Linhai MP250A overheating and loosing fluid By jburd (Read 1,762 times)

[ellpee]

Again, I have a different scoot, with the 244 Honda-clone engine. But that being said, coolant is going to circulate through one big hose ***INTO*** your radiator, and through another big hose ***OUT OF*** your radiator and probably to your water pump. And it is only going to circulate ***AT ALL*** if the thermostat has opened due to the temperature of the coolant. Clueless beginner though I am, I can pretty much guarantee you that the smaller hoses are NOT part of the primary coolant circulation "loop," they have something to do with overflow when temp/pressure rise to a certain level.

You seem to have a third "big hose" on your scoot, but it's not at all clear to me what that's all about. Maybe the problem is what "large" means. Purely guesswork, I should thing the primary hoses are going to be around 5/8" to 3/4" going both into and out of your radiator. Anything smaller than that, my guess would be they are something to do with overflow under high temp/pressure conditions.

Alley, JR, etc., where are you? I'mm pushing my knowledge envelope here.

[jburd]

From what I can see, with the design on mine, none of the hoses that come up to the radiator cap are part of the main flow. The 2 main hoses on the right of the radiator are the flow into and the flow out of the radiator. The 3rd main hose out of the top left is to the radiator cap connector. My question with this is where does the circulation come from that I have seen several people post about. The main hose on the radiator connector is in my opinion a flow out and the only logical flow in is through the very small hose going from the back of the radiator connector to the top of the radiator. I will take pictures later this evening and post here.

[ellpee]

Pictures will certainly help. I admit to being lost.

[alleyoop]

The way it works is this way:

The TOP HOSE on the radiator goes to the head which has the Thermostat. The bottom big hose goes to the pump.
When the Thermostat reaches the temp it is supposed to open the HOT fluid in the motor is pushed out by the pump and at the same time is pulling in cooler liquid. Then the thermostat closes because of the cooler liquid and the hot liquid now in the radiator gets cooled by the fan and air blowing through it. This repeats itself over and over the opening and closing of the thermostat is the key.
Alleyoop

HOW A CARS COOLING SYSTEM WORKS SAME WITH A SCOOT:

[ellpee]

Here (if I can manage to attach the picture) is a typical radiator -- maybe not the exact one for your scooter, but typical. Note the large connection at upper left and the large connection at lower right. UL is hot water coming in from the engine, LL is cooler water being pulled out by the water pump and going back into the engine. I'll bet you a grande Starbucks that if you get a good look at your radiator you're going to have the same two large connections. All the other, smaller hoses are going to have something to do with coolant overflow.

Attachments:

[alleyoop]

What is all the hoopla about just watch the VIDEO I put up, your scooter cooling system works the same way no different than on any car or truck.
The only difference is a scoot doesn't have a heater core(HAHA).
Alleyoop

[jburd]

Sorry in advance for the length of this post.
OK so I made some headway today finally. I had a friend of mine that recently bought a Jonway and we were doing a coolant flush and installing a couple other accessories on his. While we were waiting for his to cool (part of burping it) we started to work on mine. The thermostat came in and I installed that. I also went to Advance auto and bought some cooling system clean and flush. We went through that whole process with the radiator cap off. I actually saw the fluid circulating this time and actually got the fan to come on. I ran it for about 20 minutes and it never went above half on the temp gauge. It just continuously flowed. The thermostat was opening and closing as it should. I could actually tell when that was happening. We drained everything and put coolant back in and had the same success with the coolant in again the radiator cap was off. Thought it was all done. I put the radiator cap on and left it running. Within 5 minutes of doing that fluid starting back flowing out the reservoir and then the temp guage went all the way to the top and the fan quick working since it was now low on fluid.
My friend mentioned to me that he thought my radiator cap was bad. He had the same situation with his car and it had the same symptoms. He thought the spring on my radiator cap was too easy to compress. It makes sense actually. When I put the cap on, the system builds up normal pressure and the cap spring just lets the pressure off back through the reservoir. Once that happens, it is low on fluid and then overheats. I have a good feeling about this. I think we solved it. I'm going to order a radiator cap and we should be all set. In the end I think it was a combination of several things - crud in the system, bad thermostat, and also a bad radiator cap. I'm hopeful it will get back on the road soon. I hope this is helpful. If anyone has any other suggestions, let me know.

