Broken Fan Blade[s]

[tekspeek]

Ok this is weird.

I recently purchased a replacement fan blade (original) off Ebay. This was to replace my fan where about 1/2 of one blade was missing. The missing part of the fan blade was the un-reinforced part of the blade.

As I was driving to a local (Cincinnati) British Car Show I heard a quick metallic 'clink, clink, clink' from the engine compartment. When I returned home today I looked at the engine compartment and found that 1 blade of my fan was missing. I guess I know what the clink's were.

There is nothing obstructing my fan, there is no reason that I can see that would cause the failure - but my car has had at least 2 occurences of this.

Specifics - I was driving about 65 mph, around 3,000 rpm. The failure happened about 10 miles after my start and I had probably 200 miles on this fan.

Any help? Should I buy an electric fan or ???

 

[DougF]

Metal fatigue. The aluminum blades can tend to do that. Same thing happened to a friend in his 4. Be happy that it didn't come off in the upward motion and damage your hood. If you don't want to go electric, you can use a TR250/early TR6 yellow fan blade.

 

[Tomster]

How much or do the yellows improve cooling?

 

[Guest]

I've got the 13 blade red plastic fan off my 73 TR6, hub and all, in fairly decent condition. Would that work on a TR4?


Bill

 

[DougF]

From what I understand, only the yellow will fit. I know it will since a friend of mine is running one. It is not a straight bolt on as I remember. I'll see him on Saturday and ask what has to be done to make it fit.

 

[skikir]

I think you can use the red fan with the adaptor that was used with them.

 

[TR4nut]

I changed my TR4 over to a yellow fan a few months ago. Simple conversion, but you need to use a fan extension and dog bolt from a TR3. The yellow fan pulls much better than the original metal fan, and is quieter. If you go ebay hunting, the dog bolt is about $10, the extension $10-20. Moss has a new extension for $30 or so. Total conversion is in the $50 range I think.

If you like originality, hunt for a tropical fan which I think was six bladed (may be wrong there), and better pitch on the blades. Still metal, but was an original option so is nice.

I'll never go back though- the yellow fan is fine but in Houston I notice I can't stay in stopped traffic forever. If that gets to be too annoying I'll go electric fan/new radiator/alternator change etc. to update.

Randy

 

[Alan_Myers]

Hi,

Randy is right, there was a 6-bladed fan offered at least as early as TR4, possibly TR3, too.

However, all those metal fans, including the tropical one, are pushing 40 years old now. And metal fatigue happens, as you have seen first hand!

Probably the widely available yellow plastic fan (7 or 8 bladed) or a conversion to an electric fan is the way to go in terms of reliability, unless you want strict originality.

Heck, Triumph themselves had plenty of trouble with the metal fans. For the company's first factory effort at the 24 LeMans (in '56?), they entered a team of three relatively stock TR3s. After some hours, two out of three of the cars were knocked out. In both cases, fan blades broke off and punctured the cars' radiators. They finally got smart and pitted the third car to remove the fan entirely. After all, there's really no need for a fan when averaging 114 mph. Plenty of air is continually being forced through the rad at that sort of speed. Unfortunately the third car also retired early, with oil pump issues, if I recall correctly. Triumph did much better in later LeMans, learned quite a few lessons in the earlier efforts!

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[tekspeek]

Thanks All:

I just got back in town to read this post. Looks like a new fan is in order. There was some discussion about electric fans which would be fine for me - Is there any down side that I should watch out for? How are they mounted. Can I go to an 'Autozone' or similar to pick up an generic fan or it there a special fit where I have to buy it from one of the big three or Ebay?

Thanks,
Pete

 

[Guest]

Pete,
Look up www.spalusa.com of you want the best.


Bill

 

[Alan_Myers]

[ QUOTE ]
Thanks All:

I just got back in town to read this post. Looks like a new fan is in order. There was some discussion about electric fans which would be fine for me - Is there any down side that I should watch out for? How are they mounted. Can I go to an 'Autozone' or similar to pick up an generic fan or it there a special fit where I have to buy it from one of the big three or Ebay?

Thanks,
Pete

[/ QUOTE ]

Hi again Pete,

Yes, there are a number of important things to consider when installing an electric fan.

First is fit. There isn't a lot of space between the the rad and the cross tube in the engine compartment. There is only about 3.5 to 4" in there to work with, typically. So, you need to consider thinner profile fans, to have any chance it will fit.

Next, look at the fan's diameter. If it's going to be the only source of air movement (stock fan will be removed), you'll want it to pull as much as possible and that means the largest diameter possible, up to the point where it begins to overlap the edge of the radiator. I've got a 14" fan on my TR4, but I forget what the actual air draw rating is - something like 1700 cfm, which is enough for a 3-3.5 liter V6 engine if I recall correctly. (I bought from www.SummitRacing.com and they compare fans by engine size).

I've heard of as large as 16" being used, too, although with that size fan a lot of it will overhang the edge of the rad.

