Compression release for cold weather starting?

[bucktail]

I understand that if your tractor is equipped with compression release, you're supposed to spin it over a little before you start it for real, but what does that accomplish? Is it to get extra fuel into the cylinder, kind of like choking a gas engine? getting oil to the engine before it starts for longevity?

Some of the old JD and Farmall diesels had compression release so that they could be started on gas, but I'm curious as to what it's actually accomplishing here. It is a great feature when you need to bleed the injectors.

 

[85Hokie]

I understand that if your tractor is equipped with compression release, you're supposed to spin it over a little before you start it for real, but what does that accomplish? Is it to get extra fuel into the cylinder, kind of like choking a gas engine? getting oil to the engine before it starts for longevity?

REALLY NEITHER - EVEN THOUGH BOTH MIGHT BE A GOOD SECONDARY REASON.

Some of the old JD and Farmall diesels had compression release so that they could be started on gas, but I'm curious as to what it's actually accomplishing here. It is a great feature when you need to bleed the injectors.

WHEN AN ENGINE IS REALLY COLD - THE BATTERY IS NOT QUITE AS "GOOD" AS IT COULD BE - SO ALLOWING A COMPRESSION RELEASE - ALLOWS THE ENGINE TO SPIN RATHER QUICKLY - THUS AS YOU LET OFF THE COMPRESSION KNOB AND CLOSE THE VALVES, THE ENGINE HAS A LARGE MOMENTUM AND WILL START A LITTLE EASIER!

basically it is a quick way to get the engine up to speed and start easy - never use it to choke an engine off..........bad idea!

 

[North Idaho Wolfman]

bucktail,
Not trying to be insulting, but it sounds like you might little confused on how to use the compression release.
Let me see if I'm reading this right, so first you pull the compression release then turn the key and spin the motor, then you close the compression release then turn the key again to "start it for real".
Did I get that right?

Here is proper way to be doing it:
Pull the compression release, Turn the key backwards count to 10, 20, 30.... whatever you need for the glow plugs to heat. Then immediately turn the key to crank, after a couple of revolutions of the motor and while still cranking release the compression release and it should fire right up, all one motion and one action.

 

[bucktail]

Not insulted at all. I don't have an operating manual at all. My WSM is for an L175. I didn't look, but I assumed starting procedure isn't in there. Seems it should be in an operating manual. YouTube muddied the waters. I've never started it in cold weather. I've still got a half tank of the fuel it came with, so I'm not going to chance it on anything below the mid 20's, but I need to move some wood on my build site and I can't get my pickup in there yet, so I've been thinking about mounting my dirt scoop backwards and using that.

 

[Tooljunkie]

I have used it in mine, glow plug for a 20-30 count,pull release and crank. Not to worry about glow plugs cooling as they power while cranking too, release and it should fire up.
I have started tractor as cold as -20 celcius but with the assistance of a 200 watt magnetic heater and a battery charger for 4 hours.

Now i got the little putter sitting in my heated garage, its quite happy there.

 

[Dave_eng]

Hudson
Showing my age, bit back when Canadians bought British made tractors which had no provision for cold weather starting save a fuel enriching button, we were told to leave the fuel shut off and crank the engine to warm up the inside of the cylinder as the air was being compressed and no fuel injected. Then to put the throttle in wide open position and try and start. I wonder if, with an engine with a decompression lever, if there is any heating of the air inside the cylinder by the piston moving up with the decompression engaged.

A few years later British and other country's tractor manufacturers offered the thermostart system which in the simplest of terms started a fire in your tractor's intake system which the engine then inhaled.

A heating element inside the manifold would heat up to red hot and then diesel fuel would be dripped unto the red hot element resulting in flames.

This is a 43 second video if you are curious

https://www.youtube.com/watch?v=fvVW7vEDBAc

Dave M7040

 

[D2Cat]

How North Idaho Wolfman describes the feature is how the manual states "starting with weak battery or in cold weather".

It also says. "If necessary, operate preheating before pulling out the decompression know." I guess this means you don't need/have to always use the glow plugs.

Just a note for those unsure of proper use of decompression knob.

"Although engine can be stopped by pulling out the decompression knob, this should never be done except in such an emergency case that the engine cannot be stopped by pulling the engine stop knob. Especially, if the decompression knob is pulled out while the engine is running at high speed, there is the danger that the valve seat may be damaged or that the decompression device may malfunction. For this reason, be absolutely sure not to pull out the decompression knob when the engine is running except in emergency cases."

 

[Tooljunkie]

An old friend told me a story about working in a bush camp for a couple weeks, dead of winter and last shot shell to start tractor to go home. Drained water and oil and kept it inside over night to keep it warm. Throw the pails on the tin heater and when hot pour back into tractor.
Then hope it would start with the last shot. Heres a video showing a shot shell start.

https://youtu.be/CJpZfp0Ss2U

 

[bucktail]

The glow plug indicator never glows when I'm cranking it. Does that get bypassed when it's cranking? Or is there just not enough time for it to heat back up?

 

[85Hokie]

The glow plug indicator never glows when I'm cranking it. Does that get bypassed when it's cranking? Or is there just not enough time for it to heat back up?

The glow plugs require a lot of amps - nothing but pure heat. While cranking, the plugs are off, and all those amps are now used to turn the starter motor - you would not want both engaged at the same time.

DO you have a idiot light, or a glowing element on the dash? Seems to me that you might have the element, much like a "glow plug" it will turn red after a gooood deal of heating. The glow plug indicator will not turn "red" until about 20 plus seconds, maybe closer to 30 seconds.

