Temp needle never moves

Post by **dogmatic69** » Thu Oct 16, 2014 11:34 pm

Ok, shorted the correct wire and the gauge swings \o/

Any chance of getting a sender from halfords? or is this a Rick job.

Post by **Neosophist** » Fri Oct 17, 2014 4:37 am

dogmatic69 wrote:Ok, shorted the correct wire and the gauge swings \o/

Any chance of getting a sender from halfords? or is this a Rick job.

Rick / Honda dealer, there not cheap either.

Post by **speedy231278** » Fri Oct 17, 2014 10:26 am

Interestingly enough, it seems that the sender is used on some cars as well as bikes. 37750-PC1-004.

DSS only list an aftermarket one at £30. Looks the same as many on eBay for less than that and there's one seller with one in a Honda packet for £25 plus the thick end of a fiver postage. Given the very generic part number, I would suggest that it would be used on a significant number of Hondas, and there are plenty of stat housings on eBay for a lot less than £30. Personally, I'd pick one of those, cross reference the model to check if it uses the same part, and if it does, you can use that and maybe even flog the housing on....

Post by **dogmatic69** » Sun Oct 19, 2014 2:24 pm

So I picked one up from Rick for £19 delivered. But this is not over...

It still does not move, just had the bike idle for 10 / 15 minutes, thermostat housing is too hot to touch but the temp gauge has not moved. Maybe its not getting hot enough like that, but the weather is to crap for a ride right now.

Is it normal to not move when just idling for so long?

Post by **speedy231278** » Mon Oct 20, 2014 11:46 am

Several years ago I noticed that my bike took forever to start warming up and the temp gauge to move, especially in winter. I figured the thermostat might be jammed partially open, and indeed that was the case. In fact, it had died so completely it was wedged as open as was possible without actually removing it. With a new stat, it registers temperature a lot quicker because until the stat starts opening, most of the coolant doesn't get circulated through the radiators which helps the engine warm up quicker to prevent excess wear from cold use. I'd be tempted first to let the bike idle for a bit longer. Once it's been going for five mins or so don't be afraid to give some gentle blips of the throttle to help it warm up more once the oil is warmed up. If the needle starts moving after a very long time, I would then be taking a look at the thermostat. Guess what? They aren't cheap either, and they are a pain in the arse to change as the housing cap is tucked under the frame rail which restricts access to the bolts holding it on. If you have the right tools, you can (allegedly) change it without having to take the housing off the bike, but I found it easier just to take the whole lot off. If you are tight, you might get away with reusing the o-ring on the cap, but don't even take a chance on the one that goes between the housing and the engine. When I did mine, the thing was rotten and if there'd been any less of it left I reckon the bike would have leaked! You need to drop the coolant out before starting, of course.

Post by **dogmatic69** » Mon Oct 20, 2014 1:08 pm

sounds reasonable. Will order a new thermostat. I was looking at the housing, and damn it looks like a pain in the arse.

Post by **Neosophist** » Mon Oct 20, 2014 1:36 pm

its easy to remove the thrmostat but dont just replace parts for the sake of replacing them. 10 mins is good time for it to warm up... if you do get the thermostat out its easy to check by throwing in a pan of boiling water and checking it opens the minimum distance.

Also remember to rplace the origns on the stat housing.

firstly check that the wire is making good contact to the switch, try shorting it out once more before reonnecting to make sure the gauge goes to fully hot.

start with the easiest stuff first, like perhaps a bad connection...

then its not commong but could be a bad stat even thuogh tis new.

if you put a mulitmeter set to resistance to the connector wire and to the ground you will see th resistance change as it warms up to indicate its working.

Post by **dogmatic69** » Mon Oct 27, 2014 11:15 pm

Had a good burn down the motorway, +- 30 minutes. Gauge did not budge. It works 100% when shorted so I am going to rule out bad connections and replace the thermostat + seals.

Damn thing is money hungry lately, but cant complain as had 0 issues since buying it a few years back

magg · Post by **magg** » Tue Oct 28, 2014 3:12 am

Why not follow neosophist's suggestion and check for a resistance change with temperature from the temp sensor first, then move onto the the thermostat.

Post by **dogmatic69** » Thu Oct 30, 2014 8:09 pm

Ok, I got the multi meter out tonight, cold it was reading .6k ohm, turned the bike on and it slowly moved to 150ohm.

(this was with the wire disconnected)

Turned off and it sat there at 150ohm semi warm... Right, the sender works :)

So... I thought let me clean the connection, no change so I started poking about with the multi meter... That cable is direct to ground

I am guessing this should not be the case as that means both sides of the sender are connecting to ground (eg: the one half to the thermostat housing, the other half the pin, to the wire which is also ground).

I guess there is some issue with wiring, such fun!

Temp needle never moves

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