Fan 'delete'

[Dino D]

Came across a thread on BF about the fan delete again and am thinking of doing it as described in point 1 below.
I've had the viscous coupling go as well as two fans disintegrate (nearly puncturing the radiator). Already spent plenty on this fan set up an wonder when it will fail again...

Seems to work fine in US temperatures so should be fine here (although it does get rather balmy here in Kent).
Thoughts anyone?

Thread here:http://www.bimmerforums.com/forum/showthread.php?t=2168137

Randy should correct me if I'm wrong, but there are three common practices regarding removal of the mechanical fan.
Edit: Damn, I was trying to get this post in before Randy replied. =/

1) Remove the fan, and do nothing else.

The engine coolant loop system will reach the minimum operating temperature (dictated by the thermostat) quicker (which is a good thing). The system will hold minimum operating temperature by mixing in the rest of the coolant via the thermostat until the entire volume of coolant is up to operating temperature. At this point, if you're not moving through the air the coolant temps will continue to climb to optimal operating temperature (which is some point higher than the thermostat rating, but below the boiling point of pressurized coolant). If you're still not driving through the air to cause the radiator to cool, the coolant will eventually creep up to the maximum operating temperature dictated by the fan switch. This will turn on the electric auxiliary fan which will move air over the radiator and cool the fluid.

The only difference in behavior from stock will be that you will reach minimum operating temperature sooner, and if sitting still, you will reach maximum operating temperature sooner, at which point the electric fan will turn on.

This is my preferred and recommended solution.



2) Remove the mechanical fan and replace the thermostat with a slightly lower temperature unit, and replace the electric fan switch with a slightly lower temperature unit.

The engine coolant loop system will reach a lower minimum operating temperature (dictated by the lower temp thermostat). The system will hold this lower minimum operating temperature by mixing in the rest of the coolant via the thermostat until the entire volume of coolant is up to this lower operating temperature. This is a bad thing. Fuel economy and emissions suffer. At this point, if you're not moving through the air the coolant temps will continue to climb to optimal operating temperature (which is some point higher than the thermostat rating, but below the boiling point of pressurized coolant). If you're still not driving through the air to cause the radiator to cool, the coolant will eventually creep up to the lowered maximum operating temperature dictated by the lower temp fan switch. This will turn on the electric auxiliary fan (too early, which is also bad for fuel economy and emissions) which will move air over the radiator and cool the fluid.

The difference in behavior from stock will be cooler steady-state operation (which is not ideal) and a cooler upper limit (which is not ideal).

This solution never made any sense to me. The only time it ever makes any sense is if you live in Death Valley and occasionally see a slight overheating issue. Lowering the steady-state and max temp range only buys to 30-90 seconds under these conditions at which point you will begin to overheat still. If the electric fan can't handle your cooling needs, no amount of lower thermostat or fan switch will help. And it only hurts (see fuel economy and emissions reasons).


3) Remove the mechanical fan and replace it with an electric fan.

It should be obvious by now, but the only reason to do this is if you live in Death Valley and sit at stop lights for long periods of time with the A/C on. 99% of owners will not require a second fan. To do this properly, by the way, this second fan should be triggered to turn on at the same temperature as the stock auxiliary fan (or thereabouts). Otherwise you will be treating one of the fans as a fail-safe, which doesn't make sense either, and/or you will be unnecessarily narrowing your operating temp window.

Before doing this is I'd want to be sure my electric aux fan is working though as I can't say I've ever noticed it working before (or is too far forwards to be heard from inside the car?)

 

[David Cullen]

i have the viscous fan setup also, ive never heard my fan working either, or getting faster as the case may be, i havent had any problems such as you have mentioned either. I was thinking of changing to electric fan at one stage and then figured i would probably just install a slim fan and switch just in case my viscous fan failed.... simple enough task and without half the trouble of changing the whole system, just have it there as a precautionary measure ;-)

 

[oldcarman]

I'd wire a thermo switch in to the aux fan as once the clutch fan dies you can overheat fast enough to blow a head gasket before you can get a switch turned on. JIM

 

[David Cullen]

hmm getting complicated there Jim... i understand what you are saying alright,

 

[Brian H]

I have thought about this too, I see no problem with doing this but understand you need to change over the Aux fan switch for a lower rated one, IIRC the Aux fan switch is located on the drivers side of the rad about 3/4 of the way up.

 

[Ashbandicoot]

The fan switch is as simple as fitting one of these
www.eurocarparts.com/ecp/c/BMW_Z3_1.9_1997/p/car-parts/car-cooling-parts-and-car-heating/cooling/car-switch-and-car-sensor/?224110330&1&f5abc2ad9deb91d3757d5351430cb74a0ad40318&000529

It has an opening closing temp setting of 88/80 vs the stock 90/85. Over on BF there is a lot of talk of fitting an 80c thermostat aswell but I don't think this is necessary - some people suggest it is detrimental but tbh I don't have a clue either way

I don't have an aux fan though so I think I would need this this http://store.bimmerworld.com/bimmerworld-e36-3-series-electric-fan-conversion-kit-p1450.aspx

Ash

 

[oldcarman]

I have thought about this too, I see no problem with doing this but understand you need to change over the Aux fan switch for a lower rated one, IIRC the Aux fan switch is located on the drivers side of the rad about 3/4 of the way up.

Exactly @BrianH best to have something automatic to turn on that fan than simply relying on a direct switch as I was cruising down a beautiful back road and looking at the scenery and not the temp gauge until I smelt/ see the steam coming from under the bonnet. By then it's most likely too late!

