The real radiator fix.

[duibhceK]

What's weird is there was no indication of an overheat, or even close to it on the dash temp display.

By the way, the temp display shows the temperature from the sensor in the airbox, not oil or coolant temp.

 

[engineerk9]

By the way, the temp display shows the temperature from the sensor in the airbox, not oil or coolant temp.

The bar graph on the dash shows the cylinder head temp - that is the cooling water temperature

 

[engineerk9]

Here is the magical mistake of a side tank on the original.
As you can see in the last picture the thermostat comes out and is replaceable. I did not see in the parts manual where you can get it separate. View attachment 42212 View attachment 42213 View attachment 42214 View attachment 42215

The simplest modification is to remove/unclip the thermostat from the support bracket & glue a plastic disc over the thermostat opening on the support bracket

This allows the coolant to flow thru' the top half radiator into the lower half & to the water pump suction

& prevents it bye-passing the radiator

 

[duibhceK]

The bar graph on the dash shows the cylinder head temp - that is the cooling water temperature

ah, yes. Very true. I hadn't thought about that one.

 

[Baddrapp]

I have the zipty thermostat delete. Last September I did a 9 day trip to Moab Utah with a friend. The temps ranged from 28 degrees in the mornings in the mountains to 114 degrees in the deserts of California. The bike warmed up quickly and never once overheated fly down the 40 in the high temps. I way overheated stopping at every rest stops to hydrate and wet myself down. I also run zipty's coolant. Bike runs great.

 

[danketchpel]

Upon further checking some of the bubbling appears to be the coating (what is that stuff?) that has bubbled, but the cracks are kinda scary.

I rode it since seeing that and the temps are normal and the tanks do not leak, for now..... I don't believe the T-stat failed but it's extremely hard to know that for sure. It's working quite normally now. I just don't like any of that aspect of the radiator design, the T-stat or the tanks.

I contacted Fontana Radiator and they can custom build aluminum header tanks for the original core no problem. To price it they need to see the unit which is understandable. I'll pull the radiator off and make a run out there.

I'm going the aluminum route for durability, both temp and crash. I will be using a Thermo Bob external thermostat. His housings use off-the-shelf T-stats so you can choose what temp you want. The also include an insert for the bypass.

 

[drzcharlie]

The simplest modification is to remove/unclip the thermostat from the support bracket & glue a plastic disc over the thermostat opening on the support bracket

This allows the coolant to flow thru' the top half radiator into the lower half & to the water pump suction

& prevents it bye-passing the radiator

If that's the case why not do this? It should seal again and no extra futzing around.

 

[engineerk9]

If that's the case why not do this? It should seal again and no extra futzing around.

Absolutely not - your suggestion cutting thru' there ensures that all the coolant will bye-pass the radiator, guaranteeing over heating

Removing the thermostat & the 2 tangs, then gluing a blanking disc across the top will divert more than 95% (assuming some leakage) of the coolant thru' the radiator giving maximum cooling effect

 

[engineerk9]

If that's the case why not do this? It should seal again and no extra futzing around.

Coolant always flows thru' both upper & lower radiator cores, the thermostat controls the amount of coolant that can bye-pass the radiator

Actually, very clever design as there is always maximum coolant flow thru' the motor, the thermostat can in no way restrict water flow thru' the motor

If the thermostat failed (in the open position), there would always be maximum coolant flow thru' the motor & some coolant flow thru' the radiator

Riding gently (watching the dash temperature bars) would get you home without damaging the motor

If it failed in the closed position you'd very likely not notice - all coolant passing thru' upper & lower radiators

 

[engineerk9]

Upon further checking some of the bubbling appears to be the coating (what is that stuff?) that has bubbled, but the cracks are kinda scary.

I rode it since seeing that and the temps are normal and the tanks do not leak, for now..... I don't believe the T-stat failed but it's extremely hard to know that for sure. It's working quite normally now. I just don't like any of that aspect of the radiator design, the T-stat or the tanks.

I contacted Fontana Radiator and they can custom build aluminum header tanks for the original core no problem. To price it they need to see the unit which is understandable. I'll pull the radiator off and make a run out there.

I'm going the aluminum route for durability, both temp and crash. I will be using a Thermo Bob external thermostat. His housings use off-the-shelf T-stats so you can choose what temp you want. The also include an insert for the bypass.

WHY ???

 

[drzcharlie]

Absolutely not - your suggestion cutting thru' there ensures that all the coolant will bye-pass the radiator, guaranteeing over heating

Removing the thermostat & the 2 tangs, then gluing a blanking disc across the top will divert more than 95% (assuming some leakage) of the coolant thru' the radiator giving maximum cooling effect

Ok, I obviously don't know the mechanics of this radiator, in fact I've not done anything radiator related except to change the coolant and burp it.

 

[Tinken]

Coolant always flows thru' both upper & lower radiator cores, the thermostat controls the amount of coolant that can bye-pass the radiator

Have you tested this? Because I don't think this is how it actually works.

 

[danketchpel]

WHY ???

Because I'm done with this funky, fragile, and hard to service design. I really see little merit to it other than it's compact as far as the integrated T-stat goes. All my other liquid cooled bike engines simply place the T-stat on the engine under a simple to access cover and have full aluminum construction radiators.

If you look at current KTM designs they are using a stand-alone T-stat housing mounted some place between the engine and radiator.

It's not that hard to make it much more durable and easier to service. I will be fabbing aluminum mounting brackets while I'm at it to replace the flimsy plastic ones.

 

[Mark_H]

When the thermostat fails or is in it's closed position, there is no coolant flow.

NO COOLANT FLOW ??? Are you serious ?

