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Discussion Starter #1 (Edited)
Help diagnosing weak heater in 74 GTV 2000

The heat output on my 74 GTV 2000 is very weak, and I would be grateful for a checklist to follow to diagnose the problem before facing the apparently daunting task of removing the heater unit. EG: Can one flush the element? Is there a need to bleed air from the heater? The control lever inside feels fine - it appears to be doing something without slack or stiffness.
 

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Does your temp needle reach the middle or does the car always run cool? If it always runs cool the thermostat is open, not giving the coolant a chance to heat to full temp, giving you only warm heater feed instead of hot.

A thermostat change is a lot eaisier than messing with heater coils!!
 

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Some times a bit of foreign material will clog the heater core. And sometimes if you can back flush the unit the clog will break free and be washed out of the system. In my case that method didn't work :mad:and I had to pull the heater core out from under the dash and have it professionally cleaned out. It works great now!
 

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1. Make sure the engine is heating up to running temp.

2. Check to be sure that the heater valve is being opened fully by the heat control lever on the dash. Could be that the cable has slipped and isn't actually opening the valve.
 

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Discussion Starter #5
Thanks all. The engine does get up to temperature ok. I have a question re DaveDogs posting: which is the water output so I can reverse flush it? I guess you have to be a bit careful not to put to much pressure from a garden hose (eg) on it or it could turn into a sprinkler?
 

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Thanks all. The engine does get up to temperature ok. I have a question re DaveDogs posting: which is the water output so I can reverse flush it? I guess you have to be a bit careful not to put to much pressure from a garden hose (eg) on it or it could turn into a sprinkler?
That would be on the intake, where the thermostat is.

Will
 

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I put a tee fitting on the long heater hose that goes through the firewall and connected that to a hose at work which had way more pressure than my garden hose at home. I let it run for several minutes with the radiator cap off and saw a bunch of sediment and little bits of grit splash out. Then I turned off the hose and opened the drain at the bottom of the radiator to let all the water out and started the procedure all over again. You should leave the heater controls on your consol in the open position so that the water can circulate through the heater core and hopefully flush any blockage out. Good luck!
 

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Discussion Starter #8
Does anyone have a photo of the 2000GTV heater matrix? Is it a single zig-zag folded pipe (with fins) or multiple parallel channels? I'm wondering how effectively I can expect to flush it.
 

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Does anyone have a photo of the 2000GTV heater matrix? Is it a single zig-zag folded pipe (with fins) or multiple parallel channels? I'm wondering how effectively I can expect to flush it.
Here is a picture of a freshly removed core, in all its pre-restored, nasty (err... patina-filled) glory. (I'm in the middle of restoring the heater box/core.)

It seems the matrix is made of multiple parallel, thin channels.

 

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Discussion Starter #10
Thanks. So I guess chemical flushing can sometimes have only limited effect as it can bypass blocked channels. Recore?
 

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Let's try flushing it like Davey suggested before we get all gloomy and doomey and take it out. You could also flush the entire cooling system (good maintenance, probably needs it anyway) and take off the hose on the output side of the heater put, put a hose in the radiator run the engine and see how much if any water is making it through the heater core. Have someone work the heater control valve and see if that changes the flow rate. I would assume you should have a fairly good good flow, kinda like a horse on a flat rock:) sized flow. If not, it's clogged up or the valve is stuck and then you can get all gloomy, but only for a minute. Then you can take it out and get it fixed.
 

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I would visit a refrigeration/ appliance parts supply store and see what they have to clean coils. Some of these stores sell sprays and chemicals to the repairman to clean ac/furnace coils that work really well and efficiently. You dont want to use some chemical that leaves residue or worse eats the metal from the inside out. Take the coil to them and ask. Plus it will probably bbe cheaper than having someone else restore it.
 

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Bite the bullet and recore it if your funds allow. That way you'll have piece of mind and the knowledge that you'll not be clambering under your dashboard to take the thing apart again for many years to come! I had mine done for that reason alone.

Alex.
 

