I'm a project manager who's been handling equipment acquisition and parts orders for a mid-sized concrete supply company for about 8 years. I've personally made (and documented) 47 significant mistakes in that time, totaling roughly $38,000 in wasted budget and countless hours of downtime. I now maintain our team's pre-purchase checklist to prevent others from repeating my errors.
This checklist is for anyone about to buy a used Schwing concrete pump—whether it's a 36-meter boom, a line pump, or the iconic P88. It's also for the folks who need to keep that pump running with the right parts. If you're in a hurry, fine. But if you're on a budget and can't afford two weeks of downtime, read this first.
Here are the 12 steps (and a bonus pitfall) I wish someone had given me.
Step 1: Verify the Pump's Identity (Not Just the Nameplate)
From the outside, it looks like a Schwing P88 is a Schwing P88. The reality is that these machines have undergone several generations of updates. The nameplate might say 1998, but critical components could be from 1993 or 2005.
Ask for the serial number. Then call Schwing America (or a certified dealer) to get the original build sheet. This is the single most important step you can take. The build sheet will tell you the exact configuration, including the rock valve type, the main pump model, and the control system version. I skipped this once on a '92 P88. The build sheet revealed it had a legacy S-transfer tube that I thought was the newer design. That mistake cost me a $2,800 adapter kit and a week of fab work.
Most buyers focus on hours on the meter (which can be rolled back) and completely miss the parts compatibility trail. The question everyone asks is 'how many yards has it pumped?' The question they should ask is 'can I get a P88 rock valve kit for this specific serial number?'
Step 2: The P88 Rock Valve Inspection (Don't Get Fooled by Fresh Paint)
The rock valve is the heart of the P88. If it's worn, your pumping efficiency drops and your wear parts budget skyrockets. Check for excessive play in the wear plate and cutting ring. The tolerance should be tight. Look for fresh paint on the inside of the valve body. People assume that means it was 'rebuilt.' What they don't see is that fresh paint often hides pitting or thin spots in the cast iron.
I once inspected a P88 that looked pristine. The operator swore the rock valve was 'like new.' I brought a mechanic's mirror and looked behind the wear plate. We found a crack extending from the wear plate mounting surface. That crack would have failed within 50 hours. The seller dropped the price by $4,000 on the spot. A simple visual check from the outside wouldn't have caught it.
Step 3: The 'Popcorn Bucket' Check (Field-Applied Modifications)
Here's where my personal disaster started. I was looking at a line pump once—not a P88, but the same principle applies. The truck had what looked like a factory-installed clean-out system. The seller called it a 'popcorn bucket' setup. I was focused on the main pump and didn't think twice. After I bought it, I needed to order a replacement seal for that clean-out system. The part number on the bucket didn't match anything in the Schwing parts catalog. I called the dealer. It wasn't a Schwing part at all. It was a field-fabricated hopper extension made from a modified DeWalt drill stand and a steel bucket you could find in a hardware store.
Lesson: If it's not in the parts manual (available from Schwing), assume it's aftermarket or a hack job. The prep before the teardown you do not know. A simple 'popcorn bucket' misidentification cost me $450 in wasted parts orders and a 3-day production delay while I had to weld up a proper solution. Now, I take photos of every non-standard feature and send them to my parts contact for verification before I buy.
Step 4: The Water Pump Test (The 'How to Tell if The Water Pump is Bad' Check)
Concrete pumps use a water pump for the cooling system and often for the hydraulic oil cooler. If the water pump is bad, you're looking at an overheating engine and a potential $2,000+ repair.
- Look for weeps at the pump shaft. A small amount is normal on older units. A constant drip means the seal is the pump.
- Check the coolant for oil. An oily sheen indicates a bad head gasket or cracked block—run away.
- Feel the radiator hoses. They should be firm when the engine is warm (but not rock-hard, that's a different problem). Soft or collapsed hoses mean a stuck thermostat or a failing pump impeller.
- Listen for a whining noise that changes with RPM. That's usually a failing water pump bearing.
I skipped the water pump check on a 2005 42-meter boom truck. The pump failed six hours into its first job. $1,800 for the new pump, plus the tow bill, plus the customer downtime. The seller knew it was going. The small weep hole was perfectly positioned to drip onto the frame rail, making it hard to see. Don't be me. Look for the drip.
Step 5: The Hydraulic Oil Analysis (Spend the $150)
This is not optional. Take a sample of the hydraulic oil and send it to a testing lab. Standard print resolution requirements don't apply here, but the test is cheap compared to a $15,000 pump rebuild. The lab will tell you about silicon levels (dirt ingestion), water content, and particle count. A high particle count means a filter or pump is failing internally. A $150 test saved me from buying a P88 that had a $6,500 main pump rebuild waiting in its near future. The seller tried to tell me the high particle count was 'normal for its age.' Industry standard tolerance for a working system is ISO 18/15 or better. His sample was 24/21. That's a red flag, not a 'to be expected' number.
