adding a water pump & starting on cold mornings

[KellyR]

Hello everyone,

I've got a 7.7hp Changfa clone with the hopper cooling.  I've got a plate over the hopper that goes to a barrel a la thermosiphon.  It works fine. 

However, want I want to do is run the water via copper tubing to a bulk water storage tank.  The problem here is that there will be no more thermosiphon as the tank is about the same level as the engine and there will be ups and downs all through the system.  My engine didn't come with the waterpump as the Changfa 195s do.  Does anyone have any experience adding a water pump to the system? 

Second problem is that in the mornings the temperature is about 50 degrees now.  In the day, it gets to 90 or 95.  Starting the engine in the evening is no problem, but in the mornings, it just won't start.  What would people suggest?  A engine block heater? An injector line heater?

Thanks in advance,
Kelly

[carlb23]

You can use a 110 vac circulating pump for a house furnace, some of them are only 1/40hp and it will be a lot easier to plumb than a mechanical pump.
you can normally pickup one up on ebay new for less that 50 dollars.

If you are having trouble with your engine starting at 50 degrees I would look for a problem other than fuel temp. I don't own a changfa so I am not real familiar with them but I would think it should have no problem starting at those temps without the fuel being heated.

[rcavictim]

I agree you should not have trouble starting at 50 degrees F.  Since you do what will work is to keep a loaded portable propane torch and Bic lighter nearby and play a flame over the fuel injector for as much as a minute (no need to overheat it.  If too hot to touch too hot) before you try to start the cold engine.  This should make a big difference in aiding the start.  If you still have the cheap clear plastic discharge line from the injector back to the tank you should swap that for a real automotive rubber gasoline fuel line and hose clamps.  Someday that will fail and you will have fuel all over the floor.

[KellyR]

I've actually been thinking about a DC pump, but I suppose it would be easier to to run the AC given that I am indeed producing AC with the engine via the generator.  I hadn't thought about a furnace pump.  I'll check into that.

ONe would think that 50 degrees would be warm enough of an ambient temperature to start a diesel, but apparently not.  These things don't have glow plugs so the only heat at startup _is_ the ambient temperature.  I tried to start the thing four times this morning, then gave up.  It started on the first try this evening when the air temp was down to 85 degrees, but had been 95 during the day. 

The plastic drain-back line was replaced long ago.  The genset is outside (but covered) and the frame is sitting on bricks, so I don't have to worry about getting the floor mucked up.  Still I didn't want diesel all over the ground.

[Tom]

You might have low compression. Have you checked it?

[rcavictim]

Actually my Petter PJ-1 will not hand crank start below 50 F but I blame that partly on low compression and thick crankcase oil.  That led to the propane torch trick on the injector which works for me.

[Rustkolector]

I have had a lot of diesel engines, and some where hard to start. The trick was in figuring out just what the engine needed to get it to start in cold weather. I have done some strange things to start engines, but I don't understand how warming an injector helps starting a cold engine? Can someone explain please? I can understand a bad injector nozzle (pump), poor compression, or bad valve adjustment, but these should be evident in smokey exhaust and blowby. 

[KellyR]

I'll check the compression and see what that tells me.  I've never been able to handcrank the engine.  That's partially because with the current frame set-up, I skin knuckles.  I'll also clean the injector.  I'm not a diesel mechanic and am still learning about them, though learning slowly.

[buickanddeere]

  It will start at 20F if cranked with enough rpm. Now getting the required rpms is going to require a serious battery & starter. Or a gasoline "starting engine belted to the Changfa for startup.
  I did see a "red neck" system that used a centrifugal clutch equipped gasoline engine coupled to a modified electric starter. The side opposite to the pinion on the motor was bored through the end cap. A keyed shaft/sprocket with a double chain coupling connected to the centrifugal clutch's sprocket.
  No shortage of cranking torque, cranking rpm or endurance.

[rmchambers]

yeah they are called pony engines.  A friend of mine had a caterpillar tractor that had one.  Get the little petrol engine going and then it would (via a clutch of some sort) get the diesel turning with the decompressor in.   once the big engine is turning drop the decompressor and the beast came to life.  Then you had to remember to shut down the pony engine.

