Indmar LTR/LT1 Bronze Raw Water Pump

Our goal is to educate you about the purpose and function of many of the marine parts required to keep your boat running smoothly. Whether you're a veteran seaman or a novice, one thing you all know is that a boat comes equipped with hundreds of moving parts.

No one person can know everything there is to know about the proper functioning of every boat part. That's why we've tapped the collective wisdom of our long-time technical experts to share their knowledge and expertise.

What You Need to Know About the Indmar LTR/LT1 Bronze Raw Water Pump

This Indmar raw water pump is crankshaft driven and mounted directly to the crankshaft harmonic balancer rather than accessory mounted and pulley driven by a belt. It is a priority part made specifically for Indmar by Johnson Pump to fit specific engines which makes it's available only through Indmar. Being OEM specific means you have to go directly to an Indmar authorized reseller to obtain a replacement pump.

This raw water pump fits only the LT1 and LTR Indmar marine engines and provided them with a captive market. The way the water pump hub mounts on these two engine models are what makes it unique, and there is no aftermarket substitute for this pump. It is similar to another high flow raw water pump (Indmar 685001-3) which does have a substitute in the Johnson F6 Series raw water pump and looks almost identical but will not mount correctly.

The only difference between the Indmar LT1/LTR and the Johnson Pump is the mounting hub, which fits Indmar and Mastercraft LTR and LT1 engines with the crankshaft mounted raw water pumps. This engine was used primarily in Mastercraft ski boats in the 90s to early 2000s.

Servicing & Maintaining Your Indmar LT1/LTR Raw Water Pump

As far as servicing or maintaining the pump, the main wear item in the pump is the impeller. Just like other raw water pump designs, as the pump rotates the impeller will wear. Additionally, any debris or abrasive in the water drawn through the pump impeller will accelerate the wear. If you’re boating in silty or brackish water, it will tend to wear and need to be serviced more often.

The nice thing about this pump is that by simply removing four screws you can service the impeller and replace it while the pump is still on the engine. This makes it very accessible and convenient to service. A do-it-yourselfer could easily change out the impeller, which is a plus.

It’s a good idea to carry a spare impeller on board. It’s foolish to neglect this basic item when the cost of an impeller kit is negligible ($30-50) when compared to a lost weekend or vacation on the water. You can use a Johnson Pump impeller to service a worn or failed one. It’s the hub that makes this raw water pump exclusive to Indmar, not the replacement impeller.

Marine Parts Troubleshooters On Call

Once a boat part fails, it's obviously too late to repair it. When possible we've provided tips on simple ways to maintain a part to cut your cash outlay. We know you'd rather be on the water having fun than on the dock calling your marine mechanic.

That said, if you need help troubleshooting a system failure, give our technical experts a call at 866-388-0390. They'd be happy to steer you in the right direction.