21 replies to this topic

[miniBrain]

Hi,

 

To mods: meant to put this post in Mini Chat - could you move it if required, Ta.

 

Decided to fit a front-mounted radiator with electric fan to my 1275GT. Did an internet search for a suitable radiator and after some cardboard mock-ups settled on a Fiat Cinquecento type. This has about the same area as the Mini rad - and I got one for £15!:

 

 

Made up some brackets to mount it to the front panel cross-member and the slam panel:

 

 

Had to bend back the lip on the cross-member to make room for the fan and also to gain a few millimetres for clearance but it fits nicely:

 

 

There is just enough clearance to get the dizzy cap off:

 

 

Here it is all fitted with a VW expansion tank - the front grille fits nicely as well but not fitted yet:

 

 

The electric fan is controlled by an ECU via a relay, although the radiator has a port for a thermostatic switch that could be used just as well. The coolant head in the expansion tank at the “max” mark is just higher than the top hose so I can completely fill the system:

 

 

Took it out for a 20 min test drive with the thermostat removed. Chart below shows a segment of the test from the ECU data log:

 

Driving along at town speeds shows the temp drops to about 82 degrees – this is a good 10 degrees lower than the original radiator set up. Parked-up and idling you can see the temp rising and the fan kicking-in. With the fan running the temp continued to rise. Next test I need to leave it running at idle until either the temp peaks or it boils over.

 

So, it looks like the radiator is doing a good job, but I might need to add a 2^nd fan. Also, I know the MPi has a steam pipe leading from the thermostat housing. I noticed the coolant level rose by about 10mm when the engine warmed-up, indicating there's air in the system. So I probably need the steam pipe as well to help bleed air out of the system.

 

I'm sticking with it though – there's better access, it'll be more efficient and the noise level is significantly reduced.

 

One thing to note is that the coolant temp might be reading on the high side – I've not calibrated the sensor properly yet. 100 degrees was reading just above normal on the Mini's temp gauge.

Edited by miniBrain, 28 November 2015 - 11:24 AM.

[Steve220]

That's brilliant!!

[miniBrain]

That's brilliant!!

 

Cheers! 

[phil hill]

I'd put the thermostat back in, or a thermostat replacement sleave.

 

It not only controls the flow of coolant to the rad but also means the water circulates around the engine properly rather than just taking the shortest route from the water pump to the 'stat housing.

 

Phil.

[miniBrain]

I'd put the thermostat back in, or a thermostat replacement sleave.

 

It not only controls the flow of coolant to the rad but also means the water circulates around the engine properly rather than just taking the shortest route from the water pump to the 'stat housing.

 

Phil.

 

Good point Phil, will try that on next outing.

[nicklouse]

Some comments.

I would have the hose from the header going to the lower hose. And have a pipe from the stat. Housing to the header tank to allow the system to self bleed. Maybe a different header tank

And I would fit the stat. back as it will help with warming the engine up and allow the water to flow around the block/head correctly.

[miniBrain]

Cheers Niclouse - what's the benefit of connecting the header to the bottom hose? 

[nicklouse]

Coolant flow direction.

Consider the MPI or the Metros they both have the header main connection to the lower hose. And the small bleed hose from the stat. housing to the header.

[skoughi]

Looks great! I've mocked up something similar on my clubby but has done what nicklouse said and used the thermostat housing with the little pipe outlet to stop an airlock and I took the lower pipe out of the expansion tank to the lower hose between the water pump and rad. On no4 end of the head I'm goin to remake an outlet off the heater outlet that also has a bleed pipe between it and the heater that'll double up as a bypass if the heater is closed off. There's pictures of it on my build thread "my fixerupper". I like how you fitted the fan to the front of the rad. Mine is mounted on the engine side and will obviously be wired to suck air which won't be as good as a blowing fan as what you've done, also I'll be using a side exit dizzy cap to help with clearance. Good work!

[miniBrain]

Coolant flow direction.

Consider the MPI or the Metros they both have the header main connection to the lower hose. And the small bleed hose from the stat. housing to the header.

 

Thanks for clarifying - will need to do a bit of re-plumbing methinks  

Edited by miniBrain, 28 November 2015 - 08:07 PM.

[miniBrain]

Looks great! I've mocked up something similar on my clubby but has done what nicklouse said and used the thermostat housing with the little pipe outlet to stop an airlock and I took the lower pipe out of the expansion tank to the lower hose between the water pump and rad. On no4 end of the head I'm goin to remake an outlet off the heater outlet that also has a bleed pipe between it and the heater that'll double up as a bypass if the heater is closed off. There's pictures of it on my build thread "my fixerupper". I like how you fitted the fan to the front of the rad. Mine is mounted on the engine side and will obviously be wired to suck air which won't be as good as a blowing fan as what you've done, also I'll be using a side exit dizzy cap to help with clearance. Good work!

 

Cheers Skoughi, Looks like I will need a bit of re-plumbing to get the best out of it! Been ages since I looked at Fixerupper and its looking brilliant - great attention to detail. Hope you post a report on the cooling system when you get the engine running. Be interesting to compare. What rad are you using?

Bob

[skoughi]

Cheers Bob, building up the engine just now and I'd wished I'd bought one already built. Total nightmare! I did do a flow test in the garage sink with all the pipes joined up to see how the flow would go to the heater box and how the bypass pipe would work and surprisingly it work no too bad! I'm going to make a neater pipe to join onto heater take hole on the head. I'm using an MG Metro radiator and Metro (I think) expansion tank. The fan is one I bought of ebay, can't remember the rating or size. I feel the most important is to have a bleed pipe from both ends, one off the thermostat housing and another of the pipe that comes out of the heater takeoff hole at the other end of the head. I fashioned the bypass from this end so that even if the heater is closed of there'll always be a flow of water from that end to keep no4 cool. Or at least that's the theory. I'm going to use the standard heat sender on the radiator to work a relay for power to the fan.

 Regards

 Larry

Edited by skoughi, 28 November 2015 - 08:32 PM.

[miniBrain]

Hi Larry, Sounds like you've done a comprehensive job in planning it all out - look forward to seeing it up & running. I've got an electric fan on my TR7 - when it switches on it drops the coolant temp by about 5 degrees within 20 seconds. But this fan covers about 60% of the surface area of the rad, whereas the fan on the Mini only covers about 40%. The TR7 fan is two-stage - it runs at half power at the first temp threshold, then full power when temp crosses a 2nd threshold. I don't think it ever goes to full power even at the height of summer, suggesting that its more effective to have some air flow over the whole radiator rather than a more powerful airflow over a limited area. Although I've got a bit more work to do, I'm tending to think I'll need a 2nd fan for the summer with this set up.

Bob

[nicklouse]

Instead of adding a second fan you would do better to blank off the areas around the rad so as to duct all the air through the rad.

[skoughi]

Not sure how my MG Metro one will work, the top half of the radiator is fully visible through the grill (the top half takes the water out of the engine first before it turns then goes out the bottom half which is mostly hidden behind the lower half of the front panel) . The fan is over at the drivers side. Even with this much of the radiator hidden what's left is still probably a bigger area than the original side mounted radiator and it's in a much better airflow so hopefully the fan won't be required so much, with mine being mounted in a "suck" position then probably won't be as efficient as a "blow" set up. Anyway up here in the Shetland Isles then it's a fair bit colder than you chaps down in Englandshire, plus we don't have "heavy traffic" to sit in for endless hours, just lots of twisty open road!