|
Post by cyphron on Oct 27, 2009 1:44:08 GMT 1
Here I Am Again with the cooling issue.
Let me explain exactly what happens before asking for your opinion.
As you know I drained the cooling system recently because of having used pure anti-freeze instead of a 50/50 mix, which was causing the liquid to boil prematurely on the expansion tank.
In the begining, the fan started to work around 2/3 way up the temp gauge, and it was not easy to make the temp gauge get there. I've then taken some rides on the bike, letting her get really hot, which started to be not difficult at all. It seems to me that she started to get hot too easily, and after getting hot it is not easy to get cooler. Then I noticed that sometimes the fan didn't work as on the beginning, letting the engine warm almost to the top white mark. The bike is definitely overheating, and the fan is not starting automatically right now. Nevertheless, if I start to ride faster it seems to get a little bit cooler, but not much. The temp gauge stays slighly above the middle position and if I stop for a while or run at slow speed it starts climbing again. When the coolant gets this hot, I've seen some coolant drops falling from the top right hose that connect to the thermostat housing. It really seems the pressure is high there.
So : 1 - The fan sensor switch seems to work, because I've seen the fan start automatically in some of my previous 'engine heating' attempts.
2 - When engine is really hot, the pressure seems to be high on the top right hose connecting the radiator to the thermostat housing, and the bottom radiator hose seems to be not completely full or almost empty. I squeezed it very easily with my hands, and it is not as hot as the top one.
Questions :
1 - The coolant circuit should be : Water Pump, Engine, top right radiator hose, thermostat, radiator, bottom left radiator hose and finally water pump again correct ?
2 - The temperature sensor which moves the gauge is located on the thermostat housing or near it , correct ? So it seems to be measuring the temp correctly, because it 'feels' the coolant temp that comes into the top right radiator hose into the thermostat housing, letting the gauge climb almost to the top. Today, with the temperature gauge got near the top white mark and I could hear small boiling noises on the expansion tank. Stopped the engine on that moment.
3 - Despite of the gauge temperature sensor being reporting correct temperature, the fan does not start when it should, which leads me to think that the coolant is not reaching the fan switch on the left radiator side, or at least some of it don't.
4 - Can the thermostat show erratic behaviour ? Sometimes opens, sometimes dont ? I think this must be the most probable cause of the overheating problem.
5- Another possibility is the water pump. How can I check the water pump is working ? I think she is Ok and it is not likely the cause of this, because If I start the engine when cold (thermostat closed) with the radiator cap off, i see the coolant climbing a little on the filler neck and it is noticeable some movement on it. I guess the only way to see the coolant flowing from the right to the left though the filler neck with engine cold is removing thethermostat right ?
So, my bet is the thermostat. The age must be playing tricks with it. I guess I will try to remove it and run the bike without it to see what happens.
Let me hear your opinions please, taking in account all the symptoms I've posted.
I've discarded the blown head gaskets theory because everytime I drained the cooling system (3 times on 700 kms !!!) the green coolant does not show signs of oil or brown residues, and because the engine only gets really hot when running at low speeds or idling. If the problem were the head gaskets, I guess the temperature should raise no matter the conditions and eventually cause the boiling coolant on expansion tank without letting the temperature go down even when ridding at fast speeds.
I think this diagnosis will lead me to the correct solution with your help. I have lost the number of times I've removed the tank and air filter ... And I will continue to do it until the issue is solved !
Thank you very much.
