I was having a good weekend..... now my heater's leaking

[scott.venables]

It started off so well, Friday I fitted relays for the headlights and Saturday and Sunday I replaced the timing belt and checked the valve clearances.  While I had the coolant drained I thought it would be a good time to finally fit a heater tap I'd fixed up.  The heater tap was cracked 4 years ago when I put the car on the road but had lasted thanks to Araldite, sheet metal strips, tie wire and a hose clamp.  So while I fixed the heater tap I temporarily (for 6 months) plugged the hoses off in the engine bay.




This was the last thing on the car that needed attention so I was keen to knock it over.  So I fitted the heater tap, filled it up with coolant and went to pick up dinner.  When I got back I had damp carpet and there was a steady drip from the AC condensate tube that pokes out of the firewall near the steering rack.  In all the jiggling fitting the new tap I must have disrupted the core somehow. 

Looks like I'll be busy this weekend.....

Any tips? I think it's probably a dash-out job   

Scott

[Frank Musco]

When an old heater core is disconnected and allowed to dry out, the rubber seal between the plastic tanks and the metal core can shrink, which then leaks when the core is reconnected. Hopefully this is what you have which can stop leaking in around two days.

Unfortunately, plastic becomes brittle over the years and doesn't like to be touched, even if you look at it the wrong way it can leak, therefore you may have fractured it and the heater core must be replaced.

Also, if it seems to be a slight drip, thinking the plastic is not fractured, you can try some magic and buy a stop leak product. Now, I have been told never to do this, BUT, I use 'Silver Seal', which is a grey powder in a paper tube, and less susceptible to blocking your cooling system.

[scott.venables]

Thanks for the reply Frank.  I've found out the heater core is copper and the loops at the end sometimes crack.  I'm glad it's not aluminium, much harder to fix.  Unfortunately I still have to pull the dash out.  Here's a picture of the core I've been sent:

Thanks, Scott

[Frank Musco]

Sorry about that, thought it was an aluminium core with plastic tanks type of heater core.

Thanks for posting the pic.

[MD]

Scott ,

I have previously had a heater core leak in the GTV6. The removal of the assembly does not require a dash out but you do need to be contorsionist to get it out. I would think this would apply to the 75 as well.

The fix was a visit to the radiator shop with core in hand. They did a pressure test to locate the leak and resoldered it. End of leak.

[scott.venables]

Thanks guys.  MD I'll have another look but I don't think it's do-able without taking out the dash. It was hard enough just changing the heater tap, but I'll check it out.

I'm just glad it's not a aluminium/plastic heater core.

Thanks guys,
Scott

[bteoh]

Scott,
The heater box in the GTV6 can come out without removal of the dash. I have done it before but you need some long extensions and uni joints to get at the retaining nuts under the dash. Once those are out, it's easy to pull it out.  However, on the 75's, it's easier to get the dash out
My heater core also went around the copper u bends. I think the radiator shop ended up putting solder on most of the u bends to prevent other areas springing a leak later.
Good luck.  BTW, how did you repair your heater tap?

[scott.venables]

bteoh, did my picture show up?  Basically I cut the metal band that held the end (with the barb and the flange where it bolts onto the core) onto the main body, and then remade that part in brass. It's a few parts silver soldered together.  The ring with the tapped holes slides over the main tap body and sits against a step. Here's another:



Scott

[bteoh]

Well done Scott.......maybe you should make a batch up and sell them

Cheers,
Brian

[Graham Stafford]

Scott, I've just come across this thread, after searching for ages for a new or replacement heater valve for our 75, and here's an answer under my nose!  And bteoh is right, you should make some to sell - I'd like to be your first customer, unless someone has beaten me...  I'll send you some money, and my postal address, if you tell me how much $$ to make it and post it.  My email's stafford.riverland@gmail.com.

Another bit of the puzzle that is the 75 heater, is the cable operated flappy do-dah that pretends to control where the air goes - if you've ventured beyond the outside you may know something about it, but I'd better start a new thread on the topic...

Ciao
Graham

[scott.venables]

Funny this should come up now, I currently have the dash apart.  The picture of the core I posted further up is misleading.  I thought that the heater core was horizontal in the heater box but in fact it is standing vertical in the front of the box (at the bottom of the picture). The AC evaporator is behind it.  One end has the copper loops like I thought but the other has a crimped on plastic tank. I will pressure test it tomorrow and fingers crossed it is not the o-ring between the core and the end tank.

As for the heater tap, I would need a fair bit of persuasion to make anymore. Not out of the quesiton though. 

Graham, can I post any photos that would be useful?

Scott

[Darryl]

As for the heater tap, I would need a fair bit of persuasion to make anymore. Not out of the quesiton though. 

What flavour of persuasion do you accept? I'm pretty sure there is more than a little demand... Put me down for at least 2...

[Anthony Miller]

Go on Scott you know you want to..... Put me down for one too

[scott.venables]

So here's what I'm up to.  The heater core was leaking from the o-ring between the core and the plastic tank which is basically unfixable. So I went around to see Hugh at Monza and he lent me a 90 heater box so I could pull the core out of it.  It looked the same from the outside except the bottom heater hose attaches to a piece of tube that is extended to outside the box.  This is far superior to the 75 arrangement where the complete dash and heater box has to come out to replace the hose. Also, the flange for the 90 heater tap is rotated 90 degrees relative to the 75 one but since the tube with the tap flange bolts onto the side of the core we figure I would be able to swap it over. 

So I pulled the box apart and the core was more different than expected.  There is no plastic end tank, the 90 core is 3 rows wide instead of 2 and the tube to which the heater tap bolts is not bolted to the core at the other end. So to adapt it into the 75 box I had to cut the 75 heater tap flange and tube from my old core, and solder it to the tube on the 90 core.  The barb for the bottom hose was changed to 1/2" as opposed to the original 5/8"
 
The only thing is, due to the extra width the 90 core will not fit in a 75 heater box unless you swap in the 90 AC condenser, or do without the AC like I have. 

This picture shows the 75 core on the left, 90 on the right.


90 heater core modified to suit 75


So now it's all ready to put back together, I've worked some oil into the fan spindle bearings, replaced the mesh that covers the heater fan resistor pack, and fixed up a previous owners bodgy repair to the resistor pack itself.

Now the fun begins.......

[shiny_car]

Nice work Scott! 3-core could mean you'll be ever-so-toasty during winter!