Caterpillar D8 Blade repair question for Popeye an old miner

[scsmith42]

I'm selling my D8H bulldozer and am in the process of repairing any outstanding mechanical problems before it goes to the new owner.



Earlier today I noticed that the bottom center of the dozer blade had a bad spot.



The funny thing is that the steel appears to be solid above and below the void. You can't see it well in this photo, but the damage is right above the cutting edge in the center of the blade.



I'm wondering what the best way is to repair this damage? Should I just weld a plate of 3/8" or 1/2" steel across the bad spot? Maybe something 10" tall and 30" wide, or thereabouts? Or should I just V out the void and weld it closed?

I'm hoping that @popeye an old miner can chime in with some advice, as well as anybody else experienced in this area.

Thx.

Scott

[Welder Dave]

Grind or cut into the crack to get a better idea what's behind it and how thick the moldboard is. If you've got some good steel behind, grind it bigger and just fill it up with 7018. You should get on the Heavy Equipment Forum and/or Acmoc (antique Cat owners)) forum. Lots of experience and potential buyers there.

[OPUS FERRO]

scsmith42

My introduction to dozers - was maintaining a fleet of 18/D8H's
and 36/D6's in '74 [ordered two years earlier] D8K's production
began in '74 . . .

https://en.wikipedia.org/wiki/Caterpillar_D8

I have - exchanged/repaired - everything on this generation of
Cat . . . that can be done . . .

Your girl - has been ridden hard and put away wet . . .

It: has fallen arches, protruding armpits, and a carbuncle on its
blade belly . . .

Your posts have always emphasizing functional equipment - and a
weakness for appearance . . .

Unless you have fond memories - of pushing your piles of money -
I would sell 'as is' . . .

Present its mechanical integrity [records?] - and don't waste your
time - with a 'Welding & Spray' rebuild . . .

The mission - is to keep 'the new owner' liking you . . .

hth


Opus



.








D8H

[welding1]

Ive lined buckets and blades, its expensive and time consuming. Since your selling it it just cover I with a piece of 1/4" AR plate or mild steel.

[Popeye an old miner]

I'm selling my D8H bulldozer and am in the process of repairing any outstanding mechanical problems before it goes to the new owner.



Earlier today I noticed that the bottom center of the dozer blade had a bad spot.



The funny thing is that the steel appears to be solid above and below the void. You can't see it well in this photo, but the damage is right above the cutting edge in the center of the blade.



I'm wondering what the best way is to repair this damage? Should I just weld a plate of 3/8" or 1/2" steel across the bad spot? Maybe something 10" tall and 30" wide, or thereabouts? Or should I just V out the void and weld it closed?

I'm hoping that @popeye an old miner can chime in with some advice, as well as anybody else experienced in this area.

Thx.

Scott

Scott...

It looks like its wore pretty hard along the top edge of the moldboard, so you should be able to do what Dave said. Clean out the dirt good,you might have to run some 6010 or 6011 in there first to burn out any leftover dirt before you butter it up with 7018. After that you can put a blowout patch on it Like weldin1 said I would go about 4 inches to the left and right ends of it and about 4 inches or so above it. Use what youve got handy either AR plate or mild steel about 1/4 inch or so but no more than 3/8. You will probably have to do some redneck blacksmith work on the sides to close up any gaps or use dogs and wedges on the sides for it. Bring the patch down to just above the weld at the moldboard, it looks pretty thick there so that will probly be your easiest weld. If you find yourself blowing through the skin anywhere and you might do that on the sides or the top use some 3/32 6010 or 6011 as a base so you get some steel on it to weld it with 7018, it looks like a pretty easy fix though I see no big problems doin it

If the buyer isnt gonna use it real hard that should last quite a while. Put up a few pictures of it when you do it, I woukd like to see it then if possible.

You have a great day be safe and Happy Easter

Popeye

[scsmith42]

Many thanks all for the great advice, that sounds like a workable plan.

Popeye, I have a large oxy-propane set so I should be able to shape the repair plate for a good fit. Thanks for the tip re the repair thickness too. I do have some AR500 in stock (recall that it’s 3/8” thick) but may just go with 1/4” or 5/16” A36 so that I can save the AR for making targets.

Opus, this is a late H model, made in ‘73. I’m actually the second owner. The first owner was a highway building company in West Virginia. They used it pretty hard and it shows. Lots of weld repairs on it when I purchased 21 years ago. I think that it spent a lot of time working in rock.

But it’s been a solid machine; despite the appearance. I’ve probably put close to 1000 hours on it since I bought it.

It’s already sold to someone that will use it to clear some new pasture land in Va. as part of the deal they asked me to repair any outstanding problems on their nickel. We are repairing a problematic steering clutch and replacing the seals into the final drives. Also replacing any questionable hydraulic hoses.

In addition to the blade, there are a couple of short welds that need grinding out and rewelding. Only a couple though.

[Popeye an old miner]

Many thanks all for the great advice, that sounds like a workable plan.

Popeye, I have a large oxy-propane set so I should be able to shape the repair plate for a good fit. Thanks for the tip re the repair thickness too. I do have some AR500 in stock (recall that it’s 3/8” thick) but may just go with 1/4” or 5/16” A36 so that I can save the AR for making targets.

Opus, this is a late H model, made in ‘73. I’m actually the second owner. The first owner was a highway building company in West Virginia. They used it pretty hard and it shows. Lots of weld repairs on it when I purchased 21 years ago. I think that it spent a lot of time working in rock.

But it’s been a solid machine; despite the appearance. I’ve probably put close to 1000 hours on it since I bought it.

It’s already sold to someone that will use it to clear some new pasture land in Va. as part of the deal they asked me to repair any outstanding problems on their nickel. We are repairing a problematic steering clutch and replacing the seals into the final drives. Also replacing any questionable hydraulic hoses.

In addition to the blade, there are a couple of short welds that need grinding out and rewelding. Only a couple though.

TYHe 5/16 A36 would be best I think, a 1/16 dont seem like much but it will give you more wear than 1/4, and will make it easier to weld. Thats me though, anything under 3/8 is like sheet metal to me after welding 3/4 inch to 2 1/2 inch stuff my whole life

Have fun with it

Popeye