Thermo fans?

[hqhzvans]

Just wondering if any guys run thermo fans on their old cars, the temp on my van sits around half give or take a bit, had one incident where I was stuck in traffic and the temperature gauge started to climb and I shut it down not to far from the red. A mechanic told the old girls run hot but I don't really want to be in that position where it may over heat and do damage, has new radiator , water pump etc motor was all recod. Are thermos the best way to go to keep your pride and joy from over heating.

[Dr Terry]

No, the best cooling fan set-up for old Holden V8s is a factory viscous clutch fan & shroud, along with a decent radiator of course. The shear volume of air they pass, will out perform all but the best dual electric fans.

A bog stock V8 was OK with a 4-blade fan, but with a bit of a cam, they need more help.

Dr Terry

[Innuendo]

Thermo fans are capable of doing a good job when set up correctly but as Dr Terry points out they still don't shift the air as much as the horse power draining clutch fan.
Either though should be enough to cool a mild 308. I would say you have issues somewhere else. The biggest cause is cavitation http://en.wikipedia.org/wiki/Cavitation where you are not expelling all of the air when when filling with inhibitor. The fill point needs to be the highest point of the cooling system and typically the cooling system when filling needs to be level. This though is no guarantee that all air pockets are dismissed and devoid of air. Pressure filling is an option. Other issues can be the wrong, missing or incorrectly installed thermostat. You should be able to see and test the temperature change via the gauge or via an inferred thermometer as the thermostat reaches it's opening point to do the water transfer.

Also make sure your heater is open when the filling is done.
Over advancement of timing can also be a cause of overheating.

[HZSM50]

My HZ 308 ran hot as an Oven and if in traffic red hot. My mechanic just told me to completely flush out the radiator from both ends. Very important that. Since then no trouble with the temp.

[thatotherguy]

shouldnt be running that hot,i ran my 308 with no fan during winter with no problems,check thermostat and where is the temp sender unit mounted? i have one on my 350 and it is very close to the extractors and it always reads hotter than it is

[Big Rob]

The spring in the bottom radiator hose can often collapse or be missing too. That causes the hose to close up due to the suction from the water pump and block water flow.
It usually becomes noticeable at high speeds though, so it's probably not your issue. Check it anyway though....

[Innuendo]

The spring in the bottom radiator hose can often collapse or be missing too. That causes the hose to close up due to the suction from the water pump and block water flow.
It usually becomes noticeable at high speeds though, so it's probably not your issue. Check it anyway though....

That is a good point but it is not only limited to the lower radiator hose. The top hose has been known to suck flat and stop water flow. In fact my top hose in Innuendo is doing that after a turn the engine off. I've been monitoring my temp gauge but haven't noticed anything bad as yet. Check if you can compress the hoses via thumb and forefinger, it should have a decent amount of resistance and a spring to prevent it from sucking flat.

[HQSandmanute]

I'll go the other way. I've had much more success with thermo fans than any combination of engine driven fans and shrouds.

Although there are good and not so good thermo fans. I haven't found any good aftermarket fans.
Also depends how they are set up. Even a good set of fans won't do the job if they're not set up right.
How many factory cars these days use engine driven fans????

When the fan needs the most air moving though it, Car at standstill or nearly, a engine driven fan is spinning slowest. Whereas a thermo runs flat out whenever they switch on.
On the highway, where there's plenty of air getting pushed through radiator, thermo's are generally off, not needed. But engine driven fan is doing engine revs, wasting fuel and HP. A clutch fan may help here, slightly.

The get thermo's working well, there are a few things I look for.
1. Fans with good motors,& good blades that draw plenty of air. A good indicator of which cars have good thermos is standing beside them when the fan cuts in. If they're good fans, you can feel the hot air blowing out under the car.
2. Good shrouds, that cover all the radiator and seal on the edge of the radiator. That way, all the air that the thermo's draw, gets pulled through the radiator. Not like many of the aftermarket ones that have round shrouds and use pull though clips etc through the cores to hold them on the radiator. Look at the area the shroud covers, cos thats the area that air is getting pulled through the radiator.
3. trying to get fans to run cooler than thermosat. This will make fans run all the time as while the fans are cooling, the thermosat is trying to warm it up to it's set temp. I generally set fans to cut in aprox 5*C hotter than the thermostat setting.
4. Know what your thermostat setting is in *C. Know what your temp gauge reads in *C. With many factory gauges just maked C - H, it's hard to know what the span of the gauge is without checking. While the needle on the gauge may move, what might seem a lot, it may not be that much change in temp.

I had a 377sbc that had the block filled with grout to 3.5" from the deck, 400 siamesed bore block, 11-1CR, big cam etc etc, that would run around in traffic, go racing, haul trailer on the hottest of days and never had any overheating problems. Had 2 camira fans on(don't laugh) they have good metal shrouds, that joined together fit neat on a HQ radiator, pull heaps of air. Ugly as, with big long motors. But they worked great and haven't broken down in 15+yrs.

[Big Rob]

I've got thermo fans on my blown Torana and it never gets hot, my 308 Sunbird is set up similar and has no probs. But I had a VN V8 wagon a few years ago and pulled off the factory fan and fitted a thermo and it got hot as soon as it got near traffic, so I had to refit the factory one.
Problem solved!

I'm actually having trouble with my VG Valiant wagon (245 Hemi) getting hot when it sits on 100km/h for any length of time. It's totally original, so I don't want to fit a thermo, but I want to drive it on the highway too.

[HK1837]

I've never had any success with thermos on iron headed Holden and Chev V8's. Always gone back to clutch fan and shroud and never had temperature problems again.