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Which fan to fit?
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Ray White



Joined: 02 Dec 2014
Posts: 3993
Location: Derby

PostPosted: Mon Nov 16, 2020 5:12 pm    Post subject: Which fan to fit? Reply with quote

The first two photos shows the original fan blades as fitted to my XPAG engine. They are attached to the water pump by four 1/4 BSF set screws.




As can be seen there are one or two issues.

Firstly, the blades are virtually touching the supercharger drive belt. A spacer would easily fix that problem and also take the blades closer to the radiator which would be no bad thing as they are too far away at present.


My biggest fear is that these blades have been known to fail with disastrous results. This has prompted me to buy an electric fan. Not only is there no danger of fan blades breaking loose but modern fans are much more efficient and those with curved blades can also be quieter.



This 12 v. 80w multi blade fan is thermostatically controlled and has an over ride switch and light. (Turn it on or of at will)

When offered up it becomes clear that the fan housing fouls the water pump boss.



I don't know whether to cut off the boss or to buy and fit a belt driven MGB 7 blade fan.?

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Kenham



Joined: 12 Mar 2012
Posts: 195
Location: Kent

PostPosted: Mon Nov 16, 2020 6:48 pm    Post subject: Reply with quote

Is there room for an electric fan in front of the radiator ?
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MikeEdwards



Joined: 25 May 2011
Posts: 2002
Location: South Cheshire

PostPosted: Mon Nov 16, 2020 7:40 pm    Post subject: Reply with quote

Can you offset the fan so that the centre isn't lined up with the water pump? That might give you enough room.

Kenham wrote:
Is there room for an electric fan in front of the radiator ?


Then you'd need to make sure that the fan will "push" rather than "pull" as it will need to if fitted behind. (This got raised elsewhere and I made the mistake of suggesting that just wiring it up backwards might alter the direction of rotation, leaving aside the blade shape.)
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Ray White



Joined: 02 Dec 2014
Posts: 3993
Location: Derby

PostPosted: Mon Nov 16, 2020 8:07 pm    Post subject: Reply with quote

Kenham wrote:
Is there room for an electric fan in front of the radiator ?


Unfortunately, no. The grille is too close.
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Ray White



Joined: 02 Dec 2014
Posts: 3993
Location: Derby

PostPosted: Mon Nov 16, 2020 8:23 pm    Post subject: Reply with quote

MikeEdwards wrote:
Can you offset the fan so that the centre isn't lined up with the water pump? That might give you enough room.

Kenham wrote:
Is there room for an electric fan in front of the radiator ?


Then you'd need to make sure that the fan will "push" rather than "pull" as it will need to if fitted behind. (This got raised elsewhere and I made the mistake of suggesting that just wiring it up backwards might alter the direction of rotation, leaving aside the blade shape.)


I have tried moving it to one side or the other but it is not possible without considerable design changes.

As you say it needs to be a "puller" and that was a major consideration when choosing which fan to buy.

I am inclined to cut off the redundant water pump boss - but if I do that I would be making it impossible to use the MGB (yellow) fan; or for that matter, the original blades.

There is not really an overheating issue with this type of engine, although the addition of a supercharger and stainless steel exhaust manifold can add to under bonnet temperatures so I thought additional cooling air would be an advantage.

I am genuinely nervous about the original blades and I much prefer the electric fan to the MGB fan - but I need to make a decision.
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Miken



Joined: 24 Dec 2012
Posts: 348

PostPosted: Tue Nov 17, 2020 12:04 am    Post subject: Reply with quote

Ray, when you say that the original fans are known to fail im guessing you mean the spot welds can let go? I can't think what else would break .
Could you just get some extra spot welds added?
Or drill some holes through the blade and central part and get them plug welded.
Or drill and add some steel snap head rivets.
Or small high tensile nuts and bolts with the ends peened over so the nuts can't come undone.
Or fit an early B-Series metal fan if your not keen on the plastic one. MGA, Wolseley 1500 etc.
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Ray White



