MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Fan question

Hy
Does anyone know the advantages (if there are any) of changing from the 3 blade metal fan to the 6 blade plastic one. I understand it can be more eficient and especialy much lighter then the metal one. Is it a direct change from metal to plastic or should I change the pulley to ?
In the archives I can´t get a clear idea of what is best ?
Thank you for your input.
Miguel
Miguel

I think the plastic fan needs a different pulley (and has 7 blades).

Another option can be fitting an electric fan and omitting the belt-driven one. I have a Spal fan fitted, that I really can recommend: it doesn't run all the time, so there's one source of noise less and it proved highly reliable.

However: I installed it because the plastic fan was really scarred at its end, my radiator needed soldering anyway and I got the electric one for cheap. I don't know if it's true what they claim in the catalogues, that it robs less power. I also like the additional switch I have to operate it (apart from the automatic control). And: if my engine compartment was anything close to original and neat looking, I wouldn't have done it.

Jochen
Jochen Beyer

Scrap that nasty , noisy power robbing stock fan and put an electric one - easy to do , plenty of room and power is right there at the right side horn . I run a relay and it works great plus wiring it live allows the fan to cycle during the heat soak , reducing the damage caused . bonnet paint lasts longer , car starts easier when hot underhood plastic bits don't die early deaths and on and on........

MBZ has a very nice low profile fan as does Hayden , fits right in front of the radiator where it's not visable .
-Nate
Nate

The seven bladed fan is a straight swap for the three bladed one and is safer - the metal ones are known to fracture and send blades flying!
Chris Betson

Of everything that I have witnessed and read, Spal seems to make the best, most efficient fans out there for their size. They are at least as quiet as the commanly found ones, yet produce more cfm per their size for the US market than others.
Luke Staley

Thank you for your coments and advice. I want to keep a mecanical fan for originality reasons and I think the plastic 7 blades (danke Jochen) is "acceptable" in the nice looking engine bay of my 69B. I know the advantages of the automatic electric fan but apart from being much more expensive takes all the oldtimer looks of a car from the sixties. I instaled one in my previous B at the new owners request and yes it works very well. I´m not surrendering yet to those modern things (I have a pertronix but that you canot see).
I´m only waiting for the price of the plastic fan and if it is not to $$$ I´ll order one.
What would an MG owner do without this BB ?
Have fun
Miguel
Jose Miguel K. Clemente da Costa

One night as I was taking a spirited drive in my ’71 MGB and hit a dip in the road the six-blade metal fan went through the radiator destroying both. To my surprise the replacement fan was a seven-blade plastic fan that wouldn’t bolt on. I returned the plastic fan and bought a second hand three-blade MGB fan from an earlier year that did bolt on. Prior to this incident the temperature gauge always moved to the Normal position right in the middle of the “N” and never higher even in the very hot summers of Arizona. Afterward the temperature reading was always higher with a couple of critically high readings. Because I replaced the radiator core at the same time, I can’t say it didn’t play a part in the degraded cooling, but it was the same as the old radiator so I doubt it.

My guess is that the newer fan will be an improvement over the old three-blade design if it will fit. The water pump had two sets of holes that would accept either fan, but the pulley had only one set of holes. If I had it to do over, I would order a replacement pulley or modify the existing one.
George Champion

Jose,

I see your car is a 69 - these have the long nose water pump and deep pulley with wide spacing for the four bolts.

You may need to drill new holes in the plastic fan to match these holes.
Chris Betson

Chris
Now you scared me. Can I drill holes in plastic and still be safe ?
Thank´s in any case for the tip. The guy in the shop told me I can give the part back if it does not fit.
Miguel
Miguel

Yes, take off the old pulley and just line up the central hole on the pulley and fan (use a suitably sized socket) and run a 6 mm drill through the pulley holes and through the plastic from the back.

Space the new holes halfway between the original holes.

Fit the fan with 1/4 inch UNF bolts with 1/2 flat washers and spring washers, it will be perfectly safe.
Chris Betson

This thread was discussed between 07/01/2002 and 09/01/2002

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.