Watch a Seized Impeller Come Out of a Scania 6SY (Full Service Walkthrough)
- Mar 9
- 6 min read
Updated: Jun 16
How Eddie Removed the Seized Impeller on This Scania 6SY
On this Scania 6SY, Eddie closed the seawater intake valve and drained the sea strainer, then removed the pump cover and gasket to reach the impeller. He set the ImpelPro puller's arms across the impeller vanes and tightened until the teeth bit into the rubber. Because this impeller was badly seized, the rubber tore on the first attempts, so he reset the puller one vane over for a fresh bite and wound it straight off the shaft with a 9/16-inch wrench, with no prying against the housing. Then he lubed and installed a new impeller and tightened the cover evenly.
Intro
A marine impeller can seize inside the seawater pump after years of service, and when it does, getting it out turns into a fight that can wreck the pump housing if you go at it wrong. In this video, Eddie from ImpelPro walks the whole job on a Scania 6SY: isolating and draining the cooling system, extracting a genuinely stubborn impeller, and installing a new one the right way.
"A few years ago, I spent two or three hours trying to get these impellers out with a store-bought puller. I ended up throwing it in the ocean and cutting the vanes off by hand. That's the day I decided to build something better." — Eddie Protzeller
What You’ll Learn
How to safely isolate the seawater cooling system before opening the pump
The right way to drain a sea strainer so you don't dump water into the bilge
How to remove a stubborn impeller without damaging the pump housing
Why resetting the puller helps free a stuck impeller
How to lubricate and install a new impeller
How to Remove a Marine Impeller Step-by-Step
Close the seawater intake valve to isolate the cooling system.
Drain the sea strainer by removing the bottom plug and letting air into the system.
Remove the seawater pump cover and gasket.
Position the impeller puller arms across the impeller vanes.
Apply steady pressure to extract the impeller.
Reset the puller if needed for a better grip on stubborn rubber.
Lubricate the new impeller thoroughly before installation.
Install the new impeller and gasket, tightening the cover evenly in a star pattern.
Restore the system: reinstall the drain plug and reopen the seawater valve.
Mechanic Insight
A stuck impeller usually isn't the rubber's fault alone. Over time, heat cycles, salt buildup, and shaft corrosion bond the impeller hub tightly to the pump shaft. Once that happens, trying to pry the impeller out is how housings get damaged. Controlled pulling force, applied straight along the shaft, is the safe way out.
Why This Job Goes the Way It Does
Why marine impellers get stuck. Impellers seize to the shaft after long service intervals, or when a pump sits unused for a long stretch. Salt deposits and corrosion build friction between the hub and the shaft.
Why resetting the puller helps. Rubber is flexible. When the puller grips the vanes, the rubber can compress or tear before the impeller lets go. Moving the tool one vane over gives the teeth a fresh bite, and that fresh bite is often what finally breaks it free.
Signs of a failing impeller. Overheating, a weak water stream from the exhaust, or missing vanes you find during inspection.
Why lubrication matters on the new one. A new impeller should always be lubed before it goes in. That prevents dry friction at the first startup, before seawater starts circulating.
Why even bolt tightening prevents leaks. The cover compresses a thin gasket. Tighten the bolts unevenly and you can distort the cover, which causes small leaks that are a pain to trace later.
Full Transcript
Hey everyone, it's Eddie from ImpelPro. We just finished the port side, and now we're moving to the starboard side of this Scania engine.
The first step is closing the seawater intake valve. Make sure it's fully closed. After that, we'll unscrew the drain on the bottom of the sea strainer.
The strainer won't drain very well until we introduce air into the system, which happens when we remove the impeller cover. For now, we'll let it start draining slowly.
This particular boat is actually the reason the large ImpelPro tool exists. A few years ago, I spent two or three hours trying to remove these impellers using a standard puller from a marine supply store. Eventually I had to cut all the vanes off just to get it out. That kind of frustration is what led to designing a better tool for stubborn impellers.
