Cooling System Questions

[Guest boggie]

Hi All,

 

OK. In an attempt at finally nailing my cooling problems I have a couple of questions that you may be able to help me with. First let me detail the way things are:

 

I have a 4 core, competition, all alloy Mini radiator. Now you may think a Mini rad is not up to the job but the chap I bought it from was running a 200BHP turbocharged race tuned Mini. This rad kept it cool and let's not forget that the Mini radiator sits in the wheel arch so has no direct airflow through the nose either. So, by my reconing this rad should do it. There is a Kenlow fan sucking on the rear of the rad and I have cowelled inside the nose with aluminium sheet to force all air through the rad. I have fitted extra large louvres on each side of the bonnet in addition to the factory louvres on the bonnet top to remove the hot air.

 

On top of the rad I have fitted a 15psi cap but I have a pressurised expansion tank connected to the small take off connector on the thermostat housing. Mounted it as the highest point in the car and fitted a 13psi cap. My thinking is that the 15psi cap on the rad is effectively creating a sealed rad (like in the original Sierra) because the 13psi cap on the expansion tank will blow first. I filled the rad right to the top, put the cap on and then filled the expansion tank (can't remember which car it came from) to the fill level indicator line.

 

Lastly I have fitted all new (and bl00dy expensive) silicon hoses and I have removed the heater matrix so I do not get air trapped in it due to it being the highest point in the system and simply connected together the water pump heater output on the water pump to the return on the block underneath the carbs.

 

Now when I drive the car the Capri temp gauge runs a quite high, half way between normal and red (I have verified the gauge is reading correctly and that the sender is the correct one for the gauge) with the kenlow (set to 95 degrees) running on and off constantly). If I run the car stationary things get hotter. EG when I fired her up for the first time after my recent engine rebuild I needed to run the engine at 2K+ for 20-30 mins to run-in the cam and solid lifters. After 15 minutes (with the Kenlow running solidly) the temp was well into the red and the expansion tank was venting fluid. Only gently - no blow off, but I decided not to push my luck. I let her cool, topped up fluids, checked there was not an airlock in the rad and tried again but the same thing happened.

 

Now for my questions:

 

Firstly (and most obviously): What am I missing here? Surely this setup should work?!

 

Secondly: As I am not running the heater matrix can I simply block of the two pipes (out from the pump and return to the block) that would have connected to it? I read somewhere that it was not necessary to connect them together but it was OK to simply blank them off. Is this true?

 

Many thanks, Boggie

[Longboarder]

First thing is I would not run two rad caps. The higher pressure cap on the radiator will never lift and thus the rad will not self bleed air. A pressurised expansion tank is overcomplicating pinto cooling. Most run happily with a non pressurised overflow/suckback tank off the rad. Remove the thermostat housing and stat, drill a 3mm hole in the stat upper edge to allow air bleed and make sure the stat is fitted back in the correct way round, wax cylinder toward the cylinder head, with the hole at 12 o'clock. Having no warm up circulation prior to the stat opening can lead to hotspots in the engine and possible head warping. Some do this and get away with it. If you are worried about too much coolant taking this shortcut when the engine is hot fit a restrictor in this bypass pipe to reduce flow, say about 8mm but you can experiment. Most do not use the small pipe off the stat housing to bleed air but block it off like ford mostly did.

Bleeding air from the system is important. Run the engine up to temperature with the rad cap off. Air and water is often blown out when it first gets hot but simply stand by with a watering can and keep topping up till it settles. 95C is too hot for a pinto. They run cooler. Set fan on at 85 and off at 80.

I still have the heater in mine although I now have a zetec and have an air bleed in the highest point of the heater circuit

made from a 16mm copper plumbing B&Q T piece and screw cap.

 

Nigel

[Guest salty_monk]

My black one is pressurised but to be honest I would consider going to "Spit & suck back" as I had on my red one. It worked better in my opinion although the pressurised one is not that bad.

 

Dan

[Guest boggie]

Thanks guys, much appreciated

 

OK. So reading the above and spending the evening searching the forum for similar posts this is what I am thinking:

 

Drill a 3mm hole in the thermostat to bleed air (like they used to have on older cars).

Fit a 2 way, 13psi cap to the radiator so it can vent and draw back expanding coolant via the overflow pipe.

Attach the overflow pipe from the rad to the expansion tank fitted with a low pressure cap (5lb?) to gently aid the suck-back into the rad.

Block off the small pipe on the thermostat housing.

Fill the system and start the car with the rad cap off, topping up until temp is reached (thermostat open) to avoid airlocks.

