Potential Heater Core Replacement

[76tr7rules]

My car is finally running and driving, and I just realized I don't have heat. I looked under the hood and it turn out the heater core is bypassed. My car did come from a warm climate so I guess its possible its been disconnected because he didn't use it, but I really doubt it. I'm going to try and hook it back up later or tomorrow. If it does leak how bad is it to replace, the car does have A/C? I also see a "heater matrix" on eBay and it says it doesn't require seals. Is there something special with these cores?

[Graham.Fountain]

It was in the 80s that I did a heater matrix, and that on a non-aircon car. So I've got no detailed advice. However, I remember it still as one of the more awful jobs ever.

I did some research at the time and was told all manufacturers start with a different part and build the car around it, Honda with the wiring loom, Korean makers with the carpets, etc. And that these parts are therefore the hardest bits to get at. Well BL started the 7 with the heater core.

One interesting fact I remember, is that you can take the dash out, without removeing the steering wheel. But I wouldn't recomend it. The otherthing is, when you take the heater unit apart, after taking it out of the car, do it where the bits won't get lost. Better still, get a good complete (tested) one and just swap that over.

I've always though about putting in a valve to stop waterflow, because the core never turns off, some flaps sortof stop the airflow through it, mostly, sometimes, like when it was new. But I think that means an H pipe like on the Doly Sprint (under the inlet manifold).


TR7 Sprint VVC 697S (some of)
TR7 DHC Sprint A TR7 16V (fake, rusty):
B&Y '73 Doly Sprint (kids!)

[Hasbeen]

Our local Triumph specialist quotes 8 hours to R & R a heater. It is a slow painful, but in no way difficult job, removing the dash.

You must not stop the flow from the back of the head to the water pump. This causes a dead spot in the coolant flow, & overheats the rear of the cylinder head. Not wise with our heads.
The coolant must flow through the heater, or bypass the heater, but must flow from the rear of the head to the water pump.

The pipes to the matrix are fitted with a rubber grommet. I believe these are no longer available, at least they weren't quite recently. In Oz, & the UK new heater matrix are available, with solidly attached pipes, from the usual suspects. I assume they would be supplied by someone in the US.

The matrix was shot in my current car 12 years ago. The first time I drove it, drops of coolant spat out of the ventilation system. Fortunately bypassing the thing is a suitable action in my climate, so I did.

When I fitted an ex US air conditioning ventilation system to the car about 3 years ago, the matrix in that failed a pressure test, so it is also bypassed.

I would buy a warmer track suit personally, but then, I have never been in the US in winter, so what the hell would I know.

Hasbeen

[prackers]

Not difficult but time consuming. I replaced mine just because I didn't fancy fitting one of the two heater units I have, only to find they leaked after the car was finished (they didn't look in brilliant condition), then have to strip out half the interior to fix. The actual core replacement is fairly straightforward, only requiring drilling out 4? pop rivets then replacing. As already mentioned be careful when taking apart the heater unit as the various clips tend to fly off in all directions! Note: this was on a non AC car.

[FI Spyder]

The heater core is different on an A/C heater than a non A/C heater. It did not use rubber connectors. The replacement non rubber heater core is meant to replace the non A/C heater core as they make clear. I don't know if you can jury rig it to fit but it's a fairly pricey experiment with less chance of success if you still want A/C to work now or some time down the road. Since everything has to come out anyway, I would see if you could get the heater matrix recored at a rad shop. While the dash is apart clean and lube all electrical connections under the dash. A winter time project now that it's around the corner

- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

[Graham.Fountain]

So I was right about the H pipe being necessary, as a shunt, if you shut off the flow through heater core.

Interesting, though, that the Doly Sprint had no cooling system connection at the back of the head - but it does have the H pipe shunt -, so there's no component of the flow along the head that goes through the cabin heater core. Would that be because of the Sprint's lower power output and better cooling system then?

TR7 Sprint VVC 697S (some of)
TR7 DHC Sprint A TR7 16V (fake, rusty):
B&Y '73 Doly Sprint (kids!)

[76tr7rules]

I reconnected it last night and got the car good and hot. So far it hasn't leaked yet. Maybe the guy had it disconnected because it was full of gunk. I flushed it out with my garden hose both forward and backwards then flushed the cooling system and hooked it up. SO fr so good. The car makes awesome heat. The only thing I don't like is I cant get it to come out on the floor. Its either coming out the vents or defroster.

