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 - Hayden electric fan

I am considering installing one of the Hayden electric fans from Moss in my 70 BGT.

1. I only have overheating problems when stalled in traffic. Would the fan eliminate this problem?
2. The literature states the fan can be placed either in front of or behind the radiator. Which is the better position?
3. Should I remove the existing fan that operates from the engine?
4. Would I get better cooling if I used both fans?
5. For those of you who have already done this, do you have any helpful installation instructions?

Lee


Lee,

there are a couple of good discussions that might give you the answers you need. Check here:

http://www.mgexperience.net/phorum/read.php?1,772950,773102#msg-773102

and

http://www.mgexperience.net/phorum/read.php?1,775193,775193#msg-775193

BTW, I have a 10" Hayden installed as a puller (it replaced the 2 electric fans that pushed). I also installed a variable thermostat. My 78 B used to run at least halfway on the gauge and stuck in traffic, it would run hot with the original fans and thermostat.

I have the new thermostat set so fan comes on when needle is about 1/3 way up from cold and I don't have a overheat problem now. I am planning to install a manual bypass switch one of these days but it is not a priority.

Pat
Pat Harrison

How do you define overheating?
Do you have all the seals in place to keep air directed through the radiator?
Are the fins in the radiator clean and free of debri/bugs?
Have you checked the radiator for cold spots?
How old is the water pump?
Have you used an infrared thermometer to verify actual running temperature?
Is your current fan installed correctly?
Kimberly

Puller is more efficient than pusher, but you would have to ensure both the polarity of the motor is correct as well as the orientation of the fan if one kit can be mounted either side.

There is only about 1" between the mechanical fan and the rad, is the kit slimmer than that? Even if it is the engine moves forwards under braking so I'd never eat into that space by *adding* it as a puller otherwise you could end up destroying the mechanical fan, after-market fan and radiator.

Moss sell a shroud for the mechanical fan which does eliminate most of the loss of efficiency introduced by having a gap betwen the mechanical fan and the radiator, but it simply shouldn't be neccessary except under the most extreme conditions.

But mot imprtant, how do you define 'overheating', and secondly there can be any number of faults on your car that could cause trie overheating i.e. loss of coolant or steaming that an alternative fan may or may not get round. These cars run in desert states under far harsher conditions than SF has as I understand it, so you should be investigating those before considering adding bits to it.
Paul Hunt

The temperature gauge normally operates in the middle or slightly to the left. It is only during severe stop and go traffic that the gauge climbs to the line on the far right side. I do not have an overflow tank and when it heats to that point coolant blows out the radiator overflow. I consider that overheating.

The 160 degree thermostat is new, coolant seems to be circulating through the entire system normally, belt is not slipping, radiator is free from debris, system has been flushed (no rust at all), no movement or noise from the water pump, there has been no modification to the radiator or surrounds that would change them from original factory installation.

For those of you not familiar with San Francisco and the surrounding area,in a distance of less than 15 miles temperature can vary over 40 degrees F. In the area adjacent to the bay and ocean temperature averages mid 60's all year. During the summer months a short drive will give temperatures at times exceeding 100 degrees F.
Lee

Lee,

on my roadster, i use a pusher that cuts in at 84° C, on my GT V8 i have two pullers that are set to ~ 85° C. Although it seems that they are set on the 'early' side, it turned out to be the right tune for Stop & Go.

I also tried other settings but with the roadster (4 cyl. without expansion tank) 84° C seems to be just right not to exeed Temperatures of 90° C.

Using a pusher or a puller is not that essential, as i found out, the cut in point must be selected carefully with differnet setups instead.

I read about a screen for the propeller on the neck of the water pump some years ago. As far as i remember, it was made in the USA and worked well too. Just try to have a look into the archives to read more upon this item if you think it might meet yout demands too.

Ralph
Ralph

Lee If your main concern is overheating I would go with the Moss shroud that makes the standard mechanical fan more efficient. The mechanical fan will move a lot more air than any electric fan that will fit the MG.
DENIS4

Yes, that is overheating, and it certainly shouldn't do that, even in SF, as I say they don't do that in desert states. By adding stuff like an extra fan or shroud you are simply avoiding the real problem, it is that which must be addressed as it could well get worse and defeat the extra fan/shroud in time. We can get near 100 on occasion in the UK and mine doesn't do that even with a 3-bladed fan.

