B7100 hard to start

[Brandonallen]

Bottle feed the injection pump again, that will eliminate any fuel delivery issue and give you a better idea where to look.

You said you cracked the overflow line fittings to get it to run the last time, well that step seams rather odd, that normally will not help them start or run any better.

2 things to check.
The fuel level, has it gone down while sitting?
Check the motor oil level, has it gone up while sitting?

Oil level seems to be where we left it. Fuel does as well. I’m not sure if cracking those return lines helped air get pushed out or what. Maybe the injectors got clogged up sitting for a month while the block was getting sleeved? Almost has to be fuel related since it was running great two days ago

 

[North Idaho Wolfman]

Pull the injector lines, set the throttle to high and look at the injector fountains coming out of the injection pump, are they all the same height?
Should be about 2" give or take.

 

[Brandonallen]

Pull the injector lines, set the throttle to high and look at the injector fountains coming out of the injection pump, are they all the same height?
Should be about 2" give or take.

They all squirt/jump up evenly about 2” as you said they should be. What would be next? Injectors?

 

[North Idaho Wolfman]

Yep Injectors.
I would either get a local injection shop to test and rebuild them or get a set from Oregon fuel injection.
There is a lot of injectors out there on eBay, and Amazon and other sellers that are complete junk.

 

[Brandonallen]

Yep Injectors.
I would either get a local injection shop to test and rebuild them or get a set from Oregon fuel injection.
There is a lot of injectors out there on eBay, and Amazon and other sellers that are complete junk.

My local shop wants 25 a piece to test and 100-115 to rebuild. Is it worth removing injectors and hooking lines up facing outwards and cranking it to watch spray? Seems like we are at the end of the troubleshooting with everything else checking out

 

[North Idaho Wolfman]

My local shop wants 25 a piece to test and 100-115 to rebuild. Is it worth removing injectors and hooking lines up facing outwards and cranking it to watch spray? Seems like we are at the end of the troubleshooting with everything else checking out

Yes you can do that, use a piece of cardboard to see the pattern, NOT a BODY part!

 

[Brandonallen]

One is misting, one is squirting without mist and one is like halfway squirting. Going to get replacements. The Oregon website says 3-7 days. Is there any other reputable sites to get oem or quality injectors?

 

[Brandonallen]

Yes you can do that, use a piece of cardboard to see the pattern, NOT a BODY part!

What’s the chances a non oem headgasket could be too thick causing this hard start issue? What “should” compression be on a d750? We have new injectors on order but starting to second guess the compression also, I’ve read a couple posts about the head gasket thickness/shims

 

[North Idaho Wolfman]

What’s the chances a non oem headgasket could be too thick causing this hard start issue? What “should” compression be on a d750? We have new injectors on order but starting to second guess the compression also, I’ve read a couple posts about the head gasket thickness/shims

Injectors that are not spraying a very fine mist will 100% cause huge start issues.

Yes Non oem head gaskets can be too thick and cause issues.
I always use OEM head gaskets on builds.

You can do the fuse test to know if the gasket is too thick.
The fuse test is using a piece of soft solder and sticking a piece in the injection port, Holding the end, don't let it drop in, turning the engine by hand swishing the solder then measuring that swish.
.6 mm or .024 inch is what your looking for.

Do a compression test that will tell you where you are really at.
You should see numbers in the 340 to 450 range.
If it's lower than 340 you'll have hard start issues.

 

[Brandonallen]

Injectors that are not spraying a very fine mist will 100% cause huge start issues.

Yes Non oem head gaskets can be too thick and cause issues.
I always use OEM head gaskets on builds.

You can do the fuse test to know if the gasket is too thick.
The fuse test is using a piece of soft solder and sticking a piece in the injection port, Holding the end, don't let it drop in, turning the engine by hand swishing the solder then measuring that swish.
.6 mm or .024 inch is what your looking for.

Do a compression test that will tell you where you are really at.
You should see numbers in the 340 to 450 range.
If it's lower than 340 you'll have hard start issues.

Solder through the injector hole? Or the glow plug hole?
I was doing compression testing through the glow plug and was getting like 325 but the adapter was leaking. I think I will try in injector holes to get better seal and accurate numbers

 

[North Idaho Wolfman]

Do it through the injector port as the glow plug port gets you into the prechamber not the cylinder and piston.

If your getting 325 with it leaking, it doesn't sound like you have a compression issue.
I have seen these engine in the 300's and they start and run with just a little extra cranking.

 

[Brandonallen]

Do it through the injector port as the glow plug port gets you into the prechamber not the cylinder and piston.

