Komat'su PC60-7 --Just Purchased Used--Some Questions

[John C.]

Those bolts are a pain no matter how you go at them. I usually center punch them as best as i can and then drill them. I start small and work up. Try an easy out each time you get through with the next bigger drill but don't break the easy out. Many times they have to be drilled till really thin and then removed with a small half round chisel. I think they are 12 mm bolts so aren't too big. Don't try any heat as there are lots of things that can catch fire. Also try to find a young fella that you can watch and school them on how you want it done.
Good job and good luck!

 

[Mark A Weiss]

Thanks for mentioning the easy out tool. I knew there had to be something to take out stuck bolts but could not remember the name. The heads are 17mm (like most everything else on this machine) and the threaded part looks to be about 1/2" diameter, so it's not a trivial matter to take out.
I bought a set of drills at Harbor Freight, but I know those won't last through one bolt. Any recommendations for a ultra hard steel drill bit that can go the distance? I have to drill out four bolts.

 

[Welder Dave]

They might not be high strength bolts for holding a cover plate on. Probably don't need a cobalt drill but go to an industrial supplier or machine shop supply and buy some name brand drill bits like Cleveland, Chicago Letrobe, Walter or similar. Be careful not break the small ones and some cutting wax or cutting fluid to keep the drill bit cool would help. I mention wax because it may stay on better working overhead. The best ez-outs are the square shaped ones and again a name brand like Proto, etc. are better than HF or the big box store brands.

 

[John Canfield]

I consider anything at Harbor Fright (intentional misspelling) that rotates/spins to remove metal or whatever to be a one time use and a throw away. Buy quality bits, my preference is USA as country of origin.

 

[John C.]

I was thinking back on this a bit and remembered that Komatsu usually just tack welds a nut to the frame and threads a bolt into that instead of threading the frame hole. You might be able to use a die grinder and cut the tacks loose. The bolts are all alloy and very hard.

 

[Welder Dave]

That would make it easier if you could get in there. Some pics. might help so we can see what you're dealing with.

 

[Mark A Weiss]

That would make it easier if you could get in there. Some pics. might help so we can see what you're dealing with.

A bit to the left of center of this photo is the inside nut and the bolt threads protruding.

 

[heymccall]

17mm head bolt...M10x1.5
19mm head bolt...M12x1.75
On your Komatsu.

 

[Mark A Weiss]

I got the forward track line installed today. T and G Hydraulics made up the lines with the banjo fittings to match up to the track lever control fittings and I got the line in by running it in a new place (the bundle was too tight and the fitting would get stuck when I tried to pull it through). I filled the line with oil before connected the upper end at the control valve, as I did with the pilot line yesterday and tightened it down.

Note that I use an air compressor to blow all the lines out before installation, to avoid any metal filings getting into the system.

Unlike yesterday however, when I run the machine, the hydraulics are making a loud whirring noise. When I travel, the movement of the tracks is jerky, sort of a go-stop-go movement. I thought, despite adding ten gallons of fluid in the past week that maybe it's low on fluid, but there is still fluid in the tank when I look in there. No doubt SOME air got in the system, but when this happened after the first line change, it cleared up in 30 seconds and was running smoothly after that.

I need to flush the system and change filters real soon, but I've been neglecting my duties at the amp repair shop for the past three days due to dealing with the line replacements and I need to get back to paid work.

I'm going to try to get some more hydraulic fluid tomorrow, if Levine is open on Sat. or else will have to pay $11 more at AutoZone.

Is it likely air in the system that's making it noisy and jumpy? Recommended method to blead the air?

 

[Welder Dave]

Usually just extending or retracting cylinders a few times gets rid of air. If you pick up the side you replaced the hoses with the boom and slowly switch between forward a reverse should get rid of air too. The noise isn't good. You don't want guess on fluid level and try to do quick little jobs in the mean time. Pumps and motors run into the several thousand dollars range. Cavatation is not good. Fix all the leaks and fill to the proper level before doing any work.
If you have nuts tacked on the inside and can get to them is a good thing. You may be able to cut them off or attack them with a big chisel.

