Project Linkin's FZR250R 3LN3

Hang on a sec, not sure I read this correctly? A faulty cap can't "cause" a lower boiling temp. The caps only function is like a mini mini pressure relief valve. When the pressure goes above the cap's rating, the spring pushes up allowing coolant to pass through to the overflow reservoir. That way, in theory, you'll never blow the radiator to bits.

Your fan may be working, but is it working well enough? if it's spinning at a lower speed you may still not be getting enough cooling. Either that or coolant is not circulating through the engine (it's not taking heat away from the engine) hence the water pump comment/comment on blockage. Drain the coolant into a bucket and do a flush through with a hose, also take the bolts off the front of the engine (above the exhaust) to clear the coolant in the engine passage. Stick a hose in the orifices and flush through you can't really hurt anything.

 

The radiator fan is definitely working right. It comes on and off as it should and I've felt the airflow from it while at a standstill.

We did a flush of the radiator and cooling system 2 weeks ago, including taking the bolts off the head. It was boiling coolant on the way to Tamworth and on the way back when stopped. When I say boiling, you stop the bike, turn it off, and listen near the overflow bottle you can feel heat and hear bubbling. Radiator / cap is not making any noises only the overflow bottle.

We filled the cooling system and overflow, when I got back to Sydney and checked the overflow it was empty. It looks like a little coolant had come out of the overflow onto the exhaust (as it burns and leaves an ugly tan mark) but the rest I think worked its way back into the radiator/engine.

Temp gauge says its not overheating... could be wrong. Needs to be compared to other bikes. Mine sits at the screw on the gauge or just above when up to temp. Lower when moving / have airflow. Needle has never hit the red.

I do recall checking the radiator fill with the cap off and the engine running. Rev the engine and the level drops, off the throttle and it rises back up. We got a bubble or two but that may have just been air bleeding from the system.

 

Something's not right then. I can't put my finger on what it is but you shouldn't be boiling coolant if the fan is working and you're circulating through the system. You're not using water so you're not getting steam (poor heat transfer), you're probably spewing coolant out the reservoir due to the high temp, your oil isn't milky so you're not losing coolant into the oil...

Can't think of any other reason... not unless you have underfilled the system...? surely not.

 

Definitely not underfilled, I topped it off today with maybe 100ml's.

Reckon I will take a video of my temp gauge soon and upload it for analysis.

I've ordered a new cap

 

Are you sure you got enough coolant in the system and there isn't an air pocket? When I did my cars coolant I had to run it for 30mins with the rad cap off to pump the air out of the system. Then got another 2 litres of coolant in there

 

linkin, look up ebay global for chinese parts.you will be surprised at the cost compared to the local dealer. quality may not be as good but pricewise no complaint.give me a conversation for more details.

 

Thanks lads, I have a decent attack vector now... as usual waiting for bloody pay day to do anything!!!

 

When u fill from cap do u have bike upright or on stand as I found I had similar issue because on side stand causing a air lock

 

I had in on the rear stand today

 

Run it at idle on the paddock stand for 10 minutes and let cool. Then top off. It's surprising how much extra you can get in.

Also this is some gross coolant

 

When we flushed mine it came out clear straight away. @Grasshopper 's bike though? It came out like this

 

Right so the bike's temp gauge has been showing lower temps since I topped up the oil and coolant. Seems to be running smoother as well.

When I got fuel today, I heard the radiator cap hissing. So I'd say it's part of the of the problem. Replacement should be here tomorrow.

 

Changed the radiator cap and just noticed that the old one had tan coloured frothy crap on it. That is new.

Granted I was using the same funnel without cleaning it when topping up the fluids (did oil first)

Will go for a ride now and see how the temperature goes, and if it still boils the coolant

 

I'll have fingers crossed for you man, let us know how you go

 

oil and water do not mix.

 

OK so went for a ride through the CBD with the intention of seeing how hot the bike would get. Well it was bloody well cooking my legs as well as the bait and tackle! On my way home the temp gauge was pointing right up, not quite in the red zone just on the edge of it. Got home, shut off ignition, had a listen... Could not hear any boiling or hissing, which is good. Put the ignition back on and let the fan cool down the bike for a bit.

This leads me back to the water pump / impeller or the head gasket.

This fizzer is still most definitely not a virgin... f&$%^ed in every way imaginable!!!

 

do you have the proper thermostat in?try running with thermostat out.if still overheats not a thermostat problem.

 

Yeah Brian I topped it up just now with some water while the bike was idling, "burping" it I suppose.

Risky we replaced the thermostat, it was boiling coolant with the old thermostat (which still worked but had holes drilled in it) so I do not think it's relevant at this stage.

As I would rev, the coolant level would rise to the filler cap, and bubbles would come out, level drops lower. Repeat a few times until it started spitting out excess fluid from the filler cap. Filled the overflow bottle to the "low" marker. Keeping that right rear fairing off, going to go for another ride and monitor temps/overflow bottle.

I filled the bike with 2 300-400ml bottles of water, and it spat some coolant back out at me after a little while.

I also used a screwdriver on the water pump and the other end to my ear, it sounds like it is working. Not seized, but perhaps the impeller has broken off the shaft? Only way to tell is to open it and see.

Curious as to whether the bubbles are from air pockets or compression escaping from the head gasket...

Going out to test again will report back in an hour or so