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Excessive blowby in rebuilt Deere 310B

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willdozen

New User
Did inframe rebuild of 310 B backhoe in fall at 3200 hrs. New cylinder sleeves, pistons, rings. Head completely rebuilt with all new valves. Currently having lots of blowby, consuming 1 quart of oil per week with heavy use. High pressure causing oil pan to leak. (hrs now at 3326, or only 114 hrs.)
Did compression test. Cyl 1 300 psi, 2 @280, 3 @ 280, 4 @ 260 (manual says 350 for all, but all within 50 psi).

One wise mechanic says it just needs more break-in time. Been running that sucker hard, digging rocks and stumps from my new building site, I should say major boulders, as the glacier has blessed us with tractor size obstacles everywhere.

Thoughts? Really feel something is amiss.
 
Did
you check the ring gap in the sleeve. Sounds to me that the pistons might be right but the ring gap is to big. With a new rebuilt there should not be any but alittle smoke out the breather. I'm thinking the high compresin now is because of all the oil coming up around the rings.
 

Crankcase ventilation system is blocked and is pressuring the crankcase .
I hope that the optional high compression pistons were chosen , they improve winter starting .
 
Head was completely machined with all new valves. I'm using the recommended oil weight for the machine. Did not use a special break-in oil but did an oil change at recommended number of hours. Head bolts re-torqued as per specs at the specified number of hours.
Have yet to hear any comments about the compression test. Any thoughts on why all four cylinders are 50 psi below specs? This machine runs great, has tons of power, but has significant blowby. And...it has become difficult to start even on a 70 degree day unless I plug in the canister heater.
 

Because the machine shop messed up the valve job and likely ordered the plain boring ordinary pistons .
The head either needs valve seats installed to prevent sinking the valves which reduced the compression . Or mill the head to raise the valves .
Have to choose the high compression piston option .
Was the cam re-ground and the followers resurfaced ?
What is the injection pump timing ?
 
Head was redone so if the valve lash is correct the only place you can be losing compression is by the rings.

You messed up bad by not using the break in oil. Your rings didn't seat because of that. From your post you have been running it hard enough so if they aren't seated by now they aren't going to without some help. I have heard some guys have had good success by using a product ( bon ami?) I think. It is an abrasive additive just for that purpose.

Start a new thread in the John Deere forum below this one. You will get much better advice there.
 
m-man, i remember hearing about the bon ami treatment too. if memory serves me , it was for either the old caterpillar or detroit diesels. they sprinkled the powder in the air intake while the engine was running and the abrasive power would take the glaze off and re seat the rings.
 
(quoted from post at 07:40:03 10/02/20) Head was redone so if the valve lash is correct the only place you can be losing compression is by the rings.

You messed up bad by not using the break in oil. Your rings didn't seat because of that. From your post you have been running it hard enough so if they aren't seated by now they aren't going to without some help. I have heard some guys have had good success by using a product ( bon ami?) I think. It is an abrasive additive just for that purpose.

Start a new thread in the John Deere forum below this one. You will get much better advice there.
Click to expand...

Not loosing compression due to valve lash. Loosing compression because the valve seats were ground , which sinks the valves deeper into the head . This increased the volume of the combustion chamber when the piston is at TDC and reduces the compression ratio.
Need the valves as close as possible to the head deck and even proud if allowed .
Need the high compression pistons .
The rings and sleeves are fine. Problem was in parts choice and machine work.
 
You might lose 10 lbs by not changing
the seats. He has one cylinder 90 lbs
under and the rest are significant as
well. He also has heavy blowby and high
oil consumption. Grinding valve guides
will not increase either one. Putting in
the same pistons Deer used when they
built the engine will not lower the
compression either.

It is ring blowby because they did not
seat. There is a reason Deer requires
break in oil. He didn't and they didn't.
It's as simple as that.
 
I agree with you, being it has high oil consumption and low compression I suspect glazed cylinders.

I really do not think the valves are an issue.

Bon Ami time?
 

Not a big fan of dumping abrasives into an engine . Would rather find some way to work the daylights out of the engine for days with the coolant at 210F .
Still wondering if there is some obstruction in the crankcase breather system ?
 

Remove the cylinder head . Either install valve seats to raise the valves and make them flush with the surface of the head . Or plane the head until the valves are flush with the surface .
 
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