Taking a guess at the rather vague description, one of these scenarios?

The inlet hose to the heater matrix connects from a valve on the top of the cylinder head, at clutch end of engine.

The outlet hose from the heater connects to a T junction in the bottom hose at radiator end of engine, just before the water pump inlet.



Option 1:

The heater valve on the head failed, so someone removed it and fitted an oval blanking plate SRP0102 or 2A180 instead, then they closed off the inlet hose to the heater using a bolt jammed in the end and jubilee clip to clamp the hose onto the bolt.

The outlet hose from the heater usually connects to a T junction in the bottom radiator hose, just before the water pump inlet.

If you want to put this back to standard, buy valve ADU9102 plus gasket 88G221**

Option 2:

The bottom radiator hose was replaced with the earlier RH917 version which doesn’t have the T junction for the heater outlet hose. The heater outlet hose was then plugged with a bolt and clamped with a jubilee clip.

To replace the hose your mechanic doesn’t need to remove the water pump. But it’s quite difficult to access with the radiator in place. Hose you would need is GRH240KEVLAR


Option 3:

The bottom radiator hose T junction was disconnected from the heater outlet hose, and the bottom hose was plugged with the bolt and jubilee clip.

if the heater outlet hose is not similarly plugged, you’re relying on either the inlet valve seal to hold your coolant in the engine, or the heater matrix is blocked and doing that job. Either way, that’s a failure waiting to happen.

If it were me, I’d open the heater valve and see what leaks. If coolant comes out the heater outlet hose, get a half inch coupler GRH777 and join the heater hose back into the bottom hose. Then watch for leaks from the heater matrix and inlet hose, replace as appropriate.





** yes I realize the 998 should use the straight valve not the angled 1275 one that I linked to, but the angled version from MSC is much more reliable and will fit just fine.

Fix it a matrix is cheap. The extra water may be useful one day if you are running hot.

Maybe the lower radiator hose, but can't be the water pump. Anyway, there are two hoses to the heater. One lets the water flow in and the other returns it to the engine. If one of those is hooked up and the other is open it won't work. If one of those is hooked up and the other is plugged, that won't work too well either.

I took a picture of it with my flip phone. My daughter moved out so I don't have access to her iphone so I am having technical difficulties getting the photo posted.

The hose that is not plugged comes off the heater and the one that is plugged goes to the water pump I believe.

"The hose that connects to the heater box has a big bolt shoved into it with a hose clamp persuading it to stay put." That indicates to me that ONE hose has a bolt in it. It isn't very clear which hose he's referring to, whether it's on the engine side or on the heater side. That's why photos are needed.

Without pictures or any direct knowledge, can't we assume the other hose is connected to both of the heater ports on the engine?

That's how I would bypass the heater core ...

I'm confused. There are two hoses that feed water to the heater core. If one of them is plugged off, what's going on with the other one? Do you have photos of what you have?

Yes, sounds right. I will leave it alone. Nothing is leaking or getting too hot for now. I suspect they did it because of a leaking heater core.

Not sure I understand how this is routed, but a leaking heater core or matrix is a good bet at 50 years old.

The heater hose coming from the heater toward the rad would typically connect to a spigot on the lower rad hose, not to the water pump.. Perhaps somebody installed a different rad hose without the needed connection.

Unless you have the heater on the whole time, it may actually run hotter overall if you connect the heater up and run water through it without dispersing that heat into the cabin !

Ian;

She a '68 Mini made in Longbridge in July of '68. A legitimate Brit.

The hose that connects to the heater box has a big bolt shoved into it with a hose clamp persuading it to stay put.

I am just curious how much cooler she will run if I re-route to original specs. Not over-heating, but it seems unnecessary to have the plug in the hose.

It kinda depends on the model of Mini you have.... how old it is... what market/specification....  how original???

On orignal style  (60s/70s) UK and Oz Minis water was taken from the left hand end (as you look at it) of the cylinder head through the heater and back into the bottom radiator hose.  With this set-up there's no need to disturb the water pump.

Are you sure you're not confusing the heater plumbing with the bypass hose???

Its not really worth commenting more until we know more about what you actually have ..and what the problem might be.

Cheers, Ian

Not sure why the heater hose is plugged off on the 998cc '68. Mechanic said it'd run cooler if it wasn't, but need to pull the water pump
in order to reconnect it all back up. I'd go ahead and replace the water pump, hoses and thermostat while I am at it.

Is this by-passing the heater and if so, why would that be done? Maybe because the heater core is clogged?

Mechanic explained it is so the cabin will get more heat in colder regions. So I guess it doesn't apply where I live.