electric cooling fan failure

laskaboots · Postby **laskaboots** » 25 Jun 2012 15:35

I installed an electric cooling fan system on my '77 TR7 when I was nearly finished with its restoration. The fan has failed on me twice while doing shakedown drives. The first time was a few weeks ago while driving a few blocks around my neighborhood and I noticed the temp go up. I discovered that the temp control block contacts were badly corrouded and not making contact. This happened even though the car had never been driven in wet conditions. I cleaned the contacts, and installed a manual bypass switch under the dashboard in case this ever happened again. Yesterday I took the car on a 60 mile highway cruise to test it at highway speeds. Ran beautifully until going up a long hill I noticed the temp creeping up slowly to about 3/4 of the gauge, then dropping slowly to mid range when going down the hill. When I got back into town, the needle climbed back up again at stop lights, but I was next to 3 motorcycles so I could not hear if the fan was running or not. As I drove home with the guage still at over 3/4, I realised the fan was not running, even if I used the bypass switch. When I stopped to check, I found that the inline 20amp fuse container had nearly melted, though the fuse had not blown. The container had separated enough for no electrical contact. Later I replaced the inline fuse container with another, and the new 20 amp fuse blew immediately after the fan reached its threshold temp and tried to kick on. A 30 amp fuse was put in and did not blow, but I can't protect 16 ga wire original to the fan with a 30 amp fuse. Any body else have problems with electric fans? Thanks for reading.

laskaboots · Postby **laskaboots** » 25 Jun 2012 21:45

In a bit of a follow up, the engine was hot enough for some coolant to squirt out of the overflow. Liquid, not steam. The car was not running like an overheated engine, stumbling, roughness etc., but how can I tell if it suffered some head damage? I haven't driven the car enough to have developed a baseline as to what sounds and feels normal. It still starts easily, and revs up alright, and no obvious leaks of oil or water. I think I may just remove the electric fan and replace with one bolted to the pulley that will run whenever the engine is turning. May lose a little fuel efficiency, but I don't feel as if I can entirely trust the electric version anymore.

FI Spyder · Postby **FI Spyder** » 25 Jun 2012 22:40

Failed head gasket can show low compression in neighbouring cylinders, water in the oil and/or oil in the water.

I get up to 40 mpg (imp) with my car (depending on speed). Don't want to put electric fan on mine and show up all the modern econoboxes.[:p]

- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

TR7Aaron · Postby **TR7Aaron** » 26 Jun 2012 00:13

It sounds to me like the fan has some internal issues like dragging or corrosion causing it to pull more current than normal and blow fuses. I wouldn't recommend using larger and larger fuses to keep it running as that could cause a fire.
I had a similar situation happen on my wife's car. Replace the fan with a good quality one.

Aaron
1976 TR7 FHC (an ongoing project)

laskaboots · Postby **laskaboots** » 26 Jun 2012 01:52

this is a fan sold by Victoria British. had to grind off mounting ears and fabricate brackets to get it to fit on radiator. Also needed to cut off nose of original pulley to keep it from interfering. I don't know what current it normally should draw, but I would think well under 10 amps. Must be a piece of junk.....will bolt a fan to the pulley and be done with the whole issue. Can't be comfortable with parts that fail with less than 100 miles or 5 hours. thanks for the replies.

Cobber · Postby **Cobber** » 26 Jun 2012 03:06

Does the fan have any recognisable brand name? Or is it some Chinese rubbish?
The only after market fans I'll use are Davies-Craig or sometimes I might adapt a OEM unit from another model of car (of known quality & reliability )if it suits my purpose better, eg: space restrictions.

The old fashioned concept of belt driven fans is so inefficient and absurdly out of date, it's time they were pensioned off to the museum with other quaint anachronisms such as the spittoon, button up boots & the typewriter! All served well in their day but that day has long gone! 

80'Triumph TR7, , 73'Land Rover (Ford 351. V8),
'89 Ford Fairlane
'98 MG-F, 69'Ford F250.
76' Ford F100

Odd · Postby **Odd** » 26 Jun 2012 04:56

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by laskaboots

this is a fan sold by Victoria British ... <hr height="1" noshade id="quote"></blockquote id="quote"> There we have the problem!

Call Woody for the one he's got - and you will be much better off...

