Welder Dave
Senior Member
Dot 5 is synthetic I think and don't think it's compatible with Dot 3 or Dot 4 fluid or the seals in non synthetic systems.
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Caterpillar 12 grader engine is dead - please help?
- Thread starter Entropy1
- Start date
Simple enough system if you're changing all the rubber, go for it. NO WAY I'd add more brakes if you're not doing critical steep or mountainous work. If you do add more, but on the same circuit, you're just making the brakes less reliable, more places to leak fluid out. A single circuit brake system on one axle doesn't bother me at all, aren't the rear axles chained together anyway? There's always the big yellow brake.
Same with painting, no way I'd sandblast ANYTHING on that, if you're worried about lead, pressure wash only, in an out of the way designated spot, use ospho, prime with a rusty metal primer and paint over it, just like it's been painted over several times already.
Let us know what you find with the borescope, if that can be loosened up realistically, then the next step is getting the injector pump pumping. Then injectors are easy.
Same with painting, no way I'd sandblast ANYTHING on that, if you're worried about lead, pressure wash only, in an out of the way designated spot, use ospho, prime with a rusty metal primer and paint over it, just like it's been painted over several times already.
Let us know what you find with the borescope, if that can be loosened up realistically, then the next step is getting the injector pump pumping. Then injectors are easy.
Entropy1
Well-Known Member
I completely spaced that the wheels are chained together. No need for extra drums. I'd only be introducing extra points-of-failure.
If the paint is leaded, my plan is to simply avoid disturbing the paint. If I must remove paint (for whatever reason) I'll use chemical strippers to the maximum extent possible. Blasting is a non-starter with leaded paint.
The trick to converting to DOT-5 is to completely flush all DOT-3 from the system (otherwise the two fluids react to form a gel substance that plugs up the system). Once rubber parts are wetted with DOT-3 (rubber lines, o-rings, seals, etc) they cannot be cleaned enough - the DOT-3 fluid is imbedded in the surface of the rubber, and the fluids will react. Thus all rubber soft goods must be replaced when switching to DOT-5 (master cylinder, wheel cylinders, brake hoses). The steel lines can be flushed with solvent & blown dry with air - to remove all traces of DOT-3. Note that US Military vehicles have been using DOT-5 for decades. They will often park military vehicles for years at a time, and brake failures are rare - because DOT-5 is required under contract to manufacture military vehicles. The only problem with DOT-5 is that it's not compatible with virtually all modern ABS systems (plastics used within ABS micro spool valves will be attacked by DOT-5). Tip - if you ever want to retrofit a car or truck with DOT-5, make sure there's no ABS (or that you remove it).
If the paint is leaded, my plan is to simply avoid disturbing the paint. If I must remove paint (for whatever reason) I'll use chemical strippers to the maximum extent possible. Blasting is a non-starter with leaded paint.
The trick to converting to DOT-5 is to completely flush all DOT-3 from the system (otherwise the two fluids react to form a gel substance that plugs up the system). Once rubber parts are wetted with DOT-3 (rubber lines, o-rings, seals, etc) they cannot be cleaned enough - the DOT-3 fluid is imbedded in the surface of the rubber, and the fluids will react. Thus all rubber soft goods must be replaced when switching to DOT-5 (master cylinder, wheel cylinders, brake hoses). The steel lines can be flushed with solvent & blown dry with air - to remove all traces of DOT-3. Note that US Military vehicles have been using DOT-5 for decades. They will often park military vehicles for years at a time, and brake failures are rare - because DOT-5 is required under contract to manufacture military vehicles. The only problem with DOT-5 is that it's not compatible with virtually all modern ABS systems (plastics used within ABS micro spool valves will be attacked by DOT-5). Tip - if you ever want to retrofit a car or truck with DOT-5, make sure there's no ABS (or that you remove it).
