GL1200 overheating

[dan filipi]

Ok, let's take this one step at a time considering just the facts and verified checks.

1. Radiator warms up before thermostat opens and is hot to the touch well before the tstat would be opening.
What would cause this?
Temp gauge has already been verified accurate.

2. The cooling system capacity is 3.4 quarts. I'm almost certain this includes the recovery tank up to the full line, manuals dont say.
This system will only take 2 quarts up to the radiator filler neck, this is after it's been "burped" of air.
I put a 1/2 quart up to the recovery "Full" line, only about a cup more was sucked in while the system cooled.
Stone cold this morning coolant is at the top of the rad filler neck, recovery level is unchanged.
:?: :?:

I'm hoping for a air pocket causing all the trouble.
I'm going to drain it again and suck it dry from the lower hose with a shop vac then measure the fill.

 

[joedrum]

one of the things that i thought was strange was how when cold and thermostat closed the water level suck down and back up like it did. maybe this is normal. but it seems like under those conditions that would mean its getting suck in the motor somehow. you would think that if the pump was working right it would clear any ari pocket in the motor unless it was getting air at the pump or pushed into the pump this would diffinutly keep the pump from working. somehow something like this is going on. id hook that water to it reverse flow as tight as i could and let it rip for a while under full pressure id be trying to put water anywhere it would have a chance to go maybe go the other way to. maybe take your plugs out and spin it to see if water is getting in there. with the themostat in it sould bild up some petty good force in reverse flow. its diffinutly time to get aggressive with this deal maybe today is your day. good or bad it would be nice to figure it out

 

[mcgovern61]

Dan, after the tstat opens and the air starts to burp out, does it ever reach a point where the air stops burping and only water flows to the radiator? If it is an air bubble and it is trying to purge, at some point, it has to purge if you keep slowly adding water. (As opposed to a cracked block or head)

I read the post about 1200's and a potential air pocket, have you tried that remedy? (Just reaching for straws at this point)

 

[dan filipi]

I read the post about 1200's and a potential air pocket, have you tried that remedy? (Just reaching for straws at this point)

I'm trying to figure out the remedy right now.

This morning I emptied the system and with a shop vac on the lower hose fitting sucked everything I could out of the block, no water came out.
I put it back together (with the tstat in place) started it and filled, just over 2 quarts went in while running. That's with a burp which didnt lower the level much.
Now I put the cap on and let it get hot, the thermoswitch is bad so it heated up to the red line.
I could see bubbles starting to go into the recovery because it was boiling so I turned the fan bypass switch on. With the engine idling the temp started to drop slowly. This showed that coolant MUST be flowing.
As it cooled with the fan running the level in the recovery started to drop as water got sucked into the radiator.
Suspecting a air pocket, I sprayed water on the radiator to help cool it down. I could just about watch the recovery level drop.
All totalled, alittle under 2.5 quarts should be in the radiator and block.
Add .5 quarts into the recovery that leaves the total fill almost a 1/2 quart low.

So now what?

 

[mcgovern61]

So now the question is, if the engine will not take any more water, does it still burp and bubble? Does it still boil the water? Good to know that it cooled when the tstat actually opened and it does prove some water at least is circulating.

 

[dan filipi]

So now the question is, if the engine will not take any more water, does it still burp and bubble? Does it still boil the water? Good to know that it cooled when the tstat actually opened and it does prove some water at least is circulating.

With the cap on there are no bubbles into the recovery until the temperature is at the red line when the water would be boiling, at which point the cap would be letting off pressure above 13 lbs.
FYI, my non contact thermometer only goes to 240 degrees then it says "hot". When at the red line it says hot all the way down the radiator.

I just redid a fill quantity check after verifying how much I've put in with a beaker and still come up about a 1/2 quart low. At this point I'd have to let it cool to see how much more gets drawn in.

Sheesh, what next.

 

[dan filipi]

Wow, this post is almost 4 pages long already!

I drained my 1100 and got almost 3.5 quarts out so something is up with the 1200 not filling completely.
The capacities of the 1100 and 1200 are the same, actually 3.6 quarts not 3.4.
I figger I was short draining mine because some spilled and the reservoir was low.

I've done measured and filled the 1200 3 times, about the same amount goes in every time, a 1/2 qt low.
Maybe there IS a shop rag in the block :Awe:

I'll throw this out here,
supposing it's low on coolant, air pocket or whatever.
The engine warms up and has a spot in it with no coolant, a Hot spot.
Does it seem feasible that water could hit this dry hot spot and "flash" boil the water creating the bubbles?

