Defender Heat

[andrewMcF]

Tis the season to freeze your... off!

I have a 91 Defender 110 exMOD winterized... I'm thinking if this is winterized I'd hate to see unwinterized!!!

The extra radiant heaters in the back are physically disconnected.

She's drafty as hell too, I've taped the dash flaps and that's helped.

So here's the real problem, I find when the truck engine is up to temp the heat coming out of the dash is warmish to mildly hotish and the fan blows rather poorly... Is this a common state for these trucks or is there a cure?

I'm used to my series taking forever to heat up but when she does it's plenty hot and the Kodiak heater blows good and strong.

Is there upgrades I should be doing or is there a technical issue here?

I have a rad muff coming and I don't think it's the thermostat as the trucks engine temp shows the truck heating up in not too bad of time...

Andrew

[red90]

It should blow fairly well and hot if all in good shape. First make sure the thermostat is not leaking and the engine is at full temperature. Second make sure the hot/cold flap is adjusted to be tight to the hot side. Third reach into the fan and make sure it is free. They get mud in them and it does not take much to slow them down. Beyond that a full refurbish of the heater is the next thing to do.

[red90]

Also make sure the dash vent flaps are actually opening up.

[island dormy]

Hi Andrew

All the preceding advice is spot on, however if none of that helps you may find disconecting both heater coolant hoses at the heater and back flushing the heater core both ways will do wonders.
BIG WARNING though, do not use full pressure straight out of the garden hose. House pressure can be as high as 120 lbs. You will destroy the heater core. Just use enough pressure to flush it out.

The exterior fins of the heater core could also be plugged with dust leaves etc. that may also benefit from a clean out with compressed air.

Victor 1962 Dormobile

[red90]

If the core is plugged on the air side, you are best to pull the heater out of the truck and remove the core. It is the only way to clean it properly. It then allows you to check/fix the foam seals, which deteriorate with age. It is not a very big job to pull and overhaul. It is not uncommon for the cores to by plugged up with mud after the stellar military use. A new core is not that pricey either, so something to consider if you take it out.

[andrewMcF]

Thanks everyone! I know what I'm doing this weekend! Anyone want to join me? lol

[withabix]

House pressure can be as high as 120 lbs.

Is that all??

If you've got fire sprinklers and an incorrectly adjusted PRV on the non-fire 'domestic' circuit, you could be seeing 170psi... :shock:

[island dormy]

Hi Withabix

Over here on the island we are lucky to to have 50lbs of pressure barely enough to wash the dust off your trusty rover after a car show let alone wash heavy mud off the old girl after a trip up the whipsaw.

Cheers

Victor 1962 Dormobile

[andrewMcF]

So maybe I'm a little simple in the head but now I'm confused... maybe you guys can enlighten me!

I did get the matrix out, only to discover you have to drill the rivets out to get at the core... ugh! I was runnning out of time so back it went into the truck, from the cab side it looked pretty clean. I was able to adjust the flow flap so it was open more allowing more air in but she's still kind of warmish temp... I've also ensured the top leaver was all the way to warm... but... I'm confused as this setup seems a bit strange compared to normal heater systems, event he series.

There are two flaps in the heater matrix. One flap, leaver on the side, opens and closes the matrix to the cab. This can increase or restrict the flow to the cab, correct? Isn't that what the fan speed is for?

The internal flap is air mixture changing the temperature apparently somehow... Don't most vehicles just restrict the amount of coolant to the heater matrix? Like the Series trucks....

Also is there no adjustment between defrost and floor or is it what you see is what you get... lol It is a an exMOD truck so I wouldn't be surprised if it's fixed thing.

[red90]

Yes, it is a stupid design....

1) Hot/Cold control. Yes, most cars adjust the flow of coolant. In the Defender, the flow is not restricted. The hot/cold adjustment is that flap with the cable on the top that forces the air through the matrix or lets it bypass. a couple of things to watch. The flap uses a foam covering to seal to the box. Make sure this is in good shape. Second make sure the foam seal around the core is good or cold air will bypass it. Lastly make sure the air side of the core is clean. Just run a hose over it. After you drill the rivets, the core will come out and all will be clear as to what is going on.

2) Air flow control. The flap with the cable of the side of the box is just there to completely shut off the heater from the cab. Helpful when wading to limit water ingress or in hot climates to prevent hot air coming in.

