cooling fan - help please

[OZ 180]

Hi,

I'm new to the forum and bought a 2002 ZT180+ (auto) a month ago.

Is there a problem with the cooling fans having a limited lifespan? Are there any other known problems that impact on the fan?

A supplier in Australia is saying the three speed fan motor has been superseeded by a two speed motor which is supposed to be geared better and handles the hotter climates better. Does anyone know anything about the two speed motor?

Has anyone successfully rebuilt a fan motor?
Should i just buy one from our friends on Ebay?

The car overheated last week because the fan wasn't turning or was barely turning. I pulled it out and sat it on the floor, getting it to spin slowly after flicking it with my fingers. After a few encouraging taps on the concrete floor it was running properly but today the temperature warning lights came on after being stuck in slow traffic in 34 c degrees. The fans was barely turning. Any advice on the fands especially whetherthe 2 speeds are better would be apreciated.

[Keith]

Seems like I need to resurrect my old thread,

Anyway you can fit either the original three speed motor or the later two speed both have pros and cons, the motor design of the three speed tends to wear out the primary ground brush (connected to the black wire) I reckon after 50-60,000 miles there will not be much brush left

As a result you lose low and medium speeds but not high speed as that uses a second ground via the purple wire.

The two speed fans have increased brush life as the Purple and Black brushes are now in parallel but the instead now the external resistors burn out so you are still left with just one speed.

As a once only fix you can bend the tags and dismantle the motor if you are careful and then you can check if you have brush failure or not. A supplier for Brushes is still being sought but I can send you a usable one if needed.

If you want to buy new then SMC-Trading are probably the cheapest source

http://cgi.ebay.co.uk/Rover-75-MG-ZT-Cooling-Fan-Motor-NEW-A3_W0QQitemZ4645580522QQihZ002QQcategoryZ10414QQcm dZViewItem

[OZ 180]

But the motor didn't kick into the top speed, even when over heating. I seem to have lost all speeds now.

[Keith]

Ah well yours could be totally knackered if it turned initially and you could hear the relays in the control box clicking as well then the control side is probably ok

I took one apart a few weeks ago and three of the four brushes were stuck in their holders if you can get to the back of the motor give it a blasting with WD40 spraying from the front is not good enough as I don't think it will get back to the brushes in enough quantity if you are lucky as these symptoms are what you are describing the brushes will free up and you will get a few thousand more miles out of it

how many miles has you car done and do you live in a dusty climate?

[OZ 180]

Can't say I noticed the relays making a noise, but there is 14 volts running out of the first two relays. I assume the 3rd is a negative so that would be why i didn't see a current when I earthed the voltmeter.

The car has done only 50,000k (I think that is 30,000 miles) and most of that was in Sydney so it had mostly done city driving.

Yes it is very dry and dusty here at the moment as we have a drought but the car has only been in Canberra for a month.

I notices some coolant sitting in the V below what I think is the water pump. It looks like it leaked from a connection near the water pump, probably from when the engine was really hot yesterday and some coolant leaked out past the plastic clamps that hold the pipe (that runs along the V) to the water pump or some other clamp.

I ran the engine to warm it up but nothing leaked. The fan didn't start up either.

It looks like I need to avoid slow traffic for the next two days, pull the fan motor out to give it a WD40 spray on the weekend and order a new motor from the UK.

[Keith]

Yep the third switches the purple wire which is another ground so you won't measure anything.

Note, if you are looking at the Rave CD the wiring for the third relay can be drawn incorrectly

[mantianak]

I had the joy of a dead fan motor few months back. I read up on the other forum about the relay pack, wires, what does what and why. To be honest it was all very confusing to me so I just bought a new motor (smc) with the relay pack attached and fitted it. Turned out it was the motor and not the relay pack.

The only advice I can really give is to look out for it overheating if you drive it knowing the fan isn't working. The gauge on mine must be stuck or broken beacause it registers it being cold and normal temperature but it doesn't show when overheating (doesn't go over mid-point).
I had the misfortune of discovering steam bellowing out from the engine and yet the gauge says it's normal temperature.

[apywell]

Anyway you can fit either the original three speed motor or the later two speed both have pros and cons, the motor design of the three speed tends to wear out the primary ground brush (connected to the black wire) I reckon after 50-60,000 miles there will not be much brush left


Thanks for this explanation Keith. As you know, mine comes on and off when air con on. So it's the bushes that causes the problem. Seems a shame and waste of money to replace the whole component when the bushes have worn. Are the bushes easy to replace? :pic:

[apywell]

I've just had a look through Keith's thread on the cooling fan and it actually looks quite straight forward to get to the fan and take apart. Just having somewhere to perform the operation.........

[Simon]

Thanks for this explanation Keith. As you know, mine comes on and off when air con on. So it's the bushes that causes the problem. Seems a shame and waste of money to replace the whole component when the bushes have worn. Are the bushes easy to replace? :pic:

The brushes are easy to replace.

The problem is getting brushes.

As of yet no one has found a source for new brushes so you will have to get an old radiator motor from the breakers and get the brushes off that, I'm affraid.

[apywell]

As of yet no one has found a source for new brushes so you will have to get an old radiator motor from the breakers and get the brushes off that, I'm affraid.

Would it be better to get one off ebay from someone who is breaking a 75, as getting it yourself would mean stripping the front end?

Then, I guess the risk would be the condition of the brushes from the donor car. :sad:

[Simon]

Which ever suits you best, I suppose. Finding just the rad motor would obviously save you a lot of work.

From what I recall, it is usually only one of the brushes that fails. You may very well be able to savage one usable fan from two. (you may even get a fan in good working order).

The other option would be to do the retro-fit an 'improvised' fan motor. There was a method of doing this (possibly over on .org) I'll see if I can find it...

[Simon]

Not found it yet.... gotta leave to go to work :(

Can someone else help find this thread for apywell?

[JohnFol]

Apywell, just as a side note, a "fix" is possible if you can source the brushes, but bear in mind it's several hours to get to the motor. It's probably worth the £££'s that SMC charge just to make sure you can fix in 1 go and that it will last.

FYI SMC have been recommended by several members here, me included.

[OZ 180]

I installed my new fan it it works perfectly.:lol:

The only problem is that I still have a coolant leak that probably started when the engine was very hot. :mad: Fortunately I can trace the leak to near the thermostat. I couldn't tell if it was leaking from the thermostat housing itself or where a hose clamps on (insufficiently).:confused:

I have pulled the hoses off but can't quite see enough to make a call on what the problem is. I dont really want to remove the inlet manifold to get the thermostat out if it doesn't really need to come out.

Are there any known problems with the thermostat housing cracking or separating? Is it two pieces stuck together? If not I will put the hoses back on and ensure the clamps are done up correctly. Does everyone have the sprung clamps or is anyone using the crew type clamps on the hoses?