With the Thermostat in the closed or cold position it is actually an open circuit and there is little or no coolant flow across the radiator core, but there is flow in and out of the right hand side of the radiator - There has to be for the Thermostat to be heated up and react to the increased water temperature.
When the thermostat moves to its hot position it closes off the bypass and acts as a baffle to reroute the coolant flow across the radiator core instead of round the shorter circuit.


Furthermore, the dash temp display does not rely on 'coolant flow' as it comes from the sensor on the engine cylinder block, therefore in the situation of a Thermostat failure it should read high and activate the 'overheat' warning light on the dash.

Dan K's radiator definitely looks to have suffered a Thermostat failure which would cause the overheated coolant to flow only round the shorter circuit, ie in and out of the right side of the radiator only, eventually heating so much as to cause the damage. The question remains as to why he did not have high dash temp or a warning light to indicate what was happening before the damage occurred.

 

[Mark_H]

Because I'm done with this funky, fragile, and hard to service design. I really see little merit to it other than it's compact as far as the integrated T-stat goes. All my other liquid cooled bike engines simply place the T-stat on the engine under a simple to access cover and have full aluminum construction radiators.

If you look at current KTM designs they are using a stand-alone T-stat housing mounted some place between the engine and radiator.

It's not that hard to make it much more durable and easier to service. I will be fabbing aluminum mounting brackets while I'm at it to replace the flimsy plastic ones.

Like I said - You do not need a thermostat in California, so why bother ?

 

[Mark_H]

Have you tested this? Because I don't think this is how it actually works.

You don't think ??? I don't mean to get personal, but if you do not know how it works, why are you offering explanation on this problem?

See my explanation above as to how the TR650 Thermostat actually works and to further clarify the matter, have a think as to how the 'in radiator' thermostat does get heated up so as to be able to operate.

Here it is in basic terms.

In any engine liquid cooling system the thermostat is designed to close off the radiator and cause the coolant to flow around the engine only in order for it to heat up and reach normal operating temperature more quickly in cold climates.
The thermostat has to have coolant flowing across it so as it can react to the increase in the temperature of the coolant and then move to close off the shorter circuit or bypass in order to re-direct the coolant via the radiator for cooling purposes.

Therefore, with the TR650 thermostat actually being in the radiator there has to always be a flow of coolant in and out of the radiator for the thermostat to work. The coolant flows in and out of the right side of the radiator with the thermostat in cold position and then as it heats up the thermostat moves to hot position, redirecting the coolant flow across the radiator - simple.

 

[Mark_H]

The simplest modification is to remove/unclip the thermostat from the support bracket & glue a plastic disc over the thermostat opening on the support bracket

This allows the coolant to flow thru' the top half radiator into the lower half & to the water pump suction

& prevents it bye-passing the radiator

I really want to do this but try as I might, I simply cannot get my thermostat out of my TR650 radiator, it just will not move. (Hammer etc applied)

I also have a Nuda 900R with exactly the same radiator, as soon as it has had the warranty service, I will be removing the thermostat from that bike too.
Temperatures where I am rarely drop below 25C and in the daytime average 32-35 so IMHO my bikes do not need Thermostats in the cooling system.

 

[Tinken]

Someday when you actually get your thermostat out, take a closer look at it. If it worked as intended, we wouldn't be sitting here having this conversation.

 

[engineerk9]

NO COOLANT FLOW ??? Are you serious ?

With the Thermostat in the closed or cold position it is actually an open circuit and there is little or no coolant flow across the radiator core, but there is flow in and out of the right hand side of the radiator - There has to be for the Thermostat to be heated up and react to the increased water temperature.
When the thermostat moves to its hot position it closes off the bypass and acts as a baffle to reroute the coolant flow across the radiator core instead of round the shorter circuit.


Furthermore, the dash temp display does not rely on 'coolant flow' as it comes from the sensor on the engine cylinder block, therefore in the situation of a Thermostat failure it should read high and activate the 'overheat' warning light on the dash.

Dan K's radiator definitely looks to have suffered a Thermostat failure which would cause the overheated coolant to flow only round the shorter circuit, ie in and out of the right side of the radiator only, eventually heating so much as to cause the damage. The question remains as to why he did not have high dash temp or a warning light to indicate what was happening before the damage occurred.

Mark you are correct - removing the thermostat would allow the coolant to take the easiest path, ie bye-passing the radiator cores - therefore little if any cooling, virtually no coolant flow thru' the radiator cores

The dash temp comes from the cooling spaces in the cylinder head

Read my post, which states that there is always coolant flow thru' the motor, irrespective of thermostat condition, that's the clever design

Most motorcycle thermostats actually restrict coolant flow

As is suggested previously

 

[engineerk9]

You don't think ??? I don't mean to get personal, but if you do not know how it works, why are you offering explanation on this problem?

See my explanation above as to how the TR650 Thermostat actually works and to further clarify the matter, have a think as to how the 'in radiator' thermostat does get heated up so as to be able to operate.

Here it is in basic terms.

In any engine liquid cooling system the thermostat is designed to close off the radiator and cause the coolant to flow around the engine only in order for it to heat up and reach normal operating temperature more quickly in cold climates.
The thermostat has to have coolant flowing across it so as it can react to the increase in the temperature of the coolant and then move to close off the shorter circuit or bypass in order to re-direct the coolant via the radiator for cooling purposes.

Therefore, with the TR650 thermostat actually being in the radiator there has to always be a flow of coolant in and out of the radiator for the thermostat to work. The coolant flows in and out of the right side of the radiator with the thermostat in cold position and then as it heats up the thermostat moves to hot position, redirecting the coolant flow across the radiator - simple.

Mark, the thermostat does not cover the inlet or outlets of the radiator cores - effectively the radiator is 2-pass - the thermostat allows colder coolant to bye-pass the core - as the coolant heats up the thermostat closes off the bye-pass, directing more flow thru' the cores