250 Roketa 244cc cooling issue By mxmatt (Read 6,819 times)

[mxmatt]

Untitled by mxmattaz, on Flickr
Untitled by mxmattaz, on Flickr

Rich,

I am aware of the difference between the reservoir fill spout and the radiator cap spout. I continue to get a full reservoir for some reason as well. I noticed that the return line from the carb is the one that is attached to the radiator fill spout. The coolant in that line is very hot and continuously produces bubbles.

[Bashan]

The hose with the red arrow goes around and hooks onto the right side of the carb? There should be two nipples where that hooks on, where does the hose go that's attached to the second nipple? These are the nipples I'm talking about:

[mxmatt]

Bashan It attaches to the thermostat housing.

On a side note, both radiator hoses are hot so it doesn't appear that there is circulation through the radiator.

I'm thinking I have a water pump issue.

[cyborg]

radiator getting hot?

[mxmatt]

Nov 13, 2014 14:03:25 GMT -6 cyborg said:

radiator getting hot?

Yes. The top is hot the bottom is just warm.

[cyborg]

plugged rad,,,,,,,,could be a combination problem,,,,plastic impeller lost a few vanes went into rad and plugged it??,,,

[Bashan]

Agreed, the water coming out of the thermostat will be the hottest because it just came through the engine so the fact that the line to the carb is hot doesn't surprise me, it'll be around 180. But the radiator should be a more uniform temperature, not just hot and warm. I agree with Pete, you have to pull the water pump and look at the impeller and flush the radiator. It's not that big of a deal. I thought you had a radiator cap where you could look down into the radiator. I see you don't so the swirl test won't work anyway. Rich

[Guitarman]

Yep, I bet the impeller was mounted crooked or dropped before assembly or something and the pieces are jamming the rad. Take the Rad off and flush it backwards. Take the water pump out and replace it.

You CAN replace just the one part, but when it's an assembly like this, just do the whole thing.  How much stress on the rest of the parts?

[mxmatt]

Thanks boys. I'll get on that. Do I have to take all the plastics off to do this job?

[Guitarman]

No, not all of them. You can leave the front on. Once you take them off a time or two it's not difficult, just time consuming. Get yourself a powered screwdriver and you will cut your time in half.

[jct842]

The way to check to see the fluid is circulating is to use a infra red point and shoot thermometer. Check the hot side going in to the radiator and then check the output side and of course there should be a big difference, (much cooler). You have to do this on most cars as there is no cap on radiator, its on the over flow tank.

[mxmatt]

Sorry for the bump.

So I haven't been riding my scoot since November when I stalked out on diagnosing my overheating problem. It was my daily motive transportation until then.

So last Sunday I finally got around to pulling out the radiator and checking all of the hoses and the water pump.I found no obstructions whatsoever the impeller looked impeccable and there was nothing visibly wrong with the cooling system that I could detect. I blew the lines clean and reversed wash the radiator 20 times. I put it all back together and I'm still having the same exact problem.The cooling fan works. Both the original and new thermostat function properly. So guess what I am concluding?

How long is a radiator cap supposed to last on these Chinese scoots?

[jct842]

Nov 11, 2014 20:12:14 GMT -6 mxmatt said:

Nov 11, 2014 12:29:23 GMT -6 Bashan said:

Can you see the coolant moving in the radiator?

Kind of. Something I am noticing is that no matter how many times I "burp" the system and test it for a ride, there is a continuous stream of bubbles emitting into the cup the radiator cap screws onto. It is coming from the hose that is attached to the carburetor. I am thinking that I am picking up air somehow. Also, no matter how long I let the bike cool down after a good burping, when I open the cap, there is a little pressure and coolant escapes. It's not much, but it didn't do this before. I am not sure I understand the "swirling" you are referring to Rich. Is that from the coolant returning to the cup under the cap?

This is really starting to frustrate me. I have done nothing but baby this bad boy since the day it landed in my driveway. What would plug my radiator or cause the water pump to fail at 3300 miles? Oh, I double checked the weep hole on the water pump 10 times and there is not coolant coming from the hole.

Just reread the whole thread, bubbles.....bubbles scare me.

[mxmatt]

I've gotten rid of the bubbles. In fact as long as I don't ride it hard, temp gauge reads great. Once I get on it for a little while I get intermittent cooling and a full reservoir. I think the cap is weak and letting fluid out too easily.

[cyborg]

That may be Matt then after It purges a bunch of coolant it may get hot