3) The defrost/floor control is the third cable that is beside the hot/cold control in the cab. It controls flaps that close off the flow of air to the lower dash vents and that forces more air to the always open defrost vents.

4) Wash the fan out with a hose. It is a low point and collects mud. Any tiny amount of first in there and it will run slow.

[andrewMcF]

by the feel of the heater core movement there is no foam around the core itself... I took a peak at the Rovers North site and see no part for it... The foam between the matrix and heater core is definately ready to be replaced but will have to hold for now and the foam ring between the matrix and fresh air intake snorkel is deceased... lol

As for a third leaver to direct air to defrost and floor, I don't think the exMOD's have that cause I sure don't...

I am also waiting for a rad muff from Jeremy at Rocky Mountain, that will help...

I'm also considering replacing the thermostat... see if I can source a hot one.

[red90]

Oh they definitely have the lower dash vent and lever. Yours must be broken or missing for some reason. I've worked on tons of ex-MOD trucks.

For the foam, go to the hardware store and get closed cell foam weatherstriping. It is better than what Land Rover used.

Rad muff does nothing other than mask a proper elsewhere. The heater is not too bed when setup. If you truck has no insulation and is not well sealed, it does not matter how good the heater is. My truck (an ex-MOD 90) is fine at -40 as it is well insulated and leak free. The stock heater is a bit small for a 110 even well insulated and larger or second heater helps.

[andrewMcF]

Well my truck is as well insulated as one would expect for what is it is, as in none at all and the wind passes through that thing pretty good! I put some gun tape over the front flaps and that's slowed the wind down some...

As for the vent control... I have two levers on the door side....
http://s266.photobucket.com/user/buster ... 2.jpg.html
and then the fan speed control on the other side...

Where would I find the 3 cable lever, as in on the dash?

Andrew

[island dormy]

Hi Andrew

If you can borrow a heat sensing gun go for a 20 minute ride to get the tempurature up then point the gun at the thermastat housing it should be reading at least 180 F. Maybe you do have a weak thermastat that is sticking open even though the gauge says things are normal.

Just another thought.

Victor

[red90]

Your photo shows the two levers on the door side. One for the heat control. One for the defrost control.

[red90]

The fan speed lever is the one that controls the flap to shut off air from the heater as well as the fan speeds. .

[island dormy]

Hi Andrew

I have been a passenger in many defenders the heaters work fine, they can not however be compared with a kodiak the fans just do not blow very hard in the defenders.

If this defender is new to you maybe it is time to change the thermastat, flush the block , heater core and the rad. Heater hoses can colapse internally and block coolant flow. The take off points for the heater hoses can also get blocked up with sludge and scale.

One last point the heater core (which sits higher than the engine) can air lock, so with the engine idling (and a good supply of rags) pull the top heater hose off the heater core and check coolant not air comes out.

If none of these ideas help maybe invest in some of those red wool one piece long johns the old timers used to wear when driving model Ts in the 1920s.

Good luck Victor 1962 Dormobile

[andrewMcF]

Your photo shows the two levers on the door side. One for the heat control. One for the defrost control.

Right, so what I'm understanding is there should be 3 cable levers,two on the heater matrix, side one for flow into the cab and top one for temperature setting and a third one to change from defrost to floor.... correct?

If this is true I only have those two levers shown in the pic... or am I completely turned around?

Andrew

[andrewMcF]

Hi Andrew

If you can borrow a heat sensing gun go for a 20 minute ride to get the tempurature up then point the gun at the thermastat housing it should be reading at least 180 F. Maybe you do have a weak thermastat that is sticking open even though the gauge says things are normal.

Just another thought.

Victor

I'll try this! It's about a 20 minute drive to Princess Auto, go in buy a laser thermometer test my truck and then return it! LOL

[red90]

There are two levers on the right side of the instrument cluster. One is for the hot/cold flap of the heater (top of the heater box). One control the flap that closes off flow to the lower dash vents.

There is one lever on the left side of the instrument cluster. That lever controls the fan speed and the flap that closes off the heater flow into the cab (side of the heater box).

Three levers, three flaps.

[red90]

Here: http://workshop-manuals.com/landrover/d ... _controls/

[sailourboy]

"a 20 minute drive to Princess Auto, go in buy a laser thermometer test my truck and then return it! LOL"


We will be watching you:)