BMW Z3 Cooling fan

[Barry Gadd]

Still slightly worried about the, now minor, water loss but hopefully it will work out soon.

My car doesn't have an electric cooling fan and I wonder if this was a standard fitting and a previous owner may have removed it, OR if such a fan is an extra?????

The normal viscous clutch fan operates continuously and I'm puzzled as to how this should function. Should it only turn when the engine is hot if so what sensor causes it to operate?

A new electric fan is not expensive but how is it mounted?

Any help would be much appreciated

 

[GazHyde]

The viscous fan will spin continually while the engine is running, and you would only fit an electric fan if you wanted greater cooling than you have now. Standard Z3's don't need a secondary fan (unless they have air con).

A few people remove the viscous coupled fan and replace it with an electric one which is referred to as the "Fan Delete Mod"

 

[Barry Gadd]

Thanks GH. Previous cars I've had, have a thermostatically controlled electric fan and no fixed fan. Why do they use a viscous clutch if the fan is rotating when the engine is running?

I've booked the car in for the MOT today....I've been working on her since late March and have everything crossed she will pass. Wish me luck !!!

 

[GazHyde]

Why do they use a viscous clutch if the fan is rotating when the engine is running?

I have no idea, just that they do I'm sure one of the members who know what a spanner is can explain better than I can! Perhaps @Aceman or @zedonist could comment

I've booked the car in for the MOT today....I've been working on her since late March and have everything crossed she will pass. Wish me luck !!!

Fingers crossed for you, and just in time for the sunshine!

 

[Aceman]

You called

The viscous fan although rotating all the time under normal circumstanses is not providing that much cooling just a trickle of air. There is a viscous clutch between the fan and the water pump which effectively allows the fan to free wheel when the engine is on the colder side of normal operating temperature however as soon as the temperature of the engine rises on a warm day or after a spirited drive the clutch will lock and force the fan to spin at engine speed. You may have heard on occasions when the temp does rise the engine sounds like a jet taking off which is the fan spinning at engine speed and drawing more air in from through the radiator. I theory and I wouldn't recommend doing this you should be able to put your hand in when the engine is cold and stop the fan from rotating as the clutch will allow it to slip. There is also the problem which Gary has been a victim of twice in that sometimes the viscous fan can fail and lock up when it shouldn't that can cause the fan blades to shatter but also as I will explain below the fan delete mod will remove the load on the water pump bearings giving them an easier life and longevity.

With regard to the electric fan seen on some zeds this is because they were fitted with aircon and is used as an auxillary method of drawing air through the radiators specifically to cool the aircon condensor radiator. Also as we live in a relatively cool country where we rarely have weather hot enough to cause the viscous clutch on the fan to operate there is what is called a fan delete mod whereby you remove the viscous fan which will release some BHP due to there being less drag on the engine and install a lower temp electrical thermostat for the electric fan so that takes over the role of the primary fan. This is quite an easy mod for those with aircon fitted as almost everthing is in place to facilitate this but quite an involved job if you are unfortunate enough not to have aircon as standard.

 

[Cooper]

@Aceman am I correct in my reading of what you said above, that a lower temp thermostat can be installed so the aircon fan can act as the primary cooling fan after removal of the main fan? I have only seen the mod for removal of the primary fan and clutch and installing a new electric fan in its place. Do you have any more info on that? Thanks.

 

[Barry Gadd]

Mutter mutter mutter........ My car failed the MOT today......blast.......
During the emissions check the CO2 reading was high and the mechanic ran the engine at 3k revs for quite a while (not sure why but maybe this has some ability to reduce CO2? Any ideas?
The net result was the small diameter hose connected to the plastic take off pipe at the rear of the cylinder head was forced off with water pouring out....... Unfortunately the serrated end of the smaller diameter take off pipe had broken off and I thought the remaining stump would be sufficient to hold the pipe firmly in place. (I Jubilee clipped the pipe firmly in place when I installed the engine earlier)
I managed to limp home and had to top up the rad en-route (I'd put a gallon of water in the boot as a precaution before leaving for the MOT. I never dreamt I would really need it)
The car also failed for suspension balljoints. I wondered about this before booking the test but thought I'd go ahead anyway.
A couple of questions:-
1) Any idea why the CO2 reading should be high? Is this a fuel / injector related problem or indication of worn rings etc?
2) Access to the rear of the cylinder head is really tight. Any suggestions as to how to replace the plastic pipe connector without removing the cylinder head?

Back to the drawing board!!!!

 

[zedonist]

Mine failed on CO2 this year, the tester did the same as yours revved the f@*k out of it. Any way short story long, I replaced the CAT and Lambda sensor, and it passed with low emissions. These cars only have one sensor pre cat, so this is controlling the mixture of the engine, the cat is just passively reducing the consequential emissions, so good chance it is the sensor but at around £100 for each item won't really break the bank to change.

Worn rings would give you blue smoking on throttle, so easy to check.

Injectors, the cars are old now and the seals shrink, see my post on changing injectors, it can't hurt to refresh them or just change the seals.

Only suggestion on the pipe is small hands, I get my wife to help on the fiddle bits, small hands, can get to places my sausage fingers can't reach.

