mellowgold Posted March 21, 2016 Share Posted March 21, 2016 Hi everyone, I have a new to me '02 with ~25 000km on it that has an odd problem. It's still cold here (at or below freezing) and when I first start it, it will idle fine for a couple minutes but soon creeps up and sits near 4k RPM. Once the temperature gets up to ~80-90C the idle seems to settle down to ~1500RPM. I rode about 200km yesterday in slightly below freezing temperatures, and while at speed the engine was running at 65-70C (seems very cold?). So I'd ride for a while, engine would cool down to 65C and then the next time I stop at a stoplight the bike would be screaming at 4k revs. In stop and go traffic the temperature got as high as 103C at which point the fan kicked on. At this operating temperature it held an idle of ~1500. Also, not sure if it's relevant or I was imagining it or not, but the vtec transition seemed significantly jerkier when the engine was running at a cold temperature. My initial searching of the forum is pointing me towards fast idle wax unit or possible thermostat issue? Not sure of service history, the bike is pristine, but that's no guarantee that the previous owner. Any suggestions on where to start debugging this? Link to comment Share on other sites More sharing options...
Member Contributer gmtech94 Posted March 21, 2016 Member Contributer Share Posted March 21, 2016 They seem to run cold up here in the great north .I think when warm turn the idle down to about 1000 rpms or close . Wait a bit for warmer weather as the wind chill from riding over the last bit will affect the wax unit . Link to comment Share on other sites More sharing options...
Knight Posted March 21, 2016 Share Posted March 21, 2016 Thermostat: Start the cold bike with your hand on a radiator or use an infrared thermometer from a nice safe distance. If the radiator warms slowly with the engine then the thermostat is stuck open. Otherwise it should stay cool then jump to dangerous all at once at the thermostat switching point (82°C?) If you have not yet, then get the factory service manual. It is available in the download section here on this forum. I don't have a 6th so I cannot vouch for testing of the wax idle unit. Use your eyes and inspect the cooling system hoses and radiators for mineral buildup and old fluid. Even if it was delivered to you with perfectly clean fluid, mineral buildup and dark staining of the resevoire below the water line can hint at what came before that. Link to comment Share on other sites More sharing options...
mellowgold Posted March 22, 2016 Author Share Posted March 22, 2016 Thanks guys...didn't know the factory manual was available here...that's a great resource! I'm going to do a full coolant flush since I doubt that's been done yet, but I also found a thread by user danierlvfr that has the exact same problem occurring in the same conditions (including a video!) and for him it turned out that cleaning the injectors / throttle bodies eliminated the issue so I'll give that a shot and update this thread once I'm done. Link to comment Share on other sites More sharing options...
Knight Posted March 22, 2016 Share Posted March 22, 2016 I am not sure what that entails so not knowing I will add this: If you are removing the throttle body to wipe it down then consider refreshing the coolant and vacuum hoses. Also you may want to replace the thermostat even if good since everything else would already be removed. Link to comment Share on other sites More sharing options...
mellowgold Posted March 22, 2016 Author Share Posted March 22, 2016 Yeah that's a good idea. Those hoses are probably getting a little long in tooth. Link to comment Share on other sites More sharing options...
mellowgold Posted March 28, 2016 Author Share Posted March 28, 2016 Small update. Ran some seafoam through (it was still idling at 4000RPM when warm) and let it sit for 24 hours. Next day it started up and idled at 1400 RPM even when warm. The ambient temperature was 10C warmer than the previous day though. It's the warmest it's been since I've owned it, so not sure if the problem is actually resolved or not. I'll have to wait for a cold night to see how it operates in near freezing temps. Doing a rad flush as well and hopefully that will be the end of it. Would rather not pull the injectors if I don't have to. Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted March 28, 2016 Member Contributer Share Posted March 28, 2016 If the bike runs at 65C, your thermostat is jammed open, so the bike is running much cooler than it should. It should run right around 78-82C under cold moving conditions, no matter how cold it is. From what I know of the VTEC system, this won't engage unless the engine is up to operating temperature, so your rough running is probably a result of the temperature being too low. To access the thermostat means pulling the throttle bodies, and Knight is correct that you should replace the hoses around the thermostat while you are in there. The high idle can only be due to the wax unit, possibly the adjustment nut has moved so it is moving the starter plate too far. Possibly just lubricating the linkages might improve things and you could try a shot of WD40 or similar in the area to help. Link to comment Share on other sites More sharing options...
