Hi all.
I had an interesting overheating problem with my K100RS and was wondering if anyone has had a similar experience.
I was coming back from Tamworth to the Sunshine Coast Queensland a few weeks back and although it was pissing down with rain the K was purring like the proverbial kitten and I was clearing cagers with ease. Then I came to Cunninghams Gap, a pass over the Great Dividing Range between the Darling Downs and the Fassifern Valley in Queensland Australia for those not of these parts and being the end of a long weekend and school holidays the cars were as thick as flies on a dogs back, only much slower. Nothing for it but to tuck in and crawl along behind. After about five minutes I glanced down and my temperature gauge was well into the red. I pulled over as soon as possible and checked the coolant, which was fine then started up and kept going. The K had cooled down a little but soon crept back into the red. Thought that once I got some speed up it may help but there was no difference. I slowly made my way to the nearest service station and pulled in for a closer look. I thought that I may have had something blocking the radiator core but it was clear the bike didn't seem overly hot. Cut a long story short I had no choice but to keep going and hope I made it home.
Next weekend I pulled the radiator out. Emptied around four litres of coolant out first which was about right. Core was in very good nick, thermostat worked well, flushed the core and it had good flow. The electric fan was stuck, very hard to turn so I pulled it apart and freed it up. Much cursing later it was all back together and ready for a test ride. Everything back to normal, only time it heated up was when I stopped. I let it heat up to the point where the electric fan cut in and it cooled down nicely. I have given it a good work out since then and never looked like overheating.
 
Anyway just thought I'd see if there are any theories out there.
 
Cheers
Bryan.

That sounds about par for the course Bryan. I have a switch so as to turn the fan on early and have learned to keep an eye on the temp gauge and in slow traffic I turn the fan on as soon as I have to slow to under 20kph.
One thing I found was that if you blow a fork seal the oil can come back into the radiator fins and collect dirt and bugs.
Many of the other Aussie guys have done the same.
If you put the switch across the violet/yellow (terminal A2) and green/brown (terminal 15)wires that will turn the fan on and over-ride the contacts in the temp sensing relay.

Thanks mate. Thing is the core was clean when I checked it and it was raining and quite cool at the time it overheated. The temperature didn't drop even when I got up speed in the open and it had never happened before or since. The fan switch is a good idea as it heats up quickly with no air flow and our lovely Queensland summer heat.

My K100LT has an override switch.

Wonderful accessory on a really frosty morning.......

You need to be careful to bleed all the air out by laying it over on the side stand and squeezing the rubber tubes as it is filling.
An air lock can cause the fail to cool after it has overheated.
I have a 3 row core from an 84 k100 but they are hard to find in good condition and usually expensive but well worth it once you do get one.

just to add something

if the sealing washers around the filler cap are not sealing properly ,, the fluid will release too early ...and maybe not work as the system should
as suggested by sidecar paul and a few others

since finding a good fitting seal set around the filler cap I have had far less overheat situations ....the fan override is a very recommended option to install around here ..


you can actually see the temperature  decrease really markedly  when in use .


good luck

Had a similar thing happen to me last summer.  Was buzzing along at 75mph on a hot day and hit a traffic jam caused by a badge-heavy dumbshit cop who parked in a traffic lane to write someone up.  Temperature shot up to the red before I thought to turn on the fan.  Fan did not bring temperature down, neither did it come down when traffic started moving again. 

Bike and engine didn't seem that hot and since I didn't have that far to go I kept going, and when I got to my destination and shut the engine off, the needle was still in the red.  Two taps on the gauge and the needle came down and has worked properly since.

Look what I found......brand new 3 row radiators......

http://www.ebay.co.uk/itm/3-ROW-FOR-BMW-K100-RT-RS-1985-1990-85-86-87-88-89-90-ALUMINUM-RACING-RADIATOR-/272410134994?hash=item3f6ce8c9d2:g:BrQAAOSwCGVYBYPF

The question was answered in the last paragraph of the original post. If the fan isn't working, the engine will get very hot if there is little forward motion. (Always assuming the rest of the cooling system is properly maintained.)

I've added a manual switch to my fan as well, but it is primarily used to check that the fan is working, not seized with melted brush holders as was its state when I bought the bike. 

I'm fortunate that I don't have to spend much time in slow traffic, but when I do, the fan kicks in as necessary and my biggest problem is the hot air being blown on me, usually when its a hot day already. I'm not sure what the actual temperature is, with no gauge, but no problems since the fan was fixed.

