250 Linhai overheating

[robert1c]

Hi scooter gods,

Have yet another issue. My 250B Linhai is over heating.

So far i have:
Flushed and blown with compressor out all the water in the system from the cap to the drain plug.
Removed the thermostat and tested in a pot. Opened at about 180 (just didn't open much).
Tested without the thermostat and cap off and still over heated. (so I don't think it's the thermostat).

Do you guys have any advise an how to diagnose the issue?

Thanks in advance,

[WarrenS]

Check the water pump.

[robert1c]

Yes that's what I'm worried about. How does one test the water pump? Sorry if this is a dumb question

[robert1c]

Temp is pegging out in about 15 to 20 minutes.

[OverReved]

I never test a suspect thermostat, always replace. They are a cheap part and easy to install. Throwing one in a pot of boiling water doesn't tell you if it sticks- some times-but not all the time.
There's not much to do on a water pump other than a visual inspection for leaks, wiggle of the impeller shaft to check for play, and a spin by hand test for smooth bearing or bushing action.
Short of removing it you'll not know if your impeller is actually loose on the shaft or damaged in some way.
Why not replace it if you have no issues with clogs in the coolant system.
Does your bike have a cooling fan? Does it actually turn on? Is the radiator clean on the outside, no bent fins or melted bags on it? Important things to check, easy to overlook.

[robert1c]

Hi OverReved.
I also ran it some today without the thermostat (just to test it) and it stoll ver heated in the garage. I also did "burb" it a few time to insure all the air bubbles were out. Radiator seems fine and the fan is cycling on and off as it should but it still get all the way up to the "H".

I think it may be the water pump. I will be picking one up tomorrow for about 60.

Thanks!

[OverReved]

There was a thread earlier about these Linhai bikes overheating. There could be an issue with their sensors.. who knows what quality they are or what range of temperatures they will tell the gauge they are reading.
Perhaps you will have good results with your water pump replacement.

Since I'm here can you tell me what it did when it overheated with the cap off?
Did it boil over, or did the gauge peg out, or did you get a warning chime, perhaps all of the above?

[trigger]

My instrument sensor was not terribly accurate, due to a bad plug. I replaced it at the sensor and it is much better. However!

If you are not boiling out coolant, and the fan is actually turning off, then the system is probably OK. I lost the fan sensor once and it gets hot because the fan doesn't come on. I have since wired up an emergency switch if and when the fan sensor goes out again. (It is located at the bottom of the radiator, real easy to replace. So if your only indication of HOT is the instrument sensor, and the fan is cycling off and on, then you might be fine.

Good luck.

[quicksilver]

Well let's see, it was talked about the thermostat and the gauge sensor but wat was failed to talked about is the cooling fan. Noe if it is working, one thing might be looked at is which way the fan is turning. If the fan is blowing forward then it is running backwards. This can be fixed by swapping the fan wires in the plug.

[robert1c]

Hi Guru's, the fan is sucking air inwards. And the thermostat is back in now and fluids topped off. Now having said that as Trigger indicated its not boiling over when the gauge its "H". The block is hot to enough th burm and the radiator is warm hot to the touch when the fan cycles ON but no real other sign abpart from the gauge. Where is the sensor located on the block? And what is a normal operating temp? I may try checking to see if I can measure the true temp.
Thanks!

[robert1c]

another bit of information. Everytime I open the radiator cap it sems to be low. But really the fluid is going to the resevoir. So much so that's its spilling over and coming out there.

[robert1c]

Another update. I bought an enfrared gun and the temps are:
Radiator 140+
Thermostat neck 140+
Coolant at the cap 130+
Electric chocke 180+

Now where is the temp sponsor connected to the engine (reading from)? I believe it's part of the electric chocke.

Notes:
A) not sure if the water pump is actually bad as I do see some flow even though it's very little.
B) I believe the temp gauge is bad.

[kixome]

You are absolutely not overheating at those temps. overheating would be quite a bit above boiling.

[kixome]

I would say is your sensor as others stated. Would be nice if they listed the degrees on them huh?

[robert1c]

Yes it would. Where is the sensor located? I would like to test it.

[ce]

The sensor is on the right side of the engine, right below the intake manifold you'll see a few wires and one goes to the sensor on the engine. If the connector is loose or off, it won't work.

[robert1c]

Ok I found it and pulled it now I'm trying to see if I can find a parts cross reference for something at the autopart stores.

[robert1c]

Current status.
Bought replacement temp sensor. Once replaced the rectifier started smoking I had a spair so I replaced it.

After 15 mile ride at night.
Thermostat neck 220+
Radiator cap 117+
Radiator 107+
Electric choke 180+
I don't remembr the fan cutting on as per the temps above it should not have. I an still hittting "H"

Any ideas guys. I need some help as I'm lost now.

[WarrenS]

You may need a new radiator cap or gasket. It should draw the coolant back into the radiator as it cools down. Your radiator should not be low.

[robert1c]

Hi Warren, I replaced the cap and the pump. The temps are the same but the radiator is stuck at 97 which is the outside temp. Looks like the radiator maybe clogged. Looks like I will be pulling the radiator next.