|
|
|
Post by McF on Oct 27, 2009 9:36:40 GMT 1
You have described things clearly (except for the top hose arrangement - the thermostat routes the water directly back to the engine until it heats up and then it will go through the top radiator hose. Don't be too alarmed about small leaks when the engine is running and the system is hot. The operating pressure in the cooling system is about 1 bar. A few basic things to check. These will either fix the problem, or help to identify it (I hope!) drain your coolant into a clean container (so you can reuse it assuming it's still clean etc). You should get approx 1.8 litres out Remove the top and bottom radiator hoses, pour water (or use hosepipe) into the top of the radiator, it should flush straight through and out of the bottom hose. - This will confirm no blockage in the radiator. Remove the thermoswitch for the fan (on the rear of the radiator, left side. Give it a clean with fine wire wool, wash it off before refitting. It is possible to check this (but probably burn your fingers!) as it should give zero resistance at 93-97C. Basically it's an earth point, that only "switches on" when it gets hot. If you want to check the water pump, you will need a new gasket www.wemoto.com/bikes/Honda/NTV_650_J_K_Revere/88-89/picture/Waterpump_Gasket/. There isn't much that can go wrong with the pump. It's permanently driven from the rear of the oil pump. I did have one that for some reason, lost the impeller blades. Once I'd opened the pump casing, I realised what had been making the rattle - all the pieces of impeller in the bottom of the pump! Clean the temperature sender (from the thermostat housing), again use fine wire wool, wash before refitting. If you want to test this (burnt fingers again!) at 50C it should provide 130 to 180 ohms resistance 100C it should provide 25 to 30 ohms resistance illegal is a fan of removing the thermostat altogether (your bike might run cool for a lot longer before warming up but it will not cause any harm) Another simple thing to check is the radiator - is there a lot of dirt matted in the cooling fins? If so, remove it and wash (ideally with a power washer) from the back so that you blow everything back the way it got in. You may need to (tedious job!) carefully poke between each little fin to remove the dirt if it is tough to remove. I doubt this is a problem as you said the top hose was hot and the bottom hose was cooler (either the radiator is doing it's job, or there is a blockage inside the radiator) With the engine running, you should be able to see the water flow through the thermostat housing with the pressure cap removed. This should confirm that the pump is working OK without having to remove the pump top cover. The flow should be clearly visible circulating water, not just vibration from the engine running. I'm afraid all of this means more removing the tank and air filter etc. So alert your beautiful assistant and get plenty of tea ready. One final point to consider - if you want to see how effective the fan is and cleaning the thermoswitch doesn't help you could rig your own switch. I bought a "piggy back" lucar connector like this info.maplin.co.uk/module.aspx?C=SO&U=strat18&tabs=n&ModuleNo=42729&ma=red%20piggyback%20s and crimped a length of wire on it. I put the new connector on the thermoswitch and then the wire from the fan onto the "piggy back". in the workshop (assisted by your beautiful helper) you can then place the bare end of your new wire on a suitable earth and this should cause the fan to switch straight on. If you want a more permanent arrangment to use while you're out riding, run the new wire to a switch on your handlebars, then another piece of wire from the switch to a suitable earth. With the new switch in the "off" position, the fan and thermoswitch will operate exactly as normal. You have the option of switching the fan on manually. Hope this is easy to understand, but more importantly - hope it helps!
|
|
|
Post by oddjob1 on Oct 27, 2009 10:47:10 GMT 1
have similar problem on my ntv..removing thermostat helps.going to have a look at the pump.do i have to drain oil and coolant to take cover off? looks like need to remove all bolts on pump.
|
|
|
Post by cyphron on Oct 27, 2009 11:18:27 GMT 1
Thanks Mcf. I will try to follow your directions.
I guess I will have to double check this because last time I look at the coolant with the radiator cap off while the engine running the only symptom I saw was the coolant raising his level almost to the top of the radiator neck and a little swirl movement. I did not saw water clearly circulating, but maybe this was because last time I did this I filled the system completely and maybe the coolant was circulating below the radiator neck top level where I was seeing the little swirl movement.
The visible coolant circulation direction from the radiator neck should be from right to the left correct ?
Anyway, I hear no rattling noises coming from the water pump area, so I think it must be ok.
I will do the work you suggested on the radiator, removing the top and bottom hoses and also the fan switch on the back of the radiator. The radiator fins are almost completely clean, appart from some insects there is no visible dirt on it.
You mentioned the option to install a manual switch for the fan and let me tell you that the bike already has one !! I thought this should be an extra installed by the previous owner for some reason, but now I see why he has installed it ! Probably felt the same as I when discovering these the cooling issues.
I can use this switch to turn on the fan manually when the engine is getting above a certain temperature and I can see a little decrease in the temperature, but not much. What puzzles me is that the automatic switch has worked well sometimes before with no need to use the manual one, so it should keep working. Not doing so indicates a problem somewere.
If I can't find anything wrong with the radiator or the water pump I will try to remove the thermostat (although it is not easy to get to some of the hose clamps that hug on it...)
