Engine warming!

[LostKiwi]

80c seems about a std target, smaller flow, smaller rad ,more temp if you want to use motor at higher output.ie more heat. a compromise will need to be found.put a 2inch ball,gate valve in and try strangling the flow until you find that compromise then come up with a permanent version or make yrself a winter summer, poodle and flat out running.. setting on the valve handle.
i ran a water cooled 6cyl detroit on a water pump with no rad for more than ten yrs i took a bleed off the 6inch water pump it was running to a large tank about 600 lt. then i closed down a gate valve from the engine to the tank in such a way as to keep the capilary guage at 88.excess water returned to pump suction. worked great.only issue 2x a yr cleaning river silt from the tank

Bush engineering

 

[umblecumbuz]

Plumb in a radiator bypass. When the thermostat is shut all coolant goes through the bypass. When open some will go through the radiator, some through the bypass. If the bypass is smaller cross sectional area than the radiator then as the thermostat opens the preferred flow will be through the radiator with some going through the bypass. You may need to increase the size of the radiator to allow for the lost flow in the bypass.

You'll probably need to move the thermostat to be remotely mounted (and it needs to be as close as possible to the engine and bypass junction).

A thermostat is a bypass switch, and the bypass loop is already there.

If this engine is designed to run cool (compared to what we're used to with car engines) then that has to be the base to work from.

Two problems then remain:
1. It overheats when given full bore for a long period.
2. The oil is running too cool and needs to be heated somehow.

The overheating takes it into an area it was not designed for, and a large cooling capacity with a fast flow is therefore needed - just the opposite of its requirements in any other driving condition.

Possibly heat from the engine block can be diverted more effectively to the sump.

Headaches, but not insurmountable!

Extremely interesting thread.

 

[LostKiwi]

A thermostat is a bypass switch, and the bypass loop is already there.

A thermostat is a flow switch not a bypass switch.
The rest of the plumbing configuration will determine if it is a bypass or not.

 

[umblecumbuz]

A thermostat is a flow switch not a bypass switch.
The rest of the plumbing configuration will determine if it is a bypass or not.

Whatever the correct term is, it either opens a second circuit or closes it - which is the point I was making. Technically I guess I was wrong in calling it a switch, because it's more a modulating valve, adjusting the flow between two separate linked circuits, but I hope my meaning was clear.

 

[LostKiwi]

Whatever the correct term is, it either opens a second circuit or closes it - which is the point I was making. Technically I guess I was wrong in calling it a switch, because it's more a modulating valve, adjusting the flow between two separate linked circuits, but I hope my meaning was clear.

When configured like this it acts as a variable flow switch:

The rest of the plumbing around it will determine if the nett effect is a bypass.

I get where you're coming from though.

 

[KeithJG]

If you don`t like the idea of removing the spring from the radiator cap which will lower the rad. pressure and create more heat then the easiest and cost saving way is to simply use an adjustable radiator blind.

At least the rad. blind is adjustable so easy and compensates for Winter and Summer ambient temp. of the air flow.

Usually a low opening temp. thermostat is used where the engine runs at a higher temp. and so it opens earlier to give more headroom. Yours is fully open at 98c which does indicate that as other engines it should run as near to boiling point as possible to give power, economy and less wear.

A good example of higher and lower stat. is the Volvo S40 ....the Volvo engined motor has a 92c stat and the Mitsubishi engined model with a high compression ratio has the 87c stat because it is higher revving giving more bhp but shares the same cooling system.

Another way is to have a plate instead of the stat. with a hole in it .....if it runs too hot then drill that hole larger until you run at the correct temp......the warm up time will be longer but who cares on a bike as you don`t have a heater to keep warm or demist!

 

[ajlsl600]

Bush engineering

a little but sometimes one HAS to think outside the box, and it worked !!!! IN africa thinking inside pre conceived ideas dont get much done .

 

[ajlsl600]

If you don`t like the idea of removing the spring from the radiator cap which will lower the rad. pressure and create more heat then the easiest and cost saving way is to simply use an adjustable radiator blind.

At least the rad. blind is adjustable so easy and compensates for Winter and Summer ambient temp. of the air flow.

Usually a low opening temp. thermostat is used where the engine runs at a higher temp. and so it opens earlier to give more headroom. Yours is fully open at 98c which does indicate that as other engines it should run as near to boiling point as possible to give power, economy and less wear.

A good example of higher and lower stat. is the Volvo S40 ....the Volvo engined motor has a 92c stat and the Mitsubishi engined model with a high compression ratio has the 87c stat because it is higher revving giving more bhp but shares the same cooling system.

