Overheating question.

[fatbiker]

Recently got my Max running and took it out for our first test ride. The water temperature went straight up to the red line and stayed there as the fan kicked on. Coolant poured from the overflow tank and coolant steam heated my legs. Got her back home and did a flush then filled with new coolant. On our second test run she the gauge needed stayed in the middle but as soon as I stopped climbed to the red fairly quickly. Got her home and found out that there is a leak at the thermostat cap. Ordered parts from Sean Morley then went to work taking things apart. I opened the thermostat housing and found that there is not a thermostat in there! PO was to cheap to buy a new one I guess. Also found out the drain petcock was not on the ON or the OFF position but in between. So my question is, could the missing thermostat be a cause of overheating or could it be coolant was having a hard time getting past the mis-adjusted petcock? Or both?

Thanks in advance!

Fatbiker

 

[donnelly317]

Probably the petcock. There isnt a thermostat per sayblike your car under that cap.. either before or after the cap aka where you fill it theres a brass fitting with wires. Thats the thermostat all it does is turn on the fan. Otherwise I believe it just constantly flows... you can install a over ride switch cost like 5 bucks from radio shack so you can turn fan on whenever you want.. if I stop on a hot day at a light I turn it on.. keeps temps way down

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[donnelly317]

Which got me thinking a thermostat keeps closed not allowing coolant to flow.. usually sticks closed. If it sticks open coolant constantly flows threw radiatiator in the winter your vehicle will take a long time to heat up. I dont know the exact purpose of the petcock many if you leave on or drain position it doesn't allow coolant to flow?

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[fatbiker]

Hey Donnelly317, the section I speak of is next to the starter on the front of the bike. There is a thermostat housing which holds an actual metal thermostat just like the one in cars and trucks. When I pulled the housing off and opened it the thermostat was missing. I agree that the petcock was either restricting or completely cutting off coolant flow but I'm wondering if a missing thermostat can cause overheating as well.

Fatbiker

 

[donnelly317]

I did not know this! I thought there was only fab switch thermostat. Well anyways without a thermostat I would think coolant would constantly be running threw radiator keeping it cooler not over heating it.

http://www.vmaxforum.net/showthread.php?t=11177

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[wildweasel_pt]

When you drained was there crap on the coolant? May have a blocked rad.

 

[Traumahawk]

When you did a flush...did you use vineger?

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[fatbiker]

I read on another post to use vinegar so I did and no, there was not any crud in the coolant. I drained it into a clean 5 gallon bucket so I could get a good look at it. I have no idea how old the coolant was but it was a nice green color and looked clean. As soon as my new thermostat and O-rings come in I'll put it all back together and see if it overheats again. I bought a Stant 180 degree thermostat so I hope that helps.

 

[sdt354]

T-stat removal is usually done to mask an issue. It's not the right way to do it,unless to just get you home. You need to eliminate the possibility of a head/gasket problem. An automotive exhaust sniffer will quickly tell you if there is co in your coolant. I'm sure a six pack or a $20 can get someone to help you out at a small garage for a couple of minutes. After you fill and let the air burp itself out of the system, there should be no air bubbles at the cap opening. If the integrity of the heads/gasket is good-lets hope, move on to the cooling system. Drain all the coolant. There are threads here showing how to drain ALL the coolant out, and the position of the petcock for draining and running. I'd pull the radiator flush it out, or have a shop flush it. Eric's vinigar suggestion is the way to flush the whole system. Install a new t-stat. Inspect and test the cap. Your fan sounds like it's working. Refill with antifreeze/water,burp it-get all the air out by running it without the cap on the centerstand. I like the pre mixed long life stuff. I'm sure I forgot some detail. Others will chime in and help you out too, I'm sure.
Steve-o

 

[MaxMidnight]

Check that the radiator isn't blocked.
Remove the stone guard so that you can feel the fins and start the motor from cold.
It should stay cold(ish) until the thermostat starts to open.

Feel for any cool or cold spots as this would suggest that part of the rad core is blocked.

Might also be worthwhile trying another pressure cap.

Steve's suggestion for establishing if a head gasket has gone is a good one but don't let the sniffer go into the coolant.
Intercourseing the garages CO tester does tend to irritate them!

 

[bazwell]

I agree with all that ^ great advice. :biglaugh:
No thermostat and new coolant points to someone masking (or concealing) a problem. Check it out real good to find out why someone did it!


Because you asked, on some vehicles with a dual action thermostat (ie. when one passage opens, another passage closes), removing the thermostat can cause it to run hotter.
That's because not all the water goes through the radiator when it should. (It's unusual.)

 

[fatbiker]

Thanks bazwell, that's what I needed to know! I have a new thermostat and all the gaskets on order; they should be here later this week. Will update when I get them all installed.

Fatbiker

 

[sdt354]

Which got me thinking a thermostat keeps closed not allowing coolant to flow.. usually sticks closed. If it sticks open coolant constantly flows threw radiatiator in the winter your vehicle will take a long time to heat up. I dont know the exact purpose of the petcock many if you leave on or drain position it doesn't allow coolant to flow?

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The petcock, routes the coolant to assist in draining the system. It doesn't interrupt flow completely in any position.

There is a correct running position for the petcock. Dannymax has an old thread on here you can research, explaining the whole petcock story. He's not just a carb Guru.

 

[fatbiker]

My order of gaskets, o-rings, hoses, and a thermostat from Sean Morley came in yesterday. Took about an hour to get them all on, add coolant, and check for leaks. The one o-ring I did not buy was for the drain petcock and of course it has a very small leak. Once up to operating temperature I found 2 water hose leaks which were easily fixed by tightening the hose clamps. Took her out for a spin and the temp gauge hovered near the middle for the entire ride except when stopping at a light. I did rev the bike for a few minutes to see if I could get it to over heat but it never did. Temp gauge got up to the first red mark but the fan kicked on and the temperature dropped fast. Much better than my last ride where the gauge stayed on the first red line the entire time. Next up will be all new hoses as I'm sure the ones on the bike are 28 years old.

Fatbiker