Compression down on one cylinder

[keycare]

I was having issues with lack of power on my 1982 MF250 Ad3.152.

Checked the fuel lines and air etc. Then pulled off the tank to check the compression of the cylinders. 1 and 2 was 380psi, 3 was 240psi.

Then I saw this in the injector hole...which looks like the metal has been gouged. I would imagine this would affect the seal of the copper washer and might be the reason why Cyl3 is down on compression. What do you think? New Cylinder head time?

 

[keycare]

Is there anything I could use to repair or seal it?

 

[Mcrafty1]

Any evidence of exhaust gases escaping in the area around the hole pictured? If that much compression is being lost from the area pictured it should show signs of combustion gases. JMHO

 

[keycare]

Would you expect to see carbon build-up on the injector body (not the tip).

When I pulled the injectors, this is what I found - Cyl 3 is the one down on pressure...It was dry, whereas the others had a coating of oil.

 

[Mcrafty1]

If compression is getting past the copper washer, wouldn't you find carbon somewhere beyond also? Unless I'm not thinking right about this. 140lbs. is a lot of compression loss.

 

[keycare]

I think I will put it all back together and check for blow back around the injector, dip stick and on the breather hose of the rocker cover.

I might try a bit of JB-weld on a steel washer to see if I can seal that injector.

I'd like to avoid putting the fuel tank back on if possible. Is there a way to get the engine running without re-fitting the tank? Two containers? One for fuel supply, one to catch the fuel from the return pipe?

 

[Mcrafty1]

I think I will put it all back together and check for blow back around the injector, dip stick and on the breather hose of the rocker cover.

I might try a bit of JB-weld on a steel washer to see if I can seal that injector.

I'd like to avoid putting the fuel tank back on if possible. Is there a way to get the engine running without re-fitting the tank? Two containers? One for fuel supply, one to catch the fuel from the return pipe?

A couple of plastic jugs would work as long as you can adapt the suction/return lines to the system.

 

[randyrenfro7]

Do you have a bore scope you can put down the injector hole? Maybe that injector is washing down the cylinder with fuel.

 

[keycare]

Do you have a bore scope you can put down the injector hole? Maybe that injector is washing down the cylinder with fuel.

Yes I do.

What do you mean? What should I expect to see?

 

[caterpillar guy]

Seems to me if the others are all covered in oil that the one in question is sealing and the others are not sealing at the injectors . I may be all wet here but that would be my take on it from past experience. Or they are not burning all the fuel in the cylinder.

 

[wp6529]

My thought would be to recut the seating surface with something like a piloted counter bore of an appropriate size typically used for Allen cap screw recesses, cutting just enough to remove the damaged area and vacuuming with a shop vac to clear chips as you cut. Reinstall the injector with two or three of the copper crush washers as needed to properly seat. This should be able to be done without removing the head.

 

[Fritz Maurer]

Got 2 separate issues going on. There shouldn't be oil on any of them. The space between the copper washer and the dust seal is just a hole sealed on both ends. Looks like you had a valve cover leak at some point and it leaked past the dust seals on the first two.

Your gouge looks like a piece of carbon that fell in there and got pinched either by the injector or the compression tester.

 

[keycare]

Do I need to replace all 3 injectors, or can they be replaced individually?

When I put injector 3 back in to test for blowback, the thread for the banjo bolt on the top of the injector stripped - I didn't tighten it very much at all. :-( barely hand tight, so I wonder if the previous owner had over tightened it.

 

[used red MN]

You can replace only one, but replacing all is recommended. I’m a tight wad and would probably just replace the one. You could take the other two to a diesel shop and have them cleaned, reset and tested Your biggest problem is the dropping compression on cylinder 3. Depending how much and what you use the tractor for will determine the urgency of addressing the repair of that. If your finding yourself needing the tractor to produce its full power to do the tasks needed this will raise the urgency.

 

[Harry in Ky]

Why would you want to replace an injector? That's not the source of a compression loss. If you even THINK you have a bad one, have them tested.

 

[keycare]

Only replacing it because the thread for the fuel line has been stripped. So unless I can just get hold of a cap, I'll have to buy a new one.

 

[keycare]

I've removed the head. The suspect cylinder is on the right. Wetter than the other two with more carbon build up on the valves.
Poor seal on the valves causing low compression and unburnt fuel?
What do you think?

 

[used red MN]

I've removed the head. The suspect cylinder is on the right. Wetter than the other two with more carbon build up on the valves.
Poor seal on the valves causing low compression and unburnt fuel?
What do you think?

You need to turn the engine to move that piston down to see what the cylinder wall looks like, scoring/scratches and amount of ridge at the top point the rings stop. Oil coming up past the piston and rings cleans off the piston. Not real obvious in your case but could have some of that going on. Need to take a picture of the head to show the valves. Get some bolts and a piece of metal to bolt on top to pry on to push the valves down to open them up to see what the seats look like. Shinny seating surfaces all the way around means they were probably sealing okay.

 

[keycare]

I am going to have a go at re-lapping both valves and try to rotate the crank to see what the cylinder looks like.

 

[keycare]

Just checked the liner for cyl 3, completely smooth.