Bill

92KK 84WW Olaf wrote:Look what I found......brand new 3 row radiators......

http://www.ebay.co.uk/itm/3-ROW-FOR-BMW-K100-RT-RS-1985-1990-85-86-87-88-89-90-ALUMINUM-RACING-RADIATOR-/272410134994?hash=item3f6ce8c9d2:g:BrQAAOSwCGVYBYPF

that looks great ,oluf,i wonder if it lasts as long as the original k-radiator,corrossion and such 

k-rider

k-rider wrote:

92KK 84WW Olaf wrote:Look what I found......brand new 3 row radiators......

http://www.ebay.co.uk/itm/3-ROW-FOR-BMW-K100-RT-RS-1985-1990-85-86-87-88-89-90-ALUMINUM-RACING-RADIATOR-/272410134994?hash=item3f6ce8c9d2:g:BrQAAOSwCGVYBYPF

that looks great ,oluf,i wonder if it lasts as long as the original k-radiator,corrossion and such 

k-rider

i have one in my 85 and it works great (paid almost as much for shipping as the damn thing cost)  i also put the fan on a switch because of the heat here in Phoenix AZ. USA i dont know about how long they last because i only have a lil over 3000 miles on it sense i got it put togeather  , im now dealing with oil pressure trouble

I have to sort my fan too. But I have a spare radiator with a fan on it...checked the fan at weekend and its seized. Since radiator has to come off to change fan I am going to sort a fan and thermo sensor on the spare radiator and swap them over.

Those new ones don't have any external corrosion protection but that's probably easily applied.

Corrosion protection on aluminium alloy could affect the heat transfer depending on what you use. Pure aluminium does not corrode and most alloys corrode quite slowly. If you want to keep the thermal efficiency then a chromate treatment is probably the best that you can do.

When we studied this stuff even the colour affected it. Chromate is a good option but in all honesty I was figuring an ultra thin black coating. Trouble is none off these things will be pure aluminium.

There was a thread elsewhere on the forum about the effect of painting the engine on the cooling rate.

92KK 84WW Olaf wrote:When we studied this stuff even the colour affected it. Chromate is a good option but in all honesty I was figuring an ultra thin black coating. Trouble is none off these things will be pure aluminium.

There was a thread elsewhere on the forum about the effect of painting the engine on the cooling rate.

It was the use of powder coating that prevents heat transfer. I have seen it absolutely cook an air cooled engine. A liquid cooled engine wont suffer to that extent but it would have some effect on the cooling as about 20-25% of the cooling is from direct heat transfer from the external engine surfaces.

BobT's most definately right. For best heat transfer do nothing with it at all - ally forms its own microns-thick oxide coating. In general, it's only the cast stuff used for engine casings that grows a corrosion coat if its not looked after.

I knew BobT was right, as he usually is!

I was looking at some finish that would minimise the interference with the cooling. I was trying to remember the experiment in school that we did with 2 identical set ups, one with a black coating and one without to measure the effect on cooling rate and in certain situations on heating gain. We apply this same principle to radiators and external components of buildings.

How to keep an piston-driven aeroengine cool: paint the engine white and the inside of the cowlings black. Think about it.

It finally came back to me.

The Leslie cube......

Dai wrote:How to keep an piston-driven aeroengine cool: paint the engine white and the inside of the cowlings black. Think about it. Turn it off.

Fixed that for you....

92KK 84WW Olaf wrote:It finally came back to me.

The Leslie cube......

Close. Painting the block white reflects some of the radiated heat. Painting the inside of the cowlings black absorbs some of the radiated heat and transmits it to the outside world more efficiently. IIRC the experiment was done with a bog-standard flying-school type Cessna and the total temperature drop in the engine bay was about 20C. Anybody want to try it with a fully-faired K?

Just remember that too cool is as bad as too hot. If the engine is slow to get up to normal cooling system running temperature, or never gets there can be very detrimental to the life of the engine. Too hot tends to destroy the oil if you are using old style mineral oil that was the norm when the K was invented, too cool does not fully burn off the moisture in the oil causing wear and "Mayonnaise" to form.
My Rotax aircraft engine is not allowed to be used at full revs till the oil temperature is above a certain temperature, for example. Over cooling would never let it get to that temperature.

When moving, black paint will radiate more heat away from the engine than no paint.

When standing still no paint is better.

This has been proven with intercooler testing.

I'm all for the black paint!!!

And (+1) - engine cases/fins is NOT the place for powder coat!

BobT wrote:Just remember that too cool is as bad as too hot. If the engine is slow to get up to normal cooling system running temperature, or never gets there can be very detrimental to the life of the engine. Too hot tends to destroy the oil if you are using old style mineral oil that was the norm when the K was invented, too cool does not fully burn off the moisture in the oil causing wear and "Mayonnaise" to form.
My Rotax aircraft engine is not allowed to be used at full revs till the oil temperature is above a certain temperature, for example. Over cooling would never let it get to that temperature.