Joined: 02 Dec 2014
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Location: Derby

PostPosted: Tue Nov 17, 2020 1:10 am    Post subject: Reply with quote

Miken wrote:
Ray, when you say that the original fans are known to fail im guessing you mean the spot welds can let go? I can't think what else would break .
Could you just get some extra spot welds added?
Or drill some holes through the blade and central part and get them plug welded.
Or drill and add some steel snap head rivets.
Or small high tensile nuts and bolts with the ends peened over so the nuts can't come undone.
Or fit an early B-Series metal fan if your not keen on the plastic one. MGA, Wolseley 1500 etc.


Some excellent suggestions there Miken.

I am assuming metal fatigue is the cause but I will need to investigate further.

Rick had a blade break off his Dodge and I have had one go on my Austin Seven but they are relatively slow revving engines and two completely different fans!

The XPAG is a different animal altogether with a reputation for wearing itself out prematurely such is the RPM for any given ratio. I don't suppose fan blades have broken as frequently as some people would have you believe but such is the reputation that many cars now use the plastic MGB (yellow) fan. I fitted one to my Triumph GT6 I seem to remember but I eventually replaced it with a Kenlowe which was much better suited to that 6 cylinder engine. It is that experience - and a fear of what a fly away metal blade might do - which led me to buy an electric fan.

I would have had the electric fan fitted if it had not been for the problem with the water pump boss. The water pump is new and being an uprated version wasn't cheap so cutting bits off it makes me feel a bit sick but there it is.

I have mixed feelings about a continuously running fan vs an electric one. The former saps energy from the engine all the time when it really only needs to operate in heavy traffic. The electric fan, on the other hand, draws considerable amounts of current when it is working but is more efficient overall. The downside is reliability.

You know where you are with a belt driven fan; they seldom fail if the belt is in good condition. At the very least the electric fan would need an over ride switch in case the relay or thermo switch fails which after market ones seem to do quite frequently these days.
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MVPeters



Joined: 28 Aug 2008
Posts: 745
Location: Northern MA, USA

PostPosted: Tue Nov 17, 2020 1:15 am    Post subject: Reply with quote

Ray
Personally, I'd take the MGB option if you feel the original is too risky.
But I wonder if you might find a slimmer electric fan? Perhaps one with a more 'skeletal' frame. What's the distance between the pump boss & the rad?
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Ray White



Joined: 02 Dec 2014
Posts: 3993
Location: Derby

PostPosted: Tue Nov 17, 2020 1:35 am    Post subject: Reply with quote

MVPeters wrote:
Ray
Personally, I'd take the MGB option if you feel the original is too risky.
But I wonder if you might find a slimmer electric fan? Perhaps one with a more 'skeletal' frame. What's the distance between the pump boss & the rad?


Mike. You would go for the MGB fan? It seems to be quite a popular option with other T type owners.

Can I ask why this would be better than an electric one if it means having a fan running continuously in a generally cold climate.?
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MVPeters



Joined: 28 Aug 2008
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Location: Northern MA, USA

PostPosted: Tue Nov 17, 2020 2:48 am    Post subject: Reply with quote

Ray White wrote:
MVPeters wrote:
Ray
Personally, I'd take the MGB option if you feel the original is too risky.
But I wonder if you might find a slimmer electric fan? Perhaps one with a more 'skeletal' frame. What's the distance between the pump boss & the rad?


Mike. You would go for the MGB fan? It seems to be quite a popular option with other T type owners.

Can I ask why this would be better than an electric one if it means having a fan running continuously in a generally cold climate.?


Just personal preference, I suppose.
Your thermostat will control the heat actually reaching the engine.
I wonder if you could get the original tested for defects? Is it magnafluxing?
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peter scott



Joined: 18 Dec 2007
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Location: Edinburgh

PostPosted: Tue Nov 17, 2020 9:40 am    Post subject: Reply with quote

I don't think my views will be helpful because I think my agenda is rather different from yours Ray.