I chose a puller type fan, since this will be the only fan on my car. A pusher type fan would need to be smaller (12" max) to fit inside the radiator shroud, plus tends to block some air flow and is more exposed to the elements out in front of the radiator. And, I happen to have an oil cooler mounted just in front of the radiator, which I wanted a puller fan to assist to some degree.

Along with the fan, I think it's important to install a thermoswitch controller. There are adjustable ones, but I chose a 185F for simplicity. This turns the fan on at 185F and turns it off once coolant temps drop to 170F. The thermoswitch sensor needed to be mounted, so I welded a bung into the metal tube in between the two lower radiator hoses on my TR4. This also needed a ground wire, which was easily added with a small stud. There has been some discussion of this, but I personally feel the lower (return) hose is the best place to install the sensor, since coolant temps are more stable there than in the top hose or the thermostat housing.

There are other types of sensors designed to slip under the edge of a hose, or even that clip onto the fins of the radiator, but seems to me one solidly screwed into a bung and directly sensing coolant is the best way to go.

Most folks who sell you a fan also offer installation/wiring kits. The one I got from Summit included the thermoswitch/sensor mentioned, along with a relay that's now mounted alongside the fan on the radiator, and a self-resetting circuit breaker (instead of a fuse), plus wiring.

Some folks also like to add a switch on or under the dash, too, so they can manually turn on the fan when they wish. I didn't because I prefer to concentrate on other aspects of driving and don't watch the coolant temps all the time (but am adding an "idiot light" to alerts to high temps and/or low oil pressure.)

You'll find fans with both straight and curved blades. In general, curved blades are quieter running, but less efficient. I chose straight blades for maximum possible air flow, and some fan noise really isn't a concern to me.

You asked about mounting and there are a number of ways to do it. I *don't* recommend using the plastic clips that come with most fans, just to be pushed through the radiator and clamped on the opposite side. I've heard of just using J-bolts that catch on the sides of the radiator and that seems a pretty good option. I ended up fabricating two brackets that are now bolted to the frame upright on either side of my TR4's radiator, each providing two threaded mounting points for the fan and positioning it as close as possible to the radiator surface. These brackets each also have a lip shaped to enclose the 1/2-3/4" of cirucular fan shroud where it overlaps the edge of the tall, narrow radiator in the TR (a 16" fan would overlap even more).

Installing the fan and mounting brackets, I just pulled the radiator out of the car and would recommend anyone do that, not try to install with the radiator in the car. Just first measure how much clearance you have between the radiator and cross tube (between the spring towers). You might find you can elongate the lower mounting holes of the radiator, to move it forward a little and gain just a bit more clearance. You have to watch out for any interference at the rad filler cap and inside of the hood or between the rad and the radiator shroud, though.

Another key consideration is the fan's electrical draw. Most fans with adequate capacity pull 10+ amps. Along with other electrical items in the car (especially headlights, wiper motor, heater fan, any fog lights, any elec fuel pump, etc.), this is pushing the upper limits of the relatively anemic, stock generator of a TR4 (17 to 22 amps output at best, if I recall correctly). I converted to an alternator, too. (Especially since I have a pair of 7" Lucas SLR700 Flamethrowers soon to be installed on the front of the car!) I'm using the common Delco conversion that's been discussed a lot, and getting more like 65 amps out of it.

When you remove your stock fan, you'll need to leave the hub/extension in place. This serves as a vibration dampener of sorts, on the 4-cyl. TR engine. Without it, you would risk eventual damage to the bottom end of the engine and/or the gearbox.

An alternative is to use a true harmonic balancer and completely remove the fan hub/extension, which is what I did. I got a kit from www.britishframeandengine.com that included a thin belt conversion for the water pump along with the dampener. Note that the alternator came with a thin belt pulley, too, which would have needed to be changed out to accomodate the 3/4" thick TR belt if I'd not made this conversion. The less expensive harmonic dampener is is adequate for most daily driving conditions (up to 6000-6500 rpm, I think). I don't recommend anyone experiment with cheap dampeners pulled off other cars at the junk yard, even if a good one can be found to fit onto the front of the engine. It's not likely to be a good match for the needs of the TR engine, in particlar.

Where to buy the electric fan and related stuff? Well, the major Triumph vendors mostly only offer smaller 12" fans that might be adequate, but also tend to be high priced (identical fans are a lot less elsewhere!).

I've heard really good things about the Spal fan mentioned already. I chose a fan from Summit that cost under $100 (plus installation kit) and moves a lot more air than the 12". I think it was a "Mr. Gasket" brand (the parent company that owns Mallory, Jacobs, Accell, Hurst, and several other performance brands).

Other places like Jeg's, JC Whitney or just about any major parts source can get or provide universal fans at competitive prices. There has also been an eBay seller offering TR-specific fan kits lately, that appear a pretty good price but I don't know the details. Some of the smaller TR vendors might have TR-specific kits that are well-priced and easy to install, too.

One final thing, when you wire in the fan if you use a hot-all-the-time circuit, rather than one tied to the ignition switch, the fan will be able to run for a short time after you stop and turn off the car, more quickly dissapating underhood head build-up. Most modern cars have this arrangement.

Hope this helps.

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