View Full Version : Electric fan question

11-19-2012, 04:35 PM
I'm nearly convinced to install an electric fan on my '60 TR3A. I suppose also that it should be installed as a "puller". As I would need to remove the mechanical fan, what do I need to consider regarding the fan hub. I see replacement pulleys with references made to damped and undamped

What is the difference, and what are my risks in just removing the fan and hub?

Geo Hahn
11-19-2012, 05:32 PM
Since you're 'nearly convinced' I have to ask why you plan to do this. Many people who remove the crank-driven fan do so because they have changed to R&P steering or some other mod that necessitates it. Some also do so to for performance considerations.

If you are thinking 'electric' because of over-heating issues then you may be better off tackling the issues themselves.

BTW - an electric can be installed as a 'pusher' -- there are disadvantages but again it goes back to why the electric is being considered.

11-19-2012, 06:47 PM
Geo brings up some good points. I first converted to an electric fan on a previous TR3A many years ago because I was looking for a bit more power (and because my mechanical fan was ruined with no obvious replacement readily available. Things are different now.). More recently, I found that the mechanical fan on the TR3 just wasn't quite enough when doing extended stop-and-go traffic in high ambient temps. Although I try to avoid such things, it's not terribly uncommon for me to have to spend an hour or more doing no more than 10-15 mph with ambient well over 90F.

To get back to your questions, the puller configuration does seem to work better. 'Pusher' will work, but the fan seems to upset and limit air flow at higher speeds. When i installed one on my Stag (as a temporary replacement for the broken mechanical fan), it actually caused the engine to run noticeably hotter at freeway speeds, whether the fan was powered or not.

There is a big bolt that runs through the fan extension and clamps the extension, pulley and hub assembly to the front of the crankshaft. You have to keep some sort of pulley obviously, for the belt that turns the water pump and generator. However, with the extension removed, a shorter bolt and large flat washer may pull up against the end of the crankshaft and fail to clamp the hub firmly enough. Over time, the hub works back and forth against the key, eventually tearing up both of them. BTDT
I think it was Rick Patten who offers a nicely made blanking plate and bolt to solve this problem; but what I use is basically a hollow cap that fits over the end of the crankshaft, and clamps the original hub firmly. Lacking much in the way of machine tools at the time, it was made from a cast iron pipe cap, which I drilled for a center bolt and then spun in the drill press to file down the outside to fit into the hub.

The original metal fan was mounted on rubber bushings, which some believe acted to dampen some harmonic resonances in the crankshaft. At least in theory, operation at one of the resonant frequencies (rpm) causes extra stress in the crank, which can lead to a broken crankshaft. Hence the replacement pulleys with integral harmonic dampener.

But I suspect this applies mostly to racing TRs, where operation at full throttle above 5000 rpm is the rule, and the engines have been modified to produce considerably more power than stock (both of which add greatly to stress within the crankshaft). At any rate, I've driven probably over 200,000 miles with no damper and no crankshaft problems.

Another issue to consider is where the power for the fan is coming from. My current TR3 is still wearing its stock 19 amp generator, and it will not keep up with both headlights and fan. Fortunately I have a fan controller that only runs the fan for a few seconds at a time (until the water coming back from the radiator drops below 190F) so I've been getting by OK for the past couple of years. If the generator dies though, I plan to install a 'mini' alternator that puts out about 40 amps.

11-19-2012, 09:23 PM
The "why" is a running battle with overheating. I've cleaned the cooling system, for three years I've looked for a "tropical"
fan without success and tried putting a little more pitch in the mechanical fan. Timing & head gasket etc. seem to be ok. I had the temp gauge rebuilt, so I think it to be good also. I do have an original radiator with the crank hole. I have thought about a recore w/o crank hole to see if that would help. The elec fan just seems to be an alternative. I could install as a pusher just to see. Any advice will be accepted and appreciated.


Geo Hahn
11-19-2012, 09:38 PM
I used an electric fan for years but only as a 'helper' when caught in stop-n-go 100 traffic or climbing a mountain following behind an RV. I never had an overheating issue, just liked to be able to give things a boost in extreme condition.

If that is your situation then an electric fan might help -- but if you are overheating in regular driving I doubt that more fan is going to solve anything.

The radiator is definitely worth a close look as there are plenty of ways it can become inefficient w/o leaking or getting clogged.

I had a new core put in mine (but kept the crank hole) when I had it out for engine work - not cheap but the old one was pretty beat up and I figured 'do it now and be done'. As for the electric -- I diitched it when I went with a tropical fan.

11-20-2012, 12:15 AM
I agree. If your problem is at speeds more than about 40 mph, more fan is not going to help.

Twice now, my problem has proven to be the radiator even though in both cases a radiator shop pronounced it "fine". On the most recent go-round, it appears that the insides of the tubes were coated with stop-leak that had plated out and solidified. None of the tubes were blocked, but the layer of 'mud' screwed up the heat transfer. The strange part was to me was that that radiator was working just fine when the 3A got wrecked, and 'failed' during 3 or 4 years it took me to get the 'new' TR3 put together.

