hot running sorted ...update

Radar

Member
;D ;D

Hello everyone sorted my hot running problems with a combination of measures suspected some of these were needed but also had a few surprises . Car was running 2 core rad with external fan and push fan (engine side) already...

So suspected fueling issues as this is a great contributor to hot running...and so it was.......the  su carb had standard needle in it ( metro) and so that was replaced and rejetted to uprate it..timing was ok when checked dizzy all ok too. Replaced the two core rad with a new one as the existing looked choked and a little clogged with about 15 % of fins damaged or bent probably due to fitting and or fan scrape .  A new water pump was fitted with cast impellor as the existing one was the crappy pressed steal variety that was simply not as efficient as it should have been .

Tapped cylinder head and put a take off hose from there far right hand side if head as viewed from rear of car and connected that thru to  bottom hose T (think it is the water pump bypass t  which is not used in my car).

And finally fitted yet another temp gauge (previous owner had gone down this route already ) but I wanted a capillary gauge in there that is REALLY telling you what is going on in the engine/cylinder block.
the cylinder head had an air leak admitting some in  so that was fixed too.

So the hot problem was a combination of all of the above fuelling /radiator efficiency water pump etc ...she is now running like a different car and motorway cruising does not bother her at all I hammered her for 20 miles home today to see how effective the work had been and she ran like a dream temp actaully came down a little bit from normal operating temp (around 85C) when the vehicle slowed from 65 mph to 30-40 mph street speeds.

The handling has improved ENORMOUSLY as I have had all the wheels and tyres alighned etc PROPERLY the last owner had this done prior to me purchasing but whoever did it must have been muppets it was SOOOO far off she handled like a broken shopping trolley it was only because of her design and weight etc that this handling was not overly dangerous...

I wish I could say I did all this myself guys but unfortunately not it's thanx to two old school mini racing experts GREEN and WHITE minis up here that I am smiling I now feel I have the car as it should have been and as the designer intended it to be ... I think that the cooling issues that plague these freestyles can definately be sorted and not always in ways you might think ..ie water wetter and more and more cored rads and supplementary rads etc ..My lesson learned is water pump/ fuelling plays a big part as my own was running weak very weak which contributed a lot to the high operating temps and additional flow across cylinder head as described..

It's now (fingers crossed based on this 20 mile high rev run ) a well sorted well handling FREESTLE FUN buggy .
All being well I will see you guys at Newark show for a beer :) as I now have the confidence to tackle extended motorway speed running ..
Finally I a may as a winter project remove the electric fan from the outside of rad and just leave the standard fan attached to engine to push the air thru ..I think it should be enough ...I was thinking of moving the fan to the right hand side of car and putting it on the engine enclosure so that it pulls air from right hand side of car thru and across cylinder head and out via the rad side , this will aid air flow considerably I think and will cover all the bases to try and simulate the traditional front engined set up a little more .

cheers for listening and for all your helpful suggestions with this I appreciate it...


Pete

Sunday 14th ..footnote...20c today glorious sunny day took buggy out after a warm up period blasted her in all gears reving close to limit before changing up etc..and can't get her to overheat   :)    in fact hard to get her to run at 85 c at all unless extended motorway cruising. She is probably running at about 55-70c most of the time...I know running her to cold is not a good thing either but it shows how effective the remedial measures have been. Will probably remove the outer electric fan after Newark show and let the standard yellow mechanical fan do the work I think it will be adequate based on todays experience. Even today when running I switched off electric fan and despite the fact it stifles exit air flow thru the rad from engine fan temp only rose up TO 85 c not beyond although it was for a relatively short distance perhaps 2 miles at street speed 30mph. I am a happy bunny and hope that this is sorted once and for all    :)
 

Phaeton

Moderator
Staff member
I think you're right there about temperature  rise with poor mixture Pete, mine was running very lean before the RR & now the temp is lower, although not sure if gauge & sender are matched.


Alan...
 

Paul

Member
Why not remove the engine driven fan and keep the electric one?
That way you will not be wasting engine power driving a fan all the time which is not needed and improve fuel economy a bit as well. The electric fan will then only cut in at the preset temperature. You may find this will cure the cool running issues you now have.
 

Radar

Member
thanx for the suggestion Paul, the electric fan is currently on a manual switch only ie on or off for obvious reasons I have to switch it on once the engine has started. The engine fan does not worry me about sapping power it can't be that much and at least it will always run, unlike a electric which can fail with a blown fuse /bad connection or whatever. Plus it leaves the engine setup more as the engine designer intended with a mechanical engine powered fan. Electric fans are not really meant for constant running and I would have to fit a thermostatic switch to it which WILL end up keep cutting in and out as the heat/cool cycle goes wheras with the standard mechanical fan the rad and coolant is always being cooled on it's cycle therefore is not kicking on and off continually which it would definately do in a freestyle when the engine was being run espescially because of the rear engine setup we have to use .So on balance I think my original idea is best ...unless someone knows better ??? lol.

Pete
 

esdebe

New member
I'm not sure using a fan to blow air into the engine bay would make much difference, If you don't need it to cool the radiator then remove it and save the weight.

I have swapped my mini fan for a sprite on so it sucks rather than blows, that way it takes the cool air from outside the car and blows across the engine.

The biggest difference to engine bay temperature is your ignition timing and fuel mixture, to retarded and you get hot, too advanced you get very hot.  Too lean you get very hot.

You seam to have sorted everything out so if I was you I wouldn't worry about using the fan to blow air across the engine.

You may want to leave it where it is and have it just incase the fan belt snaps, or have it on a termostatic switch so it can be left running when the engine is stopped to cool the engine when you nip to the shops so it doesn't overheat when parked up.