 

[t-tony]

The things engine manufacturers squeeze between cylinder heads/blocks and bulkheads has never ceased to amaze me. A common statement in my job is " It's a shame the bloke who designed this doesn't have to work on it " Sometimes substitute "bloke" with other word or expletive.

 

[zedonist]

Too right Tony, they are designed for assembly not rework

 

[Barry Gadd]

Having stomped around for an hour or so muttering expletives, I started to attack the coolant pipe connection at the back of the cylinder head.
My fingers, luckily, are more chipolatas than sausages and I managed to get a 10mm socket on a 1/4" rachet groping at the back of the cylinder head.
I got the plastic coolant connector off without too much trouble. The top section of the smaller of the 2 moulded pipes (the ribbed part) had already broken off so perhaps it was only a matter of time before the hose was going to come off. Now ordered a replacement on ebay so hopefully will get the new one fitted in the next few days.
I need now to focus on getting a pre-cat sensor (thanks Zedonist) and removing the wishbones as these were described as knackered by the MOT guy. Has anybody removed the wishbones and just replaced the ball joints as opposed to replacing the complete unit? (This alternative seems to be a lot cheaper)

 

[t-tony]

Hi Barry to replace the ball joints you will need access to a hydraulic press and some special adapters to press the new ball joints into the original arms without damaging the new ball joints. Undoubtedly a cheaper option but if you haven't got a press it's not really a viable choice. You may have to just accept the extra cost and fit complete arms. It's not really worth changing the lower arms without fitting new rear mounting bushes either. Take care to make sure that the mountings are aligned correctly with the arms before fitting them.

 

[Barry Gadd]

I've got the 2 wishbones off the car and have ordered replacements.
Following Zedonist's recommendation of checking the O2 sensor I tried to unscrew mine but couldn't shift it.......
Has anyone managed to unscrew theirs???????
I tried with a chunky 22mm (from memory, anyway the correct size) combination spanner but couldn't budge the thing.
Is there a technique I'm missing here???
Thanks

 

[zedonist]

Plenty of penetrating fluid, I am afraid is the only answer

 

[t-tony]

Best and most risky option is run the engine till it is "stinking hot" if you don't have any other heating option, then try loosening . But be careful not to burn yourself.

 

[Barry Gadd]

Finally managed to unscrew the O2 sensor. The car is up on blocks as I've taken off the wishbones so a bit of room to squirm underneath. I put the ring end of a combination spanner on the sensor and put my hydraulic jack under the other end.Slowly pumped up the jack and the blooming thing started to unscrew (fighting all the way) It took around 3 complete turns of re-positioning the spanner and jacking before I could unscrew the thing by hand. What on earth do they screw these things in with????
I saw via Google a guy testing an O2 sensor by measuring the sensor output with a multimeter on D/C volts range. He measured almost zero volts at ambient and approx. 0.8 to 0.9v very hot (blowtorch) I held mine carefully over the gas hob and also measured the same results.
Does anyone know for sure if this indicates the sensor is really working as it should??

Also regarding wishbones and bushes,I've got the wishbones on order. They come with end and centre ball joints fitted but no bushes. I've also ordered new bushes and cut the old bushes out of my wishbone arms .
Has anybody fitted new bushes?? Is it straightforward??

Thanks again for all the help so far. I hope I will be able to help others soon (I'm getting to know Nellie intimately....)

 

[t-tony]

TBH Barry I can't really help apart from saying the bushes we fit at work are usually "standard" ones which come complete with the alloy mounting block. If you're fitting new bushes into you're old mounting blocks when you come to mount the complete item onto the lower arm make sure you have it on the correct "flats" so as to line up with the chassis properly when the ball joint pints are in their locating holes. The end of the arm is hexagonal so you could be 60 degrees out of rotation. I hope this make sense.

 

[vintage42]

The easy way...
http://fauxsuperblogs.com/2845/control-arms-arms-control/
Otherwise...

View: https://www.youtube.com/watch?v=ENJQpe50WBg

View: https://www.youtube.com/watch?v=LXoBRKQeT44

View: https://www.youtube.com/watch?v=b8GWQHvf7VQ

 

[Barry Gadd]

Many thanks t-tony and Vintage 42. I've now fitted the wishbones plus the rear bushes. It wasn't a difficult job and the hydraulic jack came in handy again pushing the ball joint tapers home to enable the nuts to be tightened.
I've also fitted the Y shaped plastic heater connector which fits on the rear of the cylinderhead so water is staying where it should be.....
I'm still unsure if I need to replace the cat or the oxygen sensor or both and I'm frustrated that I can't find a definitive test to measure which or both maybe causing the emission problem.
(I'll probably end up replacing both but it's bugging me.....)
Thanks again to all.

 

[joey]

I would like to point out that the M44 is known for running rich on start up for a good few miles, I got through the MOT by the skin of my teeth this time round because the tester did all the other bits first and then the emissions test when the car had cooled down...

I would find a friendly tester who is cool with doing the emissions the minute you arrive,just before go and drive down your local Mway in 3rd at 70 for a bit get the engine red hot and see what occurs....

I was nowhere near before and it failed, i went back the next day having put a a bottle of STP fuel system cleaner and an italian tune up on the A3 and she got through with room to spare...

i'm teaching my grandma to suck eggs here i'm sure but thought my experience was worth a mention.