapy water & left to dry out. Shiny Alu on the inside & clean painted black on the outside

How much of a job is it to get the whole thing off to clean it?

Scanner,
Apart from the fact that the intercooler must have been fitted before the other radiators (the jubilee clips were pointing forwards so a real Bu**er to get off) & the rubber seemed to be welded to the metal pipes & so still wasn't budging once they were loose.

All told, about 35 mins to get off & 10mins to put back.

The three bolts that secure it btw are reached from the tops of the brackets. The nuts underneath are spot welded on

Tony