As it seems to run OK when underway it would seem that the engine isn't producing more heat than it should, and the radiator is capable of getting rid of it under forced-air conditions. The difference between running and standing is that when stationary the only cooling is coming from the action of the mechanical fan. Is that the correct type i.e. how many blades does it have, a 1970 US spec should have a six-bladed metal (7-blade plastic from Dec 72)? Is it the correct way round? The correct distance from the radiator?

What pressure cap do you have? Should be 10lb, have you changed that? A weak one will boil sooner. Could be a combination of that plus an inaccurate gauge/sender.

You may also have a combination of factors rather than just one thing, circulation can be difficult to determine, any cool spots on the rad surface? Just what temp does it get up to as measured some other way and not just on the gauge?
Paul Hunt

Paul might have discovered the problem. I have a 7 lb. radiator cap. Moss indicated GT's from 139472 on should use a 10 lb cap.

The fan has been replaced and could possibly have been put on backwards. On each blade there is a long side and a short side. Which side should be closest to the radiator core? This is the only item that has been changed. On mine the short side is the closest to the radiator.
Lee

Hi Lee- With the install of the 10-13# cap, try a bottle of "water wetter" after you've ensured a clean glycol mix and clear radiator tubes. Water wetter alone lowered the temp on the x-flow 13 degrees last year at the Reno Hot August Nights ( HAN) in 100 - plus temps! Check the blow direction of your stock fans when they come on. Are they blowing thru the rad or cooling the headlights? Cheers, Vic
vem myers

Has the radiator been checked for internal obstructions (cold spots)? Scale and mineral deposits can internally restrict the radiator.
Kimberly

Old water pumps can have worn vanes restricting the flow of coolant. You didn't answer the question about the age of the water pump.
Kimberly

Whilst the 7lb cap will boil over sooner than a 10lb cap in rising temperature, the gauge still shouldn't get as high as you indicate.

With metal-bladed fans where the thickness is the same all the way across the tip of the blades generally has one very rounded corner and one less rounded. The well rounded corner is generally the leading edge, which has an element of safety if you should get your fingers in the way. Also the fingers coming out of the hub that the blades are rivetted to should be on the front of the fan i.e. facing away from the engine , so the more aerodynamic side of the blade is the one pushing the air.

Plastic fans tend to have a 'wing' or aerofoil profile, where the blunter edge is the leading edge and the tinner edge the traling, just like an aircraft wing.

On 3-bladed metal fans at least the hub is offset relative to the blades, which moves the blades further away from or closer to the radiator depending on which way round it is fitted. It took me some 17 years to discover my fan was on the wrong way round. The right way round the blades were much further away from the radiator and I think would have fouled the engine had I started it, because a large alloy spacer was missing. With the spacer but still the wrong way round the blades would have been much too close to the radiator. With the spacer fitted and the blades the right way round they were about the same distance from the radiator as before, but working in a more efficient way. Of course fitting the spacer I needed longer bolts as well.
Paul Hunt

Lots of good comments giving me plenty to look for. Thanks to all of you for your comments and suggestions.

Re: Kimberly's questions, I can't remember how old the pump is. I have owned the car for well over 30 years and remember replacing it in the distant past. The method I have always used to determine the condition of a water pump is movement or noise. You mentioned worn vanes might be a problem. Short of removing and disassembling the pump there is no way I would know their condition. The coolant appears to flow normally. I have found no cold spots on the radiator. Visually the radiator appears to be in excellent condition externally. The only part of the interior that is visible is beneath the radiator cap and does not have any deposits. The coolant is green and there is no indication of rust or deposits in the fluid. I change coolant once a year. Over the last 10 years, the GT is driven less than 7000 miles per year. Once again, the temperature indicates normal with the only exception of stop and go driving and high outside temperatures. It is only at that time the gauge will climb almost to the far right line.

PS: Kimberly are you going on the MG club tour of Napa Valley June 7?
Lee

This thread was discussed between 24/05/2008 and 27/05/2008

MG MGB Technical index

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