rebuilt d950, not enough comp to run 🤦🏻‍♂️

[yames]

so I posted over a year ago about this engine being low on compression, pulled it, had the block resleeved and the deck milled true, had brand new valves bedded they had to cut the seats slightly and the head milled flat all at a machine shop, checked the valves myself and they vacuum down to 30hg, put it all back together mind you this is like the third time and im having a heck of a time with it, its giving me 140psi on 1, 100 on 2 and 220 on 3, I did add a tiny amount of oil and it bumped it up some but not much, maybe 40 psi each. tried a leak down and it seems like it's leaking between cylinders which I don't understand, I used a brand new kubota gasket and followed the torque sequence and spec for the d950. I'm really just getting fed up with it if im being honest, not sure what to try next 🫤

 

[North Idaho Wolfman]

Well if it's truly bleeding compression between cylinders then you have a head, block, or head gasket issue, can't be anything else.
The only way you would know is to static test each cylinder.
You do this by loosening all the valves and pumping air into each cylinder and seeing if it leaks directly out one or more of the other cylinders.

 

[GreensvilleJay]

hmmm.... given..
head was decked
valves were done
new head gasket

by process of elimination, only thing I read is that the block isn't flat ??

really, what else could be the reason ??

 

[Lil Foot]

Cracked head or block?

 

[North Idaho Wolfman]

Oh I thought of one other reason it would act like that, Timing being off.
Did you line up all the timing marks at the same time when you rebuilt it?

 

[yames]

Oh I thought of one other reason it would act like that, Timing being off.
Did you line up all the timing marks at the same time when you rebuilt it?

the shop never mention anything about cracks, wasn't over heated or anything and the deck of the block was also milled flat. I was thinking maybe the cam could be off a tooth.
I did line everything up but the cam gear marks where kind of wonky and not exactly stamped exactly over a tooth, is it possible to check valve timing without removing the cover?

 

[North Idaho Wolfman]

the shop never mention anything about cracks, wasn't over heated or anything and the deck of the block was also milled flat. I was thinking maybe the cam could be off a tooth.
I did line everything up but the cam gear marks where kind of wonky and not exactly stamped exactly over a tooth, is it possible to check valve timing without removing the cover?

Sorry no, I don't know of a way to do that.
You'll need to pull the front gear case cover off of it.
Once you get it off you'll immediately notice that none of the marks are lined up.
That's because they only line up something like every 244 rotations, you will need to reset all of the marks.
Before you close it up again, post a picture and I can confirm if it's right or not.