Remove the oil fill/level plug on the injection pump and see if there is any oil in the injection pump. If it is silvery or very dry, you may have a problem. If it looks ok, top it up if its low. That is how the inj pump cam, lifters and bearings are lubed. Its quite often overlooked on those engines
OzDozer
Senior Member
The Cat graders all had only two-wheel brakes up until around the late 1950's, when they then started to be fitted with 4 wheel brakes. They are the biggest maintenance item on the grader, and just trying to keep them in working condition for an extended period is a black art.
I have used pure silicone brake fluid many years ago on a Cat 930 wheel loader, and it worked very well to prevent wheel cylinder rusting, the constant enemy of drum brakes.
Even though the 930 had disc brakes, the pistons in the calipers suffered from the same problems as the pistons in wheel cylinders in the Cat drum brakes - corrosion when operating in muddy conditions and enduring regular immersion in water.
I have always operated on the basis that engines are the relatively easy repair on all Cats. There are a lot more costly repair areas to become involved in, in old Cat 12's. Eliminating wear from linkages in the blade mechanism and steering linkages can become very costly to repair. The steering on the old Cats is like the steering on forklifts, it is being used constantly while the grader is in operation.
Tyres are the type of thing you can leave until they don't grip the ground any more. Yes, they are flat base, tube-type tyres with a locking ring. Either get a tyre shop to do them, or arrange to have friends help with a tyre change - they're hard, heavy work to repair.
To work on the wheel brake cylinders, you need to press off the wheel hubs and press them back on again. They're on a taper, and they're on TIGHT! Always ensure you position something to stop the hub from flying off when you pull on them.
They can travel a considerable distance unimpeded, once they come off the taper, and cause bodily injury.
Check all brake lines for corrosion which causes pinholes and leaks. The original lines were bad for corrosion, and many have been damaged by debris that was picked by the wheels (typically, stray fencing wire) which wraps around them, or which simply hits them and bends them.
I have used pure silicone brake fluid many years ago on a Cat 930 wheel loader, and it worked very well to prevent wheel cylinder rusting, the constant enemy of drum brakes.
Even though the 930 had disc brakes, the pistons in the calipers suffered from the same problems as the pistons in wheel cylinders in the Cat drum brakes - corrosion when operating in muddy conditions and enduring regular immersion in water.
I have always operated on the basis that engines are the relatively easy repair on all Cats. There are a lot more costly repair areas to become involved in, in old Cat 12's. Eliminating wear from linkages in the blade mechanism and steering linkages can become very costly to repair. The steering on the old Cats is like the steering on forklifts, it is being used constantly while the grader is in operation.
Tyres are the type of thing you can leave until they don't grip the ground any more. Yes, they are flat base, tube-type tyres with a locking ring. Either get a tyre shop to do them, or arrange to have friends help with a tyre change - they're hard, heavy work to repair.
To work on the wheel brake cylinders, you need to press off the wheel hubs and press them back on again. They're on a taper, and they're on TIGHT! Always ensure you position something to stop the hub from flying off when you pull on them.
They can travel a considerable distance unimpeded, once they come off the taper, and cause bodily injury.
Check all brake lines for corrosion which causes pinholes and leaks. The original lines were bad for corrosion, and many have been damaged by debris that was picked by the wheels (typically, stray fencing wire) which wraps around them, or which simply hits them and bends them.
Last edited:
Nige
Senior Member
The Big Yellow Brake trumps all others in efficiency. Controlability not so much...........
Entropy1
Well-Known Member
I'm curious about the oil for the injectors. Why wouldn't the injectors share crankcase oil? I'm also wondering about pressing of the hubs. I suppose lots of my questions will be answered when my manuals arrive.
My friend's borescope is lost, thus I just purchased one myself. It should get here in time for this weekend. The scope will take color digital pictures of what I'm looking at. It might also take video too, but I'm not sure. I should be able to post some nice color pictures from within the inside of the cylinders this weekend. If rainwater has in fact locked up the engine, it should be pretty obvious within the borescope pictures.
