Mini Excavator Cylinder Chrome Inspection Without a Dye Kit: A Field Method for Stick, Lift, and Blade Cylinders

If you’re looking for the answer of a cylinderate video you may never check anything for the cylinderate mistake nobody does.

If you’ve been following the path from the front (wiper) to the rear (bore), ROD, you are on your way to passing this next cylinder, which is the most critical cylinder on the machine. The blade rod is low (right behind the dozer frame) and on a Cat 305 excavator resides in a gravel plume every hour of operation. Nobody checks it. I have seen buyers walk around yards with their stick and lift rods, leaning against the blade to make notes six inches from their knee in the rod with the jacket of it full of dust, that’s an awful sight list of what was wrong with the machine.

The loading are unlike as well. Grading and back-dragging introduce shear forces in the rod to the gland bore and over hours, this bore gets oval. So instead seal land geometry fails mechanically, rather than by wear–the wiping lip will lift on one side and compress on the other and each stroke of the wiper will squeeze contamination through the gap. None of the seal kits include an oval gland.

One I found on Highway 58, while it was parked with silt blowing across the lens when it was drawn out, the gland was gone and I was able to move the blade rod by hand with the cylinder in place. Magnet test is positive, coming back as bronze dominant which means that the wiper itself was still feeding and there was no flaking of the chrome. That was inevitable with an intact screw pushing the grit past the damaged wiper, which has an oval gland. I walked.

I put my head under the center line of the rod prior to my hand contact with the rod. Chrome is a mirror. Light above, eye above, results in a reflection going right back into the pupil, and can lead to the surface being viewed as a flat grey band although it might be peppered with pits you could jam a fingernail into. Lunge with the torch low, laterally, so level with rod, chin down towards the metal. You will look like a monkey. Do it anyway.

When that geometry gets on point, that rod will look like a starfield (every pit mouth will cast a hairline shadow and 4 people walked that morning will become very apparent).

The skin on your fingertip is unable to sense the pits. Fingers Slide through Holes; holes are PITS. What your skin sees is the burr around the rim (just like chrome work is raised off the surface) and a particle (which is raised off the surface and abrasive). Hand is feeling for an upstanding object. So drag across the rod, rather than along the rod and drag slowly. Pitting which runs parallel to the stroke presents ridges along which your finger travels–like rails–with no notice given to what is in between. If you have some callus, use the sides as opposed to the top of your nail bed—clean chrome won’t have the same dry rasp or tick against your nail bed that chrome pitting initiation does.

There are 3 positions of stoke that are important. When the wiper is fully retracted, you’ll see the band that was hidden under the parked machine and breathes condensation every week the machine was parked! With the fins extended it can be seen that there is early pitting that is hidden within the gland. The one that reveals itself with a rainbow iridescent oil film is the mid-stroke one and the sheen of the’rainbow’ you see is not a leak, it’s rod seal extrusion in progress without a drip, and likely will have somewhere between 50 and 200 operating hours until it weeps the first time. It lives in the gap, the whole negotiation is iridescent oil film identification.

The one number, which does matter to me, is the Ra > 0.4µm on the working band, beyond this a fresh rod seal will not hold due to the inability of the surface to maintain a fluid film. Consider that to be a field line–not a specification. A rookie equals a wall with 0.4. A veteran uses it to calculate a slope!

There does not need to be any penetrant kit for pit mouths. Dry the rod and dust it with talcum powder and wipe one time with clean rag–powder remains packed in the low spots, and the rod is as if a map! Where only a small area is to be covered, a whiteboard marker is used in the same fashion.

Here’s one secret to the powder test: as long as there is any oil at all, the powder clumps, resulting in a hundred pits that aren’t, in fact, there. Wipe down, dry thoroughly and allow an additional minute in wet/moisture prone environments.

One more variable. A chrome-coated rod which is extended through a wet winter in high desert area can exhibit a similar corrosion under the chrome and will appear virtually identical to abrasive pitting on a rod, but it is a different issue altogether. Cracking under chrome is a slow process, and it develops from invisible to flaking rather rapidly. Ask someone the location of the machine’s bed for the night.

A 305 has an odd position, it’s too small to use the 8 ton machine’s habits and too large for the mini-excavator’s habits. The circumference of the stick rod is approximately 50-55mm in serial range and above that, and with such a small circumference absolute, the proportion of the pit, if the opening is the same as that of an 80mm rod, will be more noticeable with the stick rod. Your eye is misjudging size – its smaller than what it thinks it is.

Carry a caliper. Instead of the rod, for the circumference of the pit.

The nominal hard chrome on these rods is thin with most rods being in the range of 0.05mm to 0.15mm even if the information from the builder has a general figure, check with the OEM or range spec. This class suffers greatly from corrosion under chrome due to that thinness: there is not enough plate for a year of corrosion beneath the chrome plate to allow the surface to remain. Generally, cylinder re-chroming will rehabilitate a used cylinder at about 25%-33% the cost of a new one, and that sum is the only consideration. Re-chrome below about 40% of turned out. Clearly, list the price (new or good used) and cease the complaining. There’s definitely regional differences as mindstate shops have quoted me 30% below the coastal price, so make sure to find out just what the hard dollar price quote is before signing.

