iDRY Vacuum Kilns

Sponsors:

kubota cylinder head fix

Started by Reddog sawmill, February 05, 2017, 02:31:17 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Reddog sawmill

Hi guys first post here and i need some advice. I have a kubota diesel in my skid loader the machine hasnt ran in a couple of years.i just tore the head off of the engine today to inspect the cylinders and to my horror i noticed a large crack in the head about 1.5 inches long extending under the valve. I dont have much money to play with at the moment and dont NEED this machine but would really like to get it going because it was kind of a pet project for my grandfather who recently passed away and i. I know cast iron is a tricky material to work with but i was wondering if v-ing out the crack and brazing was an option? Not much to loose really but i cant afford a cylinder head at the moment so i would like to fix this one. Thanks in advance for the replies.

coalsmok

Welcome to the forum

You are in for spending the cash. I don't know of an effective way to repair a head with weld, especially one cracked into the valve seat and probably the intake or exhaust passage.  Even so you would still need the head and valve seat resurfaced after welding. Since you don't seem in a rush eBay and equipment graveyards may be in your favor for a decent used head.

Gearbox

A crack into the valve . Weld it is a sure fire way to drop a valve seat into the cylinder and ruin the rest of the engine . If you  have a diesel skid loader that's worth $ 5000 and up . whats it worth now $ 1000 - 1500 .
A bunch of chainsaws a BT6870 processer , TC 5 International track skidder and not near enough time

scsmith42

Many years ago I owned a machine shop and we welded up a lot of heads.

Your best bet would be to obtain a replacement head.

If you opt to have it welded, your best option is TIG welding with either nickle or stainless filler.  After welding up the crack have the valve seat machined and a replaceable seat installed.

Alternate options are stick welding with either nickle or stainless, or oxy-acytelene brazing.

All of these have the potential to crack.  Welding cast iron is very tricky and the shops that do this will typically preheat the entire head, weld it, and then post heat it to bring it down slowly.  Other tricks are to peen the weld to stress relieve it immediately after welding, pack in sand after welding, etc.

Brass (brazing filler rod) is not a good choice for the valve seat area.
Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

MT logger

Witch engine is it and where are you located I have a few Kubotas and parts.

Reddog sawmill

Thank you mt logger it is a d1402 3 cylinder

Reddog sawmill


Kbeitz

If it was my engine I would cold weld it with ni-cad arc rods.
V it out an just put a dab of weld on it and peen it with a needle
scaler and walk away. After it's cold to touch put another dab on it.
If you see any bubbles in the weld grind it off and do it again.
The bubbles come from the heat of the weld burning off gasses.
Peen after each weld and don't let it get hot. Sometimes it helps
to drill a hole at the end of the crack. The crack is always longer
than it looks. Nicad stands for nickel cadmium.
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

MT logger

Sorry closest I have is some 1505 4cylanders.

Reddog sawmill

Thanks for the advice guys. Kbeitz that is exactly the solution i was looking for, i figure if the head is already no good it wouldnt hurt to at least try to fix it. Now i need to source some ni-cad rod and try to weld her up.

scsmith42

Quote from: Kbeitz on February 05, 2017, 07:06:04 PM
If it was my engine I would cold weld it with ni-cad arc rods.
V it out an just put a dab of weld on it and peen it with a needle
scaler and walk away. After it's cold to touch put another dab on it.
If you see any bubbles in the weld grind it off and do it again.
The bubbles come from the heat of the weld burning off gasses.
Peen after each weld and don't let it get hot. Sometimes it helps
to drill a hole at the end of the crack. The crack is always longer
than it looks.

Your recommended procedure is a good one but I think that you mean "Ni" rods and not "N-cad" rods.  Ni stands for "nickle", which is the predominant arc rod for cast iron. Ni-cad stands for "Nickle Cadmium" which is not a welding rod (and cadmium fumes are not the best thing to breath in when welding...).
Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

Qweaver

Welding cracked heads is so iffy because if you do not get the entire crack fully welded, it will certainly crack again.  I would try very hard to find a good used head. 
So Many Toys...So Little Time  WM LT28 , 15 trailers, Case 450 Dozer, John Deere 110 TLB, Peterson WPF 10",  AIM Grapple, Kubota 2501 :D

Kbeitz

Quote from: scsmith42 on February 05, 2017, 11:23:59 PM
Quote from: Kbeitz on February 05, 2017, 07:06:04 PM
If it was my engine I would cold weld it with ni-cad arc rods.
V it out an just put a dab of weld on it and peen it with a needle
scaler and walk away. After it's cold to touch put another dab on it.
If you see any bubbles in the weld grind it off and do it again.
The bubbles come from the heat of the weld burning off gasses.
Peen after each weld and don't let it get hot. Sometimes it helps
to drill a hole at the end of the crack. The crack is always longer
than it looks.

Your recommended procedure is a good one but I think that you mean "Ni" rods and not "N-cad" rods.  Ni stands for "nickle", which is the predominant arc rod for cast iron. Ni-cad stands for "Nickle Cadmium" which is not a welding rod (and cadmium fumes are not the best thing to breath in when welding...).

You lost me... I can see my (i) can't you ?
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

Qweaver


It is not a ni-cad rod but just a nickel rod---no CAD.  Super Missile Weld is also a good choice for cold welding cast.  I've welded several cast heads...not always successfully...but always costly.  Also welded several Aluminum heads, always successfully.  I'd try very hard to find a good used head!!
So Many Toys...So Little Time  WM LT28 , 15 trailers, Case 450 Dozer, John Deere 110 TLB, Peterson WPF 10",  AIM Grapple, Kubota 2501 :D

Reddog sawmill

ok guys lots of good answers here yet none that really satisfy my budget, next question would be what about repowering it with a similar hp and size gas engine? Should be as easy as coupeling the engine shaft to the hydro pump shouldnt it? Or am i overlooking somthing important?

Kbeitz

Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

scsmith42

Quote from: Kbeitz on February 06, 2017, 07:43:25 PM
Ni-Cad rods...

http://www.practicalmachinist.com/vb/fabrication-cnc-laser-waterjet-plasma-welding-and-fab/nicad-welding-rod-131605/

It's what I use... On the box Ni-Cad.
It's what I just used to weld this cast iron part.



 

Could you please post a photo of the box label?  I would like to research this further.  Thanks much.
Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

Thank You Sponsors!