 

[Mark A Weiss]

Usually just extending or retracting cylinders a few times gets rid of air. If you pick up the side you replaced the hoses with the boom and slowly switch between forward a reverse should get rid of air too. The noise isn't good. You don't want guess on fluid level and try to do quick little jobs in the mean time. Pumps and motors run into the several thousand dollars range. Cavatation is not good. Fix all the leaks and fill to the proper level before doing any work.
If you have nuts tacked on the inside and can get to them is a good thing. You may be able to cut them off or attack them with a big chisel.

I thought it was necessary to open a valve somewhere to bleed the air. Just running the tracks should do it?
Maybe it lost more fluid than I thought. I will purchase 10 gallons tomorrow and try topping off the hydraulic tank.

I may be finding myself getting into welding (was pondering buying a welder last year but didn't get around to it) with this project. Though I'd much prefer if I could get those nuts out via drilling and retapping.

 

[Welder Dave]

Not something to weld on if you have no experience. Many bad things can happen, some of them very serious. Got a better look at the pic. on the computer. If you have access to the top, like it looks you do, could thread a nut on (or use a larger size that slips over) and weld it and pull the broken bolt right through. Would probably have to hire a portable welder to do it but would be an easy fix. In the mean time spray a bunch of penetrating oil on it from the top and let it soak in and repeat a few times. A little concentrated heat could be used if you clean all the crap from there. Maybe, maybe, maybe you could cut a slot in the bolt and use a big screwdriver or something to try and turn it? What ever you do don't cut the extended part off. It gives you something to work with. I think a nut welded on is your best bet. Don't put it all the way down. It would be good to be able to turn the broken bolt back and forth when trying to remove it.

 

[John C.]

Changing a pilot line will not add air into the hydraulic system and cause issues with the implements. Do you know that you need to extend the stick all the way out, open the bucket all the way and set is all down on the ground when checking hydraulic fluid in the tank? If you do that and the level is in the middle of the sight glass, you machine has enough oil. Here is a video showing the basic maintenance checks that goes for any Komatsu excavator.

 

[Mark A Weiss]

Agreed. Bad position to work in and no escape from the sparks.
Not sure if the stud stick through on all of them though.
Recall that I had to use a 25" breaker bar with the 17mm 6 point socket to loosen these bolts. Impossible for a screwdriver to have that kind of torque. Most likely, I'm going to have to get a bunch of cobalt drills and just work on each one, one a day.

 

[Mark A Weiss]

Changing a pilot line will not add air into the hydraulic system and cause issues with the implements. Do you know that you need to extend the stick all the way out, open the bucket all the way and set is all down on the ground when checking hydraulic fluid in the tank? If you do that and the level is in the middle of the sight glass, you machine has enough oil. Here is a video showing the basic maintenance checks that goes for any Komatsu excavator.

Mine has a rubber hose where the sight glass should be. So I open the tank filler and look down in there. Not sure what that level should be, but I guess it goes down when the boom is extended?

 

[John C.]

You can tap measure the middle of that hose and then stick the tape into the tank to the bottom. Look for the wet level when you pull the tape back out of the tank. If the level is below the rubber tube, I'd think about getting a new glass and installing it before filling the tank back up. The level in the tank goes up when all the cylinder rods are retracted.

 

[Mark A Weiss]

You can tap measure the middle of that hose and then stick the tape into the tank to the bottom. Look for the wet level when you pull the tape back out of the tank. If the level is below the rubber tube, I'd think about getting a new glass and installing it before filling the tank back up. The level in the tank goes up when all the cylinder rods are retracted.

Is there anything special about that glass tube? Or can it be replaced with a plexiglass tube of the correct diameter? What about seals and pressure withstanding?

So am I correct to assume that the position of the boom and stick are critical to measuring the fluid level if a sight glass is installed?

At any rate, I'll put in ten gallons more fluid tomorrow and hope for the best on that whirring noise. It was pretty nasty in the video my wife made when I first started up the machine this afternoon.

 

[John C.]

Watch the video link I posted before you do anything else.

 

[Tinkerer]

Clear vinyl hose is a good replacement for the sight glass. I have one on a hydraulic tank that is pressurized to 15 psi.
Another option for the broken bolts.↓
If you have the room, cut that nut off with an angle grinder or, drill a hole next to those broken off bolts and use a new nut and bolt.
An angle drill may be a good choice for a drill.

 

[Welder Dave]

I suggested maybe drilling new holes in an earlier post. Not sure if you have access to the nut with the plate in place. Would have to tack the nuts if you don't. If you have to get a welder in could try to remove the broken bolts.