Simon
 

Paul

Member
You said in your post that you are running at 55-70 degrees. This will now be because you are constantly cooling the engine. The whole point of the electric fan is that they run on a thermostat switch so that they are only run when required. If you set it up like this you should find that you can set your engine to run at whatever temp you want and still fit a manual overide switch if required for on particularly hot days.
I have used a lot of thermo switches on different kits over the years and by far the best is the revotec one which is fitted through a 10mm hole on the top hose. Its a lot easier to get a seal than the ones where you pass a probe through the top joint which always seem to weep.
I have this set up on mine and have just completed a track day this weekend in 20 plus degrees heat with no cooling problems. I never use mechanical or viscous fans on anything now due to the lack of control which you have on the cooling.
 

Radar

Member
thanks for the expanding on your suggestion I will definately take a closer into it.Just checking out revotec now on net their stuff looks good..

Pete
 

Phaeton

Moderator
Staff member
Radar":280qu5r5 said:
And finally fitted yet another temp gauge (previous owner had gone down this route already ) but I wanted a capillary gauge in there that is REALLY telling you what is going on in the engine/cylinder block.

Pete,

Where did you get your capillary one from, ones I've seen only seem to have 6ft of tube & not sure it'd be long enough.

Alan...
 

wurzell

Member
Years ago, when I was Rallying Minis it became apparent that the more highly tuned my engines became, the more likely they were to overheat! Anything tuned to Cooper 'S' specification or beyond (and most of my engines went way beyond!) were almost guaranteed to cook!
Cooling on 1275 engines was always somewhat marginal, but this could also apply to other cc engines, or overbored and stroked units...

One important thing that I discovered by trial and error was that the Cylinder head heater take off pipe should be routed and plumbed in to the TOP HOSE, and not the bottom hose.

Most, if not all of my Rally Cars had the Heater unit removed to save weight, so no additional cooling help there..Therefore, if you plumb the hose straight back into the bottom hose, you are just reintroducing very hot, uncooled water direct from the Cylinder Heads hotspot number 4, furthest away from its Radiator, straight back into the Engine Block UNCOOLED.....

Far better to put that very hot water back into the system via the TOP hose, force it through the Radiator as normal, at least then you are removing as much of the heat as you possibly can through the Radiators cooling action.....Obviously, your Radiator must be up to the best specification, I originally used four core Radiators, which were a bit of a pain to fit, but later switched to twin core units with very large cores, that easily kept up with my cooling requirements, and were very much easier to fit as well. Also, I usually removed the thermostat, and had the Special Tuning Blanking Sleeve installed....Only ever used the standard Mini yellow plastic 11 bladed fan, NOT the MG Midget PULL fan, you will just suck all the loose grass and mud onto the outside of your Radiator, and cook your engine!!!
This now especially applies to Buggies!!
Minispares can supply the best twin core Radiators......

So, just find an old good BOTTOM hose, with the heater inlet pipe on it, and cut it down to the approximate shape and size of a TOP hose, and fit that as your TOP hose, plumb in your Cylinder heater take off pipe, I guarantee that it will improve your cooling!........

I NEVER had any problems with overheating doing it this way, even on Full Race Eight Port Engines....
My Buggy used a Full Race 1400cc Motor, and that has NEVER overheated.......
Wurzell.
 

Radar

Member
Alan the capillary temp cable is mg or mgb I believe ( it was lying around the workshop ) so it was fitted right time at right place I guess but I am pretty sure it was mg or mgb ... hope that helps...........

Pete

Wurzell thanks for the suggestion re plumbing direct into TOP hose instead of bottom as I have done ..at the moment temp is perfectly manageble now so I may delay doing what you suggest depending on how things go ...at the moment I have done 400 miles of hard motorway driving without problem with my new set up and also thrashed it up hill and down dale(at least another 150 miles) around the country lanes near me and on some of the hottest days of the past three years ..so far so great ! lol... so cant see the need to use that top hose trick until I really really need to if at all..

ps anyone got a decent bottom hose they want to let go ? with the heater matrix take of pipe of course ??
 

esdebe

New member
After Newark I started to have cooling issues (brought on by the improved weather) what i observed from this is that while on a normal engine using an electric fan controlled by a temperature switch may improve performance and engine cooling it isn't the same for an engine at the back of a buggy that has limited / no air flow, especialy if there is engine covers over it.

I swaped my sucky fan for an electric fan and the engine warmed up very quickly, but then contined to over heat, and my oil cooler was actualy helping the oil to retain / heat too.

I've since put the sucky fan back and it keeps the air flow arround the engine while keeping the water cool at high RPMs and the elecy fan is keeping the water cool when the engine is Idleing and lower RPMs.

I've also ducted air to the oil cooler as this was useless without airflow.

My engine is a 1330 with stage 3 head, had no cooling issues when air temp was below 20 degrees but after the sun came out the cooling issues started.
 

Phaeton

Moderator
Staff member
Radar":1evsr1e3 said:
Alan the capillary temp cable is mg or mgb I believe ( it was lying around the workshop ) so it was fitted right time at right place I guess but I am pretty sure it was mg or mgb ... hope that helps...........
Pete
Which way is it routed?

Alan...
 

Radar

Member
Assume you mean me Alan with that question and assume you are talking about the capillary feed ?.

It is routed from cylinder head (of course) down left hand side (passenger side) of buggy under the black capping that runs along the whole length of bodywork up over bar under grp bonnet thing into a loop (as some spare maybe 8 ") then into the gauge in dash..
 
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