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300tdi Kenlow - shroud or not?


ZIKOMO

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Rebuilt my 300tdi with it’s 3rd head in 200k km and now looking at why it should need a new head with every cam belt . . . . .

My current thinking is it might be in need of better cooling - truck has both a full width intercooler and aircon condenser sitting in front of the radiator and when the viscous fan was swapped out for a Kenlow the fan shroud was removed.  When the head was being done I gave the radiator a chemical flush, made sure the intercooler was clear and fitted a new a/c condenser.  I also fitted a new thermostat and checked the fan switches on and off both thermostatically and when the a/c compressor clutch engages.  Now on normal running the temp gauge sits around mid way without a/c and slightly higher with.

Now I’m wondering if the fan is pulling sufficient air THROUGH the array or if, due to the absence of a shroud, it might taking air from a path of lesser resistance by drawing it from around itself behind the radiator?

It wouldn’t take too much time/effort for me to mold up a bespoke GRP shroud but before I do I’d appreciate any advice please.

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I dont think this will help you any? But when i got my 300Tdi 9yrs. ago it didn't have a fan of any sort fitted! After owning it for a couple of years with no issues i decided i wanted a fan just because it started life with one, no other reason. Fitted a viscous fan but never bothered with the shroud set up, radiator and cooler is standard set up! And still have no issues with temp.

I dont do high mileage  and little to mo towing, so again no hard work or too much load on the engine. It's my daily drive and is pretty well maintained ie regular oil change every 8 months.

Seem a bit unusual for a 300Tdi not heard of one like this before? So will be watching with interest, hope you get what ever the pronlem is sorted. 

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I have 2 300tdis and tow an Ifor 510 horse trailer (which is quite tall, so is quite a drag at speed). Both have full width intercoolers with slightly tweaked pumps, neither has a/c, and both run the viscous coupled fans with shrouds.  On a couple of occasions, relatively hot days here (not by NZ standards) , the 110  which is the favoured towing vehicle got rather hot (not boiling),  on the motorway climbing a reasonably gentle gradient, and I had to turn on the heater, and worse than that, slow down.  The 110 rad was reasonably new so I thought it was OK, so when the 90 came up for a cambelt change I got its radiator re-cored with 4 cores. I also added in a piece of steel to prevent air bypassing the radiators on the LHS where the old intercooler used to sit.  Since then I have used that towing a few times and all has been fine, even on quite long steep climbs, though again nothing like some of the NZ ones, and maybe not in quite such heat. But in winter I have tootled around with no fan solo for months quite happily.

I do think the full width intercooler does the rad no favours; add in a/c and it might be struggling. I think if you use an electric fan make sure it's big enough to lift a cat off the pavement, as when it cuts in you're going to need a lot of air. I had a 2.5 diesel Audi A4, great for towing but you could hardly speak above the fans when they were on - they were huge.

 

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Fit the shroud. If it needs a new head as a regular occurrence you've got an issue and a new fan is NOT going to fix it - it should work properly as standard.

I've heard it said that electric fans don't play well with TDi's as the thermal cycling causes the ali head to expand/contract at a different rate to the iron boat anchor block, causing head gasket issues.

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I had the first head changed by the dealer here and was just told it had failed but didn’t think to get a look at it to establish HOW it had gone.  This time did it all myself and there were 5 cracks visible to the naked eye.  Three were between valves and two running from valves to injectors.  Strangely there was very little evidence of damage to the gasket though and what there was looked very recent (slightly discoloured but otherwise clean).

I’ve located a 2nd hand shroud in the S.Island so just negotiating how to get it sent up and I’ll blank off where the original intercooler was to channel the air through the radiator to see if that helps.

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You have added a lot of air resistance in front of the rad with the condenser and intercooler, and then taken the flow muscle away by fitting a crappy electric fan in lace of the vastly more effective engine driven one and its shroud.  LR installed electric booster fans in front of the condenser to aid the big viscous fan on AC models, so running just the one electric fan alone is really not enough. The shroud is important because running without it allows the air to recirculate around the ends of the fan blades, so you end up stirring a torus of air behind the rad rather than drawing air through it.  Refit the correct fan and its shroud, and fit the electric fan in front as a pusher (may need to reverse the rotor on its spindle and reverse the polarity of the wiring if you can't fit it neatly with the same side facing forwards) and the problems are likely to be cured.  But also take a close look at the Y-piece in the coolant lines from the rad and thermostat housing to the expansion tank - if that gets blocked up, vapour locks can't purge, and the system's effectiveness will be severely hampered.

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