A question about Thermatic fans

[g72s20]

I decided to get the coolant flushed and replaced by a radiator specialist yesterday.There have been no overheating issues, the coolant appears clear and green, I just had no idea how old it was.....well i tried anyway! He took one look and said he wouldn't touch it! He went on to point out that the current fan-clutch and fan setup was too close to the radiator and, as was evident by damage to the blade tips, under certain conditions was actually clipping the bottom frame of the radiator. It appears under hard and harsh braking, the engine, being on rubber mounts, is moving forward just a little, ....throw in a bump at the same time and it travels down a little at the same time. This all adds up to enough movement to cause the contact.

As the blade damage came with the car, and I originally couldn't see how the current setup could cause it, I assumed it had been done by something that had already been removed :stupid: .......Anyway, I've decided the easy way out is to remove the current setup and fit a thermatic fan. With a little luck I won't have to buy one ..I've got an unused thermo switch left over from the Monaro, and a mate has a spare 14.5" flat motor fan in his workshop!

The radiator is just over 15" wide.

So, if anyone has any suggestions with regard to the Nissan motor and thermo fans, please, jump in and tell me what ya reckon is good, bad or just worth a mention. Thankfully I am auto electric friendly so correct wiring practices aren't a problem. Hmmm...better check alternator can cope!

Jim.

[440k]

Personally I'm not a fan of them. I fitted one to my Dat 1600 when I lived out in the sticks (Blackwater, QLD). Att he time, 99% of the driving was highway, so airflow was never a problem.

However, I drove to Melbourne one holidays, and in heavy traffic, it started to overheat. The 12" fan just couldn't draw enough air through the radiator. A motor mounted fan will draw a lot more air through your radiator than most thermo fans.

Having said that, many others have had a lot of success with these things, and a good 14" jobbie may do the trick (if it's well shrouded, and you get a good flow of air through the fan).

Despite the proposed change to thermo fan, I'd check the reason for the existing fan hitting the radiator (or being so close). Get that fixed first, specially if the eng mounts are letting the engine move forward.

Hope this helps.

Peter

[TomoHawk]

The guys on Hybridz.org are having success with the radiator fan from a Ford Taurus. You might want to check out the details on that.

General info

Wiring diagram

Fitment of fan

Extra stuff: http://forums.hybridz.org/showthread.php?t=95365

[g72s20]

Hi Pete,

Thanks for thinking about this.

I'd check the reason for the existing fan hitting the radiator (or being so close). Get that fixed first, specially if the eng mounts are letting the engine move forward.

The engine mounts are good, the problem is the large diameter fan and coupling are from another vehicle and when placed on the L28 in the KGC10 the clearance at the bottom edge of the radiator between there and the fan is less than 5mm! The clearance for the same part of the fan when at it's highest point of rotation is around 30mm. The shaft for the fan-clutch is the culprit here. It sticks the whole assembly too close to the radiator. I compared it to the same unit on my 240K and it's about 30mm longer.

If the thermo fan doesn't work out, I could try swapping them I s'pose. I think there is a bit more clearance in the 240K bay.

Hi Thomas,

...or is it really Magpie (MAG. P.I.) Thanks for the link Tommo. Comprehensive and clear! I like that. Oddly enough the fan I've been given looks identical in size and blade shape to the Taurus one in the story.

Excellent info, Thanks guys

Jim.

[HKSZ]

Reminds me of a DIY show on pay TV I saw last week. His tip to find exhaust leaks was to catch the running fan blades with his hand in a glove, this reduces air around the engine bay.

Would be a real HANDY tip if someone watching the show doesn't know the diff btw fixed and thermo fan

[Murph]

I agree witth 440k. Fix the clutch fan setup for sure. It will easily outperform the thermo fan and if the clutch is working correctly it wont cause any extra drag on the motor when it shouldn't.

[g72s20]

Due to circumstances I had to fit the thermo regardless. During the meanwhile I have modified the clutchfan setup to fit with out risk of fouling, so if the thermo doesn't work out I can re fit the clutchfan without any dramas.

