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BogMonster

Member Since: 05 Feb 2008
Location: Stanley
Posts: 400

2015 Defender 110 Puma 2.2 USW Corris Grey

Does the Puma heater get air in it easily?

Ever since I bought my 2.2 I have noticed that the heater is less effective when the engine is running slowly (low speed & load in light off road use for example, or sitting at idle for a period) and I just put it down to 'one of those things' as it was plenty hot enough when running at any speed. The coolant level was very slightly below the cold line but plenty in the header tank so had never worried about it much.

The other day I happened to have an open can of OAT antifreeze and some distilled water to hand after a job on one of our other 110s so I topped it up to the line - no more than half an inch added in the tank. Now the heater works significantly better at low engine speeds.

The only explanation I can think of is that the engine was cycling a small amount of air around which when idling, would settle in the heater matrix, but then be forced out by the higher flow of the coolant pump when the engine was working harder.

Is this a known 'Puma eccentricity'? There are no other symptoms of anything amiss. Did a search but nothing firm came up. ---
2006 Defender 110 SW 300Tdi • 2011 Ford Ranger XLT crewcab • 2015 Defender 110 Station Wagon Utility TDCi

6th Nov 2018 10:27am

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 17473

2007 Defender 110 Puma 2.4 DCPU Stornoway Grey

Yes, it is a well-known phenomenon.

It only takes a very slight drop in coolant level to make the heater significantly cooler, and this is usually what I use to tell me that I need to check the level.

The Puma heater is also well-known for other eccentricities: the temperature fluctuates greatly according to what the engine is doing, and the left hand outlets are always much hotter than the right hand due to the cunning design of the matrix*. The valve is also largely binary, so the heater is either off or in supernova mode.

All in all it is reassuring that JLR managed to keep the tradition of wonky and generally unsatisfactory heating systems alive throughout a 70 year production history.

* This feature (left side being much hotter than the right) is thought by many to be a "heritage" feature, replicating as it does the old "fug stirrer" heaters of early series days which ensured that the passenger's legs remained totally hairless whilst the driver still froze.

6th Nov 2018 5:10pm

jst

Member Since: 14 Jan 2008
Location: Taunton
Posts: 8096

2011 Defender 110 Puma 2.4 USW Stornoway Grey

I have just done a stat change, header currently overfilled, heater is really hot! Yes its all bled through! Cheers

James
110 2012 XS Utility
130 2011 M57 bespoke Camper
90 2010 Hardtop
90 M57 1988 Hardtop

6th Nov 2018 6:47pm

BogMonster

Member Since: 05 Feb 2008
Location: Stanley
Posts: 400

blackwolf wrote:
Yes, it is a well-known phenomenon.

It only takes a very slight drop in coolant level to make the heater significantly cooler, and this is usually what I use to tell me that I need to check the level.

The Puma heater is also well-known for other eccentricities: the temperature fluctuates greatly according to what the engine is doing, and the left hand outlets are always much hotter than the right hand due to the cunning design of the matrix*. The valve is also largely binary, so the heater is either off or in supernova mode.

All in all it is reassuring that JLR managed to keep the tradition of wonky and generally unsatisfactory heating systems alive throughout a 70 year production history.

* This feature (left side being much hotter than the right) is thought by many to be a "heritage" feature, replicating as it does the old "fug stirrer" heaters of early series days which ensured that the passenger's legs remained totally hairless whilst the driver still froze.

Nice one, made me chuckle. Thanks, something to keep an eye on then. It does still fluctuate between hot and hotter but much less than before. Wife likes her footwell to be in the Sahara while I drive with the window open in winter, so the mismatch in temp is spot on

---
2006 Defender 110 SW 300Tdi • 2011 Ford Ranger XLT crewcab • 2015 Defender 110 Station Wagon Utility TDCi

6th Nov 2018 9:12pm

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