FWIW, my radiator guy said the crank hole reduces cooling capacity by about 10%, so both times I opted to leave it out. The cost to add the hole was minimal, but I was a lot more interested in cooling than in being able to use a hand crank. If you do get yours recored, I suggest having them also add some reinforcement around where the extension tank joins the upper tank. I have always had trouble with mine cracking along that joint (which was why the 3A had all that stop-leak in it). When I mentioned that to my radiator guy, he said they could lay some small diameter copper tubing on top of the joint and solder it in place, which adds a lot of strength. Too soon to say for sure, but so far it seems to be working quite well.

Another strange problem that I have seen is worn carburetor jets. Apparently if the jets are not properly centered and the engine is driven that way for a long time, the needle rubbing on the side of the hole through the jet wears a groove. The groove causes the mixture curve to go rich at idle. Since you normally adjust the mixture at idle, but the adjustment changes the entire range, setting the mixture by the book caused the cruise mixture to go way lean and cause overheating. The exhaust manifold would even glow red!

11-20-2012, 03:28 AM
I installed a pusher fan. My overheating occurred at stoplights only, and the pusher fan cures that and stops the heat from rising much above 185 degrees. I'd only consider a fan if your issue were limited to traffic light overheating, or creepy crawl overheating. Good luck.

PS I'll try a new radiator one day soon, so long as I can transfer funds in the midst of other imperceptible transactions.

11-20-2012, 11:03 AM
Another add-on use for the electric fan -- in addition to traffic light or creepy crawl -- is for it to cool the radiator when you park your car. Not necessary, by any means, but useful for bringing the temperature down.

A bit like cooling down a horse in the barn after a good ride.

An aluminum radiator and high quality thermostat, with proper radiator cap, solved the overheating problem for me. My temp never goes above 185-6, no matter the temperature, speed, mountain climbing, etc., etc.

11-20-2012, 11:06 AM
My problems do occur during ninety degree Indiana summers. Short of moving my family to the UK, I will continue to ponder and tinker since these are my strongest talents. If it was easy I guess every one would have an old car.

I really appreciate the advice and will let you know if and when improvement is made.

thanks again,


Don Elliott
11-20-2012, 01:15 PM
When I installed my Kenlowe 12" fan as a pusher in my 1958 TR3A, it was overheating in stop and go traffic or when eveyone was trying to narrow down to get onto a bridge. I put it in in 1991 and decided on a pusher so it would look concours correct. At that time there were also many stories of TR owners getting a broken cheanksfat in the engine after they remover the mecanical fan to install an electrically powered "puller" fan.

Geo Hahn
11-20-2012, 01:41 PM
...I'll try a new radiator one day soon, so long as I can transfer funds in the midst of other imperceptible transactions.

PM sent.

Added to make message long enough to send.

11-20-2012, 04:55 PM
My TR 6 overheated in traffic and caused considerable damage. When I rebuilt the engine I used the original fan and installed an electric fan as a pusher. I installed a switch on the dash but plan on installing a thermal operated switch this winter and use the switch as a by-pass.

11-20-2012, 06:08 PM

I have a termal operated switch that kicks in when I park the car after a long ride and a switch on the dash (which I never use) just in case I need the fan.

I don't think the electric fan ever comes on when I am driving. It may be set to kick in at somewhere between 187 to 190, which temperature it sometimes reaches when I park and turn the engine off.

Geo Hahn
11-20-2012, 06:59 PM
...I don't think the electric fan ever comes on when I am driving. It may be set to kick in at somewhere between 187 to 190...

Or the sensor may be down at the bottom of the radiator where things should be quite a bit cooler than up at the thermostat housing where the gauge reads.

When you think about it, down low is a good place for the sensor since it is then turning the fan on when the radiator is having trouble keeping up with demand.

11-21-2012, 09:34 AM

You may be right. I'll check.

11-21-2012, 12:48 PM
I'm settled on an electric fan as a pushing helper. Today in the upper 50's I've let her idle for over 45 minutes and barely reached 180 degrees (85 on my metric dial). We go on a regional VMCCA tour each August and that is when most of my problems arise.

One last thought, I'm wondering if the electric fan would best be mounted in line with the mechanical fan, or perhaps at the top of the radiator where the highest temperature coolant would be. Does it really matter?


Don Elliott
11-21-2012, 01:59 PM
I put my 12" diameter pusher fan up near the top of the radiator in my 1958 TR3A so I could still use my handcrank throught the hole in the rad. I never had a issue since intalling my fan. But I had to trim the cardboard air deflector in a half round shape up near the top so the fan would not jam on the cardboard air deflector.

11-21-2012, 02:19 PM
Will do, and many thanks again for the help. What a great forum.

11-23-2012, 07:42 PM
LXtr3, I have thought about wiring mine that way. Now it is wired so that the switch only operates the fan when the ignition is in the run position. It would be good to have the fan operate after shutting down the engine on a hot day.

11-24-2012, 12:59 AM
Getting a little late to the party, just found out how to access the "new" new forum.
Just adding to post #3 by Randall, attached are some photos of a blanking plate that I made myself from aluminum. This was one of the first parts I made on my (new to me) lathe. This gave me the clearance I needed for the electric fan. It works well and I could not detect any ill effects.