Another way is to have a plate instead of the stat. with a hole in it .....if it runs too hot then drill that hole larger until you run at the correct temp......the warm up time will be longer but who cares on a bike as you don`t have a heater to keep warm or demist!

last para bout right i would gate valve it, get an idea of cross section size then plate it to a known size, maybe have a winter ,and summer plate....

 

[turbopete]

Or some sort of variable radiator blind

that's pretty much what I was trying to suggest in the earlier post I made. although deleted on the new shape, my Mondeo has one and it does heat up quite quickly for the size of engine, coolant capacity etc BECAUSE it has an automatic 'blind' over the radiator to block airflow when needed and allow it when its not needed. you may be able to come up with some sort of manual variation so you can shut off airflow through the rad at low engine temps and open it when the temps get higher (assuming you have a permanent visible gauge in your instrument cluster.)

 

[Arudge]

In my very humble opinion......Your probably dissipating as much heat as your generating!!! Either block off the airflow to the rad completely and/or fit water heaters, or possibly a sump heater to try and get some warmth into the oil.

 

[alexanderfoti]

So, regarding the bypass valve/stat discussion. On this engine, when the stat is closed, coolant entirely bypasses the rad, and goes Engine > header tank> Pump > Engine

So, the idea of a bypass valve isnt a bad one, but keeping the stat closed longer would be a better option.

I agree with Arudge, I think at the this point, the engine simply is not being loaded enough to generate any meaningful heat in the cooling/lubrication system.

I ran with the radiator entirely blocked this weekend, around 45 minutes but it was late and cold (2 deg c) and the engine temp stayed around 80 degrees. Oil temp was the same.

I think an oil to water heat exchanger will serve to heat the oil in this scenario which isnt a bad thing. I will have to see how the engine operates under full load though, still haven't had a chance to do that.

 

[LostKiwi]

Ah.... If when the stat closed the flow went engine, pump, engine then it would need to heat a smaller volume of water and heat up quicker.
Part of the problem is diesels also ingest full cylinders of air on each induction stroke (which petrol engines don't). On old car engines they used to fit a hot air intake with a bimetallic valve to switch to cold air after a certain temperature was reached. That may also help if it could be done (you have limited space obviously).

 

[alexanderfoti]

Ah.... If when the stat closed the flow went engine, pump, engine then it would need to heat a smaller volume of water and heat up quicker.
Part of the problem is diesels also ingest full cylinders of air on each induction stroke (which petrol engines don't). On old car engines they used to fit a hot air intake with a bimetallic valve to switch to cold air after a certain temperature was reached. That may also help if it could be done (you have limited space obviously).

I may try that, but for some reason its a massive pain to get air out of the system, I may try to insulate the header tank at least if now. Good shout about the hot air intake. The intake is already under the tank and out of the stream of cold air, not much places I can pull hot air form though,.

 

[LostKiwi]

I may try that, but for some reason its a massive pain to get air out of the system, I may try to insulate the header tank at least if now. Good shout about the hot air intake. The intake is already under the tank and out of the stream of cold air, not much places I can pull hot air form though,.

How about off the exhaust manifold?

 

[alexanderfoti]

How about off the exhaust manifold?

Its sat out of the front of the engine, just behind the radiator.

 

[Arudge]

I had a little 1.5t Nissan N120 mini digger for many years, it was fitted with a Mitsubishi K3B 800cc three cylinder diesel, not unlike yours, rated at 17 hp. I put 1300 hours on that machine before i sold it and it never missed a beat. I often poked my finger in the top of rad but it never really got that hot, by virtue i could put my finger in the top of rad it couldn't be that hot. 17 hp does not generate a lot of heat.

My point is....

Is it really that important that a machine putting out just 17hp has to reach optimum operating temperature? It's not exactly that stressed, especially if it's fitted to a Honda pudding. You'd quite possibly get away with draining all the coolant out and allow it to air cool, just like the original engine that did sit in that frame.

See my point?

 

[Arudge]

Just had a quick look..........

The Honda 250N was rated at 27hp, but it was petrol.......

Those were the days

 

[alexanderfoti]

Yes, but in the aim for fuel economy, the engine must get warm, as must the oil. With both hot it will probably net me 20+ mpg!

 

[Arudge]

Yes, but in the aim for fuel economy, the engine must get warm, as must the oil. With both hot it will probably net me 20+ mpg!

Criky, never realised it would make such a difference!!

 

[alexanderfoti]

Criky, never realised it would make such a difference!!

On this bike, probably not far off, on a car with a bigger engine probably a fair bit less.