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MG Midget and Sprite Technical - Fan / Radiator clearance

Hi all,
Managed to get my radiator back in ok, although with a lot of creative swearing.
There is not too much clearance between fan and radiator, although the fan doesn't hit the rad at all at any part of the rotation.
I cant get the shroud any further to the front of the car, and everything SEEMS to be fitted up well and isn't wobbling about
Is there a recommended distance between fan and radiator?
Cheers colin
colin frowen

What's your car Colin? Some use a spacer between the water pump and fan. If yours has this you might be able to remove it. That said the fan is at its most efficient when close to the rad, as long as there is no actual contact
GuyW

ETA: as usual someone posted whilst I was still typing.

Colin,
engine fan or electric fan?

Engine plastic or metal fan, how many blades?

Vertical or X-flow rad?

The only thing I think I can remember about your car is that it might be white, and I'm not sure about that.

If possible a couple of photo of fan to rad and shroud installed might help.
Nigel Atkins

There should be enough gap to fit a fan belt.
Rob
MG Moneypit

Hi Guys,
Sorry I didn't give enough info.
1275 Mk 3
Cross flow rad
I THINK its 5 bladed plastic - it has 4 bolts.
Ordinary engine fan
Fan does have a spacer . ( BTW, Is this really necessary- can't see the point , but I did put it back.)
I can JUST get a fan belt on by " adjusting " blades.
Oh & Nigel, close , but no Doughnut, its Flame red!
Cheers all.
Colin


colin frowen

Sounds ok to me, if you can just get fan belt on then you have sufficient, but not too much, clearance. Assuming all 4 blades are more or less in the same plain. i.e. none bent either more forward or more back than the others.
GuyW

If it’s plastic, it’ll have six blades.

From memory, I think the spacer is there so the fan clears the canister on the timing cover.
Dave O'Neill 2

ETA: just seen Dave's post, so yes to clear chain cover, and just thought you might need additional space to rad to allow for engine movement, and to get the drive belt on. Actually your fan sounds closer than I remember if you need to twist the fan blades, are you sure the cowling is fully seated.

Colin,
it's been so long since I've had an engine driven fan I couldn't remember if it was with a spacer but I *think* they were and I sold it with the 6 blade yellow plastic fan.

Photo below of plastic fan, the metal looks different.

There's not a lot of room between the end of the water pump pulley and the rad even without the fan fitted.

I meant the primer was white. :)


Nigel Atkins

My 1098 uses a 4 blade metal fan which clears the chaincase without spacer. As Dave says, it is to clear the oil separator canister, not the chain cover, which it clears on a 1098 without use of the spacer as it doesn't have the canister.
GuyW

The spacer is not just needed for the canister clearance, it's also used to align the 3 pulleys on 1275s, which had the fat crank pulley. The 1098s and earlier had the thin crank pulley similar to the Minor 1000 but without the starting handle dog...
David Smith

The pulley fits directly to the pump, so the spacer has no effect on the pulley alignment.
Dave O'Neill 2

And the extra thickness on the
harmonic balancer type crank pulley is on the front, so the pulley itself isn't any further forward either.

The only thing the spacer does is move the fan blades forwards. I think it is to improve fan efficiency too, moving it into the shrouded area as a spacer is used on (some?) pre-cannister engines as well.
GuyW

Apologies, I don't know why I put chain cover but I did, but I'm sure I'm right about the white primer(?). :)

Looking at the 1977 factory Parts Catalogue the spacer is called "piece-distance" AEG 560 and drawn as between the fan and pulley (twin pulley 12G 1542).

I removed my plastic fan and spacer when I fitted the electric fan and at the same time a modern replacement water pump.

* So, as the spacer is no longer listed with the usual suppliers I wonder if it might not be needed with modern made replacement water pumps? *
Nigel Atkins

Surely the purpose of the fan is to increase airflow over the radiator and increase the heat exchange capacity of the radiator. In that respect, it doesn't really matter how far the fan is set back from the radiator, provided the airflow provided by the fan is maintained and is largely linear. Normally the shroud provides sufficient containment in this respect, but in extremis, you could install some large ducting from the radiator with the fan at the other end and not affect the heat exchange capacity. Basically as long as the peripheral air flow generated by the fan is enclosed, you should be fine.
Oggers

True, but the radiator is quite an impediment to air flow through it. If the fan is too far from it there is a greater chance of the fan pulling air in from the sides rather than pulling it through the rad core itself. Same on the upstream side, inadequate ducting allows the ram effect from forward motion to spill around the rad rather than being forced through it.
GuyW

Guy

As I said, if you enclose the periphery - by ducting or shroud - from close to the radiator to the fan, I don't think it matters how far away the fan is.
Oggers

AH, sorry chaps - memory playing up :-(
David Smith

David, I will send you a membership of the club.

If you don't get it it'll only be because I forgot.
Nigel Atkins

Other than a safety open top cover off the rad shroud there's nothing from rad to fan.
Nigel Atkins

Nigel

You miss the point. I aprreciate there is nothing, but if the fan cannot be placed close to the rad, then a possible solution may be to introduce an extended shroud or short ducting arrrangement.

Alternatively, junk it altogether and fit an electric fan!
Oggers

Mark,
sorry yes I did miss your point. I thought the same as you earlier but there's not that much room in the area and it''d be perhaps unnecessary fabrication as I don't think/remember Colin putting before that he was having any cooling problems with his (standard?) set up.

This summer I was suggesting to a mate he might try placing bits of cardboard fabrication for testing air flow but of course it needs to be pretty secure for proper real life road testing. I also suggested his oil cooler and shrouding to it directly in front of the water rad could be a bit of robbing Peter to pay Paul. He liked neither of my suggestions and ideas!

He put together and installed a very nice looking package and asked if I'd heard of rivnuts, I'm sure it was me that mentioned them to him years back as another mate raved about them.
Nigel Atkins

Yes Oggers I was agreeing with you -reinforcing what you said.

The vertical flow rad is very much more shrouded than on a cross flow version. But neither has a full air fast ducting so spillage does occur and the closer the fan is to the rad, the less this spillage will be.
Of course, above around 35mph the fan has only a marginal effect.
GuyW

And when the car is stationary or crawling along. :)
Nigel Atkins

Yep that's its maximum ( marginal) effect!
GuyW

And it's maximum negative effect, car going at x-revs and x-speed with a cold engine on a cold day.

Shortly after I fitted my less effective in front of the rad electric fan, because of lack of space behind the rad, I read on here where someone had fitted a 1500 shroud the get enough space for a more effective behind the rad electric fan. I've never been over-lucky with timing but I'm hopeful about organising the German/Belgium vaccine UK program. It's alright, everything will go fine for me as I'm mately with the Government's local MP. I might buy the company that makes those electric classics.
Nigel Atkins

This thread was discussed between 05/12/2020 and 06/12/2020

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