I've travelled about 200Kms over the last few days since fitting the thermo fan, it's coping with no complications so far. Long freeway runs at 4k +, 30mins of stop start 1st gear only traffic , air temp ~ 28C, with the fan automatically cycling on and off as required, and everything else you get driving across Sydney. Indicated temp gets to 80C(which is dead centre of the temp gauge. and varies about a needle width either side, much the same as with the clutchfan. We'll see how it goes over the long weekend, but I will be carrying the old fan and a 10 mm ring -open ender....just in case! Next mod is a Smiths 270deg display capillary line temp gauge. The original fitted unit only has a 90deg arc of display, variable electrical resistance.

I'm off to change oil and fit new fuel filter. Have a safe Easter break, and remember ....double demerits for the duration in NSW.

Cheers,

Jim.

[Mr Camouflage]

Isn't there a difference in the lengths/width of L24 and L28 fan clutches? I think i remember reading somewere that people have a similar problem with engine swaps in 240z. Might be worth some research on here, as you may be able to use a l24 item on the l28 to get some extra clearance.

[datfreak]

hey Jim, curious if the electric fan helped with your motor revving,

Ive read that it does(because of the less drag)--what do you think?

[aarc240]

Jim, stick with your electric fan rig. 14.5" on a 15.27" radiator is a pretty good match.

If you want to improve on that then set the fan up about 20 - 25 mm away from the core and enclose the area around the fan to the edge of the radiator with an aluminium sheet shroud also spaced 25mm from the core.

Why do you need a temperature guage that has a range you will never use at the top and a range at the bottom that will only ever be used as the engine initially warms up?

Let's face it, if the engine isn't over 140 degrees F then you shouldn't be revving it hard and if it's over 220 degrees F then you better find out why real quick.

By my calculations that requires a range of just 80 degrees F.

Peter, a 12" fan on the stock radiator in a 1600 and then all electric fan systems aren't any good because that combination overheated?? Come on!

Even little crapboxes with 800cc engines run fans that big!

Just to put electric fan systems in perspective, of the current crop of new cars available in Australia just 0.7% have engine driven fans. Manufacturers don't put things in that cause recalls, maintenance issues etc so it is very probable that electric fan systems can be considered satisfactory if the installation is thought through sensibly and installed in a workman like manner.

Am I a convert on electric fans? You bet & I've been running them since the early 70's. Properly installed they have handled loads such as a 4.3 litre 6 Pack Chrysler running at 5000+ RPM on a 43 degree C shade temp day in central Australia without overheating issues. Crikey, an 18" unit coped with our 400CI Chev powered Jeep Cherokee even when crawling through sand and rocks!

Datfreak, yes it will help the motor in response and fuel. A 16" six blade fan takes around 17 HP to spin at 5000 RPM. That's one of the reasons car makers have switched.

[aarc240]

Craig, you are spot on.

There is quite a range of fans and clutches on L6's to suit the various body types.

I suspect that someone may have fitted an L28 Patrol fan/clutch assembly to Jim's engine somewhere along the line. That one is around 20mm deeper than the 'normal' L24/L26 unit, presumably because the same Patrol body was fitted with the physically larger diesel also.

[440k]

Did you bother to read past my opening comments? Obviously you didn't get as far as this:

Having said that, many others have had a lot of success with these things, and a good 14" jobbie may do the trick (if it's well shrouded, and you get a good flow of air through the fan).

FYI, the 1600 was running a heavy duty 3 core radiator, which was fitted about 2 weeks before the Melbourne trip. As I said before, with the radiator in place, it never came close to overheating on even the harshest drives - until I spent an hour in stop - start traffic.

Yes, the fan was properly fitted, in a workmanlike manner. I don't cut corners when it comes to working on cars.

Funnily enough, the RX2 rally car I have just purchased also overheats on the thermo fan. No problems at speed though. Yep - those thermo fans are the best things out there.[1]

I'll say it again - if you want airflow and cooling, you can't beat a good engine driven fan. Hey, even an inefficient fan drawing 17hp is going to shift a helluva lot more air than an efficient fan drawing 200W. You can't argue with the laws of fluid mechanics or thermodynamics.

If you're chasing performance, then switching to a thermo fan will free up some power, with a probable drop in cooling effectiveness, depending on what size, kind and number of thermo fans you use.

[1] I'm well aware that the RX2 probably has a lot more issues with the cooling system than a thermo fan. Makes a good story tho.