[ellpee]

Sounds entirely plausible. Radiator cap is supposed to let off some coolant when things get hot and the pressure reaches a certain level. If it does that too soon, it'll dump coolant into the overflow bottle, and when the bottle fills up it'll overflow onto the ground, and at some point you have insufficient coolant left in the system. Caps are cheap, worth a try.

[jburd]

I googled symptoms of a bad radiator cap and everywhere I read seemed to describe what I am experiencing. I have high hopes that replacing it will solve my problem. The alternative seems to be what I'd rather not imagine - a blown head gasket. That's what I thought at first except for not seeing oil in the coolant or coolant in the oil. From what I read, a bad radiator cap can have the same symptoms as a blown head gasket. I'll keep my hopes up and keep my fingers crossed.

[jburd]

So I finally got the time to sit down and place the order for my radiator cap. Here's my plan. As soon as it comes in, I'm going to put it on and hope it finally takes care of the issue. I am hopeful. I went ahead and ordered a head gasket just in case. My thought was if the radiator cap still doesn't solve it, the only other thing I can think of is a head gasket. Somehow too much pressure is building up in the engine. I decided to go ahead and order it so that it will be here just in case. It was only about $15 so it's worth it. I might not have to install it but at least I'll have it here just in case.
Does anyone have a good video or instructions on how to change the head gasket on the Linhai mp250a. I've seen the video regarding replacing the head gasket on the vertical 250cc engine. I believe mine is a horizontal 250cc engine. Is the process pretty much the same or is it different? I'd like to take a look at it to get an idea what's at stake.

[jburd]

So I thought I would pop in and give an update. I got all the parts in and put the new radiator cap on. I burped it several times and got the fan to kick on. Everything seemed to be working well. I took it for a spin around my neighborhood. It didn't seem to go above half on the heat gauge so I thought I was done. Well, then it happened. It just all of a sudden spiked again and started blowing fluid out the reservoir and of course then the fan didn't kick on. Back to square 1.
The only thing left was the head gasket which I was glad I ordered. I found a great manual, thanks to JR, on my scooter and started in on it. I got the head gasket off and sure enough it's pretty shot. Here's a pic of the old gasket

Next on the agenda is to clean the residue for the old head gasket off, install the new one and put it all back together. I'm going to do a valve adjustment while I have it out. Once I get everything back together it should run like new. I'll keep you all posted.

[ellpee]

Hope that does it. Odd there was no oil in coolant/coolant in oil.

[jburd]

Final update. I got everything put back together. It ran kind of rough when I first started it. I ended up having to reset the fuel air mixture. I turned it clockwise until it stopped then turned it 2.5 times counter clockwise. I kept adjusting it a quarter turn until it ran smoothly. I adjusted the idle as well. It now idles at about 2200 rpm. I'm wondering if since the head gasket was on it's way out (after seriously overheating it a while ago) the compression was really bad. Once that was fixed and I did a valve adjustment, the air fuel mixture was out of wack. I'm not sure. I'm not that knowledgeable in these things. In the end this was actually kind of fun. Until now I had never attempted changing a head gasket and felt completely intimidated. So in the end when it started up like it should, I feel pretty good. I'm expecting good things from here on out. Definitely have learned a lot through this whole process. Hope all this helps someone. Sorry if I'm too long-winded.

[richardthescooter3]

Glad you got it fix

[JR]

Awesome job! Now I would run her a spell and then check the head bolts again for proper torque.

JR