On a somewhat related note - a different friend of mine owns & operates a metal recycling yard. I told him that if an old CAT grader ever comes in, to please not cut it up (process it for recycling) - and to give me a call. Broken graders are typically scrapped in the springtime (which is right around the corner). He probably gets 5 graders per year - of various makes. I've found purchasing machine-parts at scrap-value is usually the best-value.
My friend's borescope is lost, thus I just purchased one myself. It should get here in time for this weekend. The scope will take color digital pictures of what I'm looking at. It might also take video too, but I'm not sure. I should be able to post some nice color pictures from within the inside of the cylinders this weekend. If rainwater has in fact locked up the engine, it should be pretty obvious within the borescope pictures.
On a somewhat related note - a different friend of mine owns & operates a metal recycling yard. I told him that if an old CAT grader ever comes in, to please not cut it up (process it for recycling) - and to give me a call. Broken graders are typically scrapped in the springtime (which is right around the corner). He probably gets 5 graders per year - of various makes. I've found purchasing machine-parts at scrap-value is usually the best-value.
OzDozer
Senior Member
The early fuel injection pumps on old Cats had a separate oil reservoir simply due to the engineering thinking of the era, that the pump was a separate device that needed its own oil reservoir.
I guess in that era the engineers considered it too dangerous to run a dedicated oil supply pipe to the injection pump, as the pipe could get damaged, and then the oil supply could be lost to both engine and injection pump.
The wheel hubs can be easily removed by fabricating a heavy "steering wheel puller" type of puller. Simply a heavy piece of plate or bar, with a big fine thread nut centrally welded to it, and two equidistant holes each side - to match the two threaded holes in the wheel hub. Attach the bar to the hub using two high tensile (grade 8) bolts of adequate length, and then screw a full-thread bolt into the nut to push against the end of the axle.
However, to replace the hub will require machining a threaded adaptor to fit the thread on the end of the axle, and to accommodate a hollow threaded porta-power press ram.
You also need to fabricate a press collar that goes over the axle, and which fits between the hub and the porta-power ram.
You then simply screw the adaptor to the end of the axle, slip the press collar over it, attach the porta-power ram, and press the hub back on. I STR that 25 tons of hydraulic pressure is needed.
The proper Cat hydraulic press rams have a shaft with a hole in the end of them, so the press ram can be simply pinned into position, using holes in the genuine threaded adaptor.
But if you fabricate your own press arrangement, using a standard porta-power ram, you will need to figure out how best to attach the press ram to your adaptor.
I guess in that era the engineers considered it too dangerous to run a dedicated oil supply pipe to the injection pump, as the pipe could get damaged, and then the oil supply could be lost to both engine and injection pump.
The wheel hubs can be easily removed by fabricating a heavy "steering wheel puller" type of puller. Simply a heavy piece of plate or bar, with a big fine thread nut centrally welded to it, and two equidistant holes each side - to match the two threaded holes in the wheel hub. Attach the bar to the hub using two high tensile (grade 8) bolts of adequate length, and then screw a full-thread bolt into the nut to push against the end of the axle.
However, to replace the hub will require machining a threaded adaptor to fit the thread on the end of the axle, and to accommodate a hollow threaded porta-power press ram.
You also need to fabricate a press collar that goes over the axle, and which fits between the hub and the porta-power ram.
You then simply screw the adaptor to the end of the axle, slip the press collar over it, attach the porta-power ram, and press the hub back on. I STR that 25 tons of hydraulic pressure is needed.
The proper Cat hydraulic press rams have a shaft with a hole in the end of them, so the press ram can be simply pinned into position, using holes in the genuine threaded adaptor.
But if you fabricate your own press arrangement, using a standard porta-power ram, you will need to figure out how best to attach the press ram to your adaptor.