Neat arrangement if you have one laying around you can use for it.

RC

[Doug]

I worked in the bush way back....

We had an old cat dozer just like you discribe and it worked just like discribe. Very simple and reliable.

[rcavictim]

Is the gasoline starter engine still considered a pony engine if it is larger than the diesel it is engaged to start?  That is likely with a Changfa 180 diesel around 400 cc`s displacement.

[rcavictim]

I have had a lot of diesel engines, and some where hard to start. The trick was in figuring out just what the engine needed to get it to start in cold weather. I have done some strange things to start engines, but I don't understand how warming an injector helps starting a cold engine? Can someone explain please? I can understand a bad injector nozzle (pump), poor compression, or bad valve adjustment, but these should be evident in smokey exhaust and blowby. 

Heating the injector helps a lot in getting a start when the fuel in it is oil and not straight thin store bought diesel fuel.  Thick fuel is what is presently in the single fuel system on my Petter.  My Petter does not have blowby (just a few hundred hours on fresh crosshatch and ring set) but I suspect could use higher compression (smaller bump clearance above piston).

[KellyR]

Doesnt' it seem a little over the top to add a gas-powered engine to 7.7 hp diesel to get the thing started?  I can see it on a big CAT engine, but a 400cc?  I have absolutely no trouble starting the engine after it's warmed up in the day.  It's when the temp outside is cold, like in the mornings, that the engine won't come to life.  Seems to me that the battery and starter are powerful enough.  Also, and pardon my lack of diesel expertise here, why would low compression affect starting ability in the cold?  Wouldn't heating the injector line or heating the case before starting the engine (as the glowplugs do in bigger diesels) make more sense?

[oliver90owner]

Hi KellyR,
 
You wrote: my lack of diesel expertise

Now you may well be aware that there is no spark plug on a diesel.  The diesel engine relies on compression of the air charge to release energy from the charge as heat - enough heat to make the charge hot enough to immediately burn the fuel as it is sprayed in as a fine mist/spray (the injection).

Ideally the compression is very fast and all, or very nearly all, the heat stays in the gas.  That is termed adiabatic conditions.  However if the metal surfaces are cooler than the gas, heat will pass to the metal by conduction and start to heat up the metal with consequent cooling of the gas. 
Now, under starting conditions quite a lot of the heat energy is lost as the compressed charge is swirling around in the combustion chamber.  If there is not enough temperature to spontaneously ignite the fuel as it is injected your engine will not start.  The colder it is the more heat is  lost from the compressed gas.  That is assuming the compression is adequate in the fiirst place to 'free up' enough heat energy.

That is why direct injection engines will start (and run) on much lower compression ratios than indirect injection ones (the air charge is shoved through the 'ducting' to the pre-combustion chamber in the indirect injection system and so loses more heat energy than a direct injected engine. 
That is why the original CS's had a change over valve for starting - high compression for starting and lower compresssion for running on heavy loads.

So other fixes...

Turn engine much faster - difficult with cold oil and hand cranking  or starter motor (is only one speed) and battery power is down under cold conditions etc etc.  Hence the pony (or donkey motor as it is known on our side of the pond).

Use heater plugs - squirt that fuel onto a glowing plug and that helps to get it going.

Heat the engine. Running hot water through the engine or whatever improves the starting just like starting a warm or hot engine.

Heat the in-going air - several systems from burning fuel in the inlet manifold to waving a gas torch around in the induction air.

Use a more volatile fuel - like don't try to start it on lard!

Use starting fluid - works but unless under very cold conditions I don't like this idea.  The volatile starter fluid can burn with an excessive flame path speed and easily damage the engine (detonation or explosion speeds cause shock waves which can break rings overload bearings etc).

So the choice is yours.  Which way you go might depend on whether the compression ratio is too low, compression is being lost, too slow cranking, or whatever.  A heater plug addition for cold starting may be the best plan, I don't know whether the engine could standhigher running compression or not....

Hope this helps and you understand the diesel a little more now than at the beginning.

Regards, RAB