Heater Box Removal - discovered why I had no heat

Got pretty frustrated recently, it's been cold for a couple of months and although my daily commute is less than 10 minutes each way I wasn't getting but a smidgeon of heat and defogging the windshield took nearly 15 minutes on the passenger side and the driver side took even longer!

I had flushed the coolant system multiple times, replaced all the hoses to the heater core, even bought a new heater control valve before I realized my current one is just fine and dandy. I somewhat suspected my water pump - DPO had said he had replaced it and the pulley was rock solid so I was puzzeled - I was getting hot water flowing pretty easily through the system just no heat inside!!!

I needed to figure out:
1) why I was getting a little heat and a little more airflow on the passenger side
2) why I as overall getting 'hot' air that was only a couple of degrees above ambient air temp outside the car

I suspected that many of the passages in the heater core were clogged and only part of the core was working, so I bought an upgraded heater box from BP northwest and resigned myself to what is commonly described as one of the most frustrating things to do on a MG. For those of you that are going to do this too, I would recommend you watch this this video to help orientate yourself:
MG 4 - Heater Removal

While time consuming - I don't think this is difficult at all, there's just many steps involved and maybe I had it easy as my '70 GT has a de-smogged GB engine ('68 I think) so there was little plumbing to get in the way for me. When I got to the point where the heater box was free to move around and the vent tubes removed & the control cable was free'd up – I think I spent a total of 3 minutes before I got my heater box out.. so here's the secret: Rotate the heater box counter clockwise with the axis of the rotation approximately where the fan motor is.

Standing in from of the engine looking at the heater box, pull it towards you just enough so the right angle mounting bracket on top of the heater box that attaches to the firewall will clear the edge of the body panel above it (as though you were going pull it out and up) and gently raise the heater box until you feel some resistance. Now start rocking is counter-clockwise and it'll go! You'll need to rotate it about 60 degrees CCW and you should be able to pull it out =)

So, my no heat situation was easily solved, as when I opened up the heater box I found some rocket-scientist had wrapped the blasted thing in foam!

[url=http://www.flickr.com/photos/59186289@N07/6822390391/][/url] P1050891 by MyMicro43rdslife]asdf

What an awesome idea! So I guess the uprated heater core I bought from BP Northwest for $113 wasn't really necessary... but I decided the prospects of 'enhanced' heating capability was just to good to pass up, plus it was sexy black....

[url=http://www.flickr.com/photos/59186289@N07/6822394045/][/url] P1050895 by MyMicro43rdslife]

Well it turns out I really did need that uprated heater core because I had always wanted to modify holes in the heater cover for no other purpose than to compensate for a supplier who doesn't understand how quickly critical dimensions can be checked with a couple of “go /no-go” hand held fixtures. I see this all the time, so it's really no surprise and I'm probably in a minority here finding it difficult to understand how 'looks close' is the best that suppliers can muster these days (and I'm talking about moss, vb, etc too).

[url=http://www.flickr.com/photos/59186289@N07/6822395941/][/url] P1050897 by MyMicro43rdslife]


Okay, sorry, rant over

Once the holes were relieved a bit new grommets from the local ace hardware store easily covered the new and old radius’s and then is was on to discover how the my airflow varied from once side to another. Those vent tubes weren't lined up as evidenced by the off center impressions left on the base of the rubber elbows.


[url=http://www.flickr.com/photos/59186289@N07/6822397791/][/url] P1050900 by MyMicro43rdslife]

I was able to dive into the footwell head first and look through the footwell vents back at the tubes, rotate elbows while jostling them a bit and I could confirm I got mine in correctly. Drivers side was a bit tougher to do as the brake pedal was in the way but in the end I confirmed fitment visually.


I'm pleased with the heat, not sure if the new heater core is substantially better but I'm am getting what I need and it does get plesantly warm inside – I checked and after a 20 minute drive inside air temp was 40 degrees above outside air temp and it only took about 5 minutes to get enough heat through the defrosting tubes to take care of any fog I might get on the windshield.

wow! That's crazy about the foam! There is supposed to be some foam in there, but wrapped the other way around the core to force air through it rather than around it. Glad you got it fixed! Not the most fun job in the world of MG's.

Great job, photos, and explanation, NZ. Did you get the uprated fan/motor as well? I'm going to piecemeal mine, replace the motor first, maybe then the fan, maybe then the core. Glad to know the tricks on removing the whole box.

Dave

I did buy the uprated core, but when I swapped them the new one had LESS tubes that the original one!

Heats OK though.

Your photos go on to a camera in peices. A man after my own heart. So many people don't dare taking these things to pieces, but they are often repairable. Laptops, cameras, in fact most things. Good for you not just putting it in the bin.

I had to laugh at those pictures! And someone went to a lot of trouble to foam it the wrong way.

You truly did have a DPO!! Welcome to semi-warm, which is as good as it gets.

I don't suppose you are a good candidate for judging the improvement from the upgraded core?

I'll add this...

If your commute is only ten minutes you are never going to get full heat because the engine will not have had time to reach full operating temp.

My suggestion would be to experiment with different heights of card board panels placed across the bottom of the radiator. If you cut it right it will slip into the groove openings on both sides and stay there.

You will find a happy medium where the heat is brought up to par more quickly but the obstructions does not cause the engine to actually over heat.

I would start with blocking off the lower 25 or 30 percent.

Jack.

I'm going to first try just the motor, and put the existing fan on that and see what kind of improvement I get with that very simple operation. I'll let you know!

Dave

A dyslexic heater core foam wrap. OK. 8-)

One hopes that the DPO will spend eternity (or at least several days) in a cold car warmed by a heater with the foam the wrong way.

What can you say - some dumb cluck just couldn't bring himself to pull it apart again.