Has anyone completed a successful rebuild using an aftermarket rebuild kit? I rebuilt my D722 using a Friday Parts kit. Once I was complete the engine took a long time to start up, but it did run. It has a lot of blow by and the cylinder with the most compression only had 310 psi. The service manual states I should have 337-448 psi. I had the cylinder liners replaced, then bored and honed by a machine shop. I am wondering if the machine shop bored the sleeves too much or if the parts I bought were such poor quality that they have worn away. Any advice would be appreciated.
D722 Rebuild
- Thread starter Bobcat mt50
- Start date
North Idaho Wolfman
Moderator
Staff member
Lifetime Member
Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
How long have you run it?
It will take about an hour or more of good running and temp equalization for it to seat the rings.
What was done with the head?
Did you supply the specs for the bore amount?
The more information the better!
It will take about an hour or more of good running and temp equalization for it to seat the rings.
What was done with the head?
Did you supply the specs for the bore amount?
The more information the better!
When you preformed the compression test , did you add a little squirt of oil to see if the compression came up, which may/may not elimate the rings, did you rework the head?
I have ran it for 2 or 3 15 to 20 minute increments. I did read that you should load the engine as much as possible to seat the rings, so I ran it at full rpm for about 20-30 mins while periodically lifting the bucket up and down and using the hydro attachment until it would bog down then almost stall. In that 20-30 minutes it went from being full on oil to the low level on the dipstick. I did not supply any specs to the machine shop. He wanted a piston and ring and that was all he asked for, in retrospect that makes me concerned that he did not ask for any specs or the service manual. I bolted on a new complete head along with a new head gasket. Yes, when I dropped oil in through the glow plug hole the compression would increase.
You said in post #1 " I had the cylinder liners replaced, then bored and honed by a machine shop. I am wondering if the machine shop bored the sleeves too much?" Then you said in post #4 "I did not supply any specs to the machine shop. He wanted a piston and ring and that was all he asked for."
Did you supply the piston prior to the sleeves being installed, bored, and honed, or after that work was done? Is there more than one machine shop involved with this build?
Yes, the machine shop needed the piston and rings before anything was bored. Only one shop was involved, and the engine was only machined once.
North Idaho Wolfman
Moderator
Staff member
Lifetime Member
Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
The only way your going to know what the bore is, compared to what it should be, is to pull the head and measure the bore.
Then he wouldn't need any specifications, since he took his calculations from the actual parts prior to boring and honing. Who installed the pistons? If it was you, did you make sure to follow the piston ring manufacturer's specifications concerning end gaps and piston ring gap locations? You might not have installed the pistons correctly in the bore also. I don't know your engine, but in some engines, the connecting rods are not exactly centered in the bore, and you have to make sure to have them pointed correctly or rapid wear will occur. Engine building is an art, and you have to do a lot of them to understand how to do it correctly every time. I know how, but I haven't done enough to know all the minute details involved to do it correctly without some guidance. For that reason alone, I always trust an expert to rebuild my engines, and then I will install them.
North Idaho Wolfman
Moderator
Staff member
Lifetime Member
Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
DustyRusty, brought up some good points on ring gap, and ring gap placement.
But also did you follow the ring orientation, there is an up side and a down side.
Yes the pistons on some models are directional, but they usually will just cause interference with the head if improperly installed.
The rods do have a direction to them too.
Usually getting that wrong is just a pervious wear and stress issue.
But also did you follow the ring orientation, there is an up side and a down side.
Yes the pistons on some models are directional, but they usually will just cause interference with the head if improperly installed.
The rods do have a direction to them too.
Usually getting that wrong is just a pervious wear and stress issue.