I personally hate to see modern components in old cars. I don't mind them if they are invisible. Electric fans, modern coils, alternators pretending to be dynamos, modern batteries. They are all a big turn-off for me. I like the illusion of being back in the period and these things are instant death just like satellite dishes in an edition of Poirot. (Which I've never seen.)

Peter
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MikeEdwards



Joined: 25 May 2011
Posts: 2002
Location: South Cheshire

PostPosted: Tue Nov 17, 2020 9:56 am    Post subject: Reply with quote

I have heard of people using two smaller fans, to allow the position to be adjusted a little. Something like an air-conditioning fan from a more modern vehicle.

peter scott wrote:
I personally hate to see modern components in old cars.


I'm generally with you, thought I am tempted by conversions like this if it makes the car easier to live with, and thus more likely to get used. If I think my car is going to have an overheating problem if I use it in hot weather, or if I'm queueing to get into a show, then that might put me off using it and go for something that doesn't have the problem. A reversible modification like this can just make it that bit more usable. I haven't had to do that on mine as fortunately* it all seems to work OK, and it's quite a bit more modern than the vehicle being discussed here so arguably had a more efficient cooling system originally.

* By "fortunately" I mean that I spent a lot of time making sure that waterways were clear when the engine was rebuilt, made sure the hoses, radiator and heater matrix were clear, that kind of stuff. So I didn't leave things like this:

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Ray White



Joined: 02 Dec 2014
Posts: 3993
Location: Derby

PostPosted: Tue Nov 17, 2020 9:58 am    Post subject: Reply with quote

[quote="MVPeters"

Just personal preference, I suppose.
Your thermostat will control the heat actually reaching the engine.
I wonder if you could get the original tested for defects? Is it magnafluxing?[/quote]

Yes, the thermostat will take care of engine cooling regardless but I don't think the original fan will be efficient enough to handle under bonnet temperatures which, with vapour lock a real possibility, is one of the reasons for buying the electric fan. I thought I would learn from the experiences of other T type owners with my set up who have all fitted a more efficient fan.

The MGB fan certainly works a lot better than the original and I now wish I had kept mine.

As to crack testing the original blades this is something I can do with the kit I bought for the front hub spindles. As it happens, I talked to my wife about it last night!.. She thinks I have spent too much already and if the electric fan won't fit then I should replace the original blades rather than shell out for a MGB fan which will need to be sleeved anyway.


Last edited by Ray White on Tue Nov 17, 2020 11:20 am; edited 1 time in total
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Rick
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Joined: 27 Apr 2005
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PostPosted: Tue Nov 17, 2020 10:15 am    Post subject: Reply with quote

Are you going to have a louvred bonnet (apologies if you've covered this before), that'd look the part and also help with temps.

RJ
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Ray White



Joined: 02 Dec 2014
Posts: 3993
Location: Derby

PostPosted: Tue Nov 17, 2020 10:24 am    Post subject: Reply with quote

peter scott wrote:
I don't think my views will be helpful because I think my agenda is rather different from yours Ray.

I personally hate to see modern components in old cars. I don't mind them if they are invisible. Electric fans, modern coils, alternators pretending to be dynamos, modern batteries. They are all a big turn-off for me. I like the illusion of being back in the period and these things are instant death just like satellite dishes in an edition of Poirot. (Which I've never seen.)

Peter


Peter. Your opinion is always helpful to me. I like to think we share much in common. If I want to experience vintage driving, I can always jump in the Swallow and tootle around the Derbyshire countryside; which where I live is exceptionally beautiful. I believe 'Trundles' to be one of the most original examples in existence and despite being quite inadequate in many ways I love it for what it is.

My MG TC is going to be a different thing altogether and although not "correct" it will be more authentic than a replica. I am attempting to build a usable car with a modern twist - a bit like a Morgan but to my own design. I believe much of what I am doing is rather less than MG would have done had the Morris bean counters not had their way.

If I am wrong then there is nothing that can't be undone when I am no longer on the scene.
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