62 replies to this topic

[TheFabMini]

Cylinder 1, 2 and 3 all at 125psi
Cylinder 4 at 130 psi
So that seems healthy enough for a cold engine

Plonked on the new radiator (includes cap)
Tomorrow’s weather looks dryer so I’ll go buy some more antifreeze and go for a spin after work tomorrow and see if we have had any success!
If not I’ll do the above and remove the pump and thermostat and see what I can do...
Trying to avoid removing the thermostat as I’m really happy with the nice neat job I did on cleaning up and fitting the new gasket ?

[imack]

If you're bypassing the heater I think it's recommend to connect the return into the top hose rather than the bottom hose. Theory is that if you connect to the bottom hose you're pumping uncooled water back around the engine and increasing water temperature, if you connect to the top hose then the coolant is being cooled in the rad before re entering the engine.

[TheFabMini]

If you're bypassing the heater I think it's recommend to connect the return into the top hose rather than the bottom hose. Theory is that if you connect to the bottom hose you're pumping uncooled water back around the engine and increasing water temperature, if you connect to the top hose then the coolant is being cooled in the rad before re entering the engine.

 

 

yeah ive read lots of old threads on this and it seems 50/50 with what people think is best, some say that with the heater valve shut etc that its the same as not having the matrix there

others like yourself think its best to run it a different way.

to be honest last year i had some weeping from the matrix so i just took the 2 pipes off and put a bit of copper pipe joining them together, was very hot last summer and had no issues so removed the unit all together and pulled the pipes through so that i just have the 1 pipe going across the top of the engine.

 

always willing to try any little improvements so how would i connect the return hose to the top hose?? anyone got any photos or can explain how they did it

 

im quite happy without a heater inside the car as its nice and roomy around my feet now! 

have been tempted to buy a replacement matrix and fit it somewhere under the bonnet as a 2nd mini radiator but will cross that bridge when the car actually works!

[imack]

It's not something I've done myself but I'd guess you'd need to connect it into a sandwich plate at the thermostat housing. If you tee'd straight into the top hose I think you'd get very slow warm up as water from the heater would be getting cooled in the rad before the stat opened. Putting it into a sandwich plate below the stat would give quicker warm up and then water from the heater can flow through the rad once the stat is open. Thats my thoughts anyway, sure someone will more knowledge will correct me.
Surely if the heater valve is closed then all coolant is passing through the rad?

Edited by imack, 05 June 2019 - 04:53 AM.

[TheFabMini]

It's not something I've done myself but I'd guess you'd need to connect it into a sandwich plate at the thermostat housing. If you tee'd straight into the top hose I think you'd get very slow warm up as water from the heater would be getting cooled in the rad before the stat opened. Putting it into a sandwich plate below the stat would give quicker warm up and then water from the heater can flow through the rad once the stat is open. Thats my thoughts anyway, sure someone will more knowledge will correct me.
Surely if the heater valve is closed then all coolant is passing through the rad?

Fair enough,
Like I said I may soon get a new matrix and use it like a 2nd radiator behind the grill or something

Will reassemble everything tonight and see what happens

[nicklouse]

this is a topic that goes around and in the past I have just run the hose from the head back to the bottom hose. I now have it going to the top hose. just as it makes it easier to add a second cooling element if I do.

 

what is interesting is if you look at the MPi cooling system where the heater tap is on the matrix which stops the flow through it. there is a hose that allows the hot water from the head to return to the bottom hose directly.

 

this could be to do with the front mounted rad and its cooling ability.

 

another thing I have seen is when connecting from the head take off to the bottom hose is people reducing the flow by putting a restrictor in the line. down to about 8-10mm.

 

what I will say is removing hot water from cylinder 4 on a tuned engine out ways any issue with where you plumb it back in.

[elf66]

Does the water pump turn freely when its hot? Years ago i replaced a water pump that caused the car to overheat and scream like a banshee after about 10 miles. The pump impeller fouled on the casting, but only when hot and to the point where it ceased and the fan belt sipped on the pump pulley. Once it cooled down it was god to go for another few miles.

[TheFabMini]

So!
20 miles complete and the temperature didn’t go above 93 degrees so I’m gonna call that a success!

I have had some calcium lime and rust remover in the block for the day (in tablet toilet cleaner form) so if that helped I have no idea...

Still strangely it seems to run a bit cooler around town (88-91 degrees then the temp goes up to 93 on the open road... so not sure if my timing is slightly out making it run a bit hot at advance

[luismx123]

So!
20 miles complete and the temperature didn’t go above 93 degrees so I’m gonna call that a success!

I have had some calcium lime and rust remover in the block for the day (in tablet toilet cleaner form) so if that helped I have no idea...

Still strangely it seems to run a bit cooler around town (88-91 degrees then the temp goes up to 93 on the open road... so not sure if my timing is slightly out making it run a bit hot at advance

I dont know the temps exactly, but mine runs on N in the city, and goes about halfway up between N and H during highway drives (60-70mph). Id think the cooling would work better at that speed but it doesnt...for some reason :/

[Bobbins]

At higher speeds there’s more cooling created by air flowing through the radiator ... but there’s a lot more heat created by the engine!

[TheFabMini]

As a bit of an experiment I fitted a used matrix I’d got from eBay ages when from when I intended on fixing the heater.
Fitted it with some cable ties behind the grill

Car didn’t go above 88 degrees after 15 miles of enthusiastic driving

So I’ll get a new matrix and find a prettier way of fitting it and jobs a goodun

[TheFabMini]

Drove to work and back with the heater matrix propped next to the front grill and seemed to be very happy!
So I’d say that’s all the proof everyone (including myself) needs to show the heater matrix WAS vital to the engines cooling capabilities. I’m sure many engines properly tuned could run without one as mine did the end of last year. But with it was much happier so far!

Not sure how much I like it being so close to my wiring loom though, thinking of relocating it next to the main radiator
That way it would get some airflow from the fan
Hot air admittedly but might be worth a try with some cable ties

[pete l]

I don't think your heater matrix was the cause of your problems.

On all minis, the water can be stopped from flowing through the heater matrix by pulling the heater control valve which blocks off the coolant, and the engine won't overheat.

If you really do need your heater matrix in place to stop it overheating then you still have another problem elsewhere.

[CityEPete]

^agreed

And when is the heater valve most likely to be closed off? When the weather is warm!

[TheFabMini]

^agreed

And when is the heater valve most likely to be closed off? When the weather is warm!

Well it didn’t overheat without the matrix but did run warmer..
I’m sure my car has many many more issues that I’m naive to ? but it runs, gets me to shows and I can enjoy it.. and now if it goes bang at least I’ve got lots of nice new parts to fit to a new engine


In all seriousness I will investigate further with a proper mini mechanic but I’m just glad it’s useable again