 

[Dino D]

I don't have an aux fan though so I think I would need this this http://store.bimmerworld.com/bimmerworld-e36-3-series-electric-fan-conversion-kit-p1450.aspx

Ash

Do you know why yours doesn't have an aux fan? Is it only on cars with aircon?

 

[t-tony]

Yes, it is for AC cooling.

Tony.

 

[Dino D]

Ahh...so if you have aircon you definitely have the aux fan?

 

[amancuso]

I've thought about doing this mod as well as I've read about it for years. To be honest I've only had one mechanical fan failure, and it was in my 328i. It took out the radiator. The way I see it, the plastic the fan is made of will get brittle with age and heat/cool cycles. In every BMW I've owned for the past 15 years I change the plastic fan every 60K miles as cheap insurance. You also need to keep an eye on the water pump, the minute it starts weeping, change it. I've followed this schedule and so far no disasters.

 

[Dino D]

I had an OEM fan that was only 2 yrs old lose two blades.

One failure is not good enough, two is a joke. Never had it on any other car.

Badly designed so that when it fails it takes out other parts and leaves you stranded.
This design must have come from the stone ages!

 

[roadvoyager1]

Preparing to do this job plus replacing thermostat, water pump and belts at the weekend. Last weekend we confirmed the aux fan is in good working order (it is and very quiet). One point to note is the lower temperature switch has a different internal guide to the standard higher temperature one originally fitted. This had us concerned for a while, however, having searched around a bit we found reference to trimming off the guide with a craft knife to allow the plug to slip into the socket.

Will let you know how we get on.

 

[Dino D]

Just to add that in doing this I discovered that many cars had the incorrect wiring for the aux fan from the factory! Yes from the factory!!

The fan was wired to switch on at high speed only hence I never heard it operate apart from when aircon was used...
It's well documented and there is a detailed (very) thread here with pics and diagrams, it's pretty simple once you have the info(!!)
http://www.bimmerforums.com/forum/s...ic-fan-failure/page2&highlight=Aux fan wiring

After swapping the wires I now have an aux fan that kicks in on low speed as needed. This is handy as my viscous seems to have died (again). Possibly because I stored it upside down for two weeks, I'll try to refill it and keep it stored correctly in case I ever need it again!

 

[roadvoyager1]

Thanks for that information @Dino D. We checked the fan and got it to run at both speeds. Will check the wiring is correct also before we get started.

The thread also has a very useful link to the odometer test mode, which I have seen before and was going to find again as part of our check out that all was working correctly. You saved me the time and effort, thank you. All bookmarked now for future reference.

 

[Dino D]

Definitely check the wiring- my fan also worked on both speeds when testing (by shorting the wires). However the signal from the temp sensor was wrong because of incorrect factory wiring hence it never worked correctly in practice.

 

[roadvoyager1]

Fan delete completed over the weekend. I am very lucky that my Daughter has a partner who is an excellent mechanic and enjoys working on the Z3. Any references to "we" really mean "he, and I passed the spanners". Thought it may be of interest to share some pictures and words with anybody else thinking of doing this modification.

The parts:

Wahle thermostat (11531437040 from E-Bay - Motormec) and Gates aux belt (5PK908 from Amazon -SparesHQ).

Meyle water pump with metal impeller (313 011 2001 from Amazon), Valeo Service Thermo switch (820319 from Amazon) and Gates main belt (6PK1540 from Amazon). If the belts do not come up on an Amazon search try typing the reference into Google and it may throw up a link to the Amazon page (this is what happened for me).

First challenge was the head dropping off the radiator bleed screw as soon as it was touched. The head had been broken off, a cross head screw put into the stump and the head put back on with sealer. Fortunately we had bought a new plug
(17.11.1.719.384 from local BMW dealer) before starting. Made me wonder when the coolant was last actually changed (I paid for it to be done by a local German car indy "of good repute" when I bought the car 2 years ago)!!

Main belt looking tired at 86,000 miles.

Aux belt looking very tired.

The removal method basically followed the description in this article http://www.zroadster.net/forum/viewtopic.php?
f=18&t=3631. No special tools used to remove the viscous fan though we shocked it off with a big hammer (would not recommend if you are not changing the water pump).

We also needed to replace the seals on the A/C condenser so that came out as well. Perhaps as well considering the accumulation of muck and flies.

With the front end stripped out access to do the job was easy.

Old thermostat with broken retaining lugs, which explains why the engine never reach full temperature.

New unit with the later style support legs.

Water pumps, old and new. The central hole on each side is threaded (M6). A bolt each in each is used to jack the pump out of the housing.

Nice new belts fitted. Hopefully good for another 80,000 miles.

Old and new temperature switches. Note the difference in the lower horizontal flat section. The old (lighter) switch has a keyway to the right hand side the new one has it to the left. This presumably was to detect if the wrong switch had been installed during manufacture. The radiator was made by Valeo so this feature may not be present on non OEM parts.

The plug where you can see the guide that goes into the keyway next to the "1-" marking. This has to be trimmed off for the plug to fit.

When it was all back together the coolant was refilled, see https://zroadster.org/threads/anti-freeze-which-colour.9093/#post-133977 for more information.

On start up the engine reached operating temperature quickly and the needle was rock steady in the central position. When stationary with increased rpm the electric fan switched in and putting the heater on full blast caused it to turn off, so all seems to be working as expected.

If you are thinking of doing the same job I hope you find the write up of help.

 

[t-tony]

Good to share and that is a quite common subject.

Tony.

 

[5harp3y]

great write up

 

[Paulro]

Great to see. Scaring me though!!