That same old overheating problem!!!

[TomL]

I've just returned from a 2,000mile trip to Scotland and unfortunately towards the end of the trip my bike started overheating. It first came to my attention towards the end of a good blat.

On the start of the long return yesterday, the bike got that hot on one occassion that the red overheating symbol flashed up on the display. I continued more slowly and eventually it just about came down again. The fan was running full time to no avail. I spent more time watching the temperature gauge than anything else.

I suspected that the problem was blocked cooling fins stopping the air from passing through the radiator. The other thought was that I might have a sticking thermostat or even a faulty water pump impellor or blown head gasket. All known problems on this engine.

Back home today I set about pinpointing the problem with an infra red thermometer and the belly pan, side panels and radiator cowl removed. With the engine at idle the temperature slowly rose and the fan cut in at four bars. The temperature increased to five bars and sat there with the fan going full time. The thermometer soon proved that the thermostat was opening and the radiator was getting hot all over.

With the engine revs increased to3,000rpm the temperature continued to climb until all bars were showing on the temperature gauge and I switched it off before the red overheating triangle came on.

The main problem with this cooling system is that the fan has to suck cooling air through the lower part of the radiator. The middle section of the radiator is totally blocked by the 4" wide mud flap. The fan is situated at the bottom of the radiator and can only suck air either side of the mud flap. The area at the bottom of the radiator either side of the mudflap gets all the crap off the front wheel. Despite hosing the radiator through from the back with the fan remove, the important area at the bottom of the radiator had become blocked again.

I didn't really want to drain down the system and thought about how to soak the rad in position. I managed to squeeze a plastic bucket into an oval shape and pushed it into position at the bottom of the radiator with a block of wood underneath to lift the edge of the bucket as high as the bottom hose. The radiator attachment lower bar has to be removed. The bucket is then filled with water to the brim and the rad is left to soak. That and hosing the rad from the rear got the rad as clean as possible.

Afterwards with the cowl and fan refitted, all was back to normal. As suspected the rad cooling fins were blocked with dirt thrown back by the front wheel. Although I'd cleaned the rad 6,000miles ago it had already blocked sufficiently to cause overheating. Perhaps soaking in position with the rad in the bucket will clean the rad better than just hosing through from the rear?

I had the same problem previously on my K1200S and it had ended up with having to get a new radiator which is not cheap. Hopefully this preventative maintenance will save me the cost of a new rad on this bike as well.

[stevel]

I have been thinking about this one for a long time, knowing that it's in the pipework, so to speak.

I don't think we'll ever stop the rad clogging up, unless you can convince someone to build you one with a different fin spacing (I've tried & failed on that one - they've still got my spare rad, and now won't speak to me). Even if you did manage to get one built with wider fin spacing (which would at least allow cleaning), it wouldn't have the cooling capacity of the current one.

So, I'm looking at managing the problem, rather than solving it. Came up with a few ideas, haven't settled on one yet. Might do them all...:

How about an extra oil cooler? Cooler oil, less work for the rad in the 1st place. Problem is (on an 'S' at least), there's nowhere to put one except behind the current one (and therefore in the hot airflow). Would probably need a thermostat though - wouldn't want this in the circuit on a fast run.

Maybe a couple of slim 4 row rads down the side fairings? Plumbing them in will be a pain though. Doesn't help with cooling when you're slow either (which is the real problem), unless you fit it with fans.

Bigger fan? More powerful fan (with a manual override, so you can pre-empt the problem if you know you're about to crawl though a large city)?

Or just start a mileage based fund for regular rad replacement - about 2p a mile should do it.

Any more ideas?
 

[raesewell]

Once the overheating starts, it's a one way street. You can put off the inevitable for a while by cleaning as Tom has done but in the end it'll be a new radiator. I had this exact problem on my K1200GT. I cleaned the radiator a few time which helped for a while but in the end I had to bite the £566 bullet. That was some years ago and would obviously be more expensive now. Start saving Tom 

[richtea]

One solution as being tested by one of the members (apologies for not remembering who - but maybe Sutty?):

- remove the plastic mud strip, because it doesn't allow any airflow through it

This releases about 10-15% extra surface area, but with the increased risk of stone damage.
Keeping the existing plastic grid (5mm gaps) will stop the really big stones, and it's probably worth adding an extender just to give some sort of balance between airflow and solid gunge hitting the now-clear centre of the radiator.

[raesewell]

We're still waiting on the results of that one Rich, while taking the louvre grill away will allow more airflow it will also allow more road dirt to hit the radiator, could be six and two threes. It will be interesting to know.

[Swindon Andy]

Maybe moving the centre mud shield forward would allow more air flow?

If overnight soaking helps loosen the crud, I might rig up a timed  water mist for next rad clean.