 

[bucktail]

It has the element. Takes about 10 seconds to glow in the summer. You're probably pretty close for the winter. I've had it in storage since November. Some of the postings seemed to indicate that they were on while cranking, and I figured that since it's running a 750 amp battery to turn over a 0.7L (~45CI?) engine there'd be enough power for both.

 

[85Hokie]

It has the element. Takes about 10 seconds to glow in the summer. You're probably pretty close for the winter. I've had it in storage since November. Some of the postings seemed to indicate that they were on while cranking, and I figured that since it's running a 750 amp battery to turn over a 0.7L (~45CI?) engine there'd be enough power for both.

Most older machines, you turned the key 180 degrees opposite starting for glowing, new machines (at least BX) you turn the same way, but it is before the contact to start. Either way- hard to have both engaged at the same time! Now if you had a whole separate switch - then it would be possible!

 

[Tooljunkie]

When i was troubleshooting my L1501 ignition switch for no crank, the glow plug output powered while cranking. Thats why i pointed it out earlier.
No crank was a broken wire in clutch safety circuit.

Im sure not all tractors do this, but i know of one that does.

 

[bucktail]

Your L1501 is a consecutive model to my L1500, so I would think mine probably works the same way. Kind of glad mine didn't come with all the safety switches. I'd like to get ROPS and seatbelt on it someday, but you can keep the rest of it.

 

[Berry]

bucktail,
Not trying to be insulting, but it sounds like you might little confused on how to use the compression release.
Let me see if I'm reading this right, so first you pull the compression release then turn the key and spin the motor, then you close the compression release then turn the key again to "start it for real".
Did I get that right?

Here is proper way to be doing it:
Pull the compression release, Turn the key backwards count to 10, 20, 30.... whatever you need for the glow plugs to heat. Then immediately turn the key to crank, after a couple of revolutions of the motor and while still cranking release the compression release and it should fire right up, all one motion and one action.

I'm just trying to follow up on starting with the decompression valve and reading a lot of options. I like Wolfmans answer right to the point. I always enjoy my morning reads with OTT, some great articles.
Anyway to follow up with this, I was told when using the decompression knob on startup, you should push the knob in slowly while starting not to quick. All reads say just push in.
Second question; my tractor is an older 85 vintage B7200HST. How much throttle do you use to start? Are you better off with a little fuel, or mid throttle and would this very with different temperatures?

 

[85Hokie]

I'm just trying to follow up on starting with the decompression valve and reading a lot of options. I like Wolfmans answer right to the point. I always enjoy my morning reads with OTT, some great articles.
Anyway to follow up with this, I was told when using the decompression knob on startup, you should push the knob in slowly while starting not to quick. All reads say just push in.
Second question; my tractor is an older 85 vintage B7200HST. How much throttle do you use to start? Are you better off with a little fuel, or mid throttle and would this very with different temperatures?

On the older B's - the throttle was a lever, to cut off the fuel, you pulled it back towards the operator - full throttle was towards front of tractor.

When you shut it off - the throttle would "snap" back to a high idle spot - or as you might say - "mid- throttle" This was an ideal spot to start the tractor.

As for the decomp - Once that puppy is spinning fast, I would shut the valve as fast as possible - not wanting any compression gasses to be released. It cannot "fire" until that compression gets way up there, any leaks and it will not compress the air and create heat to "explode" the fuel in the cylinder.

 

[Berry]

On the older B's - the throttle was a lever, to cut off the fuel, you pulled it back towards the operator - full throttle was towards front of tractor.

When you shut it off - the throttle would "snap" back to a high idle spot - or as you might say - "mid- throttle" This was an ideal spot to start the tractor.

As for the decomp - Once that puppy is spinning fast, I would shut the valve as fast as possible - not wanting any compression gasses to be released. It cannot "fire" until that compression gets way up there, any leaks and it will not compress the air and create heat to "explode" the fuel in the cylinder.

Thank you Hokie; I do start about mid-way. I never noticed my throttle change on shut down, i will definitely look for this.

 

[Orange man hero]

Hudson
Showing my age, bit back when Canadians bought British made tractors which had no provision for cold weather starting save a fuel enriching button, we were told to leave the fuel shut off and crank the engine to warm up the inside of the cylinder as the air was being compressed and no fuel injected. Then to put the throttle in wide open position and try and start. I wonder if, with an engine with a decompression lever, if there is any heating of the air inside the cylinder by the piston moving up with the decompression engaged.

A few years later British and other country's tractor manufacturers offered the thermostart system which in the simplest of terms started a fire in your tractor's intake system which the engine then inhaled.

A heating element inside the manifold would heat up to red hot and then diesel fuel would be dripped unto the red hot element resulting in flames.

This is a 43 second video if you are curious

Dave M7040

In the cold I always turn over the engine a bit as it does create warmth for starting and help get some peanut butter stiff oil onto at least some of the moving parts. If you get the engine to start and it quits wait a few minutes (I know this is hard to do for many) before you start again. This way the heat from those fist explosions warm the engine and prevent flooding.

 

[Berry]

Thank you Hokie; I do start about mid-way. I never noticed my throttle change on shut down, i will definitely look for this.

Good morning Hokie; I checked out my throttle this morning. After shutting down, the throttle does not snap back in any way to any position. It remains where I shut it off which I always lower the speed to minimum.
This B7200HST has what I call a cruise control, could this have an effect on that operation?