20 replies to this topic

[unburntfuelinthemorning]

I'm having problems with the heater not getting hot since the weather has been really cold.  Does it matter which way round the heater is plumbed in?  Would this make a difference if it was the wrong way round?  Which is the correct way round for the type with a upper and lower connection on the right hand side?

[MiniMadRacer]

The hot water should go to the bottom pipe, but I am sure it would make little difference.. chances are the matrix is silted up and needs a good blow through or replacing

[Carlos W]

Is the heater valve opening fully?

[cal844]

Feel the heater pipes and make sure both are hot, the outlet will be slightly cooler. Make sure the valve is fully open.

[unburntfuelinthemorning]

The hot water should go to the bottom pipe, but I am sure it would make little difference.. chances are the matrix is silted up and needs a good blow through or replacing

Mmm.  I plumbed mine the other way around so the hot water went to the top as it does with the radiator.  Everything is new and clean so shouldn't be silted up but I try using a hose on it to be certain.

[unburntfuelinthemorning]

Is the heater valve opening fully?

I think so.  It's the '70s type which bolts to the cylinder head.  It's a fairly new Minispares version.  It was partially closed until the cold weather when I opened it fully.  The hose connected to it gets very hot but the return not so much.

[unburntfuelinthemorning]

Feel the heater pipes and make sure both are hot, the outlet will be slightly cooler. Make sure the valve is fully open.

The return to the bottom hose is noticeably cooler. 

[Carlos W]

I've had success bleeding the matrix using a funnel.

Make sure there's no air in it

[nicklouse]

For the heater matrix it is best to feed it from the bottom so it can self bleed. You may have a big air pocket so no heat.

[unburntfuelinthemorning]

I've had success bleeding the matrix using a funnel.

Make sure there's no air in it

I have been wondering if there is air in it.

[unburntfuelinthemorning]

For the heater matrix it is best to feed it from the bottom so it can self bleed. You may have a big air pocket so no heat.

That's two of you who say the hot feed should go to the bottom of the matrix.  Perhaps me trying to be clever and plumb it the same way round as the radiator wasn't clever after all!

[imack]

My hot feed from the valve goes into the bottom of the matrix. The return hose has a tight pre formed 180 deg bend at the matrix end on my car, there's no way it could be fitted to the bottom pipe on the matrix.
Is the engine reaching full operating temperature?
Do you have a bypass hose?
If you don't and you have drilled the stat this can have a detrimental effect on engine running temp in colder weather.

Edited by imack, 01 January 2021 - 09:56 AM.

[unburntfuelinthemorning]

My hot feed from the valve goes into the bottom of the matrix. The return hose has a tight pre formed 180 deg bend at the matrix end on my car, there's no way it could be fitted to the bottom pipe on the matrix.
Is the engine reaching full operating temperature?
Do you have a bypass hose?
If you don't and you have drilled the stat this can have a detrimental effect on engine running temp in colder weather.

Yes, I have a capillary gauge and can see the needle drop a few degrees when the thermostat opens at around 88^oC.  I have a bypass hose.  Interesting what you say about the pre formed bend.  The hoses were replaced with generic 1/2" hose by the previous owner so the bend is long gone.  Are the hoses with the pre formed bend still available?

[imack]

I think different years of car have different hoses and matrix. Mines a 72, I bought a replacement hose from Austin rover in the late 80's, don't think they're available anymore, couldn't find them a few years ago when I replaced all the other hoses.
Picture shows original factory replacement hose with pre formed 180 deg bend. Hose off a roll will tend to kink if you bend it that much, you'd have to take a longer, smoother route to prevent kinking.

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Edited by imack, 02 January 2021 - 01:32 PM.

[Carlos W]

I put some 90 degree copper bends in mine to stop kinks