Thermostat, temperature sensor, coolant, fan.

[wayne]

Credit to Colin Packer on Facebook for this.

"I had a problem last week because the fan was not coming on, causing the bike to overheat. It is an easy problem to fix.

First, test your fan motor by unplugging the two wires from the thermo switch. It's the brass thing just under the fuel tank on the right side. With the ignition on, jump across the two wires with a paper clip or whatever and the fan should come on. If it doesn't, your fan motor may be bad or you have no power going to the switch. If the fan runs, you probably have a bad thermo switch.

They are discontinued but you can use one made for the Honda CRX automobile. Amazon and others have them for around $20 under the Beck Arnley part number 201-0817. Remove the fuel tank and unscrew the old switch. I put my thumb over the hole to keep excessive coolant from escaping. Screw in the new switch and plug it in.

I like this switch better than stock because it comes on earlier. Both my running REs have had the switch fail and your stock one is just as old!"

EDIT: additional information from Colin Packer, the new switch on two of his M models bring the fan on just before half way.

Old:



New:

[charles]

Nice! Thank you!
Should we Sticky this somewhere?

[wayne]

I don't think this one needs it. It's in trouble shooting and enough tags to show up in a search.

[tom93gts]

I have that same thermo-switch in my RE5 pretty much since I bought it 15-ish years ago. The old switch was missing a connector pin and just falling apart so a friend who had access to auto parts books from the local parts store searched through every page of thermo-switches until he found one that looked similar to what I pulled out of the RE5 and it was the CRX switch. I had no idea it came on earlier than the original Suzuki part because my original switch never worked, it's good to know!

[don07tncav]

Great information,thank you for posting it.

[re5rotary]

I think if the fan comes on just below the half way mark on the temp gauge it would be much too early on an Re5. Around town om my bike the fan would be on all the time

[nickre5]

I did some search in regard of the Beck Arnley sensor and it doesn't seem to last long on a motorcycle when you read feedbacks on Amazon from people who purchased it. Because of this I'll stick with OEM parts from Honda made for motorcycle. They cost more of course but you'll think being made for a serious manufacturer they should last also. As a matter of fact the RE5 sensor is the same one used on GoldWing ref: 37760-MB9-000

[hudson]

Thank you for posting the Honda part number. Can anyone confirm if the CRX switch controls a relay or is it directly controlling the fan motor like the RE5 ? Direct to the fan motor would require a higher current rating. Does the Goldwing use a relay or is it direct also ?

Brian

[timpa136]

Apr 9, 2020 7:51:09 GMT -5 hudson said:

Thank you for posting the Honda part number. Can anyone confirm if the CRX switch controls a relay or is it directly controlling the fan motor like the RE5 ? Direct to the fan motor would require a higher current rating. Does the Goldwing use a relay or is it direct also ?

Brian

    Looking at an illustration for the goldwing, it shows a sealing washer used instead of the pipe threaded sensor?

Also an edit from Waynes first post, that, this sounds a little too early.     

EDIT: additional information from Colin Packer, the new switch on two of his M models bring the fan on just before half way.

Old:

Others have experiences?   Thanks!     Tim

[wayne]

I'm interested in your take on the temperature envelope Tim and Hudson. The apparently late onset of the stock sensor worries lots of people (ie doesn't come on 'till nearly at the "H").

But the temp range would have been carefully selected by the Suzuki engineers. I've heard of people fitting manual switches to turn the fan on when they think it needs it rather than relying on the design parameters.

Is there much harm to be done by having a fan that comes on too early?

[ap951]

I think it has something to do with the engines ability to burn fuel efficiently.
Where I live it's a state requirement that all cars pass an emissions test each year.
One of the requirements of the test is that the engine be fully warmed up before it is tested on the dyno.
The vehicle will fail the test if it's not fully up to operational temperature.
I believe the hotter an engine runs (without overheating or damaging any parts) the more efficient it is to burn fuel

[timpa136]

ap951 and Wayne absolutely.

But the temp range would have been carefully selected by the Suzuki engineers. I've heard of people fitting manual switches to turn the fan on when they think it needs it rather than relying on the design parameters.

During pre delivery we were to test the fan, let it cycle and/or go for the test ride. The fan will bring down the temp before cycling off the ignition maintaining a balanced temperature in the proper. I agree it was a well tested setting . I added a manual switch I used before the Intake manifold insulator that I installed as soon as I was aware of one available addressing the vapor lock concern.

ap, you got it. I believe the hotter an engine runs (without overheating or damaging any parts) the more efficient it is to burn fuel

Engines run much more efficient and cleaner at the warmer temperatures let alone the ability to warm up and evaporate the condensation in the crankcase . 

I read some time back of a Diesel with no cooling system of materials I forgot.
It got increasingly better efficiency with the heat and the material used didn't melt down.

Tim

[charles]

Apr 12, 2020 11:58:49 GMT -5 timpa136 said:

Engines run much more efficient and cleaner at the warmer temperatures let alone the ability to warm up and evaporate the condensation in the crankcase .

This is where the Rotary has had a HUGE amount of research done.

When Curtiss-Wright first began research on the Rotary, "A nodular cast-iron rotor was designed and used experimentally.  It performed satisfactorily, under less stringent conditions, with no internal rotor cooling at all".  (Norbye, Wankel Engine, ISBN 0-8019-5591-2, p. 202)

SAE Paper 770044 shows where Curtiss-Wright used Rotor Inserts with an air-gap between the Insert and the Rotor Proper.  The C-W had, of course, a Pilot Injector and a Main Injector close together that worked in combination with each other beginning near Top Dead Center.

This "Hot Rotor" gave emissions that were approximately the same as a piston engine and allowed a measure of Standard Practices in dealing with the "Emission Problem".

The Audi 871 engine, the successor to the KKM-502, used a "Thin Film" Rotor Cooling Design that allowed oil circulation around the periphery of the Rotor, "cooling the edges" but not sloshing the oil around, as in the old "Rotor Cell" method.  This design allowed the Rotor Faces to heat up.  Internal Friction was reduced as well.  The oil cooling Jets were controlled to allow "Just Right" cooling.  The Rotor Faces got hotter and the Emissions came down.

You can find all this stuff on the 'Net but you have to know where to look (See: NASA Summaries. Edit Note: ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790007790.pdf Scroll down to find the description of the 871 engine, then scroll down to Section 2.5.).

This is all Great Stuff.

Our favorite engine is just waiting, like the ol' Fire Engine horse, for the Call.  It's ready to go.

CW

[wayne]

Thanks all. I'm aware of the whole thermal efficiency thing but for those who might fit the Honda replacement switch, are they doing harm?

For example, sliding components would have design tolerances presumably predicated to be at their best once they've expanded within a certain heat range. If the engine is kept outside that range is wear accelerated to a level you should be worried about? That's the angle I'm coming from for the information of people considering using non standard switches or controlling the fan manually.

EDIT: For a short period, I drove cabs 40 years ago. Half million klm and greater cab engines were not uncommon despite the fact they were exclusively city driven. The engines rarely cooled down completely. The night driver would hand over to the day driver. Says a lot about wear and tear as a cold engine runs up to operating temp.

[charles]

Slight embarrassment on my part, Wayne.
I saw something and ran with it.

Apologies.