CONPRESION TEST RESULTS?

[garrettohio]

Number one cylinder is 230 then added oil it went to 330.
Number two cylinder is at 400.
Number three cylinder is at 430

Bad thing never had a dead cylinder until I tryed different injectors.so my guess first cylinder must had more compression to ignite the fuel.any ideas to why that is?

 

[85Hokie]

Remember the oil test aint really a good thing for diesel!!!

Sounds based on you oil test that Cylinder #1 has some stuck rings !

One thing you can do it place some Marvel mystery oil in that cylinder and let it sit, do it again and then do it once again - it will take a week for all three times.

Then recheck pressure - IF it made a difference - change the oil in the machine and ride on. IF no change, then time for a rebuild!

 

[North Idaho Wolfman]

If the injector flooded the cylinder then it bent the connecting rod, or broke the piston.
Either way your looking at a tear down.

 

[GeoHorn]

I realize it’s only for diagnostics/repair-intentions….but If oil is no good…. I think Marvel Mystery is also….

I’ve repaired several stuck ring engines (gasoline) …and it Always required pulling the piston.

 

[lugbolt]

most people put too much liquid in the cylinder to test compression, resulting in bent rods, broken pistons, etc

if it's low when running a dry compression test, it's low. Find out why. Ain't hard to run a leakdown test.

I'd recommend a teardown. Pull the head and the pan, have a look-see.

 

[motorhead]

Have you checked the valve clearance on the engine? Yes I know your compression went up with oil in the cylinder but the oil can also seal a slightly leaky valve.

 

[85Hokie]

I realize it’s only for diagnostics/repair-intentions….but If oil is no good…. I think Marvel Mystery is also….

I’ve repaired several stuck ring engines (gasoline) …and it Always required pulling the piston.

The oil being in the cylinder THEN turning the engine over is "no good" - where as if the combustion gets hot enough, it too will explode that oil much like diesel.

Where as the MMO is placed in there and allowed to SIT for a long period of time - and over that time it will either seep down past the rings = OR be blown out the hole that it was placed in.

Obviously the "oil" needs to be compressed to get a compression reading, where as the MMO is simply trying to release a stuck compression ring.

If anything - the MMO will "work" and "help" or it will not - the only other check IS to pull the piston and see if in fact it is stuck.

 

[lugbolt]

reminds me...

i do drag racing (and did it professionally for a good while). Had a gallon of nitromethane leftover in an unmarked bottle. Brother and I was trying to figure out his old tractor and he thought it'd be wise to put a lil oil in the cylinder. Grabbed the bottle and started to put it into the injector hole....I caught him before he went in and mentioned that it's not oil, but nitro. On one hand I shoulda let him, to see what it'd do (I know what it'll do....) but on the other hand, I valued my shop walls, and ceiling, and everything inside of it. And our lives.

having been around it, if you get the conditions just right which isn't hard, with a cylinder that has nitro in it, stuff will take the head right off the block, along with the studs and parts of the block still attached to the studs, and send most of it to the moon. This, while cranking the engine over only...hence the reason they don't let just everyone "play" with it.

Years and years later I was messing with a kubota-I think it was a BX but I don't remember. I remember it being smaller, maybe a b series. I always put some oil in a cylinder to do a compression test too and this one was suspect, but being that we have to give the customer data, I put a few drops in, then put my gauge adapter and gauge on. Hit the key and the engine started right up-on it's own oil. Destroyed the compression gauge. MMO will run too if you compress it enough, like in the cylinder of a diesel engine.

had an exmark show up last year, guy said he ran it out of oil and it wouldn't start. Ok cool let me figure out what's wrong. Got the battery charged up, hit the key and it wouldn't shut down-was running on it's own lube oil that was coming out of the crankcase vent, which is vented right into the intake manifold, which is kind of a dangerous design, should someone roll the machine over. Smoked up the entire shop, set the fire alarms and sprinklers off, fire department shows up...all from a runaway diesel. I got it shut down eventually, had to cut off it's air supply with some hose pinch pliers that I had handy. Still ran about 5000 RPM for maybe 30-40 seconds.