It's probably changed by now but backintheday it was recommended to do thirty miles or more to get an air-cooled bike engine up to the temperature where it would burn off the condensates. As for shock-cooling aero-engines... I got my wrist well and truly slapped for pulling off the throttle too quickly when first learning to fly.

And yes, I'm gonna ask - what's the Rotax mounted in?

It is a Rotax 912s mounted in an Aircreation Tanarg Bionix. No more heavy aircraft with multiple engines for me, just a flying motorbike these days.

I never got to fly multis; just one up the front and on one occasion, one stuck at the back (XT-912). My licence has lapsed due to lack of free cash over the last few years but when possible, I still pay for/blag a ride. Next time I head for the States I have my eye on this: http://www.stallion51.com/p51-flight-ops/p51-mustang-ops.shtml. I thought about the L-39 but if I'm going to spend that sort of money, I'd rather go here: http://www.flyaspitfire.com/.

Had enough of flying in military hardware. 
Funny that your PPL has lapsed, that is what happens in the UK, you also need a medical there. Over here there is no airworthiness inspection, no licence check flights and no medical for anything sub 450 kg. You licence lasts for life however much you use it. I even have my own airfield and hangar here, I rent the land for less than it would cost to keep a trike at an airfield in the UK.
There are also no MOT or annual tax on bikes, the reason that we normally have at least 4 of them in the garage.
Why do you think that I left the UK to come and live here?

I knew it. Blame Boris.

We have no MOT on bikes either.

We have Guinness, whiskey.......

Now really what happens next is that you two need to meet and Jude will show you Dai how to ride a Ducati.....

This forum has been wonderful and we have had some fabulous camping times down near BobT. Plans are afoot for a September 2017 trip down that way too.

Olaf, I have met Jude, she is my wife, and the Ducati that she is riding was mine once. You must be losing your marbles. I think I noticed that you had been on Facebook, I must be losing my marbles too!

BobT wrote:Olaf, I have met Jude, she is my wife, and the Ducati that she is riding was mine once. You must be losing your marbles. I think I noticed that you had been on Facebook, I must be losing my marbles too!

I think that was directed at me!!!

Dai wrote:

BobT wrote:Olaf, I have met Jude, she is my wife, and the Ducati that she is riding was mine once. You must be losing your marbles. I think I noticed that you had been on Facebook, I must be losing my marbles too!

I think that was directed at me!!!

It was.

I blame Jude's squirrels for loss of my marbles.

BobT wrote:Had enough of flying in military hardware. 
Funny that your PPL has lapsed, that is what happens in the UK, you also need a medical there. Over here there is no airworthiness inspection, no licence check flights and no medical for anything sub 450 kg. You licence lasts for life however much you use it. I even have my own airfield and hangar here, I rent the land for less than it would cost to keep a trike at an airfield in the UK.
There are also no MOT or annual tax on bikes, the reason that we normally have at least 4 of them in the garage.
Why do you think that I left the UK to come and live here?

 You've made the right move there BobT - - I tried to do the same though to Canada but failed because we just could not sell our house in time(market forces as the Mad Woman would have said). So in the end I binned my EASA Annual Renewal and Medical + ECG due to age and all the costs of making sure that I flew a couple of times each and every month to avoid check flights, sold my aeroplane and went back to bikes. Even flying sub 450kg is not so easy this side of La Manche due to our generally more turbulent weather, and I never tried to qualify on flexwings, as I was a bit unsure that I'd be able to dump all the fixed wing responses knocked into me back in the'60's.


 Anyway back to the thread, I remember back in my aero engineering days, there are some specialist coatings to aid heat control in cowled installations such as aircraft and faired bikes, such as Heat Barrier Coatings applied to the exhaust headers and exhaust pipes within the cowl and heat emitting coatings based on carbon and glass  applied to sumps and oil cooler/radiator ducts which can be supplied with ram air. All this does require good airflow, not good for long time a low forward speed. So on a K probably the best we can do is keep the rad and sump fins clean and clear airflow, the correct modern high quality oil- royal or otherwise- and the water/oil pump in top condition. Personally the fan on my K rarely cuts in which is why they often seize , but the air is damp in UK, in Warhammer's neck of the woods the Arizona hot dry air won't carry as much heat so a bigger rad or oil cooler might help a lot.

Bob

You need to move to Ireland and become an Honorary Eccentric. Then, now being an EU citizen you could resume your French living...........


Like someone knew something about Brexit a while back, look who was in our local fish market......

One of my sons lived in Kamloops BC a while back ( the other son lives in Kanata ON ) so that would have been a nice K ride to have done between the two !

