B7100 Overhauled now trying to seize up

[sanddog]

I overhauled my B7100 (was not running when purchased) with new head, pistons, rings, all bearings, and had block bored 0.5 mm over to accommodate new (0.5mm over) overhaul kit. It will start and idles just fine but only runs about two minutes before it appears to get hot and tries to seize up. I have taken it back apart once and had the machine shop go back over everything to make sure all tolerances are correct. I also checked tolerances myself before putting it back together and everything, including ring end gaps appear to be correct.

I have checked the radiator and it flows water freely and is clean, blown out with water and then later compressed air. I ran water through the block and there is no indication of any blockage. New oil pressure gauge shows 45 psi.

The motor seems to run just fine. There is no smoke when running at constant speed but just a slight bit of smoke when accelerating. The motor sounds like it starts to bog down and just a slight bit of smoke appears as it dies.

The folks at the machine shop thought possibly something "downstream" was causing back pressure so I put it on an engine stand after the last reassembly, but after running a similar amount of time it died same as when on the tractor.

Does anyone have any ideas?? I did install new injectors as part of the overhaul.

Thanks for any suggestions.

 

[1970cs]

What was the piston skirt clearance? I starts well but did the injection pump get the same shims back in?

Pat

 

[sanddog]

What was the piston skirt clearance? I starts well but did the injection pump get the same shims back in?

Pat

I cannot remember exactly what the skit clearance was, but it was within limits per the repair manual I had and I believe the machine shop guys also said it was good per this size of piston - that is the manual values I used were also consistent with what they anticipated per the small piston diameter.

I did put the injection pump back exactly like it came to me. After it ran and died the first time, I checked the timing and it did appear to be off by 5 degrees so I adjusted to get it right on 25 BTDC as best I could watching very closely for the first sign of the movement of fuel at the port on top of the injection pump. One thing that is making me wonder is that when I bleed the fuel lines -- last step at the injector-- the fuel runs down from the fitting while spinning over the motor, but I do not really observe a strong spurt. The fuel is coming out and there is not doubt the system is bled, but just not a strong spurt that I recall looking back. Should there be a obvious spurt of fuel when bleeding at the top of the injector????

 

[Diydave]

I cannot remember exactly what the skit clearance was, but it was within limits per the repair manual I had and I believe the machine shop guys also said it was good per this size of piston - that is the manual values I used were also consistent with what they anticipated per the small piston diameter.

I did put the injection pump back exactly like it came to me. After it ran and died the first time, I checked the timing and it did appear to be off by 5 degrees so I adjusted to get it right on 25 BTDC as best I could watching very closely for the first sign of the movement of fuel at the port on top of the injection pump. One thing that is making me wonder is that when I bleed the fuel lines -- last step at the injector-- the fuel runs down from the fitting while spinning over the motor, but I do not really observe a strong spurt. The fuel is coming out and there is not doubt the system is bled, but just not a strong spurt that I recall looking back. Should there be a obvious spurt of fuel when bleeding at the top of the injector????

Easier to observe what the spurt looks like, if you remove the lines, on top of the inj pump...

 

[North Idaho Wolfman]

Sounds to me like a timing issue, or valve adjustment is set too tight.

Are you 100% sure that the marks on all the gears lined up perfectly?

Do you have a infrared temp gun to check head temp?

 

[sanddog]

Easier to observe what the spurt looks like, if you remove the lines, on top of the inj pump...

Guess I need to figure out how to put some short clear vinyl lines on the ports so I can direct the fire somewhere other than all over my garage. I will do this before taking off the pump to get it checked, may answer a few questions.

 

[sanddog]

Sounds to me like a timing issue, or valve adjustment is set too tight.

Are you 100% sure that the marks on all the gears lined up perfectly?

Do you have a infrared temp gun to check head temp?

I MAY NEED TO RECHECK THE VALVES, ALTHOUGH i JUST SET THEM?

i AM CERTAIN THE TIMING GEARS ARE LINED UP CORRECTLY. I WAS VERY CAREFUL THE SECOND TIME AROUND AND GOT ALL MARKS ALIGNED WITH PISTON 1 ON TDC.

I AM GOING TO ORDER AN INFRARED TEMP GUN THIS WEEK.

 

[1970cs]

Ok Sounds like you spilled timed it to 25 degrees BTDC. The manual does not tell what cylinder port to time! I would think #1 and another thing it does not tell is how many degrees of timing from commencement of injection to end in degrees. I also assumed you did this with throttle wide open? < per the service manual.

You adjusted it by five degrees? Each shim changes timing by 1.5 degrees my math with three shims is 4.5 degrees advanced or retard.

Pat

 

[CountryBumkin]

It will start and idles just fine but only runs about two minutes before it appears to get hot and tries to seize up. I

What do you mean by "tries to seize up".
You said you took it apart once and had the machine shop check everything. Was this done because of the "seizing issue" or did something else make you take it back to the machine shop? So you had the engine installed and running and then removed the engine and took back to machine shop.

1) Have you gotten the engine hot and then tried to turn it over by hand? If it won't turn by hand when hot, what if you remove the glow plugs or injectors and then try to turn by hand?
2) Are you describing a "slow to crank engine" when restarting it hot (like a "hot soaked" starter)?

Describe why you think the engine is seizing up. The term "seizing" describes a mechanical failure/condition which would leave visible marks.

 

[sanddog]

what do you mean by "tries to seize up".
You said you took it apart once and had the machine shop check everything. Was this done because of the "seizing issue" or did something else make you take it back to the machine shop? So you had the engine installed and running and then removed the engine and took back to machine shop.