Entropy1
Well-Known Member
Interesting. Do you have any pictures of these DIY parts?
This sounds almost as painful as pressing pins in excavator tracks. . . . .
This sounds almost as painful as pressing pins in excavator tracks. . . . .
Entropy1
Well-Known Member
I recently built a hydraulic power supply (pics below). I've got a tubing bender that I desire to convert from manual to hydraulic, and I needed a power unit - so I built one. It's got quick disconnects. Might also come in handy for pressing CAT 12 hubs back on. . .. 
Summit racing has a handy search function for rubber brake lines, they were relatively standard and you'll probably find ones close enough without much trouble.
What's the pressure on that hydraulic unit? most portable mechanic's type hydraulics is built off the porta power system of 10,000PSI. Cylinders on lower pressure would just be too big to handle. It's all about force, not power, so hand pumping isn't that big a deal. If you can rig it up, a 30 or 40 ton bottle jack will do the work. Way more work to set it up than to pump it for the pressing.
What's the pressure on that hydraulic unit? most portable mechanic's type hydraulics is built off the porta power system of 10,000PSI. Cylinders on lower pressure would just be too big to handle. It's all about force, not power, so hand pumping isn't that big a deal. If you can rig it up, a 30 or 40 ton bottle jack will do the work. Way more work to set it up than to pump it for the pressing.
Entropy1
Well-Known Member
I'll have to check out the Summit search engine for brake lines. They've got a pretty good radiator search function that I've used.
The other search engine I really like is WIX filter lookup https://www.wixfilters.com/Lookup/FilterBySize.aspx You can search filters by size (air, oil, hydraulic, fuel, coolant, etc). Excellent part-number cross-reference also. If you've got a mystery spin-on filter, you can find applicable filter part number through the WIX search engine.
My power unit pump is rated for 4000 psig, however the spool valve has a relief currently set for 2000 psig. I would need about a 6" diameter ram to hit 25 tons at 2000 psig, or about a 4" ram to hit 25 tons at 4000 psig. I have some surplus 6" cylinders on the shelf. They are about 30" stroke, and WAY too heavy to lift by hand. Depending on the stroke required to press the hubs, I could shorten a cylinder significantly.
The other search engine I really like is WIX filter lookup https://www.wixfilters.com/Lookup/FilterBySize.aspx You can search filters by size (air, oil, hydraulic, fuel, coolant, etc). Excellent part-number cross-reference also. If you've got a mystery spin-on filter, you can find applicable filter part number through the WIX search engine.
My power unit pump is rated for 4000 psig, however the spool valve has a relief currently set for 2000 psig. I would need about a 6" diameter ram to hit 25 tons at 2000 psig, or about a 4" ram to hit 25 tons at 4000 psig. I have some surplus 6" cylinders on the shelf. They are about 30" stroke, and WAY too heavy to lift by hand. Depending on the stroke required to press the hubs, I could shorten a cylinder significantly.
OzDozer
Senior Member
I have no pictures of hub pressing arrangements, everyone who has a lathe, has their own ideas on what to construct. There's nothing really painful or highly technical about it.
There are photos of removing the hubs with a standard OTC or Snap-on "H" bar puller in the Cat tool catalogs and in the manuals - but surprisingly, I can find no photos of the hubs being pressed back on - Cat obviously deemed it too simple a process to photograph. However, there is a list of the Cat adaptor and press components required for the Cat 12 wheel hub removal, in the Cat Tool Catalog.
Your hydraulic unit is a very well made unit, but most hydraulic pumps only work on around 2,500psi. You need a 10,000 psi pump to operate press rams.
