Engine warming!

[alexanderfoti]

Hi Pete, well its both.

The low coolant temps are causing low oil temps.

The original rad was probably twice the size of this, but obviously designed for static use, so only air driven by the fan.

The stat would be the best place to start, as If I block the entire rad off, the engine overheats in long use high load scenarios (motorway etc).

 

[alexanderfoti]

but surely the engine your using is designed to move slower , so would naturally get hotter with less wind assisted cooling ?

Yes I think part of this is the issue, a) its normally in an enclosure (tractor bonnet etc) b) its very low speed stuff so doesn't have the wind cooling and c) its a big old cast iron engine, so lots of thermal mass to get hot!

 

[bembo449]

so is that not also the answer ? getting the flow of air to balance to achieve optimum temp ?

 

[alexanderfoti]

so is that not also the answer ? getting the flow of air to balance to achieve optimum temp ?

Possibly, but being an efficient diesel, its also about getting heat into the oil and cooling system and keeping it there.

i have thought about a davis craig electric water pump and controller. I already have an electric water pump, but their controller gets rid of the thermostat and pulses the pump to increase warm up times and efficiency. Only problem is that its rather expensive (£200 ish) so would rather not go down that route.

 

[bembo449]

its an interesting issue pal , hope you find the answer

 

[alexanderfoti]

its an interesting issue pal , hope you find the answer

Thanks! Illl take it out on a fast road tomorrow with the cold weather and see what the temps do.

 

[umblecumbuz]

but surely the engine your using is designed to move slower , so would naturally get hotter with less wind assisted cooling ?

That's exactly the point Pete is making.
With the engine now fitted to a bike that goes several times faster than its original installation, the cooling effect will be far higher, which means that the motor is now seriously overcooled (as are most cars in our climate as it happens).

Whatever is done to the thermostat, it must be remembered that a 'stat does not produce heat. At best, it helps open a path so that excess heat is dissipated. If there is no excess heat then the 'stat is more or less redundant, because it will never open.

The core excercise seems to be limiting the cooling capacity while the bike is moving at normal traffic speeds, while keeping sufficient cooling capacity to cope with stationary or near stationary conditions. Not an easy compromise.

 

[alexanderfoti]

That's exactly the point Pete is making.
With the engine now fitted to a bike that goes several times faster than its original installation, the cooling effect will be far higher, which means that the motor is now seriously overcooled (as are most cars in our climate as it happens).

Whatever is done to the thermostat, it must be remembered that a 'stat does not produce heat. At best, it helps open a path so that excess heat is dissipated. The core excercise seems to be limiting the cooling capacity while the bike is moving at normal traffic speeds, while keeping a cooling capacity to cope with stationary or near stationary conditions. Not an easy compromise.

Exactly, and that's the problem.

As the stat opens at 71. and I am running a coolant temperature of roughly 74 around town, the stat is barely opening and the rad is cooling it down. If I could get the stat to start opening at 80+ that would give measurable gains. I may attempt to insulated as may open areas as possible on the engine too, but its difficult.

 

[umblecumbuz]

In theory, blanking the radiator - or bypassing it with appropriate pipework - while the bike is travelling, will improve engine temperature because its cooling mechanism (the radiator) isn't then operating. A welcome side effect will be the oil temperature, which will then improve also.

At the same time, allowing the radiator to function normally while the bike is near-stationary will keep the engine from overheating.

How to get those two opposite requirements in balance is the engineering problem. A divertor valve in the engine/radiator circuitry might do it.

 

[alexanderfoti]

In theory, blanking the radiator - or bypassing it with appropriate pipework - while the bike is travelling, will improve engine temperature because its cooling mechanism (the radiator) isn't then operating. A welcome side effect will be the oil temperature, which will then improve also.

At the same time, allowing the radiator to function normally while the bike is near-stationary will keep the engine from overheating.

How to get those two opposite requirements in balance is the engineering problem. A divertor valve in the engine/radiator circuitry might do it.

Or some sort of variable radiator blind.

There are 3 states to deal with rather than 2.

stationary riding - virtually zero engine output.
Low speed riding - low engine output
high speed riding - Full engine output

The issue is that as the bike only makes 20bhp, doing motorway speeds requires full throttle for extended periods of time, which does actually tax the cooling system, so fast speeds end up putting a considerable amount of heat into the system (being that diesel fuel=heat ). So, antyhing that keeps the system up to temp at low speed riding may end up allowing the bike to overheat on fast speed riding.

 

[umblecumbuz]

Radiator blind sounds better.

Giving what I said earlier further thought - a divertor valve is what a properly matched thermostat is! It changes the circuitry according to the cooling need.

Worth rigging up a manual radiator blind as a test, to see how big its effect would be.

 

[alexanderfoti]

Radiator blind sounds better.

Giving what I said earlier further thought - a divertor valve is what a properly matched thermostat is! It changes the circuitry according to the cooling need.

Worth rigging up a manual radiator blind as a test, to see how big its effect would be.

Its already half covered, and giving 73 degrees odd with 2 degree ambient temperature. Have a longer ride tomorrow so will see what happens with a bit more covered.

 

[Frosty149]

Can the speed of the water pump be reduced, by changing the pulley size?
My thinking being to reduce the effectiveness of the existing cooling system and so allow the stat to be more effective in regulating the running temperatures.

 

[alexanderfoti]

Can the speed of the water pump be reduced, by changing the pulley size?
My thinking being to reduce the effectiveness of the existing cooling system and so allow the stat to be more effective in regulating the running temperatures.

You have a point there. I am using an Electric water pump that is wired to 12v on ignition on. Its possible that by slowing it down the system will remain hotter. The only thing is how do I slow the pump down and know whether its too slow.

 

[umblecumbuz]

The only thing is how do I slow the pump down and know whether its too slow.

Er ... with a thermostat? Not joking - an electric 'stat would cycle the pump according to need. (Think household central heating 'stats).

There is another way of looking at this conundrum:
My marine diesel engine runs so cool that I can keep my hand on the block. It uses sea water as a cooling agent, and this is flushed through constantly. It's designed to run cool. I had an old Lister diesel stationary engine that was also designed to run cool. Would your diesel also be of the same ilk? If so, trying to get it to run at car engine temperatures might be overkill (poor choice of phrase there).

 

[Frontstep]

Its operating temperatures must be out there somewhere, so good point.
Heat after all is mainly waste, although in the coming months ducting it as required towards the rider would be appreciated.


Looked it up for interest seems running a cool Kubota isn't a problem,

http://www.tractorbynet.com/forums/kubota-owning-operating/23949-normal-coolant-temperature.html

 

[ajlsl600]

could you adapt a small oil cooler rad to yr needs or god forbid find another water pump and reduce its impellor size, or drill a few holes in it.

 

[LostKiwi]

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).

 

[ajlsl600]

Can the speed of the water pump be reduced, by changing the pulley size?
My thinking being to reduce the effectiveness of the existing cooling system and so allow the stat to be more effective in regulating the running temperatures.

if its pulley driven......

 

[ajlsl600]

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