23 replies to this topic

[Peter_NottinghamS]

Many of you will know I'm the 'owner' of a online prize Mini from UK Minis (the car was won by my son) but has been very problematic.

It's this car, Marvin:

https://ukminis.co.u...oad-mini-marvin

 

It arrived as a non-runner and dangerous brakes and my son entrusted Marvin's future to me, a former Mini owner, someone with a garage and a useful resource known as 'The Bank of Mum and Dad (TBoM&D).

TBoM&D has made the appropriate investments and provided [apparently] free garage space and Marvin has been used regularly since arriving in my custody and over the dry winter months (see separate thread).

During the summer months overheating was a problem, which considering I believed it had a Fletcher radiator, I was surprised, as these are supposed to be the the go-to radiator of choice, particularly with tuned engines (Marvin has an 1380cc, 88bhp, dyno tested engine).

When looking a Fletcher radiators online I see that real Fletcher radiators have the word 'Fletcher' embossed onto the top and when I look at Marvin's description I've noticed a clever play on words:
 

 

A nice addition of an 4 core ali radiator and Fletcher silicone hoses keep the temperature where it should be.

 

Well it doesn't: keep the temperature where it should be.  Marvin doesn't have Fletcher silicon hoses either.  The radiator does have a serial number down the face of the core. Anyone?

I've read that many of the copycat 'ali' radiators are pretty but no more effective as a traditional radiator, so in pursuit of better summer cooling, is a Fletcher radiator a wise investment?

Over the winter months the '4 core ali radiator' is providing cooling, particularly after a major flush through and clean, but I'm anxious about cooling in the summer months when Marvin's temperature would soared to the heady heights of the top of the gauge!!

So the question is: is it worth TBoM&D investing in a proper Fletcher radiator versus the 'unknown' which I have.

Thanks in advance.

Peter 

[lippo]

 I have a Fletcher radiator with standard hoses attached to my 1275 standard engine in a Clubman Estate. It has never once overheated, even in hot weather. I have had round nose minis years ago which overheated with a 1275/1380 all the time, so I was very impressed with the Fletcher rad. 

 

 I wonder if you have air pockets somewhere in the system as well?

[KTS]

i have a standard 2 core radiator in mine (1380cc, roundnose) that copes perfectly well whilst the car is moving;  a different matter in traffic so have an auxiliary fan fitted 

 

fitting a cowling around the radiator to vent the hot air through the inner wing makes a big difference

 

when does it overheat; in traffic, when driven hard, or just pootling about ? 

 

..and is it really oveheating - temperature gauges can be notoriously unreliable 

[Peter_NottinghamS]

@lippo,  air pockets? I'm not sure but I don't think so.

I had a 40-mile round trip run on the A46/Fosse Way (all dual carriageway) on Sunday and keeping a steady 66mph (with the occasional blast to the speed limit (!!) to overtake slower moving vehicles), and the temperature stayed normal all the way, so Marvin is content with the cooler weather.

I just fear the high summer temperates will have the needle on the temperature gauge to the HIGH segment.

How do I check/test for airpockets?

FYI, I'm also thinking of adding an oil cooler. I believe anyone building such a high performance engine should have an oil cooler on the 'must have' parts list.

Edited by Peter_NottinghamS, 04 March 2025 - 03:48 PM.

[Peter_NottinghamS]

i have a standard 2 core radiator in mine (1380cc, roundnose) that copes perfectly well whilst the car is moving;  a different matter in traffic so have an auxiliary fan fitted 

 

fitting a cowling around the radiator to vent the hot air through the inner wing makes a big difference

 

when does it overheat; in traffic, when driven hard, or just pootling about ? 

 

..and is it really oveheating - temperature gauges can be notoriously unreliable 

 

Marvin was running the high end of the temperature gauge most of the time, so I did a complete system flush (the coolant was full of crud) and this improved things.

He hates traffic and I wouldn't confidently drive him in a big town or city without fear of overheating.

 

When he's on the move (mainly country lanes around me) he's happy.
 

And yes, he gets hot.  Very hot.

[lippo]

 If you didn't fill the cooling system yourself, you might want to drain it completely and refill it yourself so you know it's been done properly. DKLawson has a simple guide here https://www.theminif...illing-coolant/

 

 An oil cooler will help with overall cooling. 