I will post some pics when possible and keep you informed.
Thanks
|
|
|
Post by McF on Oct 27, 2009 11:19:23 GMT 1
have similar problem on my ntv..removing thermostat helps.going to have a look at the pump.do i have to drain oil and coolant to take cover off? looks like need to remove all bolts on pump. Sorry to hear that! Coolant drain yes no need to drain the oil, provided the pump cover is not stuck on too tight. There are four bolts (plus the drain bolt) in the pump - two longer ones that bolt the pump to the crankcase and two shorter ones that hold the pump together. If the pump top comes off the body in situ - great. If the pump top remains stuck to the body, it is possible to remove the pump from the crankcase without having to drain the oil. You will need to lean the bike across to the right side. Leave it leaning while the pump is removed, plug the hole with a rag and ideally replace the two O rings before replacing the pump Once the whole pump is out you can wrestle a little more with it to seperate the two halves. Personally, I'd have a good go with a soft faced mallet to seperate the pump while still fixed to the bike. You will certainly need a new pump cover gasket though before reassembly - they go very stiff, flat and brittle. It's a waste of time trying to reuse an old one - I speak with experience!
|
|
|
Post by cyphron on Oct 27, 2009 11:25:30 GMT 1
have similar problem on my ntv..removing thermostat helps.going to have a look at the pump.do i have to drain oil and coolant to take cover off? looks like need to remove all bolts on pump. uh oh ... Two NTVs with a simillar problem ? I guess we have to 'unite' on this to discover the thing ... They are playing tricks with us ... :-)
|
|
|
Post by oddjob1 on Oct 27, 2009 11:35:48 GMT 1
yeah..seems like it..i want to get it sorted before put fairing on for winter.
|
|
|
Post by ilegalalien on Oct 27, 2009 18:51:25 GMT 1
take the radiator pressure cap off and run the bike, when it gets warm/hot you should see coolant coming from the thermostat hose and disapear down and into the radiator, if it dont then the thermo is knakkered or the impellor pump is not pushing water through, but my guess is the thermostat, impellors don't break.
|
|
|
Post by cyphron on Oct 28, 2009 15:51:38 GMT 1
So, here I am again after a 4 hour job on the bike... With no assistant or tea ... I followed McF suggestions, in order to identify the problem or try to solve it. 0 - Before unassemble the radiator hoses, I removed the radiator cap and started the engine, just to check if there was coolant circulating, and yes, I could clearly see the coolant moving in one direction which is a sign that the water pump is Ok. 1 - Removed the Top and Bottom Radiator hoses, and throwed some water through it. No blockage as you can see, and the water came clean. 2 - Removed the radiator fan sensor and cleaned it. As you can see, it is also connected to a small switch above (with I - O on the pic). So it is possible to manually turn on the fan. Usefull but not desirable in normal conditions. Here is the sensor. 3 - It seems that there are no blockage problems with Radiator and Fan Sensor seems to be also OK since it has worked before and now it has been cleaned. Next Step was removing the thermostat housing. It is not an easy task, the hoses were very tight and almost glued to the thermostat housing, and the workspace on that area is small and not very friendly. Big hands are a problem here :-). The Thermostat Housing (with dirty appearance) 4 - Opening it revealed the thermostat and also some dirt. I would not call this dirt, because it almost seemed like there were some small 'corals' like the ones we can find on some bridge pillars ... 5 - Then I put the thermostat on boiling water for some time and I could not notice any change on it while it was boiling. It sayed always on the same position. Here it is right after the boiling process. It remains always on the same position, just a little bit opened, as you can see on the pic. So I decided to remove the thermostat definitely bacause it seems to me that this must be the reason of the overheating I've been talking about. I will order a new thermostat and install it, but not for now. After reassembling everything in place and refilling the cooling system, I took a few minutes ride. It really takes longer to warm, and the gauge only starts to climb while ridding in traffic, but I could not manage to get it over the middle of the two white marks yet, so lets see how it behaves on the future. For now, it seems Ok. I Hope this info can help other users too, with similar problems. Your help has been precious.
