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Overheating DN01 (semi repost)

D

dndonkey

New member
Joined
Dec 27, 2023
Messages
7
Location
New Zealand
Hi all,

I am hoping someone else may have encountered this or a similar problem before. I made a post about my bike early last year RE overheating. Bike is still not fixed i am slowly working through what I think can be the issue before I cave and take it to Honda.

Initial Problem
Out riding (100kph) when sudden huge burst/plume of white smoke appeared from exhaust. It was like a steam train.. pulled over, let the bike cool then slowly rode home.

Work done
Suspecting the head gasket I went in and changed that in both cylinders, which was bloody difficult.I got everthing back together and the bike running.
After fixed there was then no smoke coming from the exhaust, however on the test ride the bike started to heat up again.....Engine temp light came on...

More work
Since then I have...
Changed the coolant again to try and get rid of air pockets..? replaced Thermostat, Replaced the ECT sensor? (the one up by the radiator cap/thermostat)
Checked the fan motor and the fan relay/fuses.

The waterpump seems to be working as I can see the turbulent water start after a few mins of idling with the radiator cap off

Last time i started it up i realised the radiator fan didnt come on even after about 15mins of idling..I have checked the fan motor and the relay/fuses. All work ok...

Where to go next?
I didnt want to idle the bike for more than 15mins without the radiator fan coming on as I assume it should be coming on by then? Could someone confirm this? How long under idle until your radiator fan comes on?


After some more research I think I am down to 3 options as to what is wrong? Please someone with experience in this let me know what you think? Could it be something else?

1. Air block/lock in the coolant hoses?
2. Faulty radiator cap? (would this actually cause overheating and fan not to come on though?)
3. Electrical problem from the ECU to the fan? (I cant find a clear wiring diagram online unfortunately)

Any and all advice welcomed. Really want to get this bike going so i can ride it!

Cheers
 
Well, you've changed the head gaskets - a pretty major piece of surgery, and that does sound like the initial cause of the smoke or vapour. This should have cured the initial problem, so you won't expect anything similar unless there was a reassembly error. As long as there are no air locks in the cooling system, it should all work fine unless coolant keeps disappearing and there may (still) be a gasket sealing issue. These engines do run quite hot anyway, but if you're concerned that the fans should be kicking in and they're not, then I would suggest checking the fan switch (ECT sensor) located by the coolant filler cap. Section 6-18 in the manual covers this, but if it was faulty I would maybe expect to see a flashing error code (7-1) preventing the engine from being started. Depending on the air temperature, I would expect the fan to kick in on tickover from a cold start after 10 to 25 minutes
Best of luck.
 
Cheers i have actually replaced that ect part as thats what I thought the problem was. I tested continuty from the ect plug to the ecm also and seems fine. I reflushed the coolant today again after a few months of ignoring the bike. Idled it for about 15mins and after a few blips of the throttle the fan came on! Plan on replacing the radiator cap just to be sure before I take for a proper test ride as there is steam coming from the cap but I’m unsure if that’s because I spilt coolant when filling on the thermostat assembly or if it’s not sealing properly, anyhow it’s a relatively cheap part to replace! Cheers!
 
BobF said:
Well, you've changed the head gaskets - a pretty major piece of surgery, and that does sound like the initial cause of the smoke or vapour. This should have cured the initial problem, so you won't expect anything similar unless there was a reassembly error. As long as there are no air locks in the cooling system, it should all work fine unless coolant keeps disappearing and there may (still) be a gasket sealing issue. These engines do run quite hot anyway, but if you're concerned that the fans should be kicking in and they're not, then I would suggest checking the fan switch (ECT sensor) located by the coolant filler cap. Section 6-18 in the manual covers this, but if it was faulty I would maybe expect to see a flashing error code (7-1) preventing the engine from being started. Depending on the air temperature, I would expect the fan to kick in on tickover from a cold start after 10 to 25 minutes
Best of luck.
Click to expand...
Hi Bob

Just taken it for a test ride about 10mins up to 100kph. No smoke no engine light came on…

Got home and checked the oil, the engine casing is soo hot. I just about burned myself on the dipstick handle…

Is this normal? Do they run this hot?

Cheers
 
dndonkey said:
Hi Bob

Just taken it for a test ride about 10mins up to 100kph. No smoke no engine light came on…

Got home and checked the oil, the engine casing is soo hot. I just about burned myself on the dipstick handle…

Is this normal? Do they run this hot?

Cheers
Click to expand...
Yes, they do. The dipstick handle, being under the removable cover, is effectively, insulated within a hot environment until the cover is removed. I guess it's best to leave the engine 10 mins or so with the clutch cover off before checking the oil level? If there are no warning lights or error codes, I would assume everything is OK. Enjoy!
With the weather going autumnal here in the UK, I'm probably going for my last ride(s) of the year this week before laying it up until spring.
 
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