F75 Impeller Kit | Johnson Pump 09-821BT-1

Johnson Pump F75 Impeller Kit | 09-821BT-1 | M97 | Hino MAN Volvo Penta Yanmar Diesel

The Johnson Pump #09-821BT-1 is the replacement impeller kit for Johnson Pump F75 model raw water pumps used on commercial and recreational marine diesel engines. The F75 is a heavy-duty raw water pump found on Hino, M.A.N., Volvo Penta, Yanmar, and other diesel engine platforms. The kit includes the impeller, impeller lubricant, and installation instructions. The impeller is manufactured from Johnson Pump's M97 elastomer compound, engineered for superior hub bonding, blade flexibility, and fatigue resistance compared to standard rubber impellers. Supersedes Johnson Pump 09-821B and 09-821BT.

Part Details:

• Part Number: 09-821BT-1 (Johnson Pump)
• SKU: JP-09-821BT-1
• Manufacturer: Johnson Pump
• Type: F75 Raw Water Pump Impeller Kit
• Material: M97 elastomer (Johnson Pump proprietary compound)
• Kit Includes: Impeller, impeller lubricant, installation instructions
• Supersedes: Johnson Pump 09-821B, 09-821BT
• Applications: Johnson Pump F75 raw water pumps on Hino, M.A.N., Volvo Penta, Yanmar, and other marine diesel engines
• Condition: New

Additional Information

About the Johnson Pump F75:

The Johnson Pump F75 is a flanged raw water pump used across a range of commercial and recreational marine diesel engine applications. It is a larger-displacement pump than the F35 and F4B series, designed for the higher raw water flow demands of larger diesel engines. The F75 is found on Hino marine diesels, M.A.N. marine engines, Volvo Penta diesel sterndrives and inboards, and Yanmar diesel inboards, among others. Because the F75 serves multiple engine brands under OEM supply agreements, the correct impeller kit (09-821BT-1) is the same part regardless of which engine manufacturer's name appears on the pump housing.

M97 Elastomer — Johnson Pump's Proprietary Impeller Compound:

The M97 compound used in the 09-821BT-1 is Johnson Pump's engineered elastomer formulated specifically for marine raw water impeller service:

• Superior hub bonding — M97 bonds more strongly to the impeller hub than standard rubber compounds, reducing the risk of vane separation from the hub during high-load or dry-run events
• Enhanced blade flexibility — M97 maintains flexibility across a wider temperature range, reducing vane cracking in cold-start conditions and thermal cycling
• Fatigue resistance — impeller vanes flex with every pump revolution; M97's fatigue resistance extends service life compared to standard neoprene impellers in equivalent applications

For other Johnson Pump impeller kits, also see the Johnson Pump JP-09-707B-1 (15000K) impeller kit — MC97 compound, fits Cummins 4B/6B/QSD and MerCruiser 7.3L/4.2L QSD diesel applications.

Frequently Asked Questions

1. How do I confirm this impeller fits my F75 pump?
The 09-821BT-1 fits Johnson Pump F75 model raw water pumps. Confirm your pump model designation on the pump body or nameplate before ordering. If your pump is a Johnson Pump F75 on a Hino, M.A.N., Volvo Penta, or Yanmar diesel engine, this is the correct impeller kit. Contact us at MacombMarineParts.com with your pump model and engine application if you need confirmation before ordering.

2. What is the difference between 09-821B, 09-821BT, and 09-821BT-1?
The 09-821BT-1 is the current production part number that supersedes both 09-821B and 09-821BT. These are successive revisions of the same F75 impeller kit. If your parts reference shows 09-821B or 09-821BT, order the 09-821BT-1 — it is the correct current replacement for both superseded numbers.

3. What is the service interval for the F75 impeller on a diesel engine?
Service intervals for raw water impellers on marine diesel engines vary by manufacturer and operating environment. Most diesel inboard manufacturers recommend annual or 200-250 hour inspection, with replacement at the first sign of vane wear, cracking, or hardening, or after any dry-run event. Refer to your specific engine's service manual for the OEM-recommended impeller replacement interval. Commercial marine diesel operators typically replace on a fixed annual schedule regardless of condition.

4. What should I do if impeller vanes are missing when I remove the old impeller?
If vanes are broken or missing, the fragments have traveled downstream through the raw water circuit. Inspect and flush the entire downstream cooling path — heat exchanger, thermostat housing, exhaust elbow water passage, and any other downstream components — before installing the new impeller. On a commercial diesel with a complex cooling circuit, this may require systematic inspection of each component. Installing a new impeller without recovering broken vane fragments risks the same overheating failure repeating within hours of restart.