mellowgold Posted March 29, 2016 Author Share Posted March 29, 2016 Thanks Terry. I'll give all the linkages a shot of lube. Is it possible the thermostat is just sticky in general? I feel like it's giving me mixed signals since Idling in my garage the temperature got up to 102C and I was able to hold my hand comfortably ~1cm from the rads which I thought would indicate it was stuck *closed*. Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted March 29, 2016 Member Contributer Share Posted March 29, 2016 If the thermostat was stuck closed, then the bike would overheat pretty quickly. Basically the thermostat holds the coolant in the engine block until it reaches about 78C then starts to open up. This allows the coolant to head out to the radiators. If the temperature of the coolant system then drops below 78 (as it would when moving through really cold air) then the thermostat starts to close up again to reduce flow to the radiators. Your best bet would be to use an IR thermometer to measure the radiator surface temperature. But on my VFR (I installed a new thermostat last year) I can hold on to the radiator until just before 78C and the radiator feels stone cold, then suddenly gets much to hot to hold. Before I replaced the thermostat, the radiator would start slowly heating as soon as the engine was started, which is what you would get with a stuck-open thermostat. My bike heats to working temperature within 2km from home, under any weather conditions. Here's my old stuck-open thermostat: Link to comment Share on other sites More sharing options...
Member Contributer BusyLittleShop Posted March 29, 2016 Member Contributer Share Posted March 29, 2016 If you experience high uncontrolled idle suspect an air leak... on afuel injection system *any* air that gets past the throttle bodies themap just adds the corresponding fuel... the result is highuncontrollable idle... make sure all the rubber hoses are connectedand in good shape... make sure all the intake boots are tight and ingood shape... Link to comment Share on other sites More sharing options...
mellowgold Posted March 29, 2016 Author Share Posted March 29, 2016 Thanks BLS That's a good point. I'll be going over all the hoses while I've got it torn apart. Link to comment Share on other sites More sharing options...
mellowgold Posted April 1, 2016 Author Share Posted April 1, 2016 Progress! I took the airbox off and sprayed all the linages and the wax idle unit with some liquid wrench and ran a can of seafoam through the tank and let it sit for 48 hours. I also flushed the coolant, and then ran it with some vinegar/distilled water for a bit, then flushed with distilled water twice and finally filled up with fresh coolant. Took it out today (~4deg C) and the good news is that the high idle seems to be gone. When cold it idles ~2000RPM and when warmed up that settles down to around 1400RPM. No more screaming at 4k at stop lights :) Whether that is down to the seafoam or freshly lubed linkages, or some combination of both I don't know. Easy $12 fix either way. The bad news is the bike still runs cold. If I let it sit and idle in the garage it will warm up to ~108C and then the fan will kick on and bring it back down to 102C, but out in the open air at ~80kph it runs at 65C (150F). So looks like my thermostat is probably toast. The one lingering question I have though is that even if I let the bike sit and idle it's way up to 105C (220F) I can still hold my hand almost directly on the rads and they merely feel warm instead of HOT. I guess this might happen if the thermostat is just open a small crack instead of fully open? Link to comment Share on other sites More sharing options...
mellowgold Posted April 1, 2016 Author Share Posted April 1, 2016 New 'stat on order now so hopefully have it sorted shortly. Link to comment Share on other sites More sharing options...
Knight Posted April 1, 2016 Share Posted April 1, 2016 It may be stuck partially open. Did you wait a long time for your test? If no then continue your test and that boiling hot water will replace the water in the radiators and it should not take extremely long. Water transfers heat very efficiently thus a small amount of water flow will heat up the radiator. This presuming there is not a significant amount of air introduced into the system. Link to comment Share on other sites More sharing options...
mellowgold Posted April 1, 2016 Author Share Posted April 1, 2016 OK I'll try again and let it go through a few fan cycles and see if it heats up any more. I do believe I've got all the air out of the system, but I'll see if I can see if I can coax any more out. Link to comment Share on other sites More sharing options...