1) have you gotten the engine hot and then tried to turn it over by hand? If it won't turn by hand when hot, what if you remove the glow plugs or injectors and then try to turn by hand?
2) are you describing a "slow to crank engine" when restarting it hot (like a "hot soaked" starter)?

Describe why you think the engine is seizing up. The term "seizing" describes a mechanical failure/condition which would leave visible marks.

after i first put the engine together after the machine work, it would run about 30 to 40 seconds and die. If i tried to restart immediately, the starter could barely turn it over. If i waited about 30 to 40 seconds, then it would spin over and start only to run for another 20 seconds or so. I became concerned something was off internally and took back apart before i damaged something.

A couple of the ring end gaps were too tight, but everything else was within specs. When i put it together the first time, i could not find the timing mark on the crankshaft so i brought the number one piston (front) to tdc on compression stroke and aligned all the other marks. It was initially hard to start and i adjusted the injection timing to get it running. When i took it back down, i found the timing mark on the crankshaft behind the oil slinger washer. I think i was actually one cog off the first time.

So, i carefully aligned all timing marks and put the injection pump shims back to original (as it came to me). The engine fired up quickly and ran very well after reassembly, but continued to have the same problem of appearing to seize up. I checked injection timing and it looked to be 5 degrees off so i adjusted, but i cannot tell it made any difference. I plan to put the injection timing back to "original" and i guess maybe take the injection pump in to get it tested to eliminate it as a potential source of problems.

As the engine starts to die, you can see a slight amount of black smoke just was if the motor is under a load. It dies slowly, not as if you threw a switch.

 

[sanddog]

Ok Sounds like you spilled timed it to 25 degrees BTDC. The manual does not tell what cylinder port to time! I would think #1 and another thing it does not tell is how many degrees of timing from commencement of injection to end in degrees. I also assumed you did this with throttle wide open? < per the service manual.

You adjusted it by five degrees? Each shim changes timing by 1.5 degrees my math with three shims is 4.5 degrees advanced or retard.

Pat

Yes, I followed the manual, but now you mention it, I am not sure I had the throttle wide open?? Would that make a difference in when the injection starts? I guess it could at least make it easier to see the fuel level rise in the port.

I could not tell the five degrees made any difference in how it is running, so I think I will restore it to the original shim pack.

 

[HealeyBN7]

It sounds as if you might be starving it for fuel after it starts. Are you sure all the lines are bled and the injector pump is getting an air free fuel supply. All off the mechanical and soft fuel joints need to be fully secured.

 

[BAP]

Have you checked to make sure you are getting good oil flow and oil pressure?

 

[sanddog]

It sounds as if you might be starving it for fuel after it starts. Are you sure all the lines are bled and the injector pump is getting an air free fuel supply. All off the mechanical and soft fuel joints need to be fully secured.

At one point, I replaced the fuel line between the lift pump and injection pump with a clear line and all bubbles worked their way out and still no improvement. This last time, I did bleed at the injection pump and only at one of the injectors (longest line), so I guess I could go back and break the connection at the other two just to be sure. The black smoke when it dies makes me think it is getting fuel, but I could be totally wrong about that!

 

[sanddog]

Have you checked to make sure you are getting good oil flow and oil pressure?

before putting it back together the second time, I checked every oil passage and all were clear. A new oil pressure gauge shows about 45 psi - steady. When I tore it down after it did this (apparent seizing) the first time, neither I nor the guys at the machine shop could find any indication on any of the internals where it was apparent it was seizing. I did not run it for long the first time, maybe 10 to 15 attempts at 15 to 40 seconds max. before I tore it down.

 

[BAP]

Is the lift pump good? The diaphragms in them can fail over time.

 

[D2Cat]

At one point, I replaced the fuel line between the lift pump and injection pump with a clear line and all bubbles worked their way out and still no improvement. This last time, I did bleed at the injection pump and only at one of the injectors (longest line), so I guess I could go back and break the connection at the other two just to be sure. The black smoke when it dies makes me think it is getting fuel, but I could be totally wrong about that!

There is no "longest line". All the fuel lines on a diesel engine going from the injector pump to the injectors are all exactly the same length. That is why they are each shaped differently... to get the length needed for the distance traveled. If they were different lengths, injector timing would be impossible!

Be sure to loosen the nuts at the injectors and bleed all three lines.

 

[DVoss]

There is no "longest line". All the fuel lines on a diesel engine going from the injector pump to the injectors are all exactly the same length. That is why they are each shaped differently... to get the length needed for the distance traveled. If they were different lengths, injector timing would be impossible!

Be sure to loosen the nuts at the injectors and bleed all three lines.

If need be, I can provide you a picture of a Kubota F2302 in which the injection lines are not the same length. Why would differing lengths affect timing?

 

[85Hokie]

Sand,

After reading all the posts.....

"I overhauled my B7100 (was not running when purchased) with new head, pistons, rings, all bearings, and had block bored 0.5 mm over to accommodate new (0.5mm over) overhaul kit."

DID anyone "measure the parts with a micrometer" before they were placed in? Sounds like something is expanding as it gets hot and then "slows" the engine down.

Were the mains plasticgauged when replaced?

Somewhere there is a problem with heat and expansion based on what I am reading.

 

[Diydave]

If need be, I can provide you a picture of a Kubota F2302 in which the injection lines are not the same length. Why would differing lengths affect timing?

Longer line=delay in timing. Thats why sometimes you see 2 or 3 extra loops, in a line...