[76tr7rules]

I was debating on running CLR through the system to clean it thoroughly but, Im afraid it may eat through any copper that's just a little weak and cause a leak.

[FI Spyder]

A friend ran CLR through his Toyota truck rad. Flush it out good, no more overheating problems. Left it in rad for 8 minutes (rad was out of truck). It is hard on the copper so you don't want it in too long. As we are dealing with something no longer available I would feel safer trying something like Prestone rad flush.

If you are not getting heat out of the footwells I'm betting one of the adjustments on the flap actuating rods have come loose. I would remove the heater to flush it out, replace the foam which must be pretty crumbly to disintegrating by now, grease moving parts and adjust the rods so the flaps work as they should. That means breaking the A/C hose connections. If the system still is working/has freon, you might want to just do what you can with it still in the car. Mine wasn't so when I disconnected the hose there was just a little pssst.





- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

[76tr7rules]

Let me ask, what position do the levers have to be in to havei t come out on the floor?

[FI Spyder]

The right hand lever has to be down (up directs the air to windscreen vents). The second from the right is the fan control/cabin air direct lever. The first position down is MAX, the gives maximum fan speed coupled with directing air with in the cabin to with in the cabin (air recirculation), not normally used with heat. Position 3, 2, 1 is sequentially slower fan speed. Lever 2nd from left is the heat control, cool up, hot down. Left hand lever controls side vents (off up or down on). The air path is poor so doesn't much matter where it is.

The levers on the A/C heater are slightly different than non A/C heater. How they work is not intuitive. They are described in OEM manual.

- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

[Hasbeen]

Graham I thought about that when helping a mate with his Dolly Sprint. There were no coolant system external parts with the car, so were looking at my 7 system to figure it out.

I think from memory we found it used the inlet manifold water flow to let the rear of the head flow to the water pump.

I fitted the aircon unit to the 7, still bypassed from the engine cooling system. Works well, & you don't need that incredibly expensive valve in the thing.

Hasbeen

[Graham.Fountain]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Hasbeen</i>
I think from memory we found it used the inlet manifold water flow to let the rear of the head flow to the water pump.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

No, sorry, don't understand that. Like I wrote, the Sprint has no external connection to the cooling system at the back of the head. Rather, both connections to the cabin heater come from under the manifold. As I remember - and I can't look because doly's in the garage having the bushes poly'ed - one is from the pump cover and one from the manifold.

I would have to look how water runs through the Sprint's inlet manifold, and I haven't a 2 valve one to compare with, but I thought, in both cases, that all the wet holes between the head and manifold were at the front end. I'm sure that's true for the 4 valve's twin choke manifold, which is the one I've stared at most - because it's unquestionably, and by far, the prettiest. So, if the 2 valve's head develops a hot spot without that connection, I don't see why the Sprint's does not.

Especially as, as ironically alluded to in last post, the Sprint generates slightly more power and has a smaller rad. The 190ish bhp version of A TR7 16V I had didn’t have such a connection, and never cooked. The worst thing ever happened to that was a Discovery ran in the back of it – must fit weaker brakes in future.

Confusingly, the 4 valve TR7 Sprint had such a connection at the back of the head, and the under manifold pipework connections were like the 2 valve TR7's, with only one connection to the heater core. However, I always assumed that was to do with keeping the installation of the engine assembly the same on the production line (and even BL would have been embarrassed by a pipe running from the manifold, to near the back of the head, only to turn 180 and go back to the connections to the heater core on the bulkhead), and not because the installation in the TR7's engine bay needed it when it didn't in the doly's.

So I’m not saying that either does or doesn't have this hotspot problem, or that there's not some other difference, just that I don't understand it.

Graham


TR7 Sprint VVC 697S (some of)
TR7 DHC Sprint A TR7 16V (fake, rusty):
B&Y '73 Doly Sprint (kids!)

[76tr7rules]

Is the heater valve on A/C cars mounted inside or outside?

[HDRider]

The heater valve is mounted on the side of the heater box inside the car. It is on the left side as looked at from the cabin.

Edward Hamer
petaluma CA