 Yes it was the rules regarding pensions and taxes and our age that meant that if we were to emigrate we had to sell our house at a price that after buying house, car, furniture etc., would allow us to invest enough in Canada to replace the long-term shortfall in state pension income - - - Canada is one of the countries where you do not get UK pension updates. Private pensions suffer no such restriction, but our visa validity was during the course of a huge house trading slump and if you don't get all your money into Canada within 365 days your 'Landing', Canada Tax takes 40%.  That's a way too big a risk when you're retired and a very large chunk of your equity is in a damned house!
   Sure, there are a lot of sub 400kg Class machines in UK, didn't realise it was as many as 4000 now, until 8 years ago I was also a LAA Inspector on Wood, Metal, Grp, Tubular, Aircraft, Gyroplanes and Engines and travelled around East Anglia- -I live in Norfolk- - but most of them don't get much airtime really largely due to weather.

92KK 84WW Olaf wrote:Bob

You need to move to Ireland and become an Honorary Eccentric. Then, now being an EU citizen you could resume your French living...........


Like someone knew something about Brexit a while back, look who was in our local fish market......

 Sure! but ER. is quite okay if Brexit kicks UK off into the middle of the Atlantic to become some sort of offshore satellite for Uncle Sam's  Don's fair land ,she's got a few German rellies in the family line with some big Castles and Estates to put her up!

Kando wrote:One of my sons lived in Kamloops BC a while back ( the other son lives in Kanata ON ) so that would have been a nice K ride to have done between the two !

 Yes it was the rules regarding pensions and taxes and our age that meant that if we were to emigrate we had to sell our house at a price that after buying house, car, furniture etc., would allow us to invest enough in Canada to replace the long-term shortfall in state pension income - - - Canada is one of the countries where you do not get UK pension updates. Private pensions suffer no such restriction, but our visa validity was during the course of a huge house trading slump and if you don't get all your money into Canada within 365 days your 'Landing', Canada Tax takes 40%.  That's a way too big a risk when you're retired and a very large chunk of your equity is in a damned house!
   Sure, there are a lot of sub 400kg Class machines in UK, didn't realise it was as many as 4000 now, until 8 years ago I was also a LAA Inspector on Wood, Metal, Grp, Tubular, Aircraft, Gyroplanes and Engines and travelled around East Anglia- -I live in Norfolk- - but most of them don't get much airtime really largely due to weather.

I have flown into and out of Kamloops BC, nice place. My wife used to live in Kaslo.
As for East Anglia, you will know all of the places that I have landed at there then, my home airfield was RAF Wyton for both microlighting and for Group A, I used RAF Halton for twin engine flying.
Makes me laugh when you mention pensions. My RAF pension is taxable in the UK, I have no choice in that, but I don't get a vote in brexit nor can I use the NHS, why the hell did I serve queen and country for 25 years?

Olaf, I have no intention of moving to Ireland, it is still the EU and brexit would still feck me up, besides it rains far too much there. I am best being here to host you crazy nutters when you come visit. Might see one of you on a red Ducati one day and then my K will stay at home and we'll get the Ducati club out.

Before I got the K100LT I lusted after an 860.........so maybe Ducat-itis might manifest itself.

BobT wrote:

Kando wrote:One of my sons lived in Kamloops BC a while back ( the other son lives in Kanata ON ) so that would have been a nice K ride to have done between the two !

 Yes it was the rules regarding pensions and taxes and our age that meant that if we were to emigrate we had to sell our house at a price that after buying house, car, furniture etc., would allow us to invest enough in Canada to replace the long-term shortfall in state pension income - - - Canada is one of the countries where you do not get UK pension updates. Private pensions suffer no such restriction, but our visa validity was during the course of a huge house trading slump and if you don't get all your money into Canada within 365 days your 'Landing', Canada Tax takes 40%.  That's a way too big a risk when you're retired and a very large chunk of your equity is in a damned house!
   Sure, there are a lot of sub 400kg Class machines in UK, didn't realise it was as many as 4000 now, until 8 years ago I was also a LAA Inspector on Wood, Metal, Grp, Tubular, Aircraft, Gyroplanes and Engines and travelled around East Anglia- -I live in Norfolk- - but most of them don't get much airtime really largely due to weather.

Makes me laugh when you mention pensions. My RAF pension is taxable in the UK, I have no choice in that, but I don't get a vote in brexit nor can I use the NHS, why the hell did I serve queen and country for 25 years?

 Probably for the same reason that I and loads of other young lads, we were a bit green and too trusting of adults! And certainly unaware of the quite low UK public regard for the Armed Services and duplicitous treatment by Government!

 Would I do the same again......ha.....ha...........what a laugh! When asked that question by my Wg.Cdr. on my last day, my rejoinder was ....not for my salary & pension + his + bells on!

 I wish that I'd kept my Norton, gassed it up and got as far around the world as I could have kept it going-- - after all it was a British bike with the usual foibles of bits vibrating off, leaks and Overheating

         Trevor