Use these images to identify the location of your Serial Number and Model Identification Letters.
The outside diameter is the same, but the pitch is steeper going from 7 3/8 to 7 3/8 D to 7 3/8 V6 to handle higher HP.
On jet drives in which the cooling pump is attached to the top of the bearing housing, it is not possible to provide a flushing inlet. Immersing the jet drive in a barrel of water doesn’t work either, because the water is thrown out. Backing the boat into some fresh water is the only solution. Present production provides a flushing inlet where it is possible to do so, depending on the model. If the parts book shows a flushing bolt and sealing washer, and your early jet drive does not have this, it can be added. Where to locate this threaded hole is called out on our engineering drawings.
Gouging from gravel is normal. There is considerable surface on the liner to provide pressure sealing. If it is worn such that all the shim washers are on top of the impeller, and blade clearance is still more that 1/32 inch, the liner and/or impeller need to be replaced. If you do replace the liner because of gouging, check performance before and after replacement to see how much, if any, loss the gouging caused.
We have an instruction sheet entitled “Impeller Sharpening” which can be faxed to the customer, or open the Impeller Sharpening pdf.
Grease coming out the lube hose is usually light gray. A few droplets of water coming out of the hose is to be expected but any more than that usually means, that the seals are leaking and should be replaced. If you grease after the days use, so that the bearing is not stored with moisture in it, you can delay replacement until it is convenient.
Impeller pitch and diameter is based on sea level operation. At higher elevation, you will lose RPM and may have to drop down one impeller size. Long use in corrosive conditions may create pin holes in the exhaust tube which builds up back pressure and reduces RPM. Excessive RPM is usually caused by air entering the pump. It can be caused also, during start up, if the leading edges of the blades are blunted from gravel. A rough boat bottom, keels or damage ahead of the intake can introduce air, as well as setting the motor too high.
With lots of luck, Liquid Wrench, Kroll, WD-40, heat, chisels and drills. Salt water is murder. We use all stainless steel hardware and aluminum, but the best way is to remove the jet drive once a year, wire brush the hardware, lubricate with grease or “Never Seize,” and reassemble. You won’t have difficulty after that
Stainless steel impellers work well on motors above 100 HP. They give less slippage on start up and therefore can pickup a heavier load. Top speed of, maybe, one to two mph or better. Below 100 HP, the main advantage is longer wear life.
No. There are too many differences in motor mounting bolt patterns, water pumps, driveshaft diameters, length, spline and shifting mechanisms. The model letter designation will fit only those motors listed in our jet drive kit list