Member Contributer BusyLittleShop Posted April 1, 2016 Member Contributer Share Posted April 1, 2016 The bad news is the bike still runs cold. If you see *continuous* temps higher than 220ºF (104ºC) or below 180ºF (82ºC) then trouble shooting is in order: Continuous engine temps above 220ºF or 104ºC is also a problem and the proper order of items to trouble shoot are: 1)Faulty radiator cap... system should hold 1.1 pressure ratio... 2)Insufficient coolant... 3)Passages blocked in the radiator, hose or water jacket... 4)Air in the system... 5)Thermostat stuck closed... 6)Faulty temp meter or thermo sensor... 7)Faulty fan... 8)Faulty fan switch... Engine temps below 180ºF or 82ºC is an problem... it means that the moisture produced during combustion is not getting hot enough to evaporate out the pipe as steam... instead that moisture will migrate to the oil and produce a milky white contamination... Note normal by products of combustion is water... . Every gallon of gas creates roughly 8 pounds of water vapor... we all have witnessed water escaping out of tail pipes on cold mornings... The sequence of events to trouble shoot are: 1)Faulty temp meter... 2)Thermostat stuck open... 3)Faulty fan switch... (stuck on) Link to comment Share on other sites More sharing options...
mellowgold Posted April 3, 2016 Author Share Posted April 3, 2016 Pulled thermostat tonight... As suspected! New 'stat should arrive Wed so hopefully have it back together by next weekend. Link to comment Share on other sites More sharing options...
AllWeather Posted April 4, 2016 Share Posted April 4, 2016 Did you order a new thermostat housing O-ring and the 2 x short hoses from the block to the thermostat You don't want to have to stuff around going back in there if these little bits leak after you put it back together I have seen a couple of those little hoses fail after a t/stat replacement Messy messy messy and very slippery on rear tire Link to comment Share on other sites More sharing options...
mellowgold Posted April 4, 2016 Author Share Posted April 4, 2016 I ordered the o ring but not the hoses. I'll see if I can still get them added to my order in time though I think I might be too late :/ Link to comment Share on other sites More sharing options...
mellowgold Posted April 9, 2016 Author Share Posted April 9, 2016 Thermostat installed and everything buttoned back together (except for the PAIR system which I ejected). I am very very happy to report that the new thermostat is working and the bike is purring at 1200 RPM instead of 4000! Fingers crossed all the plumbing stays sealed. Thanks to everyone who helped/offered suggestions! Link to comment Share on other sites More sharing options...
mellowgold Posted April 10, 2016 Author Share Posted April 10, 2016 Hmmm I lied. Took it out for a short ride in freezing conditions (-2C) and the good news is that it's now running at 78C (fairings are off) which seems more reasonable. However, it had the same high idle problem. Idles between 1200-2000 and then jumps to 3500-4000 once the bike warms up. It's strange that it idled fine the previous evening although that was in a significantly warmer garage. Anybody know how to verify correct fast idle unit operation? Edit: should mention that I gave the intake boots and hoses a once over and they all looked in OK shape. Link to comment Share on other sites More sharing options...
mellowgold Posted April 12, 2016 Author Share Posted April 12, 2016 Based on all my readings the most likely culprit was fast idle wax unit, so I pulled it apart again tonight and started it and noted that the wax unit never seemed to even get warm when the bike was up to temperature. I pulled it out and It was completely plugged!Before: After cleaning: Will get it reinstalled in the next couple of days and see if that does the trick. Link to comment Share on other sites More sharing options...
mellowgold Posted April 14, 2016 Author Share Posted April 14, 2016 So tonight, I reinstalled the cleaned wax unit, then refilled the cooling system and reinstalled the injectors. Started it up with the airbox off and watched for the wax unit to work its magic. Initial idle at 2000 RPM and sure enough as the bike heats up the wax unit now expands causing the startle valves to close up bringing the idle down to ~1200 RPM. Success! In summary, running cold due to stuck open thermostat and high idle caused by blocked coolant passage in the wax idle unit. Makes me afraid for what the rest of the coolant passages look like Link to comment Share on other sites More sharing options...
Member Contributer BusyLittleShop Posted April 14, 2016 Member Contributer Share Posted April 14, 2016 Congratulations... Honda's RC45 employs a cable and a knob marked "choke" to manual adjust the idle circuit... no silly wax... maybe someone could offer VFR riders a kit... Link to comment Share on other sites More sharing options...
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