[Phmode]

Two things:

Firstly, back to the additional mesh screen. When I cleaned my rad prior to the Wrinklies, I removed the old Wunderlich framed mesh screen and was going to go the B&Q/Homebase/Screwfix mesh route. In the end I removed the mesh from the clunky frame and clipped it back in place in front of the OEM plastic grille. It reduces the stone gap to about half of the original and does a much better job of collecting dead flies etc.

Secondly, I didn't like the idea of losing the 'flying rock' protection of the bit in the centre of the rad so I was 'going to' drill 4mm(?) holes all over the solid rear of the central louvred 'mud flap' to get masses of air in to the centre of the rad. In the end I never got round to it but this part is easily removed with everything else in place so it might get done during this lifetime.

I'm happy with the stone protection of the two grilles and the 'rock' protection afforded by the central louvred mud flap. Drilling holes all over the back face shouldn't interfere with its rigidity as far as staying in place is concerned and it shouldn't affect its ability to deflect rocks etc. but hopefully the holes will help with airflow.

Of course, bits of flying insect gunge, micro-pieces of confetti and other assorted road 'grime' will also be allowed through and I have a feeling that this mod may require a more conscientious cleaning regime for the centre strip of the radiator in the future

As an aside, I changed the stock, plastic rock guard in front of the wee Honda radiator for one hewn out of stainless steel by an Ozzie outfit and it was while studying this new part that a third 'mod' for the K came to mind. The mesh and the holes are easy mods and are the low-hanging fruit.

My third option was to ditch the central louvred mud flap thingy and construct a 'similar' item out of aluminium but with the rear made of mesh AND with the louvres angled down at the rear (the stock item has the louvres angled UP at the rear which allows a straight-through path for stones flicked up from the bottom of the tyre). This will deflect rocks thrown UP by the tyre but allow air to flow into and through the radiator.

Slow day at Phmode Towers so where is my collection of 4mm bits...

[richtea]

Two musings on your good thoughts, Brian:

1. Lose the top half of the mud strip as a halfway house, with the assumption that an fender extender protects that area from direct hits

2. Consider increasing the 'scooped air' area, That would need ugly extensions to the fairing (lowers only?), but another 2-3" all round, say, would increase the captured air. Tricky to do well, methinks.

Maybe the Ducati race team can help us? They have a neat line in cooling spoilers:

[Sutty]

Hello guys, you were right Rich it was me that removed the plank crud catcher and it worked a treat, I bought 2 carbon fender extenders due to a mix up on fleabay but not got round to fixing them. I've ran it for 12 mths now and all is fine, no stone damage is evident but I'm still pondering changing the fan mount/shroud as I believe it restricts the air flow in the bottom corners, and the road dust and crud does not get blown through and so builds up. Plus with the shroud there you can't back flush the rad.
We went to LeMans last year and it was really warm it took us nearly 2 hrs to exit the bike park and the fan kept it all in check. four bars to five then fan on back to four bars and so on, as soon as we got on the ring road straight down to three.
I might add I don't really ride it in the wet, only when caught out.

Best regards  Mick

[Sutty]

[Sutty]

Sorry it's so big. The rad with the plastic guard removed.

Mick

[raesewell]

C'mon Rich do your thing and resize it 

[richtea]

C'mon Rich do your thing and resize it 

Thing done!

All you have to do (having previewed the raw message) is add this inside the [img] bit:
[img width=1000]blahbalh

Users can then tap on the image to see the full size beast (or right click -> view image).

Applause can be found to the left of here.

[Phmode]

Oh, go on then! Admins don't normally get applause but I'll make an exception this time 

As to losing the top half of the cow catcher, the top half is wide open anyway and is only there to stop the catcher flying off with the wind.

I don't really fancy a wind-deflector front end a la The Flying Scotsman on its inaugural run so that's out.

I think the bottom corners are a red herring and only make a difference because of the cow-catcher wotnot blocking off the central part of the core; get more air tjrough that bit and the bottom corners become an (almost) insignificant part of the whole.

[Phmode]

So, only seven hours to do a ten minute job...

First the bloody cheap-as-chips drill stand exploded and that took a couple of hours to fix...

Then I couldn't get the bloody cow-catcher off, having only fitted it two weeks ago...

Eventually, having stared at the area to be through-flow ventilated and compared it with my 4mm drill, I punched a whole pile of 7mm holes through the crud-catcher and would put up a piccie if I did such things and as Richard knows only too well, my iPhone just hates sending piccies to (especially) him so even he can't see it (and yes, I'm connected to bothe Wi-Fi and Mobile Data is turned on...

Anyroadup, it's not neat and it's not clever but no-one will ever see it and it wasn't an engineering apprenticeship test piece anyway, it was an exercise in aerodywotsits.

I shall report back if my K temperature guage never gets off the bottom rung...