Compression test on Kohler K-321 engine

[jd52ao]

I am looking at a John Deere 214 tractor. Owner says you cannot run a compression test as they have a decompression gear in the block.
I don't understand why a compression test is any different than having the spark plug in place. Screw it in , crank the engine and see what the gauge reads. What is a reasonable compression # for an older Tractor,and where is the point of needing rebuild # wise? Thanks

 

[RogerinIowa]

Owner is right. The decompression reduces the compression at low speed, i.e. starting, so it will spin easier.
Have heard you could spin them backwards to get comp reading.

 

[wore out]

Click on the link below and you can download the Service Manual from the official Kohler site for FREE and print it all if desired, or the just pages you need. (.pdf format)

Look on Page 4.1 for info on compression testing (or lack thereof).

Kohler suggests checking crankcase vacuum as an indicator of piston ring leakage and crankcase ventilation function.

You can also download the Operator's Manual for free.

http://resources.kohler.com/power/kohler/enginesUS/pdf/tp_1346_c_all.pdf
K Series Service Manual

 

[jd52ao]

Thanks so much for the info. I did not know you could not do a compression test as used on car/tractors. He sent me a video and did not see any smoke and it fired up on the second try... Will go look tomorrow-- Thanks again---

 

[steve_in_mo]

If that engine starts and runs well with no smoke and no odd noises, running a leak-down test might not be worthwhile.
It will shake the whole tractor when you are shutting down, and that's normal. If you go to look at it in person, check the isolators by pushing on the top of the engine - left-right and front-back. There should not be any slack.
The next-most expensive problems with that tractor are likely to be the rear hubs - they get loose and wobble - and the variator.
The variator is controlled by the left-hand clutch pedal and the lever to the right of the dash.
You should be able to reduce the travel speed with either control. The lever should have an effect in the middle range of notches.

 

[DR. EVIL]

yep, checking crankcase vacuum with the home-made U-tube manometer is what KOHLER recommends because it works. Buy 4-5 feet of clear vinyl tubing, 1/4 or 3/8, a rubber stopper with a hole thru it that fits snuggly into the dipstick tube, I've made several of them, they show Kohler engine condition really well. Oil consumption is another good indicator of condition.
Kohler engine parts have just gotten completely out of control, Mother Kohler's way of saying Buy a NEW ENGINE. I rebuilt a K321 about 15 years ago, machine work was about $125, parts, new O/S piston, rings, exhaust valve, conn rod, seal & gasket kit were close to $1000. That includes a forged aluminum conn rod, not the stock diecast OEM rod, the big end of that rod was offset machined to install a Clevite 77 bearing insert, and offset the rod slightly to pop the piston up higher in the bore. It's NOT a 14 hp engine anymore. I had DAVE KIRK ENGINES install a set of his balance plates on the crankshaft too. I HIGHLY recommend them, this beast of a 14 hp engine runs as smooth as an 8 hp engine!