Compression release on tractor

[stampede38899]

i recently bought a taishan dragon 270 and was wandering what the compression release was used for and how is it suposed to be used. never saw this on one.

[swick1]

On a motorcycle you pull the compression release lever and get the engine to tdc then release the lever and kick. Be careful when kick starting your tractor. It has a lot of compression.

On my chainsaw you press the compression release and it locks in the active position. Then you pull the starter cord and it automatically releases.

[homedad]

Had one on my old L185 DT. I used it in the extreme cold when I couldn't get the engine to turn over under compression. I would release the compression after glow, crank the engine and reengage the compression once the engine is spinning. It was never as effective as warming the engine with a shop heater when it was really cold out. Don't know if that was the proper procedure but it worked for me.

[greg_g]

i recently bought a taishan dragon 270 and was wandering what the compression release was used for and how is it suposed to be used. never saw this on one.

Compression releaseon a diesel engine is a starting aid. Activating it by pulling a cable or turning a lever causes one set of valves to open slightly, temporarily disallowing compression. The starter motor then has a much easier time turning the flywheel, saving wear and tear on itself and on the battery. It also turns the oil pump, which then starts pushing oil back into the now-empty passages. My procedure was to open the compression release, engage the starter, then watch the oil pressure gauge. As soon as it was spinning fast enough to indicate pressure on the gauge, I'd let go of the compression release. Except in the coldest of conditions, that was usually enough to start on the first try.

//greg//

[RonMar]

+1, particularly the part about building oil pressure without applying load to piston and rods. This saves a lot of wear on crank and rod bearings by allowing an oil film to be built before compression load is applied. Also, diesel starters are very powerfull. If for some reason some moisture has found it's way into the cylinders(leaking head gasket or rain down the intake or exhaust ect), compression release allows this fluid to be expelled. If it is not, this could cause a hydraulic lock and the starter can be powerfull enough to bend rods, twist the crank or damage flywheel and starter...

I use mine on every start...

[Hickory Creek]

While on issue. Hickory Creek here. In old posts, I have stated that my SL 3105 engine will run with compresssion lever engaged. First, thanks to all, I have used the heck out of the tractor this year. Now, I have not tried to adjust compression release. I assume one removes valve cover. From there, are there any alingment marks or does one adjust nuts on linkage whatever so valves open just slightly or what? I am having to use two batteries to start this thing unless I use starting fluid.

[Rich Waugh]

The odds are that the compression release lever is not properly engaged inside the valve cover. On my 304 Jinma there isn't anything to adjust - it either is correctly position to lift the exhaust valves or it isn't and then it doesn't work. If you pull the valve cover you should be able to see =what needs to happen - it is a simple lever arrangement on mine.

[quicksandfarmer]

On my 354 Jinma it is very easy for the lever to come disengaged when I take the valve cover off. With the valve cover off, it's pretty easy to see how it works -- there is a shaft that runs parallel to the valve train that pushes down on the valves when it is turned. There is a lever on the outside of the valve cover that turns that shaft when it is pulled. Connecting the lever to the shaft is a metal dowel, about 3/8" in diameter and 5/8" in length, with a slot on each end. That dowel tends to fall out when the valve cover is removed, and then roll to the most inaccessible spot in the shop. It takes a lot of fiddling to get the valve cover, lever, shaft and dowel all aligned properly on reassembly. What I have to do is unbolt the lever, assemble everything else and then bolt the lever back on.

With the valve cover in place you can easily tell by pushing on the lever whether it is engaged properly -- there is either a lot of resistance, or none.

[greg_g]

I have not tried to adjust compression release. I assume one removes valve cover. From there, are there any alingment marks or does one adjust nuts on linkage whatever so valves open just slightly or what?

First thing to do is to make sure the linkage from the operator station to the valve cover is actually connected - on both ends. Then confirm that - when engaged from the operator station - there's actually rotation visible at the point where it goes through the valve cover. If those two things are happening - and you still have no compression release - only then should it be necessary to remove the valve cover. Let me know what you find before actually taking the cover off, and we'll go from there.

//greg//

[stampede38899]

So this is an aid to help with cranking, do they use that instead of glow plugs in these chunese tractors? i beleive my tractor has the plugs as my switch has a place for it.