Too hot to handle

[Thevmaxrider]

I don't think that's true, the valve below the radiator is only used when draining the rad (to get all the coolant out) the main hose runs out above that straight to the thermostat valve

Full description of what the valve does here:
http://www.vmaxforum.net/showthread.php?t=999

Incorrect, if you position that valve the wrong way your bike will overheat.

 

[johnpclynch]

Incorrect, if you position that valve the wrong way your bike will overheat.

I can't see how that can be, the default position is closed (according to the manual) mine is always closed and I don't have overheating problems.

Have a look behind your rad and you'll see a larger hose above and behind it running into the top of the thermo-valve thingy, there is no valve on that main line :confused2:

 

[Thevmaxrider]

I can't see how that can be, the default position is closed (according to the manual) mine is always closed and I don't have overheating problems.

Have a look behind your rad and you'll see a larger hose above and behind it running into the top of the thermo-valve thingy, there is no valve on that main line :confused2:

Will have to double check, but I believe it changes the flow path and the heads get insufficient coolant flow. Can have a look today and let you know. Do know that needs to be in the drain position to fully drain the coolant out of the block.

 

[johnpclynch]

When in the closed position, coolant is restricted until the thermo-valve opens (when the engine reaches operating temp) as would be expected

If left in the open position, some coolant can bypass and flow in through underside of the thermo-valve before it opens, maybe this will cause extra cooling during startup which might be a problem for sub-zero winter riding

 

[Thevmaxrider]

A quick check of the manual and a review of the coolant flow path shows why it will overheat. If it is left in the drain position it will allow a significant portion of hot coolant to bypass the radiator. If you look at page 4-1 of the manual you can see the flow path under normal operation. Normal flow is down from the coolant header (where the cap is) and then into the bottom of the thermostat, my guess is to let a small amount of coolant to always flow through the system by bypassing the radiator (hence the small size of the coolant line). In drain it opens to the bottom of the radiator right next to the hose where the "cool" coolant heads to the thermostat through a much larger line thus letting a larger volume of coolant to bypass the radiator. As the VMax cooling system has such a small volume it will not get adequately cooled. Know that the position of that valve is important because I have seen several bikes overheat just due to that.

 

[johnpclynch]

A quick check of the manual and a review of the coolant flow path shows why it will overheat. If it is left in the drain position it will allow a significant portion of hot coolant to bypass the radiator. If you look at page 4-1 of the manual you can see the flow path under normal operation. Normal flow is down from the coolant header (where the cap is) and then into the bottom of the thermostat, my guess is to let a small amount of coolant to always flow through the system by bypassing the radiator (hence the small size of the coolant line). In drain it opens to the bottom of the radiator right next to the hose where the "cool" coolant heads to the thermostat through a much larger line thus letting a larger volume of coolant to bypass the radiator. As the VMax cooling system has such a small volume it will not get adequately cooled. Know that the position of that valve is important because I have seen several bikes overheat just due to that.

I think I see what you're talking about, I'll have to take a close look at the valve and see what position it is open to the rad / header / thermostat bypass

 

[Rusty McNeil]

A quick check of the manual and a review of the coolant flow path shows why it will overheat. If it is left in the drain position it will allow a significant portion of hot coolant to bypass the radiator. If you look at page 4-1 of the manual you can see the flow path under normal operation. Normal flow is down from the coolant header (where the cap is) and then into the bottom of the thermostat, my guess is to let a small amount of coolant to always flow through the system by bypassing the radiator (hence the small size of the coolant line). In drain it opens to the bottom of the radiator right next to the hose where the "cool" coolant heads to the thermostat through a much larger line thus letting a larger volume of coolant to bypass the radiator. As the VMax cooling system has such a small volume it will not get adequately cooled. Know that the position of that valve is important because I have seen several bikes overheat just due to that.

Very true.....

On the other hand I've run mine in the wrong position for 6 months, not on purpose, with no ill effects:ummm:

 

[Thevmaxrider]

Very true.....

On the other hand I've run mine in the wrong position for 6 months, not on purpose, with no ill effects:ummm:

Interesting, a buddy of mine changed his coolant and forgot to change the position and his bike overheated within 10 miles of riding:confused2:

 

[johnpclynch]

Ok, same pic as above but with colors


Red is hot, blue is cold (obviouisly) Green flows only when the drain is OPEN and Orange is the bypass pipe that is under scrutiny.

My theory is that the Orange line will be cooler when the drain is open because the hot bypass from the header mixes with some cold from the bottom of the rad allowing my engine to run "slightly" cooler than when the tap is closed.

But to question that theory, you could say that because this Orange line is cooler while warming up then the thermo-valve will remain closed for longer (until almost the entire rad is hot) restricting the main coolant flow and causing temporary overheating

Those with weak or bad valves will have serious/terminal overheating problems, I don't have this issue because I got rid of my thermo-valve years ago

Any other theories? :ummm:

 

[FourthSeal]

My max wasn't getting that hot to boil in the over flow, but it would get to the red line on my gauge and I would have to pull over and let it cool in traffic. I put a low temp thermostat from Vmaxoutlaw.com on it and haven't has my needle go past the screw. I would try the Sentra thermostat though. Didn't know about that one. Could have saved about $50.

 

[weeborado]

Was gone for a while. Working on heat problem still. Priced a radiator cap at dealer- 47 DOLLARS. Are they kidding? Does anyone know where I can get a new replacement for a believable price?

 

[davidon]

Advanced Auto has a cap that will work

 

[KJShover]

Was gone for a while. Working on heat problem still. Priced a radiator cap at dealer- 47 DOLLARS. Are they kidding? Does anyone know where I can get a new replacement for a believable price?

Go to your local parts store (O'riley's, NAPA...) and pick yourself up a STANT cap, model #11233. It will work for you and you can pick them up from about $6-9.

 

[natnic]

+
Run without cap if it still bubbles after warm up get a co2 block check from a garage to test the h gaskit.