|
|
pongo
Restricted to 33BHP
Posts: 51
|
Post by pongo on Oct 28, 2009 16:06:13 GMT 1
5 - Then I put the thermostat on boiling water for some time and I could not notice any change on it while it was boiling. It sayed always on the same position. Here it is right after the boiling process. It remains always on the same position, just a little bit opened, as you can see on the pic. So I decided to remove the thermostat definitely bacause it seems to me that this must be the reason of the overheating I've been talking about. I will order a new thermostat and install it, but not for now. After reassembling everything in place and refilling the cooling system, I took a few minutes ride. It really takes longer to warm, and the gauge only starts to climb while ridding in traffic, but I could not manage to get it over the middle of the two white marks yet, so lets see how it behaves on the future. For now, it seems Ok. It does soundds as thought the thermostat was not working
|
|
|
Post by ilegalalien on Oct 28, 2009 16:46:21 GMT 1
Looks like people have been using tap water in those... TUT TUT... it does the same as a couch potato eating buckets of lard... i'd put some vinegar in with your water for a week or so and give it a good flush.. Thats the main reason for a cooling failure... tap water cloging up the system with limescale.
|
|
|
Post by McF on Oct 28, 2009 19:13:14 GMT 1
Looks like people have been using tap water in those... TUT TUT... it does the same as a couch potato eating buckets of lard... i'd put some vinegar in with your water for a week or so and give it a good flush.. Thats the main reason for a cooling failure... tap water cloging up the system with limescale. I'm with Alien here. Looks like blatant use of tap water. This will explain the brown colour when you drained the system. No nice way to explain it - it's rust! You can buy Cooling System Flushing products, or take illegal's advice and use a strong solution of vinegar. The thermostat housing gasket looks like it was in bad shape. Like the gasket on the water pump, it doesn't take long for them to go flat, hard and brittle. Wemoto sell them for £2.40 plus postage www.wemoto.com/bikes/Honda/NTV_650_J_K_Revere/88-89/picture/O-Ring_for_Thermostat_Housing/I'd suggest ordering a new one, running your bike until it arrives, then drain, flush and replace the gasket. Wemoto can also sell you a new thermostat for £40.77 . People have often asked on this forum which car type models will fit aNTy. If you have your thermostat out and access to a good car spares shop, perhaps you will find out and tell us? I would expect them to be a lot cheaper. Just make surer it is physically the right size and opens at 80-84C. If the one you see opens a little lower temperature, that will still be OK.
|
|
|
Post by cyphron on Oct 28, 2009 20:30:13 GMT 1
Well, well ... The story hasn't ended yet ... Today I had to go into the town centre, so lots of city driving, stop and go, etc, so the engine temperature started to climb slowly. I heard the fan coming on several times where it should, just about 2/3 way up the temp gauge. All seemed Ok, this looked like normal operation to me. When cruising on open road, the temp stays around the first 1/3 on the gauge. But when I arrived home, I let the bike idling a little to check the fan working again and it didn't started at where it was supposed to, letting the temp climb a little more making the coolant boil on the expansion tank... Bad luck isn't it ?! Note: The coolant starts to boil about 2 mm near the top white mark on the gauge. So now I am clearly suspecting of a faulty radiator fan thermo switch too, because while on the city the temp never climbed above 2/3 on the gauge because the fan started to do its job. So despite of being hot, the coolant never boiled because the temp was kept below a certain point. Not having the thermostat I'am now sure the coolant is passing through the radiator, so if the fan failed so start at least one time I guess it's better to replace the fan thermo switch also, because it is showing faulty behaviour. I know the bike has been stopped for about 3 years, maybe the age and the apparent use of tap water in the past had made these components fail, reacting erractically, like happened with the thermostat. What do you think ? Are you seeing other possibilities ? Wemoto sells these for £55.74 !!! Ouch ! .... Why are these little things so expensive ? Are these a common fault? If yes, then I'm on the thermo switch business !!!!
|
|
|
Post by cyphron on Oct 28, 2009 20:39:08 GMT 1
I noticed the gasket was not in very good shape, so not having a new one I covered it with a small portion of the same silicone gasket sealant I'have used on the rear rocker cover.
I guess it will do the job.
|
|
|
Post by ilegalalien on Oct 28, 2009 22:02:51 GMT 1
|
|