If your getting 325 with it leaking, it doesn't sound like you have a compression issue.
I have seen these engine in the 300's and they start and run with just a little extra cranking.

Rechecked compression and consistently have 275 on all 3 cylinders. Did not oil cylinders, last time readings were a tad higher but probably had some oil in there from assembly.
I am thinking if we had a valve or ring issue we probably wouldn’t have consistent 275 on each cylinder. We had all sleeves replaced by reputable diesel performance shop. He also completely rebuilt the head, new valves, springs, seals, etc. I am unsure the amount he took off the head and block but could try to see if he has that info saved. When we assembled bottom end there was no piston protrusion. I tried the solder test and my solder hardly had any impression in it. What would be the best way to know if I need the factory shim or just the factory head gasket? Or any other ideas causing the low compression?

 

[eserv]

Rechecked compression and consistently have 275 on all 3 cylinders. Did not oil cylinders, last time readings were a tad higher but probably had some oil in there from assembly.
I am thinking if we had a valve or ring issue we probably wouldn’t have consistent 275 on each cylinder. We had all sleeves replaced by reputable diesel performance shop. He also completely rebuilt the head, new valves, springs, seals, etc. I am unsure the amount he took off the head and block but could try to see if he has that info saved. When we assembled bottom end there was no piston protrusion. I tried the solder test and my solder hardly had any impression in it. What would be the best way to know if I need the factory shim or just the factory head gasket? Or any other ideas causing the low compression?

Once again, a warning! Don't oil cylinders on small Kubota engines, do a leakdown test instead! You risk very expensive repairs by hydrolocking these engines.

 

[Brandonallen]

Once again, a warning! Don't oil cylinders on small Kubota engines, do a leakdown test instead! You risk very expensive repairs by hydrolocking these engines.

We did not use oil for compression tests. I said residual oil from when we installed the pistons into cylinders. Is that bad? We turned over multiple times by hand before using starter and it never got tight

 

[eserv]

We did not use oil for compression tests. I said residual oil from when we installed the pistons into cylinders. Is that bad? We turned over multiple times by hand before using starter and it never got tight

That is ok. A common practice on gas engines is to squirt oil into the cylinders to determine if low compression is caused by rings not sealing or damaged valves. It is not a good practice on diesels though. I know many people do it and get away with it but a leakdown test is safer and at least in my experience, give me more useful information

 

[PoTreeBoy]

Do it through the injector port as the glow plug port gets you into the prechamber not the cylinder and piston.

If your getting 325 with it leaking, it doesn't sound like you have a compression issue.
I have seen these engine in the 300's and they start and run with just a little extra cranking.

Educate me. Doesn't the injector go in the pre chamber too? Or is the angle such that a long enough piece of solder can go through the pre chamber into the combustion chamber through the injector port?

 

[North Idaho Wolfman]

Educate me. Doesn't the injector go in the pre chamber too? Or is the angle such that a long enough piece of solder can go through the pre chamber into the combustion chamber through the injector port?

You know what, you are right, I guess then it's easier because of the size of the hole or the angle?
It's just the way I've done it.

 

[Brandonallen]

You know what you are right, I guess then it's easier because of the size of the hole or the angle?
It's just the way I've done it.

Does anyone have input as to why I would have consistent compression at 275 with fresh rings and cylinder head worked? Aftermarket head gasket too thick?

 

[North Idaho Wolfman]

Rechecked compression and consistently have 275 on all 3 cylinders. Did not oil cylinders, last time readings were a tad higher but probably had some oil in there from assembly.
I am thinking if we had a valve or ring issue we probably wouldn’t have consistent 275 on each cylinder. We had all sleeves replaced by reputable diesel performance shop. He also completely rebuilt the head, new valves, springs, seals, etc. I am unsure the amount he took off the head and block but could try to see if he has that info saved. When we assembled bottom end there was no piston protrusion. I tried the solder test and my solder hardly had any impression in it. What would be the best way to know if I need the factory shim or just the factory head gasket? Or any other ideas causing the low compression?

Ok, there is extra info embedded in your statement:
If material was taken off of the block that amount is super important for mutiple reasons.
Head gasket height would be one reason you could have an issue.
Also the a the amount of material taken off the block needs to be added as a shim to the shims under the injection pump as that sets the timing (Super Important).
Did all of these happen?
Rods checked for length?
Rods installed in the correct direction?
Pistons installed in the right orientation?
Ring installed in the proper direction?
Timing gears double checked for proper alignment.

 

[eserv]

Does anyone have input as to why I would have consistent compression at 275 with fresh rings and cylinder head worked? Aftermarket head gasket too thick?