Another unique correlation with the 305s is that there is a particular pathology that’s developed from the many number of 305s that have been auctioned: cosmetic cleaning at the gland. There is no compromise with length of time since a pressure washed machine with a hand wiped rod is clean and dry for the amount of time that it takes the wiper to pass through the damaged area again. If the rod appears dull instead of shiny then inquire when was the last time that machine was put to use.

Ask it.

Hydraulic cylinder rod chrome plating isn’t a line element that’s allured with beauty. Chrome fines are used as lapping compound, and bore wear is usually a justification to re-chrome and complete the cylinder, with most buys not being able to budget for the expense of this.

Now the blue eyed tease from me: if you were buying a Cat 305 excavator you wouldn’t be looking to renegotiate with one of the cylinders, it would be off the blade. Everyone is focused on the stick as it is the largest rod of the frame and the blade rod is in the dirt and no one suspects much going on before you get there, taking side load into the bushing. The Cat 305 excavator guide goes into greater detail than is necessary here regarding the geometry and service access for the Cat 305.

The fall really begins sooner than anybody can say. The initial clue that the wiper composite’s consuming is that grit or bronze-colored dust has built up at the gland; that glitter you detect between your thumb and finger on the gland that’s not magnetic. Now particles which are supposed to be stationary are on the rod and each stroke works them deeper into the rod! Then follows the initiation of pitting of Chrome. On the retraction stroke, once the rod has shed fines then it is not lost in the system, it is merely on the inward stroke, it passes through the rod seal, and into the fluid. It is honed to mirror smoothness and chrome fines in suspension form it into a lapping fixture. Last year pulled one apart that had gone bad with the bore worn into an measurable hourglass with about 400 hours after wiper failure, with the rod seal starting to spread due to grinding away by the fluid which the seal was designed to contain. Failure comes first on the rod seal, this is not the case. It fails second.

Thus there are 3 ways the decision can be made. There can be a seal kit, only if the rod surface is not pitted or contains any embedded particles and if the bore has not had any circulating fines through it, and no scoring can be seen with the fingers. Not”clean”on door: Bronze only on the magnet, clean rod under the side light- Kit solves it. Door two is rod damage; a re-chrome is simply a new surface in the hole, but the bore must be in spec–check this with a bore gauge before spending money–a new rod in a worn hole causes another failure, within the same time frame of the failure that killed the first rod. The bore damage is on door 3. There is no longer a question of maintenance, the economics have changed to reconditioning or sleeving of the body. Cost is only bounded at door #1. Each segment (or step) beyond the first is multiplied.

I did it once in a Cat 305 excavator and found the rod appeared to be in good shape in the yard, talked myself out of that door to put it in door #1 and paid for it when it began to bypass under load three weeks later. The bore was gone. From there, the film had been. Looked for it in overhead light and I still didn’t see.

Seal kit or re-chrome—the actual line is where? Kit would have to surface condition intact bore and where no fines have been utilized before. As soon as the rod loses metal, re-chrome is inevitable as the geometry (not finish) of the seal lands holds the rubber lip off the pit and away from the rod.

What about iridescent film as opposed to a weep that is visible? Film; fluid without a drip and there are 50 to 200 hours still in the day. When the window is weep, it is closed, and you are going to pay for rod seal extrusion, rather than preventing it.

What about discussing a rate for the wiper that’s done on bronze dust? Usually the most hassle-free money in the deal as the indicator is clearly visible, can be photographed and cannot be disputed when you place a magnet in the hand of the seller. What’s a little more difficult is that the majority of sellers have not heard the term, and will consider you to be somebody who is attempting to squeeze some extra cash out of them. Show the glitter. Listen to the words of the magnet!

Micro-scoring versus macro-scoring? Micro is a frosted band which is hardly noticeable and the re-chrome can be deferred while you shop around for the rest of the machine. When you start concentrating on macro (grooves under the fingernail, you’ve then been feeding the rod for too long for fines and you are purchasing capital work, not maintenance, anyway.

What if a blade rod is of length 1, 1/2 buried behind its frame? Crouch, place the torch of your mobile phone level to frame and not down on the frame. That is a low raking angle which throws a shadow-off each pit mouth. At the time I was in possession of a cold coffee and I put it straight into the dirt.

when shooting a rod, make sure that the light source is included in the picture. A torch sold at noontide is not of any value; but a buyer, who can see where the torch was, believes the picture.

An excavator cylinder rod seal test is an impress and documents way to inspect a used piece rather than a stroke band measured against the gland in daylight—or under low light and related to a rainbow sheen—the magnet swab, the powder map and so on. With nothing the yard owner could argue about, I have discounted four hundred dollars for a machine having nothing to do with a seep, but a gland bushing, and I have walked away from a machine where the owner wanted to discuss a seep versus a sheen. This was two good outcomes. Take photos prior to negotiation. Even before starting the argument a picture of a light brown frosted band is a good half way toward proving the case, plus the amount of fluid the seal is wiped away with to obtain the picture proves the rest—if it comes away with a speckle of tiny bubbles, the seal has been breathing air and the machine was sitting longer than the hour meter showed.

Type of inspection: whole inspection (30 minutes and flashlight).