 

[joedrum]

i dont think the fact that it cooled down some with the fan on means that the pump is working. when boiling the water is self moving through out and would cool some with fan on. on this bike the thermostat is not helping anything. id take it out and check the flow pump with the plugs out with the starter and with the top hose off so you can see the flow. if the water flowed good under those conditions i would put the plugs back in, top hose still off i would idle the motor check the flow and keep topping thre radiator with water. with the motor running idling if exhast gas or someting is causing a problem with flow it would show up now. point is that with the thermostat out and fan on it sould idle realy cool with no chance of boiling and obvious signs of flow and take a while for the water to get warm. check your 1100 on how the water acts under the same cercumstances as you made on your videos this sould tell a lot the cooling systems are almost identical. it might be something crazy like the cross over tube being plugged up, wouldnt that be nice?

 

[mcgovern61]

I'll throw this out here,
supposing it's low on coolant, air pocket or whatever.
The engine warms up and has a spot in it with no coolant, a Hot spot.
Does it seem feasible that water could hit this dry hot spot and "flash" boil the water creating the bubbles?

The answer to that is a resounding YES! The question is where? Take off the cooling tubes and start looking at the obvious places. 1/2 quart is a lot of fluid in this small engine cooling system, something is taking its place. How about trying a spare radiator from the parts bike and filling the system. You can at least rule out the radiator without too much trouble.

 

[dan filipi]

Radiator has been rodded.
I had the tubes off the other day and they are clear.

Gerry, when you did that crank flow video, was the thermostat in?

 

[mcgovern61]

Yes it was. But no plugs. I cranked the engine from a car battery with jumper cables. That is the '83 swap engine.

The radiator has been rodded, but was it done correctly?

 

[mcgovern61]

Did you say before that the 1200 does not have the bypass hole in the pump housing to the tstat?

 

[dan filipi]

I wasnt there when he did it but I asked "every tube clear 100%?" he said yes.

I did a video cranking, be right back.

Did you say before that the 1200 does not have the bypass hole in the pump housing to the tstat?

The 1200 does not have the bypass passage like the 1100 has.

 

[dan filipi]

Here's what I get while cranking.

[video]https://www.youtube.com/watch?v=TBpsC7bykCw[/video]

 

[mcgovern61]

That crank test is correct, the pump is pushing water! It cannot continue to push water after the initial surge because the pressure equalizes after the impeller spins a few rotations and is up against the tstat. Look at my video again and you will see the same thing.

So now the question is, why won't the system fill to capacity? Basic science here; if the cooling system is design for 3.6 quarts, 3.6 quarts must go in. If not, something is either in the way or a passage is not open from an air bubble blocking or just no room.

 

[dan filipi]

tstat is out in my video. Would that make a difference?

In your video it looks like more continues to flow, it does seem to stop after that initial surge though.

 

[mcgovern61]

tstat is out in my video. Would that make a difference?

In your video it looks like more continues to flow, it does seem to stop after that initial surge though.

The tstat being out is ok for this test, the engine is not spinning fast enough with this type of impeller to produce any more flow than that.

 

[dan filipi]

I put the plugs back in and started it.
Except for that initial surge it doesnt pump anything until close to 1000 rpm's. 800 rpm no flow.

 

[mcgovern61]

I would assume flow from 950 on up since that is normal idle. Other wise, the engine would overheat at red lights. You are not seeing flow at 800 (1200 idle speed?) with no tstat? I believe there would and should be continuous flow without the tstat in at engine rpm. Takes us back to either bad pump, impeller or restricted flow. In this case, the flow restriction is on the suction side of the pump since it is a positive displacement pump. It must have water feeding in as much as is being pumped out. No flow in, no flow out.

 

[joedrum]

i dont think that that is enough flow but it could be deceiving with the tstat in there id take it out theres no logical reason to have it in there till it proves it can run cool. that being said. with it out you can test without it being involed and maybe nail down for sure if ther is a problem on the suction side. the whole idea that you can run the bike and it hangs in there makes me think this is a fixable deal. iwould still hook up garden hose and flush that motor reverse flow and forward flow for an afternoon. it might not be air pocket as much as a restriction of flow that causes an air pocket. maybe fill the motor with some krud busting solvent over night or days. with the plugs out and seeing bad flow is a good sign to me. i'd throw everything i could think of to clean all pathways of the cooling system. i would redo the test of flow without tstat and if flow peters out then its got to be some sort of restriction in the system.