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Poor heater performance in RRC 200tdi


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I hate the heater in my 1993 200tdi Range Rover Classic! It has not been working very well for the last couple of years, blows warmish air when it is cold and cool air when it is really cold out.

At -15c on the hwy the water entering the heater core is around 80c to 90c, the water leaving the heater core is around 75c to 85c, the air coming out of the vents is 35c (55c with recirculation on).

When is is -30c to -40c, as it often is in Yellowknife, the air coming out of the vents is about 0c to maybe 10c.

I've managed to get a infrared thermometer into the heater housing and with the engine at 40c and the heater core at 35c the air coming out of it was 10c to 15c with an ambient temp of about 5c. This is pathetic.

I've just torn the whole heater assembly out of the RRC and taken it apart to try and figure out why it works so poorly. I can't find anything wrong with it. The blower is strong, the core is good and flows tap water well in both directions. The blower and core where new about 3 years ago when we did the RHD to LHD conversion.

I tired to test the internal flow of the heater by manually closing flaps in such a manner that it should have blocked air flow from the heater. This did not work and the air flow slowed only a little. I have the feeling that the air has been by passing the core but I can't figure out how.

A couple of other things I did note;
- the water flows from the thermostat housing to the core then back into the rear of the head
- the water flows into the upper core pipe and then out the lower pipe

This is the opposite of how I thought is should flow.

There is also a section of aluminum that is part of the core and blocks about 1/5th of the core, this doesn't seem right.

Any ideas on how to make this RRC warm enough to defrost windows and prevent frost bitten feet in Yellowknife?

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I assume the main radiator and thermostat are all in perfect order?

Have you flushed the engine waterways too?

My 200 kicks out bags of heat for a UK winter but the heaters aren't the best compared to a modern RR!

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I think the amount of research you have carried out is very impressive & it's a shame that it didn't result in a solution. My '87 Vogue has a very good heater (but then it's a V8) fine for the UK but I have to wonder how effective it would be in the temperatures you quote! Do normal car/truck heaters used in your region cope with such extremes? It's interesting that you got the best results from the 're-circulate' settings as I find 'fresh air' the best by far, probably because winter UK ambient temperatures are that much higher. Perhaps an independent heater is the answer.

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Hi there, I have been having the same problem in my 93 lse. Worked it out to be the vent flaps were not closing 100% (more than one). They would not respond to adjustment. Replaced the hole assembly yesterday, went out for a drive last night and had to take my jumper off! I must state that this is in English temperatures!

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I suspect you're hitting the problem that modern Diesel engines are so thermally efficient that under low loads they shed really rather little heat into the coolant.

[Example: on my 90TD5 even in UK 'cold' temperatures if I have the heater on full-power after a few minutes in slow moving stop-start commute traffic the temperature-gauge ends up in the blue sector]

Eberspacher fuel-burners are the answer.

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The main radiator is three years old as it the thermostat, both in good shape. IR thermometer measures lower T-stat temp of over 85c before the upper rad hose gets any heat in it so I believe that is working.

My other vehicle is a 1996 Chev 6.5 turbo diesel and it makes lots of heat though at -35c it does have trouble keeping the windows ice free, still comfortable for the passengers just icey windows. The RRC is freazing at those temps.

based on the fact that the water is almost as hot coming out of the core as going in I'm convinced the issue has to do with air flow not all being force through the core and somehow bypassing it.

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The blower works great, moves lots of air. Not a lack of air movement but perhaps a lack of air passing through the core.

Funny thing is the AC works better in this RRC than any vehicle I've driven, I could use it as a meat locker when it is +30 outside.

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I suspect you're hitting the problem that modern Diesel engines are so thermally efficient that under low loads they shed really rather little heat into the coolant.

[Example: on my 90TD5 even in UK 'cold' temperatures if I have the heater on full-power after a few minutes in slow moving stop-start commute traffic the temperature-gauge ends up in the blue sector]

Eberspacher fuel-burners are the answer.

I have to agree, my old Disco 200tdi struggled to get upto a temp for the emission test for it's annual mot, and that was without a fan on the pulleys.

Try putting tin foil over the grill, have you still got the fan on the engine?

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I think I may have fixed the heater. I've foam tape sealed the core into the housing and adjusted all the air flaps.

I also bent the aluminum section that covers up part of the core to an angle that seems it would allow much better air flow. Forgot to take a photo of this part.

Bench testing the heater with hot tap water and a battery to run the fan resulted in a core temp of approx 55c and a exiting air temp of approx 50c with the water exiting the core at approx 55c. I should have done this bench test before stripping the heater to establish a bench mark but it seems likely that the heater is working well now. Now all I have to do is stuff it all back into the lair of the spaghetti monster :mm


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  • 2 weeks later...

Well after all this work the heater is still not very good. By running on recirculate it is better but the main issue seems to be the fact that the engine is not hot enough. So to help this I've installed a Webasto engine heater.

Some photos of my Webasto heater installation:


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Yellowknife is in the Northwest Territories of Canada. The Range Rover starts down to a bit below -30c but it is not happy about it. With the help of an electric battery blanket and an electric lower rad hose heater it starts quite well below -30 when plugged in for a few hours. My hope is that the Webasto will enable trouble free starts at any temp we are likely to get but it does go below -40 or even to -50 at times and the Webasto is only rated to -40c so I might push it beyond it's limits.

NT_2003049.gif

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Yellowknife is in the Northwest Territories of Canada. The Range Rover starts down to a bit below -30c but it is not happy about it. With the help of an electric battery blanket and an electric lower rad hose heater it starts quite well below -30 when plugged in for a few hours. My hope is that the Webasto will enable trouble free starts at any temp we are likely to get but it does go below -40 or even to -50 at times and the Webasto is only rated to -40c so I might push it beyond it's limits.

NT_2003049.gif

Cheers for that.

+1c here today with about 5mm of snow, you'd be walking around in your boxers!

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Good/dangerous way to start a diesel in cold conditions is a burning rag by the air filter intake, works very well but may result in engine bay fire. Oh, and if the temp is so low that the engine oil is frozen, a small fire under the engine to warm it through is idea. Same safety warnings apply.

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I just driven back to Yellowknife, the heater was slightly better on the hwy than on the way down but still not great. Back in Yellowknife the RRC is much warmer around town as the Webasto keeps the engine temp up and it is already warm when I get in if I've started the Webasto with the remote ahead of time.

I like the Webasto coolant heater so much right now I'm considering a Webasto Airtop to heat the inside of the RRC in cold weather for next winter.

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