So what 'appened was...

[jasper5]

The fan is your cooling fan!

Instead of being electric, it's a fan that on tickover cools the engine but doesn't use engine power, and as the engine revs build, the fan turns faster due to the oil inside it (centrifugal force and all that).

[swiss]

I see. Interesting. Is this a GM/BMW thing or normal to find in cars? I've never heard of it before.

I presume it's separate to the electric fans on the radiator. So does the viscous fan just blow over the block?

[jasper5]

This viscous fan arrangement is a front engine, rear wheel drive thing.

The older type of vehicles used it quite a lot, like the old Jags (XJ6 etc.), BMW, VW, Mercedes, etc.my old Nissan Vanette had one, they were a power saving feature, instead of having a fixed fan that used engine power to turn it, they came up with the viscous fan which saved power, it only worked when needed, just like the electric fan we all know about.Yes, it draws air through the radiator and blows it over the block.

If you have a viscous fan, you will not have electric fans, unless you have an automatic, some automatics had a seperate electric cooling fan for cooling the transmission.

[swiss]

OK, that makes sense, but I also have the usual two electric fans in front of the rad. 'Tis an auto mind you, with an intercooler and various oil coolers... maybe it needs a combination of the fans to get enough heat out.

Gonna strip the relevant bits out tomorrow if the weather holds, so hopefully if and when the pump turns up it'll just be slap it in and go. Wifey says she thinks I can do it because she was convinced my DIY brake overhaul was going to fall apart when the pedal was pressed. Thanks, my beloved :sigh:

[jasper5]

Now that I think about it.....my old Vanette had 2 electric fans as well (manual) so, I guess your theory is valid about extra cooling, I guess I was wrong about not needing electric fans as well.

Anyway, good luck with the job, women give you such confidence don't they?

[STALLED]

If you have a viscous fan, you will not have electric fans, unless you have an automatic, some automatics had a seperate electric cooling fan for cooling the transmission.

Never heard of that - what cars had it?

Some of the froggers in Australia install oil coolers on their Autoboxes - Heat has been a known killer of plenty of AL4's - Also people do it on the R19's *vomit* to save their boxes - Infact, I believe there are more advertised with blown gearboxes than ones which are actually running. Shocking cars they were...

[swiss]

And guess what? It's raining. Woo yay.

[jasper5]

If you have a viscous fan, you will not have electric fans, unless you have an automatic, some automatics had a seperate electric cooling fan for cooling the transmission.

Never heard of that - what cars had it?

Some of the froggers in Australia install oil coolers on their Autoboxes - Heat has been a known killer of plenty of AL4's - Also people do it on the R19's *vomit* to save their boxes - Infact, I believe there are more advertised with blown gearboxes than ones which are actually running. Shocking cars they were...

Since I go a long ways back with cars, I was thinking of early Nissans, such as the Skyline 240K and the 280C models....the big 6 cylinder, rear wheel drive models.

Also, in the old days, if you were towing a caravan with an automatic, you had to fit an electric cooling fan to avoid frying your transmission.

[darrenwall]

most cars that have a viscous fan have the electric fans only to cool the condensor for the air con cos the y only come on when u switch the A/C no and i always though that the viscous fluid was sort of heat sensitive and made the fan stiffer ( oooh errr missus ) when hot for more cooling and slowed the fan when cold to stop the engine over cooling , i could be wrong tho but that s wot i have always been told

[jasper5]

What about the cars without air conditioning?

The automatic gearboxes were cooled by the radiator, the pipes actually went into the bottom of the radiator, hence the extra, electric cooling fan.

Isn't the viscous fan also called a centrifugal fan?

[swiss]

Right, almost got the rad disconnected. There's one more hose and a banjo union standing in my way.

When I tried to undo the banjo, it pissed oil all down my arm. What's that all about? I need to d/c it to remove the radiator but I don't want to lose, say, the auto fluid all down the road... anybody able to shed some light please?

It's located on the rear offside corner of the rad, almost half way up:

[jasper5]

If it is red oil, it's your transmission cooling pipes (as discussed above).

If it's engine oil, it's an oil cooler pipe.

Either way, you need to take out the banjo bolt, wrap a solid plastic bag round the pipe and tie it up so it doesn't leak....lift it up as high as possible too.

Screw the bolt back into the rad and catch as much oil as you can.....you could leave out the bolt and plug the hole in the rad with a small rag, a cork or rubber bung or something, either that or leave a drip tray of some sort under the rad to catch the oil.

When you have finished the pump job, fit the bolt back in with new copper washers.

[Welly]

Might be a cooling loop for the PAS?

[swiss]

Yeah, it's autobox fluid. The Omega forumites reckon it will 'dribble out' and not drain the box but you know, I think I'm gonna take Jasper's advice on this and bung it back up ASAP.

One guy also reckons you can de-pump it without removing the radiator. He's prolly right but with less than 1/2" space to undo the bolts and withdraw the shaft, I can't see that happening. Radiator's full of sh1te anyway, needs a scrub IMO

[swiss]

Radiator, viscous fan surround and the fan itself are off. Woo. No I have easy access to the viscous coupling and the rest of the auxy gear.

The radiator's absolutely filthy, fill of all sorts of crap. Tar, dust, grit, feathers, sweetie wrappers... gonna get a damn good clean before it goes back on, inside and out. Garden hose suitable for this?

Also, the auxy belt doesn't look too good. The inner, ribbed surface is networked with cracks. There isn't any adverse noise coming from the bay ATM, but I suppose you experienced peeps would advise a replace? We've had the car a year an a half and no idea when it was done before then.

Thanks for the continued support

Tom

[EDIT] OK, so pardon the ignorance but how does one untension this 'ere tensioner?