Not surprisingly, the Chinese manufacture a small 10,000 psi air-and-foot-treadle operated portable pump, and it's cheap. I picked up one last year for AU$134 (around US$93) and it works very well.
https://www.vevor.com.au/air-hydrau...lift-foot-pump-1-2-gal-1m-hose-p_010886091301
There are photos of removing the hubs with a standard OTC or Snap-on "H" bar puller in the Cat tool catalogs and in the manuals - but surprisingly, I can find no photos of the hubs being pressed back on - Cat obviously deemed it too simple a process to photograph. However, there is a list of the Cat adaptor and press components required for the Cat 12 wheel hub removal, in the Cat Tool Catalog.
Your hydraulic unit is a very well made unit, but most hydraulic pumps only work on around 2,500psi. You need a 10,000 psi pump to operate press rams.
Not surprisingly, the Chinese manufacture a small 10,000 psi air-and-foot-treadle operated portable pump, and it's cheap. I picked up one last year for AU$134 (around US$93) and it works very well.
https://www.vevor.com.au/air-hydrau...lift-foot-pump-1-2-gal-1m-hose-p_010886091301
Entropy1
Well-Known Member
The 10,000 psi rams are convenient - in that they're lightweight & compact. The rams, valves, and hoses can also be quite expensive to procure.
I prefer to run larger cylinders at lower hydraulic pressures. The oil runs cooler, there's less stress on the pump, the cylinder-seals last longer, and I can run off-the-shelf standard hydraulic hose, valves, fittings, cushioning valves, flow-regulators, etc (in lieu of the specialized 10,000 psi components $$$). Again, just a personal preference.
Just for chit-chat - my little Takiuchi excavator runs at about 2800 psig hydraulic pressure and works great. My larger Komatsu however runs at 5100 psig system pressure. Komatsu could've easily designed slightly larger displacement cylinder/motors and utilized lower pump pressures. Why they designed for such high hydraulic system-pressure is beyond me. I blew a hose last summer and I thought someone fired a shotgun next to the machine.
I prefer to run larger cylinders at lower hydraulic pressures. The oil runs cooler, there's less stress on the pump, the cylinder-seals last longer, and I can run off-the-shelf standard hydraulic hose, valves, fittings, cushioning valves, flow-regulators, etc (in lieu of the specialized 10,000 psi components $$$). Again, just a personal preference.
Just for chit-chat - my little Takiuchi excavator runs at about 2800 psig hydraulic pressure and works great. My larger Komatsu however runs at 5100 psig system pressure. Komatsu could've easily designed slightly larger displacement cylinder/motors and utilized lower pump pressures. Why they designed for such high hydraulic system-pressure is beyond me. I blew a hose last summer and I thought someone fired a shotgun next to the machine.
Welder Dave
Senior Member
Higher pressure is much more efficient in addition to being able to use smaller cylinders.
For a pipe bender or log splitter, yes. Nobody could build a modern excavator competitively without higher pressures though. Something like this hub puller that will be used a few times, a bottle jack or $100 porta power pump and more expensive cylinder seems the easy way to me.
Ironic that we're having this discussion on a thread about a knuckle buster grader
Entropy1
Well-Known Member
Still waiting on the borescope to arrive.
To pass the time, here's some pictures of my gantry crane. I purchased a cool horizontal milling machine (old US Navy surplus) and it was beyond the capacity of my forklift, so I built a gantry crane to move it. This crane is how I intend to pull the CAT 12 grader engine for rebuild (if required). The crane is point-loaded with about 8000 pounds within the picture.
To pass the time, here's some pictures of my gantry crane. I purchased a cool horizontal milling machine (old US Navy surplus) and it was beyond the capacity of my forklift, so I built a gantry crane to move it. This crane is how I intend to pull the CAT 12 grader engine for rebuild (if required). The crane is point-loaded with about 8000 pounds within the picture.
Entropy1
Well-Known Member
More chit-chat - here's my 10 HP rotary phase converter - to power these old metal working machines. I took the electric motor from an old concrete cutting saw (purchased at auction). I put it on wheels so I could roll it around the garage. It turns out I never have to roll it around. . . . It works pretty good though. 