Most buyers focus on engine hours and cosmetic appearance. The hydraulic oil analysis tells you the truth about the pump's internal health. The question everyone asks is 'does it run?' The question they should ask is 'what's the ISO cleanliness code of the hydraulic fluid?'
Step 6: Parts Catalog Compatibility (The P88 Specifics)
If you're buying a used Schwing P88, you need to verify parts availability for its specific generation. The P88 has been around for decades, and some early models use parts that are now obsolete or extremely expensive.
- Rock valve wear parts: Are the wear plates and cutting rings still a standard stock item? A good number of Schwing dealers stock them, but confirm for your serial number range.
- Main pump: Is it a Rexroth or a Parker? That changes the seal kit cost and availability. A Rexroth pump on a 1990 P88 might be a discontinued model. Find out before you buy.
- S-Tube (transfer tube): The S-tube material changed over the years. Early P88s had a certain type of hardened steel. Later ones improved. If you need to replace it, know the cost upfront (it's not a $200 part).
- Electrical system: After 2000, the controls got more complex. A simple controller board failure on a 2005 P88 can be a $1,500 part and a two-week wait. Ask about the control system history.
Saved $80 by skipping the parts compatibility check on a used trailer pump. Ended up spending $400 on a rush reorder of a wear ring that turned out to be for the wrong generation of pump. The 'just look it up later' choice looked smart until we had the machine down for 10 days. Net loss: $400 + 10 days of rental fees for a replacement pump.
Step 7: The 'Is This a Small Client Machine?' Pitfall
Look, when I was starting out and buying my first used pump, the vendors who treated my $15,000 orders seriously are the ones I still use for $150,000 orders. Small doesn't mean unimportant—it means potential. I'm not saying you should buy a junk pump just because it's cheap. I'm saying this: don't let a fast-talking seller push you into a decision you're not comfortable with, just because you feel like a 'small' buyer.
To be fair, some dealers really don't want to deal with a $20,000 used pump sale. They'd rather flip a $200,000 P88. That's their choice. But if they're not giving you the time of day, or if they refuse to provide the build sheet or oil analysis, that's a red flag. A good seller treats a small order the same as a big one. A bad seller will cut corners for everyone eventually.
Step 8: The Frame and Axle Inspection (Don't Forget the Forgotten Parts)
Concrete pump trucks live hard lives. Mud sets, washout water, and constant vibration take a toll on the truck chassis. Look for cracks around the subframe mounting points, the outrigger pads, and the axle brackets. A cracked frame is not a weld-it-and-forget-it repair—especially not on a P88 boom pump, where the cantilevered load is enormous. I've seen a frame crack that was hidden under an inch of dried mud. A pressure wash before the inspection is a buyer's best friend. Insist on it.
Step 9: The Hopper and Mixing System
The hopper is where concrete enters the pump. Look for excessive wear on the hopper bottom, the washout door, and the agitator paddles. A worn hopper can be relined (cost: $500-$1,500), but if the steel is cracked or rotted through, you're looking at a major welding job or a $4,000 replacement. Stick your phone inside the hopper and take photos. Look for thin spots, especially where the concrete rubs against the sides. That's a high-wear area that a fresh coat of paint won't show.
Step 10: The Parts Bill of Health (The 'Schwing P88 Parts' Check)
Before you finalize the purchase, get a quote from a reputable source (like Schwing Stetter's parts network) for the common wear items:
- Wear plate
- Cutting ring
- Snap ring set
- Rock valve seal kit
- Seal kit for the main hydraulic pump
- Grease fittings (check they're all accessible and not blocked)
Add up the cost of these parts. If the total is more than 15-20% of the pump's asking price, you need to negotiate hard. A used pump with $8,000 in imminent parts costs is not a $40,000 pump—it's a $32,000 pump.
Step 11: The Paperwork Trail
Get the original purchase invoice (or a service history log), the owner's manual, and the parts and service manual. If the seller can't produce the service manual for a P88, that's a bad sign. The service manual is the bible for troubleshooting and ordering parts. You can often find one online (e.g., from Schwing America), but it's better to get the original one that came with the machine, as it might have machine-specific addendums.
Step 12: Trust Your Gut, but Verify Everything
Look, I'm not saying every used pump is a ticking time bomb. I'm saying that in my experience, the best deals come with a full paper trail, a seller who doesn't dodge questions, and a price that accounts for the known wear. The worst deals come with a story, a fresh coat of paint, and a seller who says 'she runs great.'
Bonus Pitfall: On a $3,200 parts order for a P88, I once ordered a complete rock valve service kit based on a serial number the seller gave me verbally. I checked the number myself, approved the order, processed it. We caught the error when the parts arrived and didn't fit. The serial number was off by one digit. $2,800 wasted in parts that were correct for a different generation, plus a 1-week wait for the correct ones. Lesson learned: Get the serial number and confirm it with the OEM.
I hope this checklist helps you avoid the $38,000 in mistakes I've made. It's not paranoia. It's experience.