 

 Is your fan on the correct way?

[KTS]

 

i have a standard 2 core radiator in mine (1380cc, roundnose) that copes perfectly well whilst the car is moving;  a different matter in traffic so have an auxiliary fan fitted 

 

fitting a cowling around the radiator to vent the hot air through the inner wing makes a big difference

 

when does it overheat; in traffic, when driven hard, or just pootling about ? 

 

..and is it really oveheating - temperature gauges can be notoriously unreliable 

 

Marvin was running the high end of the temperature gauge most of the time, so I did a complete system flush (the coolant was full of crud) and this improved things.

He hates traffic and I wouldn't confidently drive him in a big town or city without fear of overheating.

 

When he's on the move (mainly country lanes around me) he's happy.
 

And yes, he gets hot.  Very hot.

 

 

OK - so sounds like the radiator has the capacity to cool the engine, but you're struggling to get enough air through it at low speeds for it to do it's job

 

you could try a smaller fan pulley to increase the fan speed at lower revs, but at the risk of the water pump impeller cavitating at higher revs

 

as Lippo says, check the fan is on the right way round (..it *looks* ok from the photos), or consider an alternate fan design

 

other than that; fit an auxiliary fan to help with cooling in traffic, and a cowling to direct the hot air out of the engine bay

 

with regard to an oil cooler;  unless you're pushing the engine very hard for long periods of time it's unlikely the engine needs it, and in reality it won't provide any help with your overheating issue as at low speeds there's won't be much air or oil flowing through it anyway

Edited by KTS, 04 March 2025 - 04:34 PM.

[lippo]

 Here's a pic of my engine bay with the Fletcher rad. My top hose isn't kinked like yours. I hadn't looked at your photos before commenting earlier, it does look like your fan is the correct way round.

 

[nicklouse]

Alloy Rads are not the go to. A modern copper/brass one is way superior to any alloy one.

[GraemeC]

 Here's a pic of my engine bay with the Fletcher rad. My top hose isn't kinked like yours. I hadn't looked at your photos before commenting earlier, it does look like your fan is the correct way round.

 

 

 

Yours is a clubman so you radiator is further away from the engine - differnet radiator brackets
His fan does look to be correct

Edited by GraemeC, 04 March 2025 - 06:07 PM.

[Spider]

Contrary to popular belief, Aluminum has about 1/2 the thermal conductivity as copper. They also need to use a thicker section Aluminum as it's fatigue resistance is poor, this so they don't crack. They are also a big risk in regards to chemical incompatibility with the other metals in the cooling system.

[nicklouse]

Just a note the early Fletcher Rads we’re not stamped as they were just cheap stuff from China.

[Earwax]

Hi . Hard to tell for my eyes, but have look at the distance the fan is away from the actual radiator and how much fan is overlapping under the shroud. As pointed out above, different models can have differing spacers?  Having spent time in some hot and humid places, my experience is that for road going minis- the oil cooler is not appropriate ( too cool) . I do find that a little extra water capacity can make a difference for some motors who tend to run on the hot side. I have used heater cores ( the small tank plus the extra length of hoses gives slightly greater capacity) or overflow tanks ( I like the moke style one- and if fitted as an expansion tank , it is very stable for temp..

 

In regard to an aluminium radiator - I have found some imported tanks work fine - but again standard original style radiators do too.  For me the big finding - after ensuring the alum ones actually fit - is that although they look similar some come with 40mm core and some come with 50 mm core.. ( same external width of about 58 mm) .  and as a final thought bubble - if you are pulling radiators out or trying to get near the fan etc - do a little grind of the bottom radiator bracket just to make a space large enough for a fan belt to slip through.

 

Again, not trying to tell people anything as such, just adding some ideas for you to consider or disregard. Cheers D

[Cooperman]

If you suspect that your Mini is overheating, the first question is 'does it blow steam out of the rad cap pressure relief pipe'?

If not, then the net thig to do is to fit a capillary type temp gauge to see what the actual temperatures are. My 'S' appeared to overheat, despite having a 2-core radiator and aux fan, but when I fitted a capillary gauge it was actually running at around 85 to 90 C going up to just over 100 C on hot days and hard driving, which is fine.

[68+86auto]

Getting hot could easily be the result of poor tuning.