Page created: 8-Sep-06

Re-published: 1-Nov-09

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Uprated Intercooler

EGR Valve Removal

As I'd noticed a gradual lack of 'get up and go' in my Disco, coupled with a gradual increase in fuel consumption, I decided to give my intercooler a spring clean. It's possible to buy some cleaner for this purpose from Land Rover but, as it's extortionately expensive, instead I used a four litre can of paraffin, branded Parasene, bought from B&Q and it brought it up like new.

I took the intercooler out in the morning, laid it on its back and filled it with the paraffin (it takes about 3 liters). I then let it soak for about 3 hours, drained it of the now very black paraffin, and poured in the remaining litre or so. This I sloshed about to rinse out any residue and again drained it. Next, I rinsed it out with a hosepipe and at this stage I was quite surprised to see even more black crud being flushed out. I let the water run through until it was clear. Finally, I laid it in the sun to dry and used my wifes' hair dryer (I asked first!) to blow out any remaining paraffin fumes before re-fitting.

Taking the intercooler out is not too difficult. Undo the four bolts (with captive nuts) at the ends of the steel panel across the top of the radiator, prize out the two spring clips holding the fan cowling in place, and lift the panel clear to reveal the top of the intercooler. Undo the bolt that holds the power steering fluid reservoir to the slam panel and the steel side panel to the radiator/intercooler assembly can then be moved to one side. Undue the hose connections to the top and bottom of the intercooler and, with a bit of jiggling of the fan cowl, it can be lifted out vertically. Re-fitting, as the saying goes, is the reverse of removal.

I was pleasantly surprised by the difference in performance and I hope this will translate to an improvement in fuel consumption. If your tdi Discovery has covered 100k or more, then cleaning the intercooler is a very worthwhile, and cheap, thing to do.

NOTE: Make sure your intercooler is completely dry and free from paraffin fumes before re-fitting or 'bad' things may happen!

Whilst I had it apart, I also took the opportunity to blank off the EGR (exhaust gas recirculating) valve by fitting a plate in a joint in the link pipe between the valve and the intake pipework. This valve allows an amount of exhaust gases to mix with the intake air in an attempt to reduce the combustion temperature and thereby reduce the amount of nitrous oxide (Nox) emitted. In practice however, all it seems to do is coat the inside of the latter part of the intake air pipework and the inlet manifold with oily crud.