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Unless you really have to drive the car, I suggest taking the time to pull out the heater assembly and do a refurbishing of the system. It was one of the first things I did on my 69 and it was worth it. I even wrote an article about the R&R procedure.
 

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Discussion Starter #15
Living in Chicago you would be well motivated! I remember seeing Lake Shore Drive, though not quite as bad as this photo!
 

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Heater

It was 4 F(about -15C, if my math is correct) this morning, but the GTV isn't coming out the door until the streets are clear again. I do drive it in the winter when roads are dry and clear of salt. The refurbishing of the heater box is relatively easy one removed from the car. I rmeoved the seats and center console entirely to make it easier. Four small nuts hold it to the studs under the dash. Releasing the cables from the heater control rods was a little difficult, but not impossible. I cut the heater hoses and replaced them as part of the project. I was then able to carefully remove the entire box as a unit after carefully disconnecting the tubes running to the demister vents. It is a "Rubic's" puzzle trying to get it out, but it is do-able. Once the box is out, it is easy to remove the heater valve and disassemble the box. I had to do so to replace the motor, but I used the opportunity to clean up pivot points, put in new seals and generally R & R the whole box. With a refurbished heater valve(I wanted to keep the original - Obsessive/compulsive that I am, I found a way to refurbish the internal rubber "mushroom-shaped" valve.) Doing all of that work made a heater/demister that actually works very nicely. It took a few hours of actually sitting and carefully removing and re-gluing some parts, finding acceptable replacements for some broken bits, but I was in no hurry and I had access to two Alfa shops here who were very helpful in finding replacement pieces. I was in the process of also replacing the wiper motor, so I refurbished the linkage there and replaced the drain hose from the cowling area. That hose is relatively easy to replace when you already have the heater assembly removed. The heater core was checked by a local specialty shop and pronounced in good order. They flushed and repainted it. Reattaching the box and controls was slow and frustrating as I lay on my back with my head under the dash dropping nuts and various bits on my head. Connecting the new heater hoses was, as I remember, the most difficult even with the correct hoses, but you only have to do it once (HOPEFULLY!). Reinterating what I have said before, it is a job worth doing if you hope to enjoy the car in cold weather. With an old car, the simple things such as all windows, lights , instruments working, etc make the difference, in my estimate, of having a car worth having and just a junk heap. Spend the time and money to make it right!
 

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I agree with Dr. Don - although I am only halfway down the process (removed the heater box, and currently working on rebuilding it.) I might change my mind if the rest of the job turns out to be a real pain in the neck! :)

Here are some links from the BB that I've found useful:
http://www.alfabb.com/bb/forums/car-restoration/3922-heater-box-rebuild.html

http://www.alfabb.com/bb/forums/gt-1965-1974/22153-sprint-gt-heater-box.html
http://www.alfabb.com/bb/forums/gt-1965-1974/54588-heating-box-your-help-please.html
http://www.alfabb.com/bb/forums/gt-1965-1974/9132-removing-refurbishing-heater-box.html


I am also keeping track of my work in my blog (shameless plug alert):
Q's House of Speed


Good luck.

enrique
 

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Dr. Don, could you tell us how you refurbished the wiper linkage? Did you find any aftermarket suppliers that can do the job or did you just buy a used, but in good shape linkage? Mine has quite a bit of play in it plus all the rubber bits have deteriorated and I just can't find anyone around here that is willing to rebuild mine. There's one on ebay right now but I'd prefer a rebuilt one if it's at all possible.
 

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I just put my heater box back in this evening, put the bolts and washers on the left side first and the slide the heater box up and onto those then put the right ones on. There is a lot more access on the right and trying to get the nuts started on the left with it up in there is darn near impossible.
Davey, is your play in the linkage in the ball and socket joints in the linkage?
 

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gigem, yes it is. Plus all the rubber boots have deteriorated long ago so I'm thinking it just makes matters worse. It's funny that almost all other body and mechanical parts are available for these cars but not the wiper linkage. I won't be driving the car any time soon due to body repairs and such, but I'd like to get all the parts I need to put the car back together in the meantime so I'm not waiting for a part and holding up the restoration.
 
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