Mod to widen the heater hole in bulkhead - Defender Source
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  #1  
Old June 28th, 2009, 03:24 AM
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mark kellgren
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Question Mod to widen the heater hole in bulkhead

I have read on several accounts in other threads people refer to the efficiency gains in heater output by cutting a larger hole in the bulkhead for the blower motor to pass air through. Those that have done it seem to perceive that it doubles the heater output, which would really be impressive if even close to that. Unfortunately, I have yet to find any details on how this was done, instructionally.

Given that every winter, we have seasonal threads pop up of people complaining about heater output, I think this is one of those "Best Mods Ever" that should have a dedicated thread in the interest of the greater Defender community. Summer is probably the best time to do this mod as well, since it's labor intensive.

I definitely plan on doing this when I get back from Iraq in the spring, and definitely need it since my diesel runs cool. I have never removed my heater assembly and A/C, and want to visualize what I'm getting into, and any parts that I may need to have on hand.

So for the few that have done this mod, or know exactly how to do it, any details on procedures, and pictures of what the mod actually looks like, and/or conceptual markups by experts of what should be done (using MS Paint or equivalent), please post on up!
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  #2  
Old June 28th, 2009, 05:21 AM
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Another mod here in the UK, is to dis-assemble the geater unit itself, remove the "core" (the little radiator thing.... and whilst you're doing that you can get upgraded ones with more surface area) but then to refit it but totally seal it all the way around the outside, so no air can "bypass" the heater....not sure how to seal it, maybe cut some polystyrene or rubber blocks?, also whilst it's in pieces, get a tube of seam sealer and seal all the internal corners and edges, as they're not totally air tight, this will stop excess warm air from leaking out and warming the engine bay instead of your feet
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Old June 28th, 2009, 09:26 AM
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Opening up the hole in the bulkhead is a very simple affair. When you remove the heater assembly from the bulkhead you will see that the flange and mating rubber gasket are much larger than the hole in the bulkhead. I took measurements and opened up the hole with a sheet metal nibbler so that the two corresponded.
Opening up the hole in the bulkhead is only one step. You also need to enlarge the opening in the lower dash tray/heater plenum where it mates to the bulkhead on the inside of the truck. Once these cuts have been made- yes it moves a lot more air. Last winter as cold as it was, I only used low speed on my heater.
My problem now is getting the diesel to make heat.

a couple of not so clear photo's I took with my blackberry while making these cuts are in the lhd conversion write up here: http://www.dividingcreekroverimports...ive_conversion
Hopefully those will give you some better idea.
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Old June 28th, 2009, 10:38 AM
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Not a how to, but shows pix at least.
As other said, dead easy mod.
It doesn't double output, but helps some.

http://www.eastcoastrover.com/97.html
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  #5  
Old June 28th, 2009, 01:24 PM
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About how long does this take with a rover thats put together. With tools in front of you.
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Old July 17th, 2009, 05:12 PM
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Can someone tell me what gauge thickness the bulkhead sheet is around this hole? want to make sure I can a nibbler that can handle it.
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  #7  
Old July 17th, 2009, 07:36 PM
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Quote:
Originally Posted by JohnsD90
About how long does this take with a rover thats put together. With tools in front of you.
A couple/three hours maybe. Pretty easy to pull the heater.
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Old July 17th, 2009, 08:07 PM
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I have done this on both trucks.. You have to take the lower dash off so a few hours for sure...
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Old July 17th, 2009, 10:33 PM
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Quote:
Originally Posted by TDI Guy
You have to take the lower dash off so a few hours for sure...
Really? You can't just cut the hole from the engine side?

Also, why not replace the blower motor with a better one? I saw a Youtube video of a guy with a Series truck who replaced the motor with an American version. All it required was a slightly larger hole to mount it. He posted several videos of rebuilding the truck and taking it to an event, with all its exciting shortcomings!

While I prefer fixing the problem correctly, I wouldn't mind taking the potentially easier route of replacing the motor.


I would only consider this for a Tdi, as I find the NAS heater excellent for flow and heat.
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Old July 18th, 2009, 12:08 AM
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Personally, from looking over the whole system, I find it hard to believe the bulkhead hole is causing much restriction. It is smaller within parts of the heater box and in the wing intake and much smaller at the vents.

My advice is normally to reseal the heater box internals, open up the lower vents, adjust the cables correctly and add better insulation. I've run at -40 with a nice warm cab. My truck heats up faster than my modern cars.
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