As the system drains, we'll wait a moment for air to enter the top so the water level drops. The goal is to avoid a big rush of water when we remove the pump cover.
Now that the level has dropped enough, we can remove the cover. A little water comes out, but nothing excessive, because we let the system drain first.
Next we remove the gasket and grab the puller tool along with a 9/16-inch wrench. Open the arms of the puller and position them across from each other on the impeller. Tighten the thumb screw firmly so the teeth bite into the rubber.
As we start applying pressure, the bearing system inside the tool lets the force transfer smoothly into the arms without excessive drag. You'll notice the rubber starting to deform slightly as the teeth grip the impeller. If the tool slips, loosen it and reposition for another bite.
In this case, the rubber is soft and the impeller is very stubborn, so we reset the tool one vane over and try again. You can hear the creaking as the impeller begins to move. The teeth have taken a strong set in the rubber, but with a little patience and another reset, the impeller finally breaks free.
Looking at the impeller now, you can see how the teeth dug into the rubber. On some attempts the rubber may tear slightly before the impeller releases, which is why repositioning the tool can help.
Now that the impeller is out, we'll prepare the new one. We apply marine lubricant evenly across every vane and along the entire length of the impeller. This ensures smooth installation and keeps the impeller from running dry during initial startup. You can also apply a little lubricant inside the pump housing.
Next, we insert the new impeller and make sure it sits flush. It's important not to force it into place using the pump cover, because that can push on the shaft and damage the pump bearings.
Install the gasket and begin tightening the cover bolts evenly. Work around the cover gradually so the gasket compresses uniformly. Using a small ratchet helps prevent over-tightening these smaller bolts.
Once everything is snug, reinstall the sea strainer drain plug, reopen the seawater valve, and run the system to confirm proper operation.
Common Questions
Why does resetting the puller help remove a stuck impeller?
Rubber impellers are flexible, so the puller teeth can compress or tear the rubber before the impeller releases. Moving the tool one vane over gives the teeth a fresh, solid bite, which is often what finally frees a stubborn impeller.
How do you drain a sea strainer before opening the pump?
Close the seawater intake valve, then remove the drain plug at the bottom of the strainer. It drains slowly until air enters the system, which happens when you pull the pump cover, so let the level drop first to avoid a rush of water into the bilge.
Should you use the pump cover to push a new impeller into place?
No. Forcing the impeller in with the cover pushes on the shaft and can damage the pump bearings. Seat the impeller by hand so it sits flush, then install the cover.
Why should you tighten the pump cover bolts evenly?
The cover compresses a thin gasket. Tightening evenly, in a star pattern, compresses the gasket uniformly. Uneven tightening can distort the cover and cause small leaks that are hard to trace later.
Related Marine Maintenance Videos
• How to Remove an Impeller in a Tight Engine Room • How to Reinstall a Large Marine Impeller (Lube-and-Twist Method) • Why Impeller Maintenance Is Critical for Your Boat's Performance • When to Replace Your Impeller: The Complete Maintenance Guide
What is ImpelPro Impeller Puller?
The ImpelPro impeller puller is a marine tool that removes flexible rubber impellers from seawater pumps without prying or damaging the pump housing. See what makes it different: What Makes ImpelPro Different from Other Impeller Removal Tools.
Topics Covered
• impeller removal
• marine cooling system maintenance
• seawater pump service
• stuck impeller troubleshooting
• generator and engine cooling systems
• marine impeller replacement
About the Author
Eddie Protzeller is a Seattle tugboat and yacht mechanic, and the inventor of the ImpelPro® Impeller Puller. With 15 years of hands-on experience servicing inboard engines and generators, he designed ImpelPro after struggling to remove a severely stuck impeller in a tight engine compartment. He specializes in boat cooling systems and impeller maintenance. For more about Eddie, visit About Us.