Beans · Postby **Beans** » 26 Jun 2012 08:14

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Cobber

... The old fashioned concept of belt driven fans is so inefficient and absurdly out of date, it's time they were pensioned off to the museum ... <hr height="1" noshade id="quote"></blockquote id="quote">
Together with the TR7 that's also absurdly out of date [}:)]

<center>

1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)
[url="http://www.tr7beans.blogspot.com/"]My full Weblog[/url]</center>

Cobber · Postby **Cobber** » 26 Jun 2012 08:34

Now now Beans [:D], my point is that we need not suffer from the limitations of the marginal cooling system which is a limiting factor in the enjoyment of our cars.

My family have been using thermatic fans in our race, road and offroad cars/trucks since the early seventies, without any problems from properly installed electric fans. Which is more than I can say for the belt driven rubbish on anything that hadn't got around to being converted yet ( or couldn't be converted due to the regulations applicable to the racing formula )

In fact the first thing I do to any car/truck I buy now is bin the belt driven fan. 

80'Triumph TR7, , 73'Land Rover (Ford 351. V8),
'89 Ford Fairlane
'98 MG-F, 69'Ford F250.
76' Ford F100

Tack · Postby **Tack** » 26 Jun 2012 11:16

Although I have yet to install it, I also have a fan I bought from VB. After much googling etc, I'm pretty sure the fan is a Maradyne "Challenger MC136K". Read on some online parts place that it was recommended to install with a relay; fan draws 13 amps.

Recommended wire harness and relay is a MFA100. Costs almost as much as than the fan.

http://www.maradynehp.com/products/challenger/mc136.php

http://www.maradynehp.com/products/acce ... nesses.php

http://www.maradynehp.com/pdf/Maradyne_ ... e_2012.pdf

Their catalog claims to sell the challenger series also as a "private label series - white box only" product. Mine came in a plain white box.

Probably too late now, but there's my two cents worth.

1980 TR7 DHC pageant blue

Beans · Postby **Beans** » 26 Jun 2012 11:59

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Cobber

... we need not suffer from the limitations of the marginal cooling system which is a limiting factor in the enjoyment of our cars ... <hr height="1" noshade id="quote"></blockquote id="quote">
When you have cooling problems with a TR7 and the original viscous fan (in good condition of course) your problem is some were else.
As you (could) have read in my weblog's account of the 10CR last year the engines temperature remained rock steady under all conditions with a new viscous coupling. So absolutely not a limiting factor.
Personally I rate a belt driven fan with a viscous coupling higher than a proper electric one, as does BMW ...

I'll get my coat [:p]

<center>

1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)
[url="http://www.tr7beans.blogspot.com/"]My full Weblog[/url]</center>

FI Spyder · Postby **FI Spyder** » 26 Jun 2012 14:38

I agree with Beans except I'm not convinced of his assertion that a viscous fan clutch locks up at temperature (it may change resistance). I know the definition of a viscous clutch is such but wouldn't make sense for a cooling fan. It is known that if the speed of a fan (or propeller) exceeds 3,000 rpm you get air cavitation with the result that little air gets moved. That's why prop planes are limited to that rpm. To get more speed you change the angle of attack or use a bigger propellor (fan) where you are limited by the speed of the tip as it goes towards hypersonic (not a problem in a car with limited space). The more air you move the greater the resistance until it matches the slip resistance of the clutch (what ever that is at operating temperature) but is set to limited the speed of the fan to around the 2,500 rpm the maximum efficiency of the fan. The force required for this isn't that great. None clutched fans go into the inefficient speed above that speed and their cooling is by air flow through the rad one gets at speed.

Now granted an electric fan (when off) is less noisy than a clutched fan and you do get a quieter engine but I'd rather have constant cooling smoothly regulated by thermostat than have an electric fan going of and on (maybe) as the temperature swing wildly between off and on at the temperature limits of the switch. Mind you an FI TR7 is said to run cooler than a carbed version and for the A/C versions, we have those twin electric fans for those really, really, really, hot days.[8D]

- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

laskaboots · Postby **laskaboots** » 26 Jun 2012 16:59

If I temporarily hot wire the fan, it seems to run smoothly without any mechanical noise, or wobble or vibration. I've also had a clutch type fan sieze-up which caused the plastic blades to come apart destroying the radiator. I didn't know about the cavitation effect at over 3000 rpm, but that makes sense. A pulley that would turn at about half engine speed might be a good alternative? I don't know the name of the VB fan, it's not stated in the catalog. When I get home from work I will stick my face down in the engine compartment to try to find a lable. Thanks for the discussion.

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electric cooling fan failure

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