Refit rad cap, making sure the level is right up to the top and that there is still a little water in the expansion tank when cool.

Lower the Kenlow temp switch to 85 degrees.

 

Will that do it? Is there anything I have missed? A couple more questions if that's ok:

 

Where can I get a low pressure cap (do I need one?)? I have read some people use a 5lb but all I can find is a 7lb. Or should I just remove the spring and have zero lbs?

I assume from Nigel's comments I cannot simply blank off the heater matrix pipes from the pump and back to the block, Have I got this right? If so have any of you suggestions for an 8mm restrictor?

 

Thanks again, with all your help I am sure to finally beat this!

Boggie

[Guest salty_monk]

Sounds fine to me..... track down a cap for a morris minor. Same style but 4lb of pressure... perfect.

 

If you can't get one from Halfrauds or similar... BULL MOTIF will have one.

 

http://www.bullmotif.com/

 

Dan

[Longboarder]

When you remove the thermostat housing to check the stat is in the right way round it would be worth popping it in a pan on the stove. Only use closed thermostats for this. Discard any that are open or have broken shells. Fry the shallots in a little butter until golden brown, add the white wine, more butter, crushed garlic, salt and pepper to taste and cook till all the thermostats have opened, about five minutes, add the cream and give it two minutes more. Serve with fresh baked crusty bread and butter. Actually this works better with mussels but its the same principal. Dead ones are open already or stay closed when cooked.

 

I would leave the overflow tank open to the air and make sure the rad cap seals well on the rad neck and the overflow pipe is also well sealed on the rad neck pipe. I ran this on the pinto and currently on the zetec with no problems. I have a heater still, some just use a loop from manifold to waterpump, unrestricted, some zetec users have to restrict the flow in this loop but I haven't heard of any pinto users doing this and some get away with no warm up circuit. Personally I can't see why you would not want a heater.

 

Nigel

[Guest pwlcarz]

...... Personally I can't see why you would not want a heater.

 

Nigel

 

Masochists?

[Guest boggie]

When you remove the thermostat housing to check the stat is in the right way round it would be worth popping it in a pan on the stove. Only use closed thermostats for this. Discard any that are open or have broken shells. Fry the shallots in a little butter until golden brown, add the white wine, more butter, crushed garlic, salt and pepper to taste and cook till all the thermostats have opened, about five minutes, add the cream and give it two minutes more. Serve with fresh baked crusty bread and butter. Actually this works better with mussels but its the same principal. Dead ones are open already or stay closed when cooked.

 

Nigel

 

[Guest salty_monk]

I used to run the 1.6 Primera stat in my first one... overkill really with a good setup. It did have a rudimentary bleed valve that worked like your 3mm hole!

 

Dan

[Guest boggie]

I used to run the 1.6 Primera stat in my first one... overkill really with a good setup. It did have a rudimentary bleed valve that worked like your 3mm hole!

 

Dan

 

Thanks Dan,

 

Like this?:

 

 

This is actually from a 2.0 Primera but I was hoping they are the same. It is also 82 degrees and has the bleed. However it looks deeper and prortudes more from the flange than the cosworth 82 degrees unit I was considering:

 

 

But it is much cheaper.....

[Longboarder]

Big Jim's NW Hoodies site is a treasure trove of hints, tips, pics, circuits and part numbers. Including a thermostat which fits and starts to open at 77. Perfect for pintos.

 

Nigel

[Guest boggie]

Big Jim's NW Hoodies site is a treasure trove of hints, tips, pics, circuits and part numbers. Including a thermostat which fits and starts to open at 77. Perfect for pintos.

 

Nigel

 

Thanks Nigel,

 

Any idea what the thermostat is from or where I can get one? I searched online and have come up with nothing so far.

 

B

[Guest Tim Norman]

Maestro thermostat opens at 74 degrees

[Guest salty_monk]

See here: http://nw.rhocar.org/parts.htm

 

Some very nice man took pics of before & after the modification... just cut with a hacksaw & file smooth. It's from a 1.6 Primera, a 90's one I think. They will be able to look up by QTH number at the factors too.

 

Dan

[Guest boggie]

See here: http://nw.rhocar.org/parts.htm

 

Some very nice man took pics of before & after the modification... just cut with a hacksaw & file smooth. It's from a 1.6 Primera, a 90's one I think. They will be able to look up by QTH number at the factors too.

 

Dan

 

Interesting, thanks Dan but I just got the QTH370 from a local motor factor. He cross referenced my request with the pinto and gave me a 76 degree QTH370 that needs no modification.... :-)

B