Heater box

[Mg_Bizzle]

Having a few problems with my heater box. It decided it was time to leak yesterday and water was coming in through the left heater vent by the floor in the cabin.

Iv tried to take it apart today, Iv undone all the screws and clips but the cover facing the engine bay just wont come off, something below the blower motor seems to be holding it on, shall I just force it off?

The heater matrix also appears to have some sort of sponge around it...could this be someones bodge to fix the problem?

 

[jlaird]

Hehe, they all have that sponge, it forces the air to go through the core rather than around it. No clue on your box front but someone will.

 

[bcliff]

There is also some foam down around where the defroster hoses attach. After 27+ years, that foam will turn to cement. I have never pulled just the heater cover, I have taken the whole heater. This causes the lower foam (Cement) to break. I am now on the verge of putting the heater back. So my question is how to replace the lower foam??
Bruce

 

[tony barnhill]

The front cover has a lip that extends down into the opening on an MGB - try lifting it upwards about 3/8-inch

 

[1965_MGB]

Once all the bolts are out, you have to disconnect the cable at the bottom. You should be able to get at it from the right side floor vent. Once that is loose, you should be able to wiggle the whole unit out. This way, the inside can be cleaned and painted. Make sure you put new pads and grommets in the box. The pads keep air from getting by (thus more heat) and the grommets will make sure that the new core does not rub against the lip of the box.

 

[DrEntropy]

"Forcing" it will break things. The plate behind the console where the tranny tunnel is, has some screws holding the defrost tubes in place and the plate along with two nylon tubes behind it to the box must also be removed.

 

[Mg_Bizzle]

damm looks like more of a job then I expected then, I was meant to be fitting a new fuel tank this week /bcforum/images/%%GRAEMLIN_URL%%/rolleyes.gif

Whats likely to be the cause of the leak, the heater matrix?

Thanks for the tips il let you know how I get on.

 

[Rob_Edwards]

The heater core might not be your problem. Was the liquid just water or was it engine coolant? If it was just water, then the problem is likely to be that the drain tube for the fresh air intake plenum (under the chrome grille, at the base of the windscreen) is clogged. There's a bulb at the bottom with a slit in it. (The bulb is called "Tom's knob," named after it's designer). It's intended to be a one-way valve that lets water out but excludes engine fumes from coming back in and getting into the cabin. Over the years, the rubber it's made from petrifies and any trash that gets into the tube gets stuck, so water collects in the plenum and rots it out and also sloshes on your feet when you got around a turn.

To clear it, run a coathanger wire down through the chrome grille and down through the bottom of the tube. It's on the right (passenger, in the US) side. It can be a little hard to find but if you probe around a bit you'll get it.

To slow down the accumulation of trash in it, you might consider fitting one of the black or chrome screens available from Moss, VB, and most other vendors.

HTH!

 

[Mg_Bizzle]

It was definatly engine coolant.

 

[Rob_Edwards]

Sounds like it's time to remove the heater box then. Sorry about that!

 

[jlaird]

If it is the core leaking a decient radiator shop may be able to help.

 

[Mg_Bizzle]

Im having enough trouble removing the heater box!

Iv removed the centre console, including the knob that adjusts wheather the heats going to the windscreen or interior. Iv also taken away the tubes that go from the heater box to windscreen vents, The only thing I can see stopping the heater box from being removed is the cable going from the knob iv removed into the heater box.

Does this have to come up with the heater box?

Iv got pics to show where am at I just can't find the camera lead atm /bcforum/images/%%GRAEMLIN_URL%%/mad.gif

 

[DrEntropy]

Have you removed the oval shaped plate inside the cabin and pulled the nylon tubes from the box? Removing the cable from the vent flap inside the plenum can be done, but reattaching it becomes a skill test. Best way is to un-do it from the control on the console and allow it (just the cable) to come out with the box. A butter knife can help with getting under the lip of the box on the bulkhead to "unstick" the gasketing, and there may be some of the foam one left directly behind the blower motor at the back of the box. It "seals" the blower output to the bulkhead.

Photos would be helpful.

 

[hottvr]

Hey MG_Bizzle,
When removing the heater box, bend the upper metal flange that holds the uppermost screw to the firewall as flat as possible to the heater box to avoid the metal brake lines above. When all bolts have been removed from the box, lift box from the right side of the car and loosen the control cable from the barrel with small socket(think 1/4" or 7mm) and extention.You can get to the barrel by lifting the box out of the hole from the right side and leaning it forward away from the firewall.
Good luck
Rick

 

[DrEntropy]

PST!!! RICK! RHD. /bcforum/images/%%GRAEMLIN_URL%%/wink.gif Hydraulics are all on th' starboard side.

 

[hottvr]

The 2 brake lines leading to the master brake cylinder above the heater box need to be avoided so the screw flange needs to be bent down. Please explain your reply Doc (just curious).
Rick

 

[DrEntropy]

The lines on the B-GT in question aren't where yours are. I believe his is Right Hand Drive. England. He shouldn't need to torture that tab the way we do here inna Colonies. /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif

I MAY be mistaken.

 

[Mg_Bizzle]

Pics:





Whats the hose in this pic for?





Hopefully they help?

 

[Rob_Edwards]

Whats the hose in this pic for?

That's the drain I was telling you about. It does not need to be disturbed to take out the heater box.

HTH!

 

[DrEntropy]

Rob is correct, no need to disturb that hose. The cable passing next to it is the flap control to be undone at the control unit. Easiest is to remove the knob then unscrew the nut holding the control to the facia. Then you may easily detach the cable from the control and draw it out with the box assembly. The reason for this is that trying to reattach the flap end with only that little hole to work thru is a maddening, time consuming task compared to threading the cable thru the hole on reassembly.

It appears as if you have only aged seals and the cable making this difficult. BTW: you can reattach the blower motor to the case to make it less a "juggling act". Go around the base with a palette knife or similar, same at the joint I mentioned between the bulkhead and the box; at the point just behind the blower motor to sever the seals. It ~should~ lift out of the plenum once the seals are cut.