What is the compression suppose to be in a KM385 Jinma 284

[Northoffrisco]

So I have acquired this weird knocking noise, it is not all the time and there is no real time when it does it, so it does it at full throttle sometimes and other times its at idle, this is where it gets weird, it goes away and maybe be a day or so before it comes back, first it sounded like it was coming from the front of the motor but it is so hard to pin point it, the last time it did it I was at 2200 rpms and it started to cut out and sputter, which this is a first, leading me to believe it is a fuel issue, so I pulled the injectors and had them tested yesterday, all 3 are prefect no problems, the exhaust pipe inside is dry no oil, there is no diesel in the oil and I did remove the radiator cap to see if it was bubbling out of the cap and nothing. I pulled the valve cover to check to see if I had a broken rocker or push rod nothing all is clean, so my next step is to run a compression test but it seems that noone has that info
I'm sure someone on here has run a compression test on these so please could you give up that info
thanks
Bryan

 

[Affordable]

The compression should be in the high 300 -400 PSI, however I still think you are having a diesel knock, which is a injector clogging or bad fuel. A internal engine knock will be consistent, not every now and then. When you say the injectors were perfect ? What pressure did they pop at ? What was the spray pattern ? Who tested them, where did you get the pop pressure at ? You are having fuel problems, that also accounts for the hesitation and low power

Tommy
Affordable Tractor Sales
"Your Jinma Parts Superstore"
Home of compact Jinma, Foton, and Koyker Tractors and Parts, Wood Chippers, Backhoes - Affordable Tractor Sales Company

 

[Northoffrisco]

I had the injection shop next door to our shop test them I will have a print out sometime today, I kinda agree I might have a diesel knock but at this point I'm not to sure
300 to 400psi sounds a little low for a motor that has 22.1 compression I would think some where around 450 to 550 but the only real way I can figure this out is to take a complete measurement of the cylinder radius and then pie it then take into consideration the piston top and head so at this point I'm not willing to pull the hole motor down and remove it out of the tractor to figure this out, I'm going to more then likely if the injectors do not solve this pull the pump and start looking into that,

 

[Northoffrisco]

After thinking about this I could have put old diesel into the tractor, I have 10 cans of Diesel I always rotate them but as I recall there was on can that was left on the side of the garage that I grabbed in a hurry and I'm thinking this was for something other then the tractor, I'm going to drain the tank change out all the filters while I'm doing this I'm going to also cut open the oil filter to see if the paper element has any shaving in it, Cant do this till the weekend but I will keep you posted

 

[rsallen]

Yeah, around 400 lbs. I'd think.

Keep in mind the reason you won't see any real high compression is that you're only reading at the rpms the starter will develop and probably on dry cyl. walls at that.

 

[SPIKER]

To get a better / more accurate measurement bring engine to operating temp, shut it off then try & get on the pressure tests ASAP while engine is still warm & has oil coatings on everything.

Harder to work on a HOT engine but it is more accurate. Look for water in fuel indication in the fuel bowl too that will cause a lot of knock if it spit some condensation thru it.

Mark

 

[Northoffrisco]

I want to thank everyone so far that has tried to give me advise on this tractor,
I brought the tractor back to my work place so I work on it here since working out in the field can be a challenge to say the least, since the last time, I put in the injectors in and did bleed all the air, I could not run a compression test as I did not bring the correct fittings that I needed, and being as far as I was from my shop I decided to try and get it started, I was successful in getting it started but it did not solve the loud knock noise, I double checked the injectors to make sure there was no air in the system, but still the loud knock noise was ever so present. I shut it down and based on that it got loaded up on a trailer and came back with me, Last night I had a few to work on it and this is so far what I have discovered,
when I pulled the valve cover I rotated the motor and noticed that my rockers were not moving at ALL!, so I decided to remove the radiator, so I can gain access to the front cover, I pulled the little inspection cover that is infront of the cam gear bolt, once I did that I noticed that the cam gear bolt was just about to fall out, I proceeded to remove the front cover this morning and low and behold, the cam gear bolt was completely out, just sitting there, how it backed out is beyond me, I have noticed that almost all the bolts were not tight, snug at best, this tractor has 364 hours on it, I spoke to the previous owner about this tractor but did not reveal this issue, I aksed him about the hard starting on the tractor and he expressed to me that since new it has always been extremely hard to start this thing up, That being said I think now I might have found out some of the issue, I'm going to pull the head next to see if I bent a valve or 2 or 3, I'm sure I will have to replace the cam at this point, so Tommy here comes some more of my hard earn money your way!
the bad part about this whole thing is I put 14 hours on this thing and have replaced these items
1. alternator
2. rebuilt the injectors
3. replaced all the fuilds
4. replaced the battery with the correct one
5. glow plugs
6. hoses
7. the key switch
8. thermostat and gaskets
9. some wiring
10. I have not started drinking

I'll post some pictures of this process as I continue to supply my tractor with the care and love it needs!!!! o-ya money too!

 

[greg_g]

Compression ratio (when new) is 22:1, but the math to convert to PSI is a little over my head. So I used a conversion program that says 22 atmospheres is ~323 psi, and 22 bar is ~319 psi

//greg//

 

[Northoffrisco]

Compression ratio (when new) is 22:1, but the math to convert to PSI is a little over my head. So I used a conversion program that says 22 atmospheres is ~323 psi, and 22 bar is ~319 psi

//greg//

14.50377 (PSI) = 1bar
1.0197 (at) = 1bar technical atmosphere
0.9692 (atm) = 1bar standard atmosphere


right now the hole top end is off the motor
doing a simple leak down test on the valves to see if they are bent, going to have to pull the cam for sure and lifters, lifters are not rollers and looks like they come out from the bottom, this ought to be fun to get them back in

 

[greg_g]

This is the one that was over my head:

//greg//