Compression release as starting aid

[twomany]

I've got an older B7200. It starts and runs just fine. In fact, It seems to be getting better with age. I wish that was the same for me ;-)

It has a compression release control that functions as it's designed to.

I've never been able to see a benefit in starting the tractor in cold weather using this feature.

If the battery is UP, the tractor starts on glow preheat. regardless of the temp (-10f)

If the battery is not UP, the tractor won't start even if the engine gets spinning rapidly by using the compression release.

I've never been let down when the battery is up. That tiny dynamo is an issue when short operation is needed in winter. A start sequence with glow and starter leaves the battery down somewhat.
I put the battery on a tender all winter so the tractor is ready to go any time. It would be nice not to need the stretch to the tractor shed all winter.

Am I missing something? What is your experience.

 

[Rosher18]

My L185DT is from '77 and I use the compression release (along with holding the fuel rack to shutoff position with my foot) to crank until the oil pressure light goes out. Gives me peace of mind that I'm going to start at low idle with oil pressure where it needs to be.

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[North Idaho Wolfman]

Compression release on these unit became mainly obsolete / unneeded because battery technology got much better.

 

[fj40dave]

Compression release's are evil.....they can really mess ya up if ya forget to make sure they are not in the full "off" position after adjusting the valves and disconnecting /removing the cable......

 

[Dave_eng]

Kubota used to recommend bringing the battery inside at night in cold weather.

As NIW stated much has changed in the world of batteries.

Dave

 

[D2Cat]

The compression release has a spring that when allowed to work will shut off the release. The compression release was originally designed to open the valves so the engine would turn over easily, taking less battery power then if no release, then using the engine turning over to heat the engine some. This allowed the engine to start better.

As mentioned, battery quality has changed dramatically in the last 40 years!! I have a 730 Case tractor that has a battery box for two batteries, because it was needed when it was new. I now use one battery and lay tools on the other space.

 

[SDT]

My L185DT is from '77 and I use the compression release (along with holding the fuel rack to shutoff position with my foot) to crank until the oil pressure light goes out. Gives me peace of mind that I'm going to start at low idle with oil pressure where it needs to be.

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That's how I once started my JD 730DWES.

Get her spinning quickly and turn on the fuel and release the compression at about the same time.

Cold weather or otherwise, it's easier on just about everything.

Edit: I might add that my procedure was the same procedure provided in the Owner's manual. Summer or winter, pony motor or electric start, the recommended procedure was the same.

Dean

 

[GeoHorn]

My L185DT is from '77 and I use the compression release (along with holding the fuel rack to shutoff position with my foot) to crank until the oil pressure light goes out. Gives me peace of mind that I'm going to start at low idle with oil pressure where it needs to be.

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I know several folks who with their equipment (boats, airplanes, equipt, etc) have some similar concept of using a starter to turn the engine over until oil pressure is indicated before adding fuel or ignition to make the actual start. Their reasoning is similar. I think it’s somewhat defective thinking.
Mechanical oil pumps (such as the majority of engines have) are gear driven, positive displacement pumps, which means that a certain number of revolutions are required before oil is moved through the system.... and THEN SOME MORE revolutions (because starter-RPMS are slower than running/idling RPMS) before an oil pressure gauge will make any indication.

I believe that if one is moving pistons/rings up/down cylinder-walls that are DRY until the crankshaft “slings” oil up into the cyls.... that a starter-driven motor-until-pressure (MUP)... actually INCREASES wear/tear. A faster, more efficient method of getting useful oil pressure UP is to simply start and idle at low RPM until Oil Press is indicated.

Meanwhile, the starter and flywheel-gear is saved LOTS of wear-and-tear.

My 2-cents

 

[SidecarFlip]

I'